2

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CHAPTER -2 CONSTRUCTION MATERIALS

1.0 GENERAL

Flood management and river training works in the form of

embankment, bank revetment, spurs, porcupines, sluices, Gabions, Retaining walls, Diaphragm walls etc. are provided to manage/control the floods, to check the bank erosion and to improve drainage system. Construction of these works makes use of different kind of materials depending on the nature of problem and the structure provided.

2.0 TYPE OF CONSTRUCTION MATERIALS

Different construction materials have their own uniqueness and are used according to the site conditions, availability, transportability, cost effectiveness, low maintenance cost etc.

Materials like boulders, timber are in use since ages, but due to their

increased usage in other sectors leading towards reduced supply and their environment un-friendly nature, use of them now-a-days is decreasing. High wear and tear of timber structures in underwater and near water situation makes it less suitable for their use in anti- erosion measures.

Now–a-days, new innovative materials like Geo-textile in the form of Geo-textile bags, Geo-textile tubes, Sand filled Geo-mattress, Neo-web, submerged vanes and RCC porcupines, Gabions, Steel Sheet Piles ,Diaphragm walls are being increasingly used in construction of revetments, spurs, groynes, embankments etc. These materials are used due to their unique characteristics like durability, resistance to chemical waste, environment friendly nature, easiness in installation etc. Different construction materials being used for structural measures for flood management are described below in detail.

2.1.1 RIVER BED MATERIALS

Considering economy and ease in availability, river bed materials including sand and boulders are widely used in flood management and Flood Protection works. However, rounded river boulders are used in contained forms like gabions/crates but avoided in loose for pitching of the banks.

2.1.1.1 SOIL

The soil is used as a fill material for flood embankments and spurs. The soil is also used for filling Geo-textile bags, mattress and tubes. The soil shall preferably be coarse sand and free from organic material. Loamy and clayey type soil should be avoided

2

2.1.1.2

2.1.2

2.1.3

BOULDER

BouconembweibouthicTherela

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12

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2 | P a g e

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2.1.4

2.1.5

REINFOR

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14

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5 | P a g e

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16

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6 | P a g e

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17 | P a g e

accordance with EN 10223-3.

Elongation: Elongation shall not be less than 10%, in accordance with EN 10223-3.The length of the sample should be more than 25 cm for conducting this test

2.3.1.2.1 ZINC COATING

Minimum quantities of zinc should meet the requirements of EN 10244-2. The adhesion of the zinc coating to the wire shall be such that, when the wire is wrapped six turns around a mandrel having four times the diameter of the wire, it does not flake or crack when rubbing it with the bare fingers, in accordance with EN 10244. The mesh wire shall show no rusty spots on any part of the surface excluding the cut ends. Minimum quantity of zinc (gm/sqm) based on the internal diameters of 2.2 mm, 2.7 mm & 3.4 mm should be 230, 245 and 265 respectively

2.3.1.2.2 PVC COATING

The initial properties of PVC coating material shall have a demonstrated ability to conform to the following requirements. The Specific Gravity should be in the range from 1.30 kg/dm3 to 1.35 kg/dm3, when tested in accordance with Test method ISO 1183. Tensile Strength should not less than 20.6 Mpa, when tested in accordance with test method ISO 527. Elongation at break should not be less than 200% in accordance with ISO 527. The PVC coating shall not show cracks or breaks after the wires are twisted in the fabrication of the mesh.

Wherever, there is high changes of corrosion, alternate wetting and

drying, high salinity, presence of shingles in water etc a further refinement in coating shall be used like Galmac (where Zinc + 10% Aluminum) coating to the main steel wire mesh. Further, if there is more severe condition, an additional coating of PVC coating shall be applied

2.3.1.2.3 MESH CHARACTERISTICS

Mesh wire: Diameter – Inner diameter shall be 2.7 mm for the Zinc coated wire and when measured with PVC coating the outer diameter shall be 3.7 mm.

Selvedge wire: Diameter – Inner diameter shall be 3.4 mm for the Zinc coated wire and when measured with PVC coating the outer diameter shall be 4.4 mm.

Mesh opening: Nominal Dimension D =100 mm.

Lacing and stiffener wire: Diameter – Inner diameter shall be 2.2 mm for the Zinc coated wire and when measured with PVC coating the outer diameter shall be 3.2 mm

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2.3.1.2.4 BOULDERS

The boulders for gabions shall be hard, angular to round, durable and of such quality that they shall not disintegrate on exposure to water or weathering during the life of the structure. The size may be between 0.15 m and 0.25 m. The range in sizes shall allow for a variation of 5% oversize and/or 5% undersize rock, provided it is not placed on the gabion exposed surface. The size shall be such that a minimum of three layers of boulders must be achieved when filling the gabions of 1m thick

2.4 TOLERANCES

Wire: Wire tolerances based on the internal diameters of 2.2 mm, 2.7 mm & 3.4 mm should be ± 0.06 mm, ± 0.06 mm and ± 0.07 mm respectively in accordance with EN 10218-2.

Mesh opening: Tolerances on the hexagonal, double twisted wire mesh, opening shall not exceed -4% to 16% on the nominal dimension value.

Gabions: 5 % (±) on the length, width, and height

2.5 TESTS FOR THE GABIONS

Different tests to be carried on the gabion material are tabulated along with references and standards in Table 2-2.

Table 2-2: Tests for the gabions

Mesh Type 10' x 12' References of Specifications

Mesh Opening “D” mm 100 EN10223 Mesh Tolerance +16% to –4% EN10223 Unit Dimensions Tolerances in sizes of units ± 5% ASTM A975

Mesh Wire Diameter (mm) 2.7/3.7 (Inner Dia/Outer Dia) EN10223

Tolerance (±) mm 0.08 BS1052 Zn Coating Min (gsm) 240 ASTM A 641 Selvedge/Edge Wire Diameter (mm) 3.4/4.4 (Inner Dia/Outer Dia) EN10223

Tolerance (±) mm 0.10 BS1052 Zn Coating (Selvedge/Edge Wire) Min (gsm)

260

ASTM A 641

Lacing Wire Diameter (mm) 2.2/3.2 (Inner Dia/Outer Dia)

Tolerance (±) mm 0.06 BS1052 Zn Coating (Lacing Wire) Min (gsm) 220 ASTM A 641

Fasteners (mm) 3.0/4.0 (Inner Dia/Outer Dia)Stiffeners (mm) 2.2/3.2 (Inner Dia/Outer Dia)Zn coating on fastener/ stiffener (gsm) 240 ASTM A 641

PVC Coating Colour Grey-RAL 7037 ASTM D 1482Thickness Nominal (mm) 0.50 ASTM A 975

19 | P a g e

Thickness Minimum (mm) 0.38 ASTM A 975

Specific Gravity 1.30 – 1.35 ASTM D 792 Tensile strength Not less than 20.6 MPa ASTM D 412 Modulus of Elasticity Not less than 18.6 MPa ASTM D 412 Hardness Between 50 and 60 Shore D ASTM D 2240Brittleness temperature Not higher than –90C ASTM D 746

Weight loss Less than 5% after 24 hour at 1050 C

ASTM D 2287

Abrasion Resistance The percentage of weight loss shall be less than 12% ASTM D 1242

Salt spray Exposure and Ultraviolet Light exposure

a) The PVC shall show no effect after 3000 hours of salt spray exposure

b) The PVC shall show no effect of exposure to ultraviolet light with test exposure of 3000 hours using apparatus Type E at 630C c) After the salt spray test and exposure to ultraviolet light, the PVC coating shall not show cracks or noticeable change of colour, or blisters or splits. In addition, the specific gravity, tensile strength, hardness and resistance to abrasion shall not change more than 6%, 25%, 10% and 10% respectively from their initial values.

ASTM B 117 ASTM D 1499 and G 23

2.6 GEO-TEXTILE AS FILTER

The material should be woven with multifilament yarn in both warp and

weft direction or non-woven needle punched type with continuous filament. The geo-textile shall be preferably made of polypropylene. The material may have about 70% polypropylene and rest may be polyethylene or any other equivalent material. The standard roll length and width should be 100 m and 5 m.

Table 2-3: Properties of geo-textile as filter

Properties Marginal Value

Reference for Test Method

Mechanical Properties 1 Tensile strength (Warp/Weft)(=>) 28/26 KN/m IS 1969 2 Elongation at designated peak tensile load

(Warp/Weft)(<=) 25%/25% IS 1969

3 Trapezoid tear strength Warp/Weft) (=>) 300 N/300N ASTM D 4533 4 Puncture Strength(=>) 250 N ASTM D 4833

Hydraulic properties 1 Apparent opening size(<=) 75 microns ASTM D 4751 2 Permeability(=>) 10 l/m2/s ASTM D 4491

Physical Unit Weight(=>) 140g/sqm ASTM D 3776

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2.7 GEO-TEXTILE BAGS.

Geo-textile bags are made of woven/non-woven polypropylene/polyester geo-textile. Double layer geo-textile bags using woven and non-woven geo-textile are used for harsh conditions. Geo-textile used to manufacture geo-textile bags should have high mechanical properties for enhanced durability along with enhanced puncture, abrasion and U.V. resistance characteristics. Geo-textile should be inert to biological degradation and resistant to naturally encountered chemicals, alkalis, and acids.

Geo-textile used to manufacture geo-textile bags made of non-

woven material may conform to the properties listed in Table 2-4.

Table 2-4: Properties of non-woven geo-textile bag

Properties Reference for Test Method

Unit Values

Properties of Geo-textilePolymer Type Polyester/PP Nominal Mass ISO 9864 Gms/Sq.

m≥400

Tensile' Strength ASTM D4595 kN/m ≥20Tensile Elongation ASTM D4595 % ≥40% & ≤ 90% Puncture Resistance ASTM D4833 kN ≥' .40Opening Size ASTM D 4751 mm ≥0.07mm & ≤0.16mmUV ' resistance ASTM' D 435 %/Hr 70/50

Properties of Geo-textile BagSeam Type Double Seam Preferably flat dimensions

103 cm x 70 cm

Geo-textile used to manufacture geo-textile bags having double layers both for woven and non-woven material should conform to the properties listed in Table 2-5.

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Properties Reference for Unit Values

Woven

Properties of Geo-textile Polymer Type PP PP

Weight ISO 9864/ ASTM D5261 Gms/Sqm ≥300 ≥230

Tensile Strength ASTM D 4595 kN/m ≥12 ≥35

Tensile Elongation ASTM D 4595 % ≥30% & ≤90% ≥05% & ≤30%

Tensile Strength ASTM D4632 kN ≥0.80 ≥1.5

Grab Elongation ASTM D4632 % ≥30% & ≤90 ≥05% & ≤3' %

Puncture Resistance ASTM D4833 kN ≥' .40

Opening Size ASTM D4751 mm ≥0.06 & ≤0.17 ≥0.10 & ≤0.25

UV Resistance ASTM D4355 %/hrs 70/500 70/' 00 Properties of Geo-textile Bag

Seam Type Double Seam Preferably flat dimensions

2.00m x 1.50m

Table 2-5: Properties of double layer geo-textile bag

Test Method Non Woven

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2.8 GEO‐TEXTILETUBES

Geo-textile tubes should be made of high-tenacity polypropylene yarns which are woven into a stable network such that the yarns retain their relative position. These geo-textile tubes are often filled hydraulically with slurry of sand and water, although many other fill materials may also be used. Each fill port may consist of a Geotextile sleeve having a length of at least 1.5 m and a circumference slightly greater than that of the filling pipe. Sometimes double layer of sheets of woven textiles may also be required in consideration of added UV protection for a prolonged life and sufficient abrasion resistance. The geo-textile tubes should be constructed to meet the dimensions, type of materials and properties mentioned in Table 2-6, table 2-6 and table 2-7 respectively.

Table 2-6: Dimensions for Geotextile tube

Property/Parameter Units Values Geotextile tube length M 20Geotextile tube diameter M 3Filling port length M 2Filling port diameter M 0.5Filling port spacing M 5Seam strength efficiency(=>) % 40

Table 2-7 contains type and structure of material to be used for geo- textile tubes.

Table 2-7: Type of fabric for geo-textile tube

Property Reference for Test Method

Units Values

Polymer n/a n/a Poly propylene Roll dimensions (LxW) n/a n/a 100mx5mStructure

n/a n/a Woven with multifilament yarn in both warp and weft directions

Weight per unit area ASTM D 3776 Gm/m2 >=330Properties of geo-textile tubes are given in and

Table 2-8 contains properties of geo-textile tubes.

Table 2-8: Properties for geo-textile tube

N Properties Marginal Value Reference for Test Method

Mechanical Properties 1 Tensile strength (Warp/Weft)(=>) 80/78 KN/m IS 1969 2 Elongation at designated peak tensile

load (Warp/Weft)(<=) 25%/25% IS 1969

3 Trapezoid tear strength Warp/Weft) (=>) 1600 N/1600N ASTM D 4533 4 Puncture Strength(=>) 600 N ASTM D 4833

Hydraulic properties 1 Apparent opening size(<=) 250 microns ASTM D 4751 2 Permeability(=>) 18 l/m2/s ASTM D 4491

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2.9 VETIVER FOR BANK PROTECTION

The vetiver is a special type of grass having longer roots of length. This grass is infertile in nature. Due to their long roots and high tensile strength this grass is resistant to the high velocity streams and checks the erosion Desirable properties of the vetivers are given in Table 2-9.

Table 2-9: Properties of vetivers for bank protection

Sr Properties Mar Value 1 Average tensile strength 75 MPa 2 Root length Up to 3 m 3 Life under 14 m of water Up to 5 months 4 Air temperature range for sustainability -140C to 550C 5 Soil Ph 3.0 to 10

2.10 REFERENCES

Design practices and specifications adopted by the Maccafferi India Pvt Ltd.

Draft for 2nd revision of IS code 8408.

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24 | P a g e

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226 | P a g e

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27 | P a g e

28 | P a g e

1.1.1 REQUIREMENT OF DATA

BIS code 12094: 2000 stipulates that the following data is required for planning of an embankment

1.1.2 TOPOGRAPHICAL DATA

Index plan showing area to be protected, contour survey plan of the area, past river courses, plan and section of earlier executed works

1.1.2.1 HYDROLOGICAL DATA

Discharge, gauge, velocity, carrying capacity, extent of spill of river, cross sections and longitudinal section of river, Design data of Sant Sarovar ,Design Flood of Sant Sarovar, Water Surface Elevation at Design Flood and Check Flood and river behavior like aggrading or degrading etc.

1.1.2.2 DEGREE OF PROTECTION

BIS code 12094: 2000 stipulates that the height of embankment and the corresponding cost and Benefit Cost Ratio will be worked out for Design Flood and Check Flood of Sant Sarovar. The degree of protection which gives the optimum Benefit Cost Ratio should be adopted.

1.1.2.3 EMBANKMENT FOR PREDOMINANTLY AGRICULTURAL AREAS

The design flood for this type of embankment is kept 25 years for fixation of crest level

1.1.2.4 EMBANKMENTS FOR GIFT CITY AREA

The design flood for Protection of GIFT City embankment will be carried out for Flood discharge of 7.25 Lacks Cusecs and Check Flood of 8.38 Lacks Cusecs as GIFT City is located just D/S of Sant Sarovar and no other Intermediate catchment between them.

BIS code 12094: 2000 stipulates following guidelines related with

the alignment and spacing of the embankment. 1.1.2.5 ALIGNMENT

The embankments will be aligned on the natural bank of the river, land is high and soil available for the construction of embankments. The alignment is planned such that important township, vital installations, properties, cropped area is well protected by the embankment. The alignment is such that high velocity flow is quite distant from the toe of embankment to avoid scouring of the same also slope and toe protection in the form of pitching along with launching apron using the stones in wire crates, geo-mattress, Diaphragm wall is proposed. Alignment should also be planned so that land acquisition is feasible and not prolonged.

29 | P a g e

1.1.2.6 SPACING.

The spacing of the embankment and their alignment needs careful consideration with respect to their vulnerability to the river and the rise of high flood levels on account of reduction in flood plain storage by construction of the embankment.

The spacing of embankments along the jacketed reach of the river

should be aligned according to existing Toe of the River Bank and which is almost equal to Lacey wetted perimeter for the design flood discharge. Lacey wetted perimeter Lacey wetted perimeter (P) =4.75 (Qdesign)½] respectively.

Length of the embankment: The length of the embankment directly

depends upon the alignment and both ends of the embankment will be tied up to some high ground or existing highway or railway or any other embankment nearby conforming to the design height of the embankment.

2.0 DESIGN OF EMBANKMENT

BIS code 12094: 2000 is used for design of the embankment

2.2.1 TYPES.

Type of Embankment proposed is Homogeneous Type of Embankment.

1) Homogenousembankment.

This is the simplest type of earthen embankment and consists of a single material and is homogeneous throughout. A blanket of relatively impervious material (stone pitching) shall be provided at river side. A purely homogenous section is used, when only one type of material is economically or locally available.

A purely homogenous section, abutting with the existing Banks is

proposed, there is no need of stability of D/S Slope only U/S Slope stability for sudden Draw down condition and other conditions mentioned in BIS Code 12094 for U/S Slope will be adopted.

2.2.2 FREE BOARD

The top of the embankment should be so fixed that there is no danger of overtopping, even with the intense wave wash or any other unexpected rise in water level due to sudden change in river course or aggradations of river bed or settlement of embankment.

Free board will be taken as 1.8 m for Design discharge of 7.25 Lacks Cusecs and Adequacy of Free Board will also be checked for Check Flood of 8.38 Lacks Cusecs.

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2.2.3 TOP WIDTH

The top width of the embankment should be sufficiently enough to accommodate the vehicular traffic. The top width of the embankment is kept as 5.0 m. Turning platform of length 15 m to 30 m and 3 m width at C/S side slope at an interval of 1 km or more will be provided. An embankment should be provided with suitable soling over filter for proper drainage.. For embankments protecting towns, industrial and vital installations, necessity of providing all weather roads of 3 m to 3.5 m width will be provided.

2.2.4 SIDE SLOPE

The side slopes are dependent upon the material and height of the embankment. The side slope should be flatter than the angle of repose of the material of the embankment. For drainage purpose, longitudinal drains on the berm and cross drains at suitable places will be provided to drain out the water.

2.2.4.1 RIVER SIDE SLOPE

The river side (R/S) slope should be flatter than the under-water angle of repose of the material. The slope should not be steeper than 2H:1V and in case of high embankments, slope should not be steeper than 3H:1V, when the soil is good and to be used in the most favorable condition of saturation and drawdown.

In case of higher embankment protected by rip-rap/pitching, the slope

of embankment may be 2H:1V or 3H:1V depending upon the type of slope protection.

If the construction material is sandy, the slope should be protected with a cover of 0.6 m thick good soil; and It is usually preferable to have more or less free draining material on the river side to take care of sudden drawdown. In case of high and important embankment, slopes may be protected by the stone pitching, concrete blocks with open joints or sand filled geo-mattress to protected against sudden drawdown or erosive action of river flow.

Stability of Embankment will be carried by slip circle method for finalizing river side slope (IS 7894).

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31 | P a g e

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32 | P a g e

2.2.7 SLUICES

Sluices with regulating arrangements would be provided for country side drainage. The size of sluice will depend upon the intensity of rainfall and the catchment area to be drained. Sluices may be designed as per provision of BIS code IS 8835:1978.

2.2.8 CAUSES OF FAILURE OF EMBANKMENT

As stipulated by the CBIP publication - 1989 River Behavior Management and Training Volume-I, in the absence of proper maintenance and supervision, embankments are susceptible to breaches due to various causes given below.

(a) Improper compaction and settlement of embankment. (b) Transverse cracks due to unequal settlement. (c) Inadequate drainage and pore pressure development. (d) Erosion of riverside slope due to river current and wave wash. (e) Caving-in of the banks. (f) Increase in moisture content of the soil material.

2.2.9 PROPOSED PROTECTION WORK FOR EMBANKMENT

An embankment under direct attack of a river needs protection against failure. Different protective measures which are commonly employed to protect embankment are as under.

(a) Revetment/mattressing to protect against erosive action of river. (b) Spurs/groynes to deflect/dampen high velocity attacking the embankment (c) Improving shear strength of embankment soil by growing shallow rooted

vegetation.

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3.0 STABILITY ANALYSIS FOR HIGH EMBANKMENTS

The criterion for stability analysis for high embankment is based on the stability analysis of embankment dams.

The most important cause of failure of an embankment is sliding. A

portion of the earth may slide downwards and outwards with respect to remaining part, generally along a well defined slice surface. The failure is caused when the average shearing stress exceeds the average shearing resistance along the sliding surface due to various loading conditions.

Slope stability is generally analyzed by “Swedish Slip Circle‟ method,

the rupture surface is assumed cylindrical or in the cross- section by an arc of a circle. The sliding wedge method assumes that the failure surface is approximated by a series of planes.

High embankments the section proposed should be checked for stability

by Swedish Circle method. The minimum factor of safety aimed at should be 1.3.

3.1.1 SELECTION OF DESIGN PARAMETERS

The embankment material shear strength is obtained by performing tri- axial tests of borrow area materials compacted to densities aimed at during construction. The foundation material strength is obtained by tests with undisturbed samples from tri-axial shear testing. Testing in each case shall be from zero to maximum normal stress expected in the embankment.

The design shear parameters for fill material is fixed at 75% availability

from an adequate number of samples, and for foundation soils minimum shear strength values along foundation obtained are adopted after rejecting extreme or freak values.

3.1.2 ANALYSIS PROCEDURE

The procedure of arriving at driving and resisting forces involves assumption of a tentative cross-section of the embankment, a possible circular failure surface, division of the slip circle mass into a number of slices, calculation of forces on each slice and summation of the forces. The factor of safety against sliding for assumed failure surface is obtained by the equation:

34 | P a g e

FS = ∑S/∑V = C + (N-U) tan/W sin

Where: FS = Factor of safety S = Resisting or stabilizing Force T = Driving or actuating force C = C1x (b/ Cos ) N = Force normal to the arc or slice U = Pore water pressure. = Angle of shearing resistance W = Weight of the slice Α = Angle made by the radius of the failure surface with the vertical at the centre of slice. C1 = Unit cohesion, and b = Width of the slice

3.1.3 STABILITY COMPUTATION

The slope stability analysis is carried out to get the minimum factor of safety for a tested section under different loading conditions for upstream slopes. The computer programmes used for static analysis are used for the computations

3.1.4 FINAL SELECTION OF EMBANKMENT SECTION

Based on the results of studies for slope stability by static and pseudo static method, final section of the embankment may be selected. In this selection, great emphasis is put on the experience of the designer and the data of behavior of embankments constructed in almost identicalsituations.

35 | P a g e

3.2 MERITS AND DEMERITS OF EMBANKMENTS

Merits and demerits of flood embankments have been listed out below:

MERITS

Merits of embankment as method of river training works are as under:

Embankments are the main mean of preventing inundation during flood season.

The initial cost of construction of embankment is low, although when raised subsequently, they may become a bit expensive.

Construction is easy and presents no difficulty, as it can be done by utilizing local resources in unskilled labor and materials. Maintenance is equally simple and cheap.

They can be executed in parts, provided that’s ends are properly protected DEMERITS

Embankments cause rising of high flood levels. In the event of a breach, there is a sudden and considerable inflow

of water which may cause damage in the country side and deposition of sand making the area infertile.

Embankments are susceptible to direct attack of the river flow which can erode and undermine them.

In the case of river carrying considerable amount of silt, then deposition of silt on the river bed causes rise in the water level which may be lead subsequent overtopping of the crest level of embankment.

3.3 REFERENCES

1. BIS code 12094:2000 2. BIS code11532:1995 3. Preliminary draft Guidelines for planning and design of river

embankment (Levees) (Second revision of IS 12094) (Feb, 2011) 4. Embankment manual (1960) 5. Irrigation Engineering and Hydraulic structures-1995 - S. K. Garg 6. River Behavior Management and Training Volume-I (Central

Irrigation and Power (CBIP), 1989

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38 | P a g e

4.3.1.4 DEGREE OF PROTECTION

The design flood for pitching/revetment will be calculated for Design Flood.

4.4 DESIGN OF BANK REVETMENT

IS code 14262:1995 provides for following provisions regarding design of bank revetment.

4.4.1 WEIGHT OF STONES/ BOULDERS

Stones/boulders, used in revetment for bank protection, are subjected to hydrodynamic drag and lift forces. These destabilizing forces are expressed in terms of velocity, tractive forces etc. The stabilizing forces acting against these are component of submerged weight of the stones and downward component of force caused by contact of the stones.

The weight of stones on slopes (W in kg) may be worked using the formula given below

:W (in kg) = 0.02323*Ss*V6 /K* (Ss-1)3 -------------------------------- (1) Where K (correction factor for slope) =[1-Sin2θ/Sin2Φ ]1/2

Ss=specific gravity of boulders (may be adopted as 2.65) Φ = Angle of repose of material of protection works (adopted as 300 for boulders) θ= Angle of sloping bank2 (H) :1 (V) (26.560) V= Velocity in m/s K =[1-Sin226.560/ Sin2300]1/2 = =0.447 Hence weight of stones for 2H:1V slope W (in kg) = 0.02323*Ss*V6/0.447* (Ss-1)3

For river training works, sub-base is to be graded to a stable slope depending upon the angle of repose and cohesion of bank material under saturated condition and height of the bank. For a high bank, berm needs to be provided. For important works, stability of bank with designed slope and berm should be checked by slip circle method. For normal bank protection works, a slope of 2H:1V or flatter is recommended

4.4.2 SIZE OF STONE/ BOULDER

Size of stone (Ds in m) may be determined from the following relationship.

Ds (in m) = 0.124* (W/Ss) 1/3 ------------------------------------------- (2) Where W= Weight of stone in kg Ss= Specific gravity of stone (may be adopted as 2.65) Minimum dimension of stones > Ds

Generally, the size of stone should be such that its length, width and thickness are more or less same ie stones should be more or less cubical. Round stones or very flat stones having small thickness should be avoided.

39 | P a g e

4.4.3 THICKNESS OF PITCHING

Minimum thickness of pitching (t) or protection layer is required to withstand the negative head created by the velocity. This may be determined by the following equation.

Minimum thickness of pitching (t in m) = V2/2g (Ss-1) ------------ (3) V= Velocity in m/sec g= Gravitational acceleration in m/sec2 Ss= Specific gravity of stone (may be adopted as 2.65).

Two layers of stones of minimum size should be provided, when pitching

is being provided with boulders in loose

4.4.4 PITCHING IN CRATES

At high velocity, required weight of stones (to be found by equation No (1) comes out to be higher, which makes handling and placing of stones a bit difficult. In such cases or in case when requisite sized stones are not available, small size stones filled in GI (Galvanized Iron) wire crates may be used for pitching purpose. In this case single layer of GI wire crates filled with stones having thickness more than may be used as pitching. The specific gravity of the crate is different from the boulders

due to presence of voids. Porosity of the crates (e) may be worked out using the following formula.

E = 0.245+ 0.0864/ (D50)0.21 --------------------------------------------- (4) Where D50= mean diameter of stones used in mm. let us assume D50

as 250 mm e = 0.245 + 0.0864/ (250)0.21= 0.27

The opening in the wire net used for crates should not be larger than the smallest size of stone used. The mass specific gravity of protection (Sm) can be worked out using the following relationship.

Sm = (1-e) *Ss-------------------------------------------------------------- (5)

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40 | P a g e

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41 | P a g e

4.5 TOE PROTECTION

IS code 14262:1995 mentions following provisions regarding toe protection.

To prevent the sliding and failure of the revetment on slope, toe is

required to be protected. This may be in the form of simple toe-key, sheet pile/Diaphragm wall or launching apron.

4.5.1 TOE WALL

When hard strata is available below the river bed at a reasonable depth torecommended. The thickness of the toe wall depends upon height of wal anoverlaying pitching. The toe wall may be design as retaining wall and be comasonry along with provisions of weep holes etc

4.5.2 TOE KEY

Simple key may be provided at the toe (may be called as toe key) when rock or un-erodible strata is available just below the river bed and the overlaying banks are erodible. The key is in the form of stone/bricks or concrete blocks filled in the trench below the hard river bed for depth equal to the thickness of pitching “t” for proper anchorage. Sole purpose of this key is to provide lateral support to the pitching. The key may be of mortar or in geo-bags, if the pitching is provided in mortar or geo- bags.

4.5.3 SHEET PILES /DIAPHRAGM WALLS/CUT OFF WALLS OR LAUNCHING APRON

When firm strata is not available at reasonable depth below the river bed, toe protection in the form of sheet pile or launching apron may be provided. The sheet pile may be made of RCC, steel. The sheet piles/Diaphragm walls may be drilled below the river bed up to maximum scour depth.

Sheet piles/Diaphragm walls/Cut off walls are difficult to drive;

therefore Launching apron is preferred and provided with revetment. Launching apron should be laid at low water level (LWL). The launching apron may be laid using the stones or geo-bags. The stones/geo-bags in the apron should be designed to launch along the slope of scour and provide a protection layer so that scouring is checked. The size of launching apron should be such that it should form a protection layer up to level of maximum scour depth. Slope of launching apron may be taken as 2H:1V. Filter below the launching apron may also be provided so that river bed material is safe against suction.

42 | P a g e

4.5.4 SIZE OF LAUNCHING APRON

Width of the launching apron depends upon the scour depth below HFL. Depth of scour below HFL (D) may be worked out using the following formula:

D = 0.473 (Q/f)1/3 -------------------------------------------------------------- (6.1) and D= 1.33 (q2/f)1/3 ------------------------------------------------------------------ (6.2) Where Q = design discharge in cumecs and q = design discharge per unit width or design discharge intensity in cumecs/m f is silt factor. Silt factor (f) may be calculated using the following formula f= 1.76 (d) 1/2----------------------------------------------------------------------- (7) where d is mean particle diameter of river material in mm

Generally scour depth (D) below HFL should be calculated using the design discharge (equation no. 6.1). In some cases (for braided rivers) scour depth may be calculated using the design discharge intensity (equation no. 6.2).

Maximum scour depth (Dmax) below HFL= 1.5* Scour depth (D below HFL). Maximum Scour depth (Dmax) below LWL = (Dmax) below HFL – (HFL-LWL)

If the launching apron is being laid at LWL then width of the launching apron should be calculated using the following formula. Width of launching apron= 1.5 * (Dmax) below LWL

Thickness of launching apron (T) = 1.5* thickness of pitching (t). In some cases, thickness of the launching apron is kept different from “T” due to size of crates etc (if launching apron is being provided in crated stones), then width of the launching apron may be revised keeping the volume of stones/geo-bags same per unit length of the apron.

4.6 ANCHORING

IS code 14262:1995 mentions following provisions regarding anchoring. Proper anchor is required for keeping the revetment in place and serving the desired function. Upstream edge from where the revetment starts should be secured well to the adjoining bank. Similarly, downstream edge where the revetment ends also needs to be secured well .

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43 | P a g e

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FIGURE 11‐

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44 | P a g e

5.2.2

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45 | P a g e

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46 | P a g e

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47 | P a g e

Normally the effective length of spur shouldn’t exceed 1/5th of width of flow in case of single channel. In case of wide, shallow and braided rivers, the protrusion of spur in the deep channel should not exceed 1/5th of the width of channel on which the spur is proposed excluding the length over the bank. The spacing of spurs is normally 2 to 2.5 times its effective length.

5.3.2 TOP LEVEL/TOP WIDTH AND SIDE SLOPE

The top level of spur will be above design flood level with adequate free board. Free board may be adopted as 1m/1.5m. Non-submerged spur will be tied with the embankment, and top level of embankment and top level of spur may be kept same with similar free board and design HFL. The top width of spur should be 3 to 6 m as per requirement. Side slopes of the spur may be kept 2H:1V or 3H:1V depending upon the material being used for construction

5.3.3 WEIGHT OF STONES FOR PITCHING

Stones/boulders used in pitching are subjected to hydrodynamic drag and lift forces. These destabilizing forces are expressed in terms of velocity, tractive forces etc. the stabilizing forces acting against these are component of submerged weight of stones and downward component of force caused by contact of the stones.

The weight of stones on slopes (W in kg) may be worked using the formula given below.

W (in kg) = 0.02323*Ss*V6 /K* (Ss-1) 3 ---------------------------------------- (1) Where K (correction factor for slope) =[1-Sin2θ/Sin2Φ ]1/2

Ss = specific gravity of boulders (may be adopted as 2.65) Φ = Angle of repose of material of protection works (adopted as 300 for boulders) Θ = Angle of sloping bank 2 (H) :1 (V) (26.560) V = Velocity in m/s K = [1-Sin226.560/ Sin2300]1/2 = 0.447 Hence weight of stones for 2H:1V slope W (in kg) = 0.02323*Ss*V6/0.447* (Ss-1)3

48 | P a g e

5.3.3.1 SIZEOF STONE/BOULDER.

Size of stone (Ds in m) may be determined from the following relationship.

Ds (in m) = 0.124* (W/Ss) 1/3 --------------------------------------------------- (2) Where: W = Weight of stone in kg Ss = Specific gravity of stone (may be adopted as 2.65) Minimum diminution of stones > Ds

Generally, the size of stone should be such that its length, width and thickness are more or less same ie stones should be more or less cubical. Round stones or very flat stones having small thickness should be avoided.

5.3.4 THICKNESS OF PITCHING

Minimum thickness of pitching (t) or protection layer is required to withstand the negative head created by the velocity. This may be determined by the following equation.

Minimum thickness of pitching (t in m) = V2/2g (Ss-1) ------------------ (3) V= Velocity in m/sec g= Gravitational acceleration in m/sec2 Ss= Specific gravity of stone (Generally adopted as 2.65).

Therefore thickness of pitching should be higher than t (as obtained above). Two layers of stones of minimum size t should be provided when pitching is being provided with boulders in loose.

5.3.4.1 PITCHING IN CRATES

At high velocity, required weight of stones (to be found by equation no 1) comes out to be higher, which makes handling and placing of stones a bit difficult. In such cases or in case when requisite sized stones are not available, small size stones filled in GI (Galvanized Iron) wire crates may be used for pitching purpose. In this case single layer of GI wire crates

filled with stones having thickness more than „t‟ may be used as pitching. The specific gravity of the crate is different from the boulders due to presence of voids. Porosity of the crates (e) may be worked out using the following formula

e = 0.245+ 0.0864/ (D50) 0.21 ---------------------------------------------------(4) Where D50 = mean diameter of stones used in mm. let us assume D50 as 250 mm e = 0.245 + 0.0864/ (250)0.21

= 0.27

49 | P a g e

The opening in the wire net used for crates should not be larger

than the smallest size of stone used. The mass specific gravity of protection (Sm) can be worked out using the following relationship.

Sm= (1-e) *Ss------------------------------------------------------------------- (5)

This mass specific gravity may be used to work out the weight of

the crates and this weight should be more than weight of stone required, worked out by the equation no.1.

Crates should be laid with long dimension along the slope of the

bank. Crates must be tied to each other by 5 mm GI wire as additional protection. If crates are being provided in layers then each layers should be tied to each other at suitable interval using the 4 mm GI wire.

5.3.5 FILTER

A graded filter of size 150 mm to 300 mm thickness may be laid beneath the pitching to prevent failure by sucking action by high velocity. Geo- synthetic filter may also be used as that is easy to lay, durable, efficient and quality control is easy. A 150 mm thick sand layer over the Geo- synthetic filter may be laid to avoid rupture of fabric by the stones.

5.4 LAUNCHING APRON FOR SPUR

IS code 8408:1994 & 14262:1995 mentions following provisions regarding launching apron.

To prevent the sliding and failure of the spur due to scouring action by

the river current, provision of launching apron is kept to take care of the scouring at nose and at shank (portion in the river) of the spur.

Launching apron should be laid at low water level (LWL). The launching

apron may be laid using the stones or geo-bags. The stones/geo-bags in the apron should be designed to launch along the slope of scour and provide a protection layer so that scouring is checked. The size of launching apron should be such that it should form a protection layer up to level of maximum scour depth. Slope of launching apron may be taken as 2H:1V. Filter below the launching apron may also be provided so that river bed material is safe against suction

5.4.1 SIZEOFLAUNCHINGAPRON

Width of the launching apron depends upon the scour depth below HFL. Depth of scour below HFL (D) may be worked out suing the following formula.

D = 0.473 (Q/f) 1/3 -------------------------------------------------------------- (6.1) and D= 1.33 (q2/f) 1/3 ---------------------------------------------------------------- (6.2) Where Q= design discharge in cumecs and q= design discharge per unit width or design discharge intensity in cumecs/m. f is silt factor. Silt factor (f) may be calculated using the following formula f= 1.76 (d) 1/2---------------------------------------------------------------------- (7) where d is mean particle diameter of river material in mm

50 | P a g e

Generally scour depth (D) below HFL should be calculated using the design discharge (equation no.6.1). In some cases (for braided rivers) scour depth may be calculated using the design discharge intensity (equation no. 6.2).

Maximum scour depth (Dmax) below HFL= 1.5* Scour depth (Dbelow HFL). Maximum Scour depth (Dmax) below LWL = (Dmax)below HFL – (HFL-LWL)

If the launching apron is being laid at LWL then width of the launching apron should be calculated using the following formula at different locations of the groyne.

Thickness of launching apron (T) = 1.5* thickness of pitching (t).In some cases, thickness of the launching apron is kept different from due to size of crates etc (if launching apron is being provided in crated stones), then width of the launching apron may be revised keeping the volume of stones same per unit length of the apron.

5.5 DESIGN OF PERMEABLE SPURS

Draft for 2nd revision of IS code 14262:1995 mentions following provisions regarding permeable spurs

5.5.1 INTRODUCTION

Unlike impermeable spurs which do not allow any water to flow through its body (except seepage due to differential head),permeable porcupines are pervious enough so that the flow takes place across the groynes through their bodies. Up to 35% permeability (defined as the area of opening to the total area of flow intercepted by spurs i.e. the product of its length normal to the flow and the depth of flow), the behavior of a permeable spur, as far as its effectiveness in bank protection is concerned, is almost similar to that of an impermeable groyne. As the permeability increases, the length of the protected reach of bank gets reduced since eddies are reduced. As the flow passes through the permeable groynes, the micro eddies and the turbulence produced downstream of the groynes cause dampening of flow (due to energy dissipation) and consequent reduction in velocity. As a result the erosive power of the flow is reduced.

(i) Width of launching apron at nose (2-2.5) * (Dmax) below LWL

(ii) Width of launching apron at transition from nose to shank and first 30 m to 60 m in u/s

1.5 * (Dmax) below LWL

(iii) Width of launching apron in shank portion for next 30 m to 60 m

= 1.0 * (Dmax) below LWL

(iv) Width of launching apron at transition from nose to shank and first 15 m to 30 m in d/s

= 1.0 * (Dmax) below LWL

51 | P a g e

5.5.2 PORCUPINES SPURS

They are made of RCC having cubical shaped box at the central portion with their legs extending in different directions. The central box is filled with stones for the stability of the individual units of porcupines having size varying from 2 to 3 m. The individual units are placed side by side in a row and are tied. The spacing between the two consecutive units of porcupines will depend upon the desired permeability varying from 30 to 50%. The spacing of two consecutive rows of porcupines varies from 3L to 4L, where L is the length of spur.

5.5.3 SUBMERGENCE OF SPURS

Unlike impermeable spurs which are un-submerged with freeboard, permeable spurs may be either un-submerged or submerged. Submergence up to 50% is acceptable for porcupines.

5.5.4 LENGTH AND SPACING OF PERMEABLE SPURS

Considerations similar to those as already discussed for impermeable groynes under clause 5.2 should be followed in deciding length and spacing of permeable spurs. Very long spurs should not be provided due to difficulties in construction as well as maintenance against scour. The spacing of spurs will be determined by their lengths. Shorter spurs at closer interval is desirable in curved outer banks of a meandering stream compared to those in the straight reach of rivers. Arrangement of RCC Porcupine structure adopted in River Ganga is shown in Figure 14

Permeable spurs are less costly compared to impermeable ones. Submerged types is proposed for meandering reaches with deep water near concave bank. Due to dampening of flow, the sediment carrying capacity of flow behind the spurs get reduced resulting in deposition of sediments and building of banks along the affected reach.

FIGURE 14: PLAN SHOWINNG TEMPORARRY PROTECTIOON WORKS AGANGA

ADOPTED IN TTHE EROSION PRONE REAC

52 | P a g e

CH OF RIVER

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53 | P a g e

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54 | P a g e

6.1.3 STRUCTURAL ELEMENTS

The elements used in the RCC porcupine spurs are as under:

(a) Members: The porcupines are made of RCC members/elements. These members are casted in-situ at the site or location near the site. Generally six members are used to construct one porcupine.

(b) Nails: Standard commercially available nails of length 100 mm to 150 mm are used to join the porcupine members. Double nailing at critical joints may be provided.

(c) GI Wire: 4 to 5 strands of 4 mm GI wire should be used for interconnecting the porcupines and may be anchored with the ground. Alternatively, 12 mm 3-4 strands wire ropes should be used for the interconnecting the porcupines.

6.2 LIMITATION OF RCC PORCUPINES

(a) In case of high velocity flows, implementation of only RCC porcupine works is not favored. However, use of RCC porcupine works in between the reach of two solid boulder spurs is more effective

(b) .Generally additional quantities of RCC porcupines is kept for placing the RCC porcupines in 2nd year or during consequent years at locations where partial silting has been taken place after implementation of RCC porcupines in 1st year. In the absence of placing additional porcupine, the silted region near the bank may not become firm.

6.3 REFERENCES

1. Guidelines for planning and design of Permeable structures in alluvial rivers

7.0 LIMITATION OF SPURS

CBIP-manual “River Behavior Management and Training Volume-I -1989” stipulates that the success of repelling type spur depends upon the extent and the quickness with which scour occurs at the nose, and also on how quickly the pockets between the spurs get filled up with sediment. This condition make the impermeable groynes useless in boulder rivers, in which the rate of silt deposition may be slow or in flashy rivers in which floods rise and fall so quickly that desired silting doesn’t take place. The spurs can’t be relied upon to afford immediate protection.

It is also observed that silting between the successive spurs can be accomplished only when their lengths are sufficient. Short spurs don’t offer sufficient protection.

In case of narrow and deep rivers, the cost of solid spurs above high water is substantial. Moreover, because of the narrow width of rivers, solid spurs can’t be extended much as otherwise they can cause harmful conditions on the opposite bank or further d/s. In such cases submerged spurs are recommended.

55 | P a g e

As the tractive force on the slope is maximum at 1/3 depth from the bottom, the top of spur should be kept at least half of depth of water. A single submerged spur may not be as effective as series of submerged spurs. Since flow over the spurs produces turbulence and scour below them, silting may not take place as rapidly as required. It may be concluded that permeable spurs are effective only in rivers which carry heavy suspended load.

8.0 REFERENCES

1. IS code 8408:1994. 2. Irrigation and Hydraulic structures- S. K. Garg. 3. River Behavior Management and Training Volume-I (Central Irrigation and Power (CBIP), 1989).

4. Draft for revision of IS code 8408:1994

56 | P a g e

9.0 Estimate Cost estimate per running meter for proposed bank protection work by constructions

of embankment with stones in wire crates and launching apron and constructions of embankment with stones in wire crates and cut off wall is calculated below .

The Rates for the proposed work are taken from following SOR.

1) SOR of Ahmedabad Irrigation Department of year 2012-2013 2) SOR of Narmada Water Resources water supply and Kalpsar Department 2012-

2013 for South Gujarat

57 | P a g e

SR DESCRIPTION NO LENGTH BREATH DEPTH UNIT TOTAL

1

Stripping the Canal Construction width and Borrow area in all sorts of soil soft murrum including depositing the materials as and where directed for inspection road etc with lead upto 1 KM and all lifts etc comp . SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 1 Sr No 3

1 1 53.7 0.3 Cum 16.11

Trimming of Slope in 3.5H:1V

H=12m Therefore L=12*3.5 =42 m Slope length =(42^2+12^2)^0.5 =43.7 m

Slope length= 43.7 +10 =53.7 m

2

Earthwork in embankment from Borrow Pits in all sorts of soil and Soft murrum or other suitable Strata as directed including breaking the clods and dressing to the design sections including cutting the proud section with lead as under and all lift including site clearing etc complete . SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 1 Sr No 3.

For Lead 200 to 1000 Mt.

EMBANKMENT QUANTITY

1 0.5 17.25 6.9 Cum 59.52 1 1 5 6.9 Cum 34.5 1 0.5 17.25 6.9 Cum 59.52

1 1 17.25 6.9 Cum 119.0

3 1 1 5 13.8 Cum 69 1 0.5 3.6 1.8 Cum 3.24

DEDUCTION 1 0.5 42 12 Cum 252 1 1 6.1 12 Cum 73.2

TOTAL 19.61

58 | P a g e

3

Compaction of Earth work in Embankment in layers of 15 cms to 23 cms thick at requisite moisture content to required dry density including necessary watering and rolling with roller of suitable type. SOR Ahmedabad Irrigation Department 2012-2013 Chapter 5 Sr no 10

1 Cum 19.61

4

Hexagonal Zn Pvc Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In River Side Slope Sor Narmada Water Resources Water Supply And Kalpsar Department 2012-2013 For South Gujarat Region Chapter 6 Sr No 14

1 1 42 1 No 42

5

Providing and laying Dry Rubble pitching with base of inverted filter as per design and Drawing including providing Headers or hand packing trimming and dressing of slopes etc complete for leads as specified and all lifts etc complete SOR Narmada Water Resources water supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 1 Sr no 13

1 1 4.02 1 Sqm 4.02

30 cm thick pitching with 15 cms filter.

59 | P a g e

6

Hexagonal Zn Pvc Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In Launching Apron Sor Narmada Water Resources Water Supply And Kalpsar Department 2012-2013 For South Gujarat Region Chapter 6 Sr No 14

1 1 9 1 No 9

7

Providing and laying 7.5 cms thick controlled cement concrete lining of M-15 grade in Bed ,side, slopes and curvature including weight ,batching, mixing, transportation, placing ,vibrating dressing the slopes and bed in earth to correct profile with finishing as required to the exposed surfaces making asphalt joints as directed and watering curing including dewatering where required etc complete SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 4 Sr No 11.

1 1 42 1 Sqm 42

8

Proving And Laying Geo Fabric Filter (Gwf-50-300 Category ) Over The Excavated Surface As Per Specification Including Stitching With Overlap To Design Profile As Directed In Tidal Range Etc complete. SOR Narmada Water Resources water supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 6 Sr no 1

1 1 51.1

6 1 Sqm 51.16

B = 42.16+9 =51.16 m

60 | P a g e

Sr no

DESCRIPTION UNIT Quantit

y Rate TOTAL

1


Cum 16.11 30.5 491.36

2


Cum

For Lead 200 to 1000 Mt. 19.61 61 1196.21

3


Cum 19.61 16 313.76

4

Hexagonal Zn Pvc Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In River Side Slope SOR Narmada Water Resources Water Supply And Kalpsar Department 2012-2013 For South Gujarat Region Chapter 6 Sr No 14

No 42 2299.75 96589.5

Note: Rate for Gabion Mesh Per meter Length = Gabion Mesh of Size 4x1x1/4

61 | P a g e

5


Sqm 4.02 250 1005


6

Hexagonal Zn Pvc Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In Launching Apron Sor Narmada Water Resources Water Supply And Kalpsar Department 2012-2013 For South Gujarat Region Chapter 6 Sr No 14

No 9 2299.75 20697.75

Note: Rate for Gabion Mesh Per meter Length = Gabion Mesh of Size 4x1x1/4

7

Providing and laying 7.5 cms thick controlled cement concrete lining of M-15 grade in Bed ,side, slopes and curvature including weigh, batching, mixing, transportation, placing ,vibrating dressing the slopes and bed in earth to correct profile with finishing as required to the exposed surfaces making asphalt joints as directed and watering curing including dewatering where required etc complete SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 4 Sr No 11.

Sqm 42 306 12852

8

Proving And Laying Geo Fabric Filter (Gwf-50-300 Category ) Over The Excavated Surface As Per Specification Including Stitching With Overlap To Design Profile As Directed In Tidal Range Etc. Complete. SOR Narmada Water Resources water supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 6 Sr no 1

Sqm 51.16 78.9 4036.53

TOTAL RS PER RUNNING METER 137183

62 | P a g e

SR NO

DESCRIPTION

NOLENGTH BREATH DEPTH UNIT TOTAL

1


1 1 53.7 0.3 Cum 16.11

Trimming of slope in 3.5H:1V

H=12m

Therefore L=12*3.5 =42 m

Slope length =(42^2+12^2)^0.5

Slope length= 43.7 +10 =53.7 m

2



0.5 17.25 6.9 Cum 59.52

1 5 6.9 Cum 34.5

0.5 17.25 6.9 Cum 59.52

1 17.25 6.9 Cum 119.03

1 5 13.8 Cum 69

0.5 3.6 1.8 Cum 3.24

DEDUCTION 0.5 42 12 Cum 252

1 6.1 12 Cum 73.2

TOTAL 19.61

63 | P a g e

3


1 Cum 19.61

4

Hexagonal Zn PVC Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In River Side Slope SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 6 Sr no 14

1 1 42 1 No 42

5

Providing and laying Dry Rubble pitching with base of inverted filter as per design and Drawing including providing Headers or hand packing trimming nd dressing of slopes etc complete for leads as specified and all lifts etc complete SOR Narmada Water Resources water supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 1 Sr no 13

1 1 4.02 1 Sqm 4.02


6

Excavation in all sorts of soil with yellow ,sandy gravelly soil including sorting and stacking and depositing the excavated stuff in uniform layers as and where directed up to lead of 30 mt and lift as shown below including clearing the site etc complete.(including dewatering ).SOR Ahmedabad Irrigation Department 2012-2013 Chapter 5 Sr no 1

0 to 3 m Depth 1 1 0.6 3 Cum 1.8

3 to 6 m Depth 1 1 0.6 6 Cum 3.6

64 | P a g e

7

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25Grade in Cut off wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc. complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 4 Sr no 10

1 1 0.6 6 Cum 3.6

8

Providing and laying HYSD Steel bar reinforcement for R.C.C Works and anchor bars with providing binding wires including cutting ,bending, welding, binding in position hooking, placing in position with all leads and lift etc. SOR Ahmedabad Irrigation Department 2012-2013 Chapter 3 Sr no 7

1 80 kg/m3 Kg 288

9

Providing and laying 7.5 cms thick controlled cement concrete lining of M-15 grade in Bed ,side, slopes and curvature including weight ,batching, mixing, transportation, placing ,vibrating dressing the slopes and bed in earth to correct profile with finishing as required to the exposed surfaces making asphalt joints as directed and watering curing including dewatering where required etc complete SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 4 Sr No 11.

1 1 42 1 Sqm 42

10


1 1 42 1 Sqm 42

11

Providing and laying (Paralink 200) 200 KN/m High Strength uniaxial Geogrid with low creep characteristics, Geogrid consisting of PET and having an outer protective coating of low density polyethylene sheath conforming to detailed specifications and drawings.

1 1 10 1 Sqm 10

At Cut Off

65 | P a g e

SR NO DESCRIPTION UNITQUANTITY

RATE TOTAL

1

Stripping the Canal Construction width and Borrow area in all sorts of soil soft murrum including depositing the materials as and where directed for inspection road etc with lead up to 1 KM and all lifts etc comp . SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 1 Sr No 3

Cum 16.11 30.5 491.36

2



TOTAL 19.61 61 1196.21

3


Cum 19.61 16 313.76

4

Hexagonal Zn PVC Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In River Side Slope SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 6 Sr no 14

No 42 2300 96600

5


Sqm 4.02 250 1005


66 | P a g e

6

Excavation in all sorts of soil with yellow ,sandy gravelly soil including sorting and stacking and depositing the excavated stuff in uniform layers as and where directed up to lead of 30 mt and lift as shown below including clearing the site etc complete.(including dewatering ).SOR Ahmedabad Irrigation Department 2012-2013 Chapter 5 Sr no 1

0 to 3 m Depth Cum 1.8 54 97.2

3 to 6 m Depth Cum 3.6 56 201.6

7

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25Grade in Cut off wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 C

Cum 3.6 4639.4 16701.84

8


Kg 288 53.86 15511.68

9

Providing and laying 7.5 cms thick controlled cement concrete lining of M-15 grade in Bed ,side,slopes and curvature including weight ,batching, mixing, transportation, placing ,vibrating dressing the slopes and bed in earth to correct profile with finishing as required to the exposed surfaces making asphalt joints as directed and watering curing including dewatering where required etc complete SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 4 Sr No 11.

Sqm 42 306 12852

10


Sqm 42 78.9 3313.8

67 | P a g e

11

Providing and laying (Paralink 200) 200 KN/m High Strength uniaxial geogrid with low creep characteristics, Geogrid consisting of PET and having an outer protective coating of low density polyethylene sheath conforming to detailed specifications and drawings.

Sqm 10 220 2200


E

hath

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68 | P

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69 | P a g e

1.1 DEFINATIONS Terramesh is defined as PVC coated heavily galvanized steel wire mesh box-

shaped basket with a section of the mesh extending into the soil to act as soil reinforcement into the backfill soil. The basket is filled on site with clean-hard stones.

The selvedges of the Terramesh are the thicker perimeter and edge wires to

which the wire mesh is securely tied to withstand sudden or gradual stress from any direction.

The diaphragms are the internal wire mesh partitions which divide the

Terramesh box into approximately equal sized cells. Lacing and bracing wire is the wire used to assemble and join

the Terramesh units. Connecting wires are the internal wires used to prevent the Terramesh from

bulging during filling.

1.2 GENERAL DESCRIPTION

Terramesh is made from flexible woven wire Heavily Galvanized and PVC Coated 80mm type mesh boxes with integral panels of dimensions as specified in the Contract drawings or an approved equivalent.

Terramesh system can be placed in two ways

1)Terramesh with Vertical Face 2)Terramesh with a Battered Face.

FIGURE 16

The front fcontinuouvertically oreinforcem

6: FIGURE SHO

face box ans mesh panon the gab

ment panel.

OWING TERRAM

nd the soil nel For Terion face an

MESH SYSTEM

reinforcemrramesh thnd perpend

M WITH VERTIC

ment tail shahe mesh twdicular to t

CAL FACE AND

all be madewists are orthe front fa

70 | P

BATTERED FA

e from one riented ace in the

a g e

CE

FIGURE 17: FIGURE SHOWING TERRAMESH SYSTEM WITH WIRE CRATES

71 | P a g e

1.3 STEEL WIRE

(i) General

All steel wire used in the fabrication of the Terramesh, and also in the wiring operations during construction, shall be to BS 1052, having a tensile strength of not less than 380 N/mm2 and not exceed 550 N/mm2.

(ii) Wire Diameter

Wire diameters and relevant tolerances shall be in accordance with the following table:

Wire Diamet

Wire use Tolerance

2.20 Lacing Wire ± 0.06 2.70 Body Wire ± 0.08 3.40 Selvedge Wire ± 0.10

(iii) Zinc Coating

All wire used in the fabrication of the Terramesh and in the wiring operations during construction shall be heavily galvanized and exceed BS 443, the minimum mass of the zinc coating shall be according to the figures shown in the table below:

Diameter of Wire

Weight of Coating

2.2 242.7 263.4 27

The adhesion of the zinc coating to the wire shall be such that when the wire is wrapped six times around a four wire diameter size mandrel it shall not flake or crack to such an extent that any zinc can be removed.

(iv) PVC Coating

All wire used in the fabrication of Terramesh and in the wiring operations during construction shall have extruded onto it (after coating it with zinc in accordance with the foregoing specification) a coating of Poly Vinyl Chloride, otherwise referred to as “PVC”, or other plastic material having superior characteristics than PVC as otherwise approved.

72 | P a g e

The coating shall be 0.50mm average thickness with a tolerance of ± 0.05mm, and nowhere shall be less than 0.40mm thickness.

The PVC shall be grey in colour.

It shall be capable of resisting deleterious effects of natural weather exposure, immersion in salt water and not show any material difference in its initial characteristics which are :

a) Specific GravityShall be 1.30 to 1.35 in accordance with ASTM D 792-91

a) Durometer HardnessShall be 50 to 60 shore D, in accordance with ASTM D 2240-91 (ISO 868-1985)

b) Volatile LossAt 105°C for 24 hours - Shall not be greater than 5% In accordance with ASTM D 2287-92 E2. Residual Ashes shall be less than 2% according to ASTM D2124-62T.

c) Tensile StrengthShall not be less than 210 kg/sq.cm in accordance with ASTM D 412-92.

d) ElongationShall not be less than 200% and not greater than 280% in accordance with ASTM D 412- 92.

e) Modulus of Elasticity at 100% of ElongationShall not be less than 190 kg/sq.cm in accordance with ASTM D 412-87.

f) Resistance of AbrasionThe loss in volume shall be less than 0.30cm3 in accordance with ASTM D 1242-56.

g) Creeping CorrosionMaximum penetration of corrosion of the wire core from a square cut end shall not be greater than 25mm when the specimen has been immersed for 2000 hours in a 50% solution of HCL (Hydrochloric Acid 12 BE).

73 | P a g e

Testing for deterioration shall be as described below. Variation of the initial characteristics may be allowed, as specified hereunder, when the specimen is submitted to the following tests :

Salt Spray

According to ASTM B 117-90 Period of test = 1500 hours

Exposure to Ultraviolet Light

According to ASTM D 1499-92 and ASTM G 23(93) apparatus type E. Period of test = 2000 hours at 63°C.

Exposure at High Temperature

According to ASTM D 1203-89, (ISO 176-1976) and ASTM D 2287-(92)E2. Period of test = 240 hours at 105°C.

Brittleness temperature : cold bend less than -30°C test method BS2782-104A; cold flex less than +15°C in accordance with BS2782-151A(84).

After the above tests have been performed, the PVC coating shall exhibit the following properties :

a) Appearance

The vinyl coating shall not crack, blister or split and shall not show any marked change in colour.

a) Specific Gravity

Shall not show change higher than 6% of its initial value.

b) Durometer Hardness Shall not show change higher than 10% of its initial value.

c) Tensile Strength


d) Elongation Shall not show change higher than 25% of its initial value.

e) Resistance to Abrasion


f) Brittleness Temperatures Cold-bend not exceeding -20°C; cold-flex not exceeding +18°C.

1.4 W

W

T

ththa

T

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WIRE MES

Wire meshhexagonalpair of wirtwist), in s

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h shall be l woven mres througsuch a ma

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her wire diThe wire m

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74 | P

a uniformwisting eas double

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75 | P a g e

Mesh X ( mm ) Y ( mm ) Tolerance % 8 82 122 + 5 %

1.5 SELVEDGES

The cut edges of all mesh used in the construction of Terramesh

System, except the bottom edges of diaphragms and the end of the soil reinforcing tail shall be tightly selvedged with a wire having a diameter of at least 3.40 mm.

The side selvedge of all and any mesh panels shall be woven

integrally with the main mesh as described in the above clause 1.5 with a selvedge wire of at least 3.40 mm in diameter.

Where the selvedge is not woven integrally with the mesh but has to

be fastened to the cut ends of the mesh, it must be attached by mechanically binding the cut ends of the mesh two and half turns around the selvedge wire or by other approved method, provided that the force of not less than 8.5 kN applied in the same plane as the mesh, at a point on the selvedge of a mesh sample one metre long, is required to separate it from the mesh.

1.6 DIAPHRAGMS AND END PANELS

The rear/side panels shall be selvedged on the top, bottom and vertical sides as described in clause1.6. The diaphragms shall be selvedged and on the top and vertical sides.

The rear and side panels of the box gabion section of the

Terramesh unit shall be formed by a continuous panel connected to the main panel, along the bottom of the rear panel, either by a spiral wire through the mesh openings or by being mechanically placed with four connecting rings.

1.7 LACING AND BRACING WIRE

Sufficient lacing and bracing wire must be supplied with the gabion

cages to perform all the wiring operations to be carried out in the construction of the Terramesh work.

76 | P a g e

The lacing and bracing wire shall be made from Heavily Galvanized

Wire, coated with PVC and have a core diameter of 2.20 mm.

1.8 UNIT SIZES

Terramesh shall be mechanically pre-fabricated in such a manner that the sides, ends and diaphragms can be assembled at the construction site into rectangular baskets of the standard sizes indicated below or as specified and shown in the contract drawings.

Mesh type 80mm Width (W) 2m

Length (L1) 1m Length (L2) To suit design Depth (D) 0.5m and 1m Diaphragm Every 1m

All Terramesh dimensions shall be within a tolerance limit of 5% of the required size.

Terramesh shall be mechanically pre-fabricated in such a manner that the

sides, ends and diaphragms can be assembled at the construction site into rectangular baskets of the standard sizes indicated below or as specified and shown in the contract drawings.

Mesh type 80mm Width (W) 2m Length (L1) 1m Length (L2) To suit design Depth (D) 0.5m and 1m Diaphragm Every 1m

All Terramesh dimensions shall be within a tolerance limit of 5% of the

required size.

1.9 STONE FILL FOR FACING BOX

The material used for Terramesh facing box fill shall be clean, dense hard

and durable stone, rounded and angular shape.

No rock shall exceed 250mm and at least 85% by weight of the stone shall have a size equal to or larger than 100mm. No rock shall pass through the mesh.

77 | P a g e

1.10 STRUCTURAL EMBANKMENT

The embankment forming the reinforced soil structure should be

constructed with material having the soil properties as specified in the design and approved by the Engineer.

Ideally, the backfill shall be granular, free draining and have the following

specification, unless otherwise approved by the Engineer : not more than 15% by mass of total material to be finer than 75 micron

sieve opening. at least 90% by mass of total material to be finer than the 100 mm sieve

opening maximum particle size to be limited to 125 mm.

The soil should not exhibit any deterioration in these characteristics with time

2.0 CONSTRUCTION METHODOLOGY FOR TERRAMESH SYSTEM UNIT REINFORCED WALLS

2.1 SCOPE

This part of the specification details the requirements from the assembly

stage through to the final wiring of the completed Terramesh units.

The contractor shall provide to the Engineer, for his approval, full details and specifications of the Terramesh he proposes to use in this contract. Only those products so approved by the Engineer shall be allowed to be incorporated in the works.

2.2 PREPARATION

The site shall be surveyed, cleared, trimmed level and the ground compacted

accordingly.

Prior to assembly, the Terramesh units shall be opened out flat on the ground and stretched to remove all kinks and bends.

The Terramesh units shall be assembled individually by raising the front panel (with lid), the hinged rear panel, and the two ends vertical ensuring that all creases are in the correct position and that tops of all four sides are even. The diaphragm panel should be located in a vertical plane centrally within the facing box.

78 | P a g e

The four corner edges of the facing box shall be laced first followed by the

edges of the internal diaphragm to the sides.

In all cases, lacing shall commence by twisting the end of the lacing wire

tightly around the selvedge/s. It shall then pass round the two edges being joined using alternate single and double loops at 100mm intervals and be securely tied off at the bottom. The ends of all lacing wires shall be turned to the inside of the box on completion of each lacing operation. Each loop shall be pulled tight to prevent the joint opening during filling.

3.1 ERECTION

Only assembled boxes, or groups of boxes, shall be positioned in the

structure. The side, or end, from which work is to proceed, shall be secured either to the completed work, or by rods or stakes driven into the ground at the corner. These stakes must be secure and be high enough to reach at least to the top of the gabion box.

Further gabion boxes shall be positioned in the structure as required, each

being securely laced to the preceding one along all common corners and diaphragms using the lacing technique described above.

Adjacent panels shall be laced longitudinally to provide a homogeneous

reinforcement layer. All lacing wire shall be PVC coated. 3.2 GEOTEXTILE

Non-woven geotextile, as specified in the contract drawings and approved by

the Engineer, shall be placed vertically at the back of each gabion box section of the Terramesh units, and extend backwards into the fill at least 0.5m parallel to the mesh of homogeonous lower panel and also 0.5m below the panel directly above the unit, to prevent migration of fines.

3.3 STRETCHING

Final stretching of the gabion boxes shall be carried out using a pull-lift of at least one tonne capacity, firmly secured to the free end of the assembled gabion boxes.

Whilst under tension, the gabion box section of the Terramesh units shall be securely laced along all edges (top, bottom and sides) and at diaphragm points, to all adjacent boxes.

79 | P a g e

3.4 FILLING

Filling shall be carried out whilst gabion boxes are under tension.

The front face and all other faces which will be exposed in the completed

structure shall be “hand packed” with the stones placed so as to produce a neat face free from excessive bulges, depressions

and voids.

Internal bracing wires shall be provided on the exposed faces at the rate of 4/cu.m at 330mm centres to prevent distortion of the units during filling and in the completed structure. These bracing wires shall be wrapped around two of the mesh wires and extend from front to back. Additional bracing wires shall be provided on exposed ends at a rate of 4/sq.m of face.

Mechanical filling equipment may be used with the approval of the Engineer, providing adequate precautions are taken to protect the PVC coating from abrasion during filling operations.

Tension on the gabion boxes shall be released only when fully laced and

sufficiently full to prevent the mesh from slackening. All gabions shall be overfilled by 25mm using flat stone to allow for minor

settlement and to provide a level surface for subsequent layers.

3.5 STRUCTURAL EMBANKMENT MATERIAL Select backfill shall be placed between each subsequent mesh panel layer to

the full extent of the mesh reinforcement at each level.

3.6 COMPACTION OF BACKFILL

The select backfill shall be compacted in lifts not exceeding 250-300 mm to 90% of maximum density as determined by Test or specified by the engineer.

Care shall be taken to ensure heavy compaction equipment does not come

into contact with the mesh panels or within 1.0 m of the front face. Tracked construction equipment shall not be operated directly upon the mesh reinforcement. A minimum fill thickness of 150mm is required prior to operation of tracked vehicles over the mesh.

During construction, the surface of fill should be kept horizontal. A slight

sloping surface shall be maintained to facilitate drainage of surface water run-off.

80 | P a g e

Compaction adjacent to the front edge should be done using hand operated rollers or plate compactors.

3.7 MERITS OF THE TERRAMESH SYSTEM:

Permeability of the front face, guaranteeing drainage of the backfill. Flexibility ,enabling the structure to tolerate differential ground settlement

without compromising structural integrity Ease of construction Significant soundproofing characteristics (18-28 decibels) The reduction of environmental impact through the use of vegetation

incorporated into the front face of the structure The Versatility of gabions, which allows the formation of a structure with

vertical, battered or stepped front face as required and minimization of environmental impact.

3.8 DEMERITS OF THE TERRAMESH SYSTEM: Maintenance

For very tall gabion stacks, any damage to the lower areas requires the removal of the upper wall elevations, which can be costly and time-consuming.

Wall Assembly and Cost Although gabion walls offer a good economic choice for most applications,

they remain more expensive to install. Gabion walls require heavy equipment to construct, since mechanical lifting is required to set heavy walls sections in place.

Endurance In instances of high velocity streams and wave interaction, gabion wall wire

mesh baskets can abrade and tear open, spilling the rock fill.

81 | P a g e

3.0 ESTIMATE

Cost estimate per running meter for proposed bank protection work by

construction of Gabbion Retaining Wall With Teramesh System.


1) SOR of Ahmedabad Irrigation Department of year 2012-2013 2) SOR of Narmada Water Resources water supply and Kalpsar Department 2012- 2013 for South Gujarat

82 | P a g e

SR NO

DESCRIPTION NOS

LENGTH

BREATH

DEPTH

UNIT TOTAL

1

Stripping the Canal Construction width and Borrow area in all sorts

of soil soft murrum including depositing the materials as and

where directed for inspection road etc with lead up to 1 KM and all lifts etc comp . SOR Ahmedabad Irrigation Department 2012-2013

Chapter No 1 Sr No 3

1 1 53.7 0.3 Cum 16.11

Trimming of slope in 3.5H:1V H=12m

Therefore L=12*3.5 =42 m Slope length =(42^2+12^2)^0.5 Slope length= 43.7 +10 =53.7 m

2

Earthwork in embankment from Borrow Pits in all sorts of soil and Soft murrum or other suitable

Strata as directed including breaking the clods and dressing to

the design sections including cutting the proud section with lead as under and all lift including site

clearing etc complete . SOR Ahmedabad Irrigation Department 2012-2013 Chapter No 1 Sr No 3.

1

For Lead 200 to 1000 Mt. 1 5 7 Cum 35 1 5 14 Cum 70 1 32 14 Cum 448 0.5 3.6 1.8 Cum 3.24

DEDUCTION 0.5 42 12 Cum 252

TOTAL 304.2

4

3


1 Cum 304.2

4

83 | P a g e

4

Proving And Laying Geo Fabric Filter (Gwf-50-300 Category ) Over The Excavated Surface As Per Specification Including stitching With Overlap To Design Profile As Directed In Tidal Range Etc Complete.

1 1 1 14 SQM 14

5

Hexagonal Zn Pvc Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed Etc. Comp In River Side Slope SOR Narmada Water Resources Water Supply And Kalpsar Department 2012-2013 For South Gujarat Region Chapter 6 Sr No 14

14 1 4 1 No 14

6

Providing and laying (Paralink 200) 200 KN/m High Strength uniaxial Geogrid with low creep characteristics, Geogrid consisting of PET and having an outer protective coating of low density polyethylene sheath conforming to detailed specifications and drawings.

14 1 6.75 1 Sqm 94.5

At Cut off 1 1 10 1 Sqm 10

TOTAL Sqm 104.5

7

Excavation in all sorts of soil with yellow ,sandy gravelly soil including sorting and stacking and depositing the excavated stuff in inform layers as and where directed up to lead of 30 mt and lift as shown below including clearing the site etc complete.(including dewatering ).SOR Ahmedabad Irrigation Department 2012-2013 Chapter 5 Sr no 1

0 to 3 m Depth 1 1 0.6 3 Cum 1.8 3 to 6.5 m Depth 1 1 0.6 3.5 Cum 2.1

84 | P a g e

8

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25Grade in Cut off wall with cement sand and coarse aggregates including centering shuttering batching missing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 4 Sr no 10

1 1 0.6 6 Cum 3.6

9


1 80 Kg/m3 Kg 288

10

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 20 Grade in Anchor slab l with cement sand and coarse aggregates including centering shuttering batching missing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 B

1 1 5 0.2 Cum 1

11


1 25 kg/m3 Kg 25

85 | P a g e

SR NO

DESCRIPTION UNITQUANTIT

YRATE TOTAL

1


Cum

16.11 30.5 491.36

2



TOTAL Cum

304.24 61 18558.64

3


Cum

304.24 16 4867.84

4

Proving and Laying Geo Fabric Filter (Gwf-50-300 Category ) Over The Excavated Surface As Per Specification Including Stitching With Overlap To Design Profile As Directed In Tidal Range etc Complete.

SQM 14 78.9 1104.6

5

Hexagonal Zn Pvc Coated Box Wire Mesh Gabions Size 4mx1m X1m Filled With 30 To 50 Kg. Trap Rubble Stone (Approximate 4.5) Tone With Mesh Size 10x12cm Including Packing Interlocking Of Stones And Fusing Top Of Gabion And Tying To Each Other & Laying To The Required Line Level Slope With All Leads & Lifts As Directed

No 14 2300 32200

86 | P a g e

Etc. Comp In River Side Slope Sor Narmada Water Resources Water Supply And Kalpsar Department 2012-2013 For South Gujarat Region Chapter 6 Sr No 14

6

Providing and laying (Paralink 200) 200 KN/m High Strength uniaxial Geogrid with low creep characteristics, Geogrid consisting of PET and having an outer protective coating of low density polyethylene sheath conforming to detailed specifications and drawings. (Market Rate)

TOTAL Sqm 104.5 220 22990

7

Excavation in all sorts of soil with yellow ,sandy gravelly soil including sorting and stacking and depositing the excavated stuff in inform layers as and where directed up to lead of 30 mt and lift as shown below including clearing the site etc complete.(including dewatering ).SOR Ahmedabad Irrigation Department 2012-2013 Chapter 5 Sr no 1

Cum

0 to 3 m Depth 1.8 54 97.2 3 to 6.5 m Depth 2.1 56 117.6

8

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Cut off wall with cement sand and coarse aggregates including centering shuttering batching missing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 C

Cum

3.6 4639.

4 16701.84

9


Kg 288 53.86 15511.68

87 | P a g e

10

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 20 Grade in Anchor slab l with cement sand and coarse aggregates including centering shuttering batching missing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 B

Cum

1 4507.

1 4507.1

11


Kg 25 53.86 1346.5

TOTAL RS PER RUNNING METER 118494.36

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89 | P

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90 | P a g e

1.0 GENERAL

Diaphragm walling is a technique of constructing a continuous

underground wall from the ground level. Diaphragm walls provide

structural support and water tightness. These reinforced concrete

diaphragm walls are also called Slurry trench walls due to the reference

given to the construction technique where excavation is made possible

by filling and keeping the wall cavity full with bentonite-water mixture

during excavation to prevent collapse of vertical excavated surfaces.

These retaining structures find following applications: earth retention

walls for deep excavations; basements, and tunnels; High capacity

vertical foundation elements; Retaining wall foundations; water control.

Typical wall thickness varies between 0.6 to 1.1m. The wall is

constructed panel by panel in full depth. Panel width varies from 2.5m

to about 6m. Short widths of 2.5m are selected in less stable soils,

under very high surcharge or for very deep walls. Different panel shapes

other than the conventional straight section like T, L are possible to

form and used for special purposes. Traditionally, panel excavation is

carried out using cable supported Grab. Hydraulic grabs with Kelley

arrangement have recently been introduced in India on large

Infrastructural projects. More recently developed hydraulic cutter type

machines are not being used in India hence have not been discussed

here.

91 | P a g e

Slurry wall technique is a specialized technique and apart from the

crane mounted Grab, other equipment involved are cranes, pumps,

tanks, de- sanding equipment, air lifts, mixers etc.

Steps involved in the construction of diaphragm wall can be broadly listed as follows:

• Guide wall construction along alignment

• Trenching by crane operated Grab/ hydraulic grab

• Bentonite flushing

• Lowering reinforcement cage

It must be remembered that Diaphragm walls are constructed as a

series of alternating primary and secondary panels. Alternate primary panels are constructed first which are restrained on either side by stop-end pipes. Before the intermediate secondary panel excavation is taken up, the pipes are removed and the panel is cast against two primary panels on either side to maintain continuity. Water stoppers are sometimes used in the construction joints between adjacent panels to prevent seepage of ground water.

1.1 DESIGN PHILOSOPHY

Diaphragm walls are commonly designed as flexible retaining walls.

Such retaining systems are considered to be vertical cantilever

designed to resist lateral earth and ground water pressures, and to

rotate about some point b below the dredge level). The flexibility

leads to development of passive pressure at the toe in the backfill

side of the wall. Blum’s simplification replaces the passive pressure

behind the retaining wall with a force applied to the wall at some

height above the toe . The necessary depth of penetration is found by

taking moments about the replacement force position, C. Moment

equilibrium gives the required depth of penetration, provided that

the net pressure diagram is calculated including the effects of

groundwater. The computed may be increased by 20 to 40% beyond

the point required by equilibrium (Teng, 1962); or the effective

horizontal pressure on the passive side may be reduced by applying

a factor of safety of 1.5 to 2.1 before the embedment depth of pile is

computed. Unit length of diaphragm wall is considered for

determining its reinforcement requirements, whilst for contiguous

piles, the c/c spacing is used for estimating reinforcement quantity.

92 | P a g e

NE T P A S S I V E (P p- Pa)

A. C A N T I L EVE R SH E E T - P I L E W A L L D E SI G N PR I N C I PL E S

a

ACT I V E

NE T P A S S I V E

(P p- Pa)

( a ) ASSU M E D M O D E O F W A L L M O VE M E N T ( b ) I D EA L I Z E D P R ESSU R E D I STR I BU T I O N

A DESIGN PRINCIPLES OF DIAPHRAGM WALL SYSTEM 1.2 MERITS AND DEMERITS

Diaphragm wall construction is relatively quiet, and minimum

noise and vibration levels make it suitable for construction in

urban areas. The water tight walls formed can be used as

permanent structural walls and are most economical when

used in this manner. The finished structural wall formed prior

to excavation allows subsequent construction of the basement

in a water tight and clean environment. Once the diaphragm

walls are constructed, work can be planned to proceed

simultaneously above and below the ground level. There is a

minimum of space wasted. Work may be carried out right

against existing structures and the line of wall may be

adjusted to any shape in plan.

1.0 GENER

RAL

CouproThefor betcancouheecounot20.

B. D E

unterfort ojecting ue thicknes cantilevetween the ntileveredunterfortsel where munterfortst practica

FIG

E S I G N A S S U M

cantilevepward fross of the sered walls counterfo elements

s are tapermoments s and the l for walls

GURE 20 COUN

P TI O N F O R C A

red retainom the hestem betw) and spaort (wing)s and are red down are higheinfill stems less tha

NTERFORT RE

A N T I L E V ER S H

ning wallsel of the

ween counans horizo walls. Th structura to a wide

er. The higm walls man about 1

ETAINING WA

H EET- P I L E W A

s incorpor footing innterforts iontally, ashe counteally efficieer (deepergh cost of

make such16 feet hig

LL

L L S

rate wing nto the stis thinners a beam,erforts actent becaur) base at f forming

h walls usugh. See Fi

93 | P a g e

walls em.

r (than t as se the the the ually igure

94 | P a g e

2.0 PROPORTIONING

The spacing between counterforts for economical design is usually

one-half to two-thirds the wall height. The width of the footing will usually be about two-thirds the wall height, or larger for surcharges or sloped backfill

3.0 DESIGN OVERVIEW

As per preliminary design following sections for counter Fort wall is adopted.

Top thickness of stem = 0.20m

Base thickness of stem = 0.75m

Width of Toe slab =2.00m

Width of Heel slab = 3.75m

Thickness of Slab = 0.75 m

Spacing of counterfort= 4.0 m c/c

Thickness of counterfort= 0.60m

Height of wall from the foundation =10.0m

Grade of Concrete = M25

Grade of steel= Fe-500 TMT/HYSD bar

The design of a counterfort wall can be somewhat complex because the number of components which must be designed differently than for a conventional cantilevered wall. The steps in the design of a reinforced concrete counterfort wall are as follows (each step will be discussed later):

a) After establishing the retained height, select a spacing for the counterforts,

usually one-half to two-thirds of the retained height. Determine the footing width required and soil bearing at both the toe and heel because you will need these dimensions to establish the counterfort dimensions, and for stability calculations design as if the wall is a continuous cantilevered wall. You can add an estimated weight of the counterforts prorated as a uniform longitudinal axial load.

b) Design the wall as described in the following section as a two-way slab, fixed at the base and at the counterfort crossings and free at the top.

c) Design the footing toe as a cantilever from the wall. d) Design the heel as a longitudinal beam spanning between counterforts. e) Design the counterfort. It will be a tapered trapezoidal shaped tension

member.

Check the final design for stability, overturning, sliding, and soil pressures

95 | P a g e

4.0 ESTIMATE

Cost Estimate Per Running Meter For By Construction Of Rigid RCC Counter Fort Wall With Diaphragm Wall Construction.


1) SOR of Ahmedabad Irrigation Department of year 2012-2013

2) SOR of Narmada Water Resources water supply and Kalpsar

Department 2012-2013 for South Gujarat

96 | P a g e

SR NO

DESCRIPTION NOLENGTH

BREATH DEPTH UNIT TOTAL

1


1 1 53.7 0.3 Cum 16.11

Trimming of slope in 3.5H:1V H=12m Therefore L=12*3.5 =42 m Slope length =(42^2+12^2)^0.5 Slope length= 43.7 +10 =53.7 m

2


1 1 10.75 4 Cum 43 1 1 31.25 13.8 Cum 431.25 DEDUCTION 1 0.5 42 12 Cum 252 TOTAL Cum 222.25

3


1 Cum 222.25

97 | P a g e

4

Excavation in all sorts of soil with yellow ,sandy gravelly soil including sorting and stacking and depositing the excavated stuff in inform layers as and where directed upto lead of 30 mt and lift as shown below including clearing the site etc complete.(including dewatering ).SOR Ahmedabad Irrigation Department 2012-2013 Chapter 5 Sr no 1

0 to 3 m Depth 1 1 0.6 3 Cum 1.8 3 to 6m Depth 1 1 0.6 3 Cum 1.8

5

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25Grade in Cut off wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 4 Sr no 10

Below River Bed 1 1 0.6 6 Cum 3.6

Above River Bed 1 1 0.6 4 Cum 2.4

TOTAL Cum 6

6


1 80 kg/m3 Kg 480

7

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 20 Grade in Anchor slab l with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 B

1 1 8 0.2 Cum 1.6

98 | P a g e

8


1 25 kg/m3 Kg 40

For Anchor Slab

9

Providing and laying plain /Reinforced ordinary Portland cement concrete of P.C.C M 15 Grade below Anchor slab with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 B

1 1 8 0.15 Cum 1.2

COUNTER FORT RETAINING WALL

10

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Bottom slab of Counter Fort Wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 C

1 1 6.5 0.75 Cum 4.87

5

11

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Stem of Counter Fort Wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for

1 1 10 0.475 Cum 4.75

99 | P a g e

South Gujarat Region Chapter 10 Sr no 10 C

12

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Counter Fort Placed at 4 m c/c with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012-2013 for South Gujarat Region Chapter 10 Sr no 10 C

1 10 2.025 0.6 Cum 3.04

13


80 Kg/m3 Kg 1013

.2

For Counter Fort Retaining wall

100 | P a g e

SR NO DESCRIPTION NOS UNIT QUANTITY RATE TOTAL

1

Stripping the Canal Construction width and Borrow area in all sorts of soil soft murrum including depositing the materials as and where directed for inspection road etc with lead up to 1 KM and all lifts etc comp . SOR Ahmedabad Irrigation Department 2012‐2013 Chapter No 1 Sr No 3

1 Cum 16.11 30.5 491.36

2

Earthwork in embankment from Borrow Pits in all sorts of soil and Soft murrum or other suitable Strata as directed including breaking the clods and dressing to the design sections including cutting the proud section with lead as under and all lift including site clearing etc complete . SOR Ahmedabad Irrigation Department 2012‐2013 Chapter No 1 Sr No 3.

TOTAL 1 Cum 222.25 61

13557.25

3

Compaction of Earth work in Embankment in layers of 15 cms to 23 cms thick at requisite moisture content to required dry density including necessary watering and rolling with roller of suitable type. SOR Ahmedabad Irrigation Department 2012‐2013 Chapter 5 Sr no 10

1 Cum 222.25 16 3556

4

Excavation in all sorts of soil with yellow ,sandy gravelly soil including sorting and stacking and depositing the excavated stuff in uniform layers as and where directed up to lead of 30 mt and lift as shown below including clearing the site etc complete.(including dewatering ).SOR Ahmedabad Irrigation Department 2012‐2013 Chapter 5 Sr no 1

0 to 3 m Depth 1 Cum 1.8 54 97.2

3 to 6m Depth 1 Cum 1.8 56 100.8

5

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25Grade in Cut off wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012‐2013 for South Gujarat Region Chapter 4 Sr no 10

1 Cum 6 4639.4 27836.4

101 | P a g e

6

Providing and laying HYSD Steel bar reinforcement for R.C.C Works and anchor bars with providing binding wires including cutting ,bending, welding, binding in position hooking, placing in position with all leads and lift etc. SOR Ahmedabad Irrigation Department 2012‐2013 Chapter 3 Sr no 7

1 Kg 480 53.86 25852.8

7

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 20 Grade in Anchor slab with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012‐2013 for South Gujarat Region Chapter 10 Sr no 10 B

1 Cum 1.6 4507.1 7211.36

8

Providing and laying HYSD Steel bar reinforcement for R.C.C Works and anchor bars with providing binding wires including cutting ,bending, welding ,binding in position hooking, placing in position with all leads and lift etc. SOR Ahmedabad Irrigation Department 2012‐2013 Chapter 3 Sr no 7

1 Kg 40 53.86 2154.4

For Anchor Slab

9

Providing and laying plain /Reinforced ordinary Portland cement concrete of P.C.C M 15 Grade below Anchor slab with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012‐2013 for South Gujarat Region Chapter 10 Sr no 10 B

1 Cum 1.2 3963.9 4756.68

COUNTER FORT RETAINING WALL

10

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Bottom slab of Counter Fort Wall with cement sand and coarse aggregates including centering shuttering batching missing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012‐2013 for South Gujarat Region Chapter 10 Sr no 10 C

1 Cum 4.875 4639.4 22617.08

102 | P a g e

11

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Stem of Counter Fort Wall with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012‐2013 for South Gujarat Region Chapter 10 Sr no 10 C

1 Cum 4.75 4639.4 22037.15

12

Providing and laying plain /Reinforced ordinary Portland cement concrete of M 25 Grade in Counter Fort Placed at 4 m c/c with cement sand and coarse aggregates including centering shuttering batching mixing transportation placing vibrating smooth finishing curing etc complete for all leads and lift SOR Narmada Water Resources Water Supply and Kalpsar Department 2012‐2013 for South Gujarat Region Chapter 10 Sr no 10 C

1 Cum 3.04 4639.4 14103.78

13

Providing and laying HYSD Steel bar reinforcement for R.C.C Works and anchor bars with providing binding wires including cutting ,bending, welding, binding in position hooking, placing in position with all leads and lift etc. SOR Ahmedabad Irrigation Department 2012‐2013 Chapter 3 Sr no 7

For Counter Fort Retaining wall 1 Kg 1013.2 53.86 54570.96


1.1 G

1.2 P

1.2.1

GENERAL

IS objedispopeavoto rwat

Theare somoutas f

Proinsufloo

PLANNIN

Varwordrabelo

1 REQUIR

Forwill

CH

L

code 8835ect of relieposing of serations. Thoid its percrise in the ter logging

e drains m generally

me cases intfall conditforced or d

viding adeufficient isods in the

NG OF DRA

rious asperks includains, alignmow.

REMENT O

r the plannl be collecte

HAPTER-3

5:1978 stieving excesurplus wahe proper colation do water tab.

may be natu aligned aln order to tions, the ddiversion re

equate dras the basiarea. A cro

FIGURE 21

AINAGE IM

ects relatedding data ment of dr

OF DATA

ning of thed.

3DRAINA

ipulates thess water fater whichdisposal o

own to thele thereby

ural or artilong the va reduce thdrains are eaches.

ainage sysc requiremoss draina

1: A CROSS DR

MPROVEM

d to planncollection,ain, capac

he drainage

AGE IMP

hat drainsfrom agric

h is not reqof surplus re water lev aggravatin

ificial. As palley lines

he length o taken acr

tem wherement to leage work is

RAINAGE WO

MENT WO

ning of dra degree o

city of drain

e/channel

ROVEME

s are conscultural anquired for nrain water

vel which mng or crea

per accepte between r

of the drainross valleys

e natural ssen the d

s shown in

ORK

ORKSainage/chaf protections etc. are

l improvem

1

NT WORK

structed wnd other anormal agrr is also esmay otherwting the pr

ed principlridges. Hon or to havs. These ar

drainage sdistress ca Figure 21

annel impon, classifie described

ment follow

03 | P a g e

KS

with the areas and ricultural sential to wise lead roblem of

les, these owever, in ve proper re known

system is aused by .

provement fication of d in paras

wing data

1.

1.

1

1.3

.2.1.1 TOP

Planarea

.2.1.2 HYD

Discsect

.2.2 DEG

IS dayrequmaybe jdescros

CLASSIF

IS Cintoare

(a) Outfriver

(b) Link

POGRAPHI

n showinga, plan and

DROLOGICA

charge, gtion of rive

GREEOFP

Code 883y rainfall uiring highy also be ajustified inigned for ss drain un

FI

FICATION

Code 8835o the follow construct

fall drainsr from a pak Drains- T

ICALDATA

g area afd section o

ALANDM

gauge, flower etc.

PROTECTI

5:1978 stof 5 yearher degreeadopted. An term of 3 day rainnder the e

GURE 22: CRO

N OF DRAI

5:1978 stiwing categed:

- These ararticular cThese are b

A

ffected, baof earlier ex

ETEOROL

w depth,

ION

tipulates tr return e of protecAdoption off economicnfall of 50mbankme

OSS DRAIN UN

NS

ipulates thgories acco

re the maincatchment.branch dra

ank slopexecuted wo

OGICALDA

velocity,

that drainperiod. H

ction, retuf higher recs. Cross 0 year retunt is show

NDER THE EM

hat the drording to th

n drains ou. ains draini

e, type of orks.

ATA

cross se

ns may beHowever, irn period eturn periodrainage w

urn periodwn in Figur

MBANKMENT

rains are bhe purpos

ut falling in

ing sub-ca

104

f soil, catc

ctions an

e designedn specificof 10 or 1

od rainfall works sho. Construcre 22.

broadly clae for which

nto a nalla

atchment i

4 | P a g e

chment

nd long

d for 3 c cases 15 year should ould be ction of

assified h these

ah or a

nto the

1.4 A

outf

ALIGNMEN

IS alig

Thevalloutdramafrompertakcondep

In far In emordin t

As thaslu

fall drain. T

NTOFDRA

code 85gnment of

e drains sley line. Atfall draiained. If arshes, thm the drformanceke the drannect it tpression.

selecting as possithe forcebankmen

der to minthe emban

far as poat the fulluice with g

These are a

FIGU

AINS

535:1978 f the drain

should geAs far asin shouldthe align

he drain difficultiese of the ain away to the dra

alignmenible theseed reachents of thenimize thenkments.

ossible, thl supply gates

aligned alo

URE 23: EMBA

envisagenage chan

enerally fs possibld be in nment crshould n in excadrain. Infrom the ain if it i

nts, care e do not s, care se drains e danger o

he alignmlevel is b

ong subsid

ANKMENT WIT

es follownnel.

follow thee the alithe cen

osses anynot pass avation, in such ca depressiois require

should bpass thr

should beare not o

of flooding

ment of thbelow the

diary valley

TH SLUICE

wing guid

e drainageignment otre of thy depressthrough it affectsases, it ion or poned to dra

be taken rough ville taken tof an exceg in the ev

he drain s natural

105

y lines.

delines fo

e line ie. of the mhe area sions, ponthese, as the hydis preferand, and suain the po

to see tlage habito see thessive hevent of br

should besurface le

5 | P a g e

or the

lowest main or

to be nds or

s apart draulic able to uitably ond or

hat as itation.

hat the ight in eaches

e such evel. A

1.5 Capaci IS

cap

Nordisccasas Whporexcprounrcharetutheareacceveprominprosur

ty/desigcode 8

pacity/des

rmally thcharge w

ses, no emto allow

herever emrtion of cavated sovided in restricted annel capurn to the forced o, howeve

commodatn in suc

oper alignmnimum. Iovided in rrounding

FIGURE 24

gndischa8535:197sign disch

he drain where drambankmenw free flowmbankme

the desoil will

the emb inflows,

pacity, the channelor diversioer, providted withinch cases ment to kIn such c the em

g areas. A

4: A GATED S

argeofdr8 envis

harge of th

is providains follownts shoulw of watnts are nesign dibe very

bankmentand in ca

he water l freely whon reachded as tn the cuattempts

keep the hcases, inmbankme typical dr

LUICE

rains. ages folhe drainag

ded to aw naturald be prover from tnecessaryscharge

y costly, ts on eithase of disshould s

hen the dhes, emba

he desigt section should height of lets of a

ents to rain is sh

llowing ge channe

ccommodal valley vided alonthe surro

y for accor wherlarge ga

her side scharges hspill over

discharge ankmentsgn discha of the dbe made the embadequate admit thown in Fi

106

guidelineel.

date the lines. In

ng the droundings commodare dispoaps shouso as tohigher thr the arein it reced on both

arge canndrain. Ho by selec

ankments size shouhe water gure 25.

6 | P a g e

es for

design n such rain so areas.

ting a sal of uld be o allow han the ea and des. In

h sides not be owever, cting a to the uld be from

Icdd

1.5.1

Ib

1.5.2

Intensity ocountry indays. Theduration s

1 DESIGN

In fixing tbe taken i

a) Econoccunevedraiacce

b) Perfto ddiscdraisize discfree

c) Landinvocult

d) Desday yearcaseyearneed

2 PERIOD

The the submsignshou10

of Rainfalndicates terefore, foshould be

NFREQUEN

the designinto accou

nomics- Drurrence prer designedinage projeepted. formance- Tdeterioratecharge freins tend to remain in

charges wit board. d requirem

olve larger ivated landign freque rainfall or frequences requirinr can alsod to be jus

DOFDISPO

period of tolerance mersion f

nificant dauld aim atdays. Ba

FIGURE 2

ll- Analysthat geneor designe taken

NCYOFRA

n capacityunt:

rains of a rove to bed to cater ect, occurr

The experie fast, as quently. o get siltedn a betterth margina

ment- On land acqd.

ency- Geneof 5 year fcy gives opng a highero be adoptified in te

OSAL

f disposal of individufor a periamage. Thet disposingsed on e

25: A TYPICAL

sis of therally the n of the d

AINFALL

y of the d

bigger size costly cofor the wo

rence of d

ience indic these arConsequend soon. Onr conditional scour of

account oquisition r

erally the frequency.ptimum ber degree ofpted. Adoprms of the

of the excual crops. iod of 7 erefore, ing of the raiexperience

DRAIN

e storm durationdrains, a

drain the

ze for cateompared torst conditamage at

cates that re not reqntly in cn the othen and canf bed and

of small laesulting in

drains sh. Studies enefit costf protectionption of sue economic

cess rainfaCrops Liketo 10 d

n paddy gin water in the follo

rainfall n of the sa storm r

following

ering a rainto the bentions. In otperiodical

drains of quired to carrying ser hand, Dn occasionsides and

and holdinn a perm

hould be dcarried out ratio. Hon, the frequch highecs

all is entire paddy caays witho

growing arn a periodowing per

10

throughostorm is arainfall of

g factors

nfall of innefits. Drather words intervals

a bigger scarry themaller di

Drains of anally carry encroachm

ngs, biggeranent loss

designed fut indicateowever, in quency of 1er frequenc

rely depenan generalout sufferreas, the d varying fr

riods of d

07 | P a g e

out the about 3 f 3 day

have to

frequent ains are s, in any is to be

size tend e design scharge,

a smaller y higher ment on

r drains s of the

for three e that 5 specific 10 or 15 cies will

ndent on lly stand ing any drainage rom 7 to disposal

108 | P a g e

are recommended.

# Crops Period of Disposal (i) Paddy 7 to 10 days(ii) Maize, bajra and other

similar crops 3 days

(iii) Sugarcane and bananas 7days(iv) Cotton 3 days(v) Vegetables 1 day (in case of vegetables, 24 hour rainfall

will have to be drained out in 24 hours)

1.5.3 RUN‐OFF

Run-off coefficients depends on the type of soil, crops, general topographical conditions like land slopes, etc. In plain areas, the run- off percentage is generally of the order of 15 to 20. In semi- hilly areas the percentage may be higher. Until precise data becomes available, the following run-off coefficients for different soils are recommended for plain areas.

# Type of catchment Run-off Coefficient

(i) Loam, lightly cultivated or covered 0.40 (ii) Loam, largely cultivated and suburbs with gardens, lawns,

macadamized roads 0.30

(iii) Sandy soils, light growth 0.20 (iv) Parks, lawns, meadows, gardens, cultivated area 0.05-0.20 (v) Plateaus lightly covered 0.70 (vi) Clayey soils stiff and bare and clayey soils lightly covered 0.55

1.5.4 RUN-OFF FOR COMPOSITE CROPS

In large areas, there are often different types of crops grown. In such cases, the field and link drains can be designed on the basis of the crops grown in a particular area. For the outfall drain, either a composite discharge can be worked out or the total discharge can be worked out by taking into account the discharges from individual link drains. As the area grows larger, the chances of synchronization of discharge from the entire area become less. As such, working out a composite discharge may also serve the purpose. However, individual cases will have to be studied on their own merit. A typical gated sluice for high embankment is shown in Figure 26.

1.6

1.7

6 CAPACIT

IS alwathe caushighdrainhighaparirrigmuc

All ta 3dsamshou

DESIGN D

Thesiltifor cha

Velocity oWhere Qworked obed mateHydraulArea of cQ/V We(Q) 1/2 an(3340*Q

IS cthe

FIGU

TY/DESIG

code 853ays designdrains. Th

sed to theher than tn. Besides

her dischart from igation canach dislocat

the cross day rainfal

me dependiuld be take

DISCHARG

e drain shoing/scourithe drain

annel by La

of the flowQ = design dout using erial size inic mean dechannel setted perimnd Bed slo

Q1/6)

code 8535 drainage c

URE 26: A TYP

GNDISCHA

35:1978 sned for a his is maie structurethe designs, any remarges will involving dals, etc. Thion. The p

drainage ll of 50 yeing on theen to see th

GE FOR C

ould be deng is occu

nage channaceys theor

w (V in m/sdischarge the formu

n mm epth (R in ection (A in

meter (P in mpe (S) = (f

5:1978 envchannel.

PICAL GATED S

ARGEFORC

stimulates higher di

inly on aces in the eed rainfal

modeling onot only

dislocationhe drains resent pra

structuresear frequene type of chat afflux

CROSS DRA

signed as urred in tnel may bry. The des

sec) = (Qf2/in cumecs

ula f = 1.7

m) = 2.5* (n m2) = m) = 4.75 5/3) /

visages fol

SLUICE DRAIN

CROSSDRA

that croischarge tccount of event of flol, can be

of the stru be costl

ns to facilcan, howe

actices vary

s should, ncy, time crop. In fiis within t

AINAGE W

per Laceyhe drain s

be done asign proce

/140)1/6

s and, f is 76 (d) 1/2, w

(V2/f)

llowing gu

N

AINAGEW

oss drainthan the the fact t

ows result much m

uctures at ly but tilities like ever, be remy considera

therefore, of disposa

fixing the he permiss

WORKS

s regime tsection. D

as per desdure is as

the silt facwhere d is

uidelines fo

109

WORKS.

nage workcut sectio

that the ding from rore than a later daime consuroads, raimodeled wably.

be designal remainiwaterwayssible limits

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1.7.1 VELOCITY

The drain section shall be adequate to carry the designed discharge and the velocity shall be non-silting, non-scouring to be determined by Mannings formula.

1.7.2 DISCHARGE CAPACITY OF THE DRAIN

In order to obtain the discharge capacity of a drain it is necessary to know the mean velocity of flow as obtained above which when multiplied by the area of the cross section of the drain in square meters will give the discharge in m3/s.

1.7.3 SIDE SLOPES

In selecting the side slopes for the drain, it will be necessary to consider the kind of material through which the drain is to be excavated. Generally side slopes of 1.5H : 1V are provided.

1.7.4 CROSSSECTIONSOFTHEDRAIN

Although deeper sections of the drain may be desirable, the width to depth ratio should be so selected that the section is both hydraulically efficient as well as economical in excavation. In the case of drains with embankments, the berm width equal to the depth of the drain, subject to a minimum of 1 m should be provided between the toe of the embankment and the section of the drain. The top of the embankments should be 1 m higher than the design full supply level. Wherever, there is likelihood of backing up effect on account of floods in a river into which the drain outfalls, the top of the embankments should be so designed that the flood levels on account of back water conditions are accommodated within the section over which the minimum freeboard is to be provided.

1.7.5 FIXATIONOFFULLSUPPLYLEVEL(FSL)ATOUTFALL

Whenever the drain is out falling into a river, the FSL should be slightly higher than the dominant flood level. The dominant flood level is the stage of river/outfall which is (a) attained and not exceeded for more than 3 days at a time; and also (b) attained and not exceeded 75% of time over a period of preferably not less than 10 years. In cases where the topography permits, the FSL can be above the highest flood level. However, if such a level results in flatter slopes or in FSL becoming higher than the natural ground level, FSL at outfall should be kept slightly above the dominant flood level. In such cases, there will be backing up in the drain when the river rises above the dominant flood level.

Such occurrences being infrequent and of short duration can be

tolerated. Care shall, however, be taken in determining the dominant flood discharge and the level.

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1.7.6 HYDRAULIC SLOPE

The FSL of the drain as far as possible should be at or below the ground level. Where it cannot be ensured, the FSL should in no case be more than 0.3 m above the average ground level at the starting point of the drain. The hydraulic should then be determined adopting the stipulation and the criteria laid down for fixation of FSL at outfall.

1.7.7 FALLS

Normally no falls should be provided in drains except in rare cases where there is a sudden appreciable drop in the natural surface level or where the FSL s likely to be more than natural surface level without provision of falls.

1.8 LONGITUDINALSECTION

IS code 8535:1978 envisages following guidelines for deciding the longitudinal profile of drainage channel.

1.8.1 COLLECTIONOFDATA

The following data should be collected while carrying out surveys along different alternatives alignments of drains:

(a) Cross section of drain. (b) Natural ground, design bed and full supply levels . (c) Locations of inlets of link/field drains with related hydraulic data. (d) Full data of all crossings like roads, railways, irrigation canals, etc.

1.8.2 PREPARATIONOFLONGITUDINALSECTION

(a) Fix outfall level considering the dominant flood levels in the river/drain and the likely backing up.

(b) Hydraulic slope to be determined on the basis of the ground levels, permissible submersion and the outfall levels determined in (a).

(c) Plot the natural ground levels, design bed levels, full sully levels.

1.9 REFERENCES

1. IS code 8535:1978: Guidelines of Planning and design of surface drains.

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CHAPTER-4 CONCLUSIONS From the following studies and discussions the following conclusion can be drawn

1) As present site is located just 1200 meter d/s of Sant Sarovar weir ,the design flood of 7.25 Lack cusecs considered for Sant Sarovar Design will be adopted for protection work design between Shahpur Bridge and d/s of GIFT City. The check flood of 8.38 Lack cusecs adopted for Sant Sarovar will hold god for protection work also.

2) Looking to the Flood discharge and water way of River Sabarmati only existing alignment will be adopted for proposed protection work.

3) For the protection work existing bank alignment will be strictly adhered and eroded

Banks, Farms and agriculture land will be reclaimed by Flood protection schemes.

4) Embankment construction will be carried out from River Bed material and Borrow pits location will be adopted as specified in the IS 11532 and IS 12094.

5) The velocity calculated by model study for Sant Sarovar at 1200 m d/s and at Shahpur

Bridge varies from 4.86 m/s to 5.32 m/s on right and left bank respectively. Considering erosive effect due to these velocity on the banks the protection works will be designed accordingly.

6) The velocity mentioned above will be calculated by mathematical model study based on

Total station survey and cross section collected at certain interval along the river by HEC-2 Computer program developed by Hydrologic Engineering center, US Army corps of Engineers ,U.S.A and protection work will be designed accordingly.

7) Water surface elevation will be worked with protected banks/Jacketing river course for

adopted design flood as well as check flood by HEC 2 Computer program.

8) Free board of 1.8 m will be adopted and water surface elevation corresponding to check flood of 8.38 lacks cusecs will be contained within the Proposed free board will be ensured.

9) The foundation investigation will be carried out along the banks for engineering

classification, Grain size analysis , Silt factor and shape bearing capacity.

10) Silt factor will be adopted for working out scour depth and 1.27 times scour depth will be adopted for scour at the banks and design of Launching apron ,cut off ,Diaphragm ,sheet pile will be carried out accordingly.

11) Existing Drains outfall discharging from country side in to the river Sabarmati will be

effectively Drain into river by constructing appropriate structures.

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12) For protecting erosion prone bank Spurs/Groynes type of structures can be proposed

transverse to the river flow and extending from the bank into the river. However additional scour at curvature and meandering of river additional depth of scour will be worked out and depth of cut off /Diaphragm wall/Sheet pile will be provided .Launching Apron length and thickness will be extended for addition la scour at curvature .The bank protection with additional erosive effect at curvature shall be protected with Rigid boundary protection on slopes and excessive scour by additional depth of cut off and additional length of launching apron will prevent construction of spur and groynes. Rigid boundary will create permanent regime condition and further change in course of river and meandering will be prevented.

13) Based on preliminary design for protection works 3 alternatives have been worked out and which are as follows

ALTERNATIVE 1: CONSTRUCTIONS OF EMBANKMENT WITH STONES IN WIRE CRATE The Homogeneous embankment will be constructed with River side slopes of 2.5:1

abutting with existing banks with berm of width 5 m at intermediate level with available River bed material as borrow area and protection works on Banks with Stone in Wire crates and Geo Fabric filter.

For Scour protection 2 alternatives are proposed 1) Launching apron in wire crates 2) Cut off wall/Diaphragm wall/Sheet pile.

Based on preliminary design following geometrical parameters are considered bank height required of 13.8 m, side slope of 2.5:1,intermediated berm of 5 m country side slope of 2:1

The protection works on the banks consist of Geo Fabric filter ,1 m thick stones in wire crates ,country side slopes protected with 300 mm thick dry stone pitching ,for aesthetic purpose as well as to improve conveyance carrying capacity of the river 7.5 cm thick lining with paver finish is proposed .

The river bed is protected with Launching Apron of 9 m length and 1m thick Gabion

Mattresses and Geo filter below mattresses .Alternatively River Bed protection with 600 mm thick cut off wall /Diaphragm wall/sheet pile with anchorage at top with Wire mesh is proposed.

The top of embankment can be developed as assess road all along the Bank as well as

river front and intermediate berm can act as lower promenade ,Jogging Street.

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Cost of construction for Embankment with stones in wire crates and launching Apron is Rs 1,37,183 and for Embankment with stones in wire crates and Cut off wall is Rs 1,49,994

ALTERNATIVE 2: CONSTRUCTION OF GABION RETAINING WALL WITH TERRAMESH SYSTEM The Flood protection retaining wall with Terramseh system consisting of Fascia of stones

in wire crates and reinforced earth with Geo Mesh is proposed. The total height of retaining wall is divided in two parts of height 7 m each with intermediate berms of 5 m.

Granular material available in river bed is most adequate for reinforced earth technology

proposed here . Layers after Layer in control lift thickness of 30 cm will be constructed at OMC to 95% Proctor Density by vibratory roller and reinforcing with GEO Mesh will be carried out and stability of the same will be ensured by slip circle analysis.

Geo Fabric filter is proposed behind the stones in wire crates for preventing Fine particles

migration from the stones in wire crates. The river bed is protected with Ln with 600 mm thick cut off wall /Diaphragm wall/sheet

pile with anchorage at top with Wire mesh is proposed. Due to vertical Flood protection wall construction additional land of approximate width

of 30 to 35 m will be available at the top which can be developed as Service road/River Front Road with various recreational facilities.

For the above alternative cost of construction per running meter is calculated as Rs

1,18,494

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ALTERNATIVE 3: RIGID R.C.C COUNTER FORT /CANTILEVER WALL WITH DIAPHRAGM WALL/SHEET PILE CONSTRUCTION. The Flood protection wall consist of R.C.C Retaining wall of approximate height of 10

m from the stagnant water pool / full reservoir level extending above lower promenade as proposed in Ahmedabad Sabarmati River FRONT Development is proposed .

Cut off wall /Diaphragm wall/sheet pile is proposed below river bed for scour protection

and same wall is extended above stagnant pool water level /full reservoir level with adequate free board and lower promenade of 10 m wide is proposed

The lower promenade will be submerged during high flood level and will act as a part of

River Front and other recreational facilities. The depth of cut off wall is worked out to 6 m based on check flood discharge of 8.38

lack cusecs and thickness provided is 0.6 m and same is extended up to lower promenade level i.e. above full reservoir level.

Due to vertical Flood protection wall construction additional land of approximate width

of 30 to 35 m will be available at the top which can be developed as Service road/River Front Road with various recreational facilities.

Cost of construction per running meter is calculated as Rs 1,98,944.

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