Chapter 1

EARTHWORK

1.0 INTRODUCTION

The Earthwork consists of preparing areas upon which embankments are to be placed

excavating for the roadways and channels, including the removal of all material encountered

not being removed under another item; constructing embankments with the excavated

material and material from other approved sources as necessary to complete the planned

embankments furnishing and incorporating all water required for compacting embankment;

disposing of unsuitable and surplus material finishing shoulders, slopes, and ditches, and

proof rolling

All excavation is considered unclassified excavation. If the excavation contains

regulated materials such as garbage, solid waste, and hazardous waste or material, the

contract documents will detail the removal for these items. Use all suitable excavated

material in the work. Alternatively, legally use, recycle, or dispose of all excavated materials

according to applicable federal, state and local regulations.

Foto 1.0a : Earthwork in Highway Construction

1.1 SITE CLEARANCE.

The whole area to be occupied by the completed works is to be cleared and grubbed plus a

clearance of 2m from tops of cuttings and toes of embankments. Clearing includes removal

and disposal of all trees, stumps, logs, timber, scrub, vegetation, rubbish and other material

unsuitable for incorporation in the work. Grubbing is to be carried out to the level of 0.5m

below natural surface or 1.5m below finished earthworks level. Holes left after grubbing

under proposed embankments are to be filled with sound material and compacted in layers as

for embankments. Timber and combustible material shall be disposed off-site or shall be

burnt in suitable disposal areas with due care and in accordance with any relevant regulations.

Non-combustible materials shall be disposed off-site.

Foto 1.1b : Site Clarence of Ste

1.1.1. REMOVAL OF TOPSOIL AND UNSUITABLE MATERIAL

Topsoil shall be removed over the area which will be occupied by the completed

works plus a clearance of 2 metres. Topsoil shall be placed in a stockpile clear of the

work to enable its re-use in landscaping and vegetation. Unsuitable material includes

topsoil, peat and other highly organic soils, logs, stumps, perishable material, rubbish,

material susceptible to spontaneous combustion, free draining materials susceptible to

scouring, very fine sand, silt and organic clay and material such material shall be

excavated and disposed off-site except for top soil required for vegetation.

1.2 EXCAVATION FOR CUTTINGS

Excavation shall be carried out to the lines, levels, dimensions and slopes shown on the

Drawings. The excavated faces shall be neatly trimmed and the top edges of the cuttings

neatly rounded. Under cutting of slopes will not be permitted under any circumstances. Batter

slopes in rock cuttings in excess of 3m high and closer than 6m from the track centreline shall

be determined on the advice of GM ISP or nominated Geotechnical representative. If not

otherwise specified, cutting slopes should be in accordance with the following:

Foto 1.2c: Excavation Work

SlopeMaterial

Horizontal : Vertical

Sand 2 : 1Wet clay, loose gravel 2 : 1Sandy clay, boulders and clay compactgravelly soil, talus

2 : 1

Poor rock 75 : 1Sound shale dipping sharply towardsrailway formation, tight cemented gravel

1.5 : 1

Ordinary rock 1 : 1

Excavation shall be carried out in such a manner as to prevent erosion or slips,

working faces shall be limited to safe heights and slopes, and surfaces shall be drained to

avoid ponding and erosion. Slopes shown on the Drawings represent the estimated

requirements for the expected types of material and will be subject to re-determination on the

basis of site inspection and investigation during excavation.

.

Overhanging, loose or unstable material likely to slip should be cut back removed or

stabilised. Rock cuttings and exposed rock surfaces shall be excavated so as to obtain smooth,

uniformly trimmed surfaces. Batters in cuttings shall be carried around curves in an even and

regular manner. Finished batters shall not have a slope steeper than that specified. Excavation

at the base of cutting shall be finished at a level to suit the capping thickness, normally

150mm, and with crossfalls shown on the drawings. Tolerance on levels is between +0 and -

50mm. Compaction of the top 150mm layer in the base

1.3 DRILLING AND BLASTING IN ROCK CUTS

Where rock encountered in a cut requires drilling and blasting,

all necessary precautions shall be exercised to preserve the

rock in the finished slope in a natural undamaged condition,

with the surfaces remaining reasonably straight and clean. The

Contractor shall presplit rock and shale along proposed

backslopes which are designed at inclinations steeper than one

to one and where depths of cut in rock or shale exceed 5 feet

(1.5 m).

The Contractor shall first completely remove all overburden soil along the line(s) of

presplitting to expose the rock surface prior to drilling the presplitting holes. The Contractor

shall then drill 2 to 3 inch (63 to 76 mm) nominal diameter holes, spaced not more than 3 feet

(0.9 m) center to center along the required slope line and at the required slope inclination to

the full depth of the cut or to a predetermined stage elevation. If any cut is presplit by vertical

stages (lifts), the presplit drill holes for the next stage may be offset a distance of not more

than 1 foot (0.3 m) inside the previously presplit face, but in no case shall any of the presplit

holes be started inside of the payment line. No payment will be made for additional

excavation quantities caused by these offsets.

Before placing the charge, each hole shall be tested for its entire length to ascertain

the possible presence of any obstruction. No loading will be permitted until the hole is free of

all obstructions for its entire depth. All necessary precautions shall be exercised so that the

placing of the charge will not cause caving of material from the walls of the hole. The charge

for each hole shall consist of not less than 1/4 pound (0.11 kg) nor more than 1 pound (0.45

kg) of 40 percent dynamite per foot (0.3 m) of hole and spaced not more than 20 inches (0.5

m) center to center of charge, except that 1/2 to 2 ½ pounds (0.23 to 1.13 kg) of dynamite

shall be placed in the bottom of the hole, and except near the top of the hole the charges shall

be reduced sufficiently to eliminate overbreak and heaving.

The top charge shall not be less than 2 ½ feet (0.76 m) nor more than 3 feet (0.9 m)

below the top of rock. The spacing of the dynamite charges in each hole shall be

accomplished by means of securely taping (or attaching by other approved means) each piece

of dynamite to the detonating fuse at the required intervals, or by deck loading. If the latter is

used, the dynamite must be in intimate contact with the detonating fuse to assure detonation

of all charges.

1.4 PREPARATION OF EMBANKMENT BASE

Preparation includes clearing, grubbing, removal of topsoil and removal of unsuitable

material and subsequent restoration. It also includes cutting of terraces into slopes, scarifying

and compaction of embankment base and provision of drainage works as specified below.

Where embankments are to be constructed on a natural slope or on the slope of an existing

embankment steeper than 4 to 1 (horizontal to vertical), the existing slope is to be cut in

horizontal terraces at least 1.5m wide. The terraces are to be cut progressively as the

embankment is constructed. Suitable material excavated in cutting the terraces may be

incorporated in the embankment but unsuitable material must be disposed off-site.

Chapter 2

SLOPE FAILURE

2.0 INTRODUCTION

A landslide can be defined as the mass movement of earth down slope. It is a rapid slipping

of a mass earth or rock from a higher elevation to a lower level under the influence of gravity

and water lubricant. Landslide describes a wide variety of process that result in the downward

and outward movement of slope-forming materials including rock, soil, artificial fill, or a

combination of these. The materials may move by falling , topping, sliding spreading, or

flowing.

According to Wikipedia for landslides, Landslide or landslip is define as a geological

phenomenon which includes a wide range of ground movement, such as rock falls, deep

failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore

environments. Although the action of gravity is the primary driving force for a landslide to

occur, there are other contributing factors affecting the original slope stability. Typically, pre-

conditional factors build up specific sub-surface conditions that make the area/slope prone to

failure, whereas the actual landslide often requires a trigger before being released.

2.1 CLASSIFICATION OF LANDSLIDE

The following table shows a schematic landslide classification by Varnes, 1978 and with the

modifications made by Cruden and Varnes, in 1996,Landslide can be classified into five main

group:

2.1.1 Falls

Falls is a complex movement of materials on a slope, includes rational slump.

Varnes, 1996 stated that “A fall starts with the detachment of soil or rock from a

steep slope along a surface on which little or no shear displacement takes place. The

material then descends mainly through the air by falling, bouncing, or rollin”. The

secondary falls is involves rock bodies already physically detached from cliff and

merely lodged upon it" (Hutchinson, 1988)

The speed for the falls will be from very to extremely rapid and and maybe

happen in just a second. The leaning soil that we call slope is start from 45

degrees to 90 degrees inclined. Falls is happens when there are Vibration,

undercutting, differentia weathering, excavation, or stream erosion imposed on

the slope.

igure: Falls occur where a block of material free-falls from a slope

Picture2.1.1 a: Falls occur at SAINT-JUDE

2.1.2 Topples

Topples is the end-over end motion of rock down a slope. Topples also can be

define as the forward rotation out of the slope of mass of soil or rock about a

point or axis below the centre of gravity of the displaced mass. Toppling is

sometimes driven by gravity exerted by material upslope of the displaced mass

and sometimes by water or ice in cracks in the mass" (Varnes, 1996)

It is involve rock or soil that tilts and/or rotates forward on a pivot point. There

is not necessarily much movement; however it may lead to falls or slides of the

displaced material. The speed of this type of landslides is extremely slow to

extremely rapid. Type of slope angle 45-90 degrees and also can be cause by

Vibration, undercutting, differential weathering, excavation, or stream erosion.

Figure2.1.2b: Topples occur when the end-over end motion of rock

down a slope

Pictur2.1.2c: Jasper National Park- Canada Landslide type: Topple-Wikipedia

2.1.3 Slides

A slide is a down slope movement of soil or rock mass occurring dominantly

on the surface of rupture or on relatively thin zones of intense shear strain.

(Varnes, 1996). It also can be state as movement that parallel to planes of

weakness and occasionally parallel to slope.

It has been develop when there are a crack forms at the top of the slope.

There are three types of slide:

a) Rotational rock slump – the surface of rupture is curved concavely

upward and the slide movement is roughly rotational about an axis that

is parallel to the ground surface and transverse across the slide. (figure

(a))

Figure (a): Rotational Slump

b) Traditional debris slide – the landslide mass move along a roughly

planar surface with little rotation or backward tilting.(Figure (b))

Figure (b): Traditional Landslide

c) Earth block slide – Translational slide in which the moving mass

consists of a single unit or a few closely related units that move down

slope as a relatively coherent mass.(Figure (c))

Figure (c): Block Slide

2.1.4 Lateral Spreads

Spread is defined as an extension of a cohesive soil or rock mass combined

with a general subsidence of the fractured mass of cohesive material into

softer underlying material. (Varnes, 1996). In spread, the dominant mode of

movement is lateral extension accommodated by shear or tensile fractures

(Varnes, 1978)

These type of landslide involve sudden horizontal movement on very gentle

terrain. Its often initiated by earthquakes that liquefy the layer below the

moving materials. (Figure (d))

Figure (d): Lateral Spread.

2.1.5 Flows

Flows are a spatially continuous movement in which surfaces of shear are

short-lived, closely spaced, and usually not preserved. The distribution of

velocities in the displacing mass resembles that in a viscous liquid. The lower

boundary of displaced mass may be a surface along which appreciable

differential movement has taken place or a thick zone of distributed shear

(Cruden & Varnes, 1996)

Flows vary in type of material and the speed their travel. There are five basic

categories of flows that differ frrom one another in fundamental way.

a) Debris Flow - very rapid to extremely rapid (>5 m/s), the angle

20-45 degrees, it will cause of high intensity rainfall (Figure (e))

Figure (e): Debris Flow

b) Debris avalanche - Debris avalanche is a very rapid to extremely

rapid shallow flow of partially or fully saturated debris on a steep

slope, without confinement in an established channel." (Hungr et

al., 2001). The angle of the slope is 20-45 degree and it will be

caused of High intensity rainfalls. (Figure (f))

Figure (f): Debris avalanche

c) Earthflow - intermittent flow-like movement of plastic, clayey earth."

(Hungr et al.,2001), the speed is slow to rapid (>1,8 m/h). The slope

angle is 5-25 degrees. (Figure (g))

Figure (g): Earthflow

d) Mudflow - very rapid to extremely rapid (>5 m/s), involving

significantly greater water content relative to the source material

(Plasticity index> 5%)." (Hungr et al.,2001), the angle 20-45 degrees

and it will causes of high intensity rainfall (Figure(h))

Figure (h): Mudflow

e) Creep – imperceptibly slow, steady, downward movement of slop-

foeming soil or rock. Movement is caused by shear stress sufficient

to produce permanent deformation, but too small to produce shear

failure. (Figure (i))

Figure i: Gradual movement of slope materials- creep flows.

2.2 CAUSES OF LANDSLIDE

The Mameyes Landslide, in barrio Tibes, Ponce, Puerto Rico, which buried more than

100 homes, was caused by extensive accumulation of rains and, according to some

sources, lightning. Landslides occur when the stability of a slope changes from a

stable to an unstable condition. A change in the stability of a slope can be caused by a

number of factors, acting together or alone. Natural causes of landslides include:

groundwater (pore water) pressure acting to destabilize the slope

Loss or absence of vertical vegetative structure, soil nutrients, and soil

structure (e.g. after a wildfire)

erosion of the toe of a slope by rivers or ocean waves

weakening of a slope through saturation by snowmelt, glaciers melting, or

heavy rains

earthquakes adding loads to barely-stable slope

earthquake-caused liquefaction destabilizing slopes

volcanic eruptions

Landslides are aggravated by human activities, Human causes include deforestation,

cultivation and construction, which destabilize the already fragile slopes

vibrations from machinery or traffic

blasting

earthwork which alters the shape of a slope, or which imposes new loads

on an existing slope

in shallow soils, the removal of deep-rooted vegetation that binds

colluvium to bedrock

Construction, agricultural or forestry activities (logging) which change the

amount of water which infiltrates the soil.

2.3 LANDSLIDE FACTORS

a) Ground Condition

Such as sensitive material, Collapsible material. Weathered Material, sheared

material, Jointed or fissured material.

b) Geomorphologic Processes

Such as erosion of the lateral margins. Subterranean erosion (solution, piping).

Vegetation removal

c) Physical Processes

Such as intense (short period rainfall), earthquake, Volcanic eruption, shrink and

swell weathering of expensive soils.

d) Man-made Processes

Such as excavation of the slope or its toe, loading of the slope or its crest, Drawdown

(of reservoirs), defective maintenance of drainage systems, vegetation removal.

2.4 LANDSLIDES MIGATION

Landslides can be triggered by many often concomitant causes. In addition to shallow

erosion or reduction of shear strength caused by seasonal rainfall, causes triggered by

anthropic activities such as adding excessive weight above the slope, digging at mid-

slope or at the foot of the slope, can also be included. Vulnerability to landslide

hazards is a function of location, type of human activity, use and frequency of

landslides events. the effects of landslides on human and structures can be lessened by

total avoidance of landslide hazard areas or by restricting, prohibiting or imposing

conditions on hazards-zone activity. Local governments can reduce landslide effects

through land-use policies and regulations. Individuals can reduce their exposure to

hazards by educating themselves on the past hazard history of a site and by making

inquiries to planning and engineering departments of local governments. They can

also obtain the professional services of an engineering geologist, a geotechnical

engineer, or a civil engineer, who can properly evaluate the hazard potential of a site,

built or unbuilt.

The hazard from landslides can be reduced by avoiding construction on steep

slopes and existing landslides, or by stabilizing the slopes. Stability increases

when ground water is prevented from rising in the landslide mass by;

i. covering the landslide with an impermeable membrane

ii. directing surface water away from the landslide

iii. draining ground water away from the landslide, and

iv. minimizing surface irrigation.

Slope stability is also increased when a retaining structure and/or the weight of

a soil/rock berm are placed at the toe of the landslide or when mass is removed

from the top of the slope. However, landslide can be maintain with;

i. Modification of slope geometry

ii. Drainage

iii. Retaining structure

iv. Internal slope reinforcement.

Chapter 3

SLOPE RESISTANCE

3.0 INTRODUCTION

Weathering can produce a thick mantle of unconsolidated material on slopes that may fail as

a result of human activity or natural processes. Mass wasting is the downslope movement of

material under the influence of gravity and mass wasting phenomena can be linked to

weathering processes. Mass wasting processes may be slow and gradual or swift and deadly.

Weathered debris may collect on slopes or form new slopes in areas with relatively rapid

weathering rates.

This unconsolidated material is susceptible to collapse resulting in slope failure. The

downslope movement of material under the influence of gravity is termed mass wasting and

represents one of the most active processes in modifying the landscape in areas of significant

relief. Mass wasting involves material other than weathered debris (notably in rock slides) but

most mass wasting phenomena occur in a thick mantle of regolith, the rock and mineral

fragments produced by weathering. The general term landslide is used to describe all rapid

forms of mass wasting.

3.1 SLOPE FAILURE FACTOR

Gravity can be divided into components acting parallel to a slope and perpendicular to the

slope. Failure is more likely to occur if the effect of friction on the potential sliding surface is

reduced. The physical properties of the slope materials such as cohesion between grains may

reduce the potential for slope failure. The angle of repose is the maximum slope generated

when loose unconsolidated material is formed into a pile. The addition of excess water may

destabilize slopes by adding weight, destroying cohesion between grains, and reducing

friction.

Gravity acts on all objects on Earth’s surface. Gravity can be divided into two

components for objects resting on sloping surfaces. One component is parallel to the

slope and one is perpendicular to the slope. On steep slopes (>45 degrees) the

component parallel to the slope will be greatest and will act to pull objects downhill.

On gentle slopes the component perpendicular to the slope will be greatest and will

act to hold the object in place. However, gravity alone does not determine if the object

will move downslope. There are numerous steep slopes that are not currently

undergoing mass wasting. A physical trigger is often required to initiate slope failure.

The properties of the surface between the object and the slope (e.g., friction)

and the physical properties of the sliding object itself all contribute to the potential for

mass wasting. The object is more likely to move if friction between the object and the

slope is reduced. In contrast, a slope will be less likely to fail if the cohesion between

the grains in the material is increased.

3.2 LANDSLIDE MAINTENANCE.

There are several ways to maintain a slope from the landslide such as:-

i. Modification of slope geometry

ii. Drainage

iii. Retaining Structures

iv. Internal slope reinforcement.

3.2.1 Modification of slope geometry

The Modification of slope geometry is the second most used method. These type of

maintenance is the least costly from the four major categories of landslide

maintenance. Modification of slope geometry is a most efficient method particularly

in deep seated landslides. However, the success of correcyive slope regarding is

determined mot merely by size or shape of the alteration, but also by position on the

slope. (Kyōji Sassa, 2008)

3.2.2 Drainage

According to Kyōji Sassa, 2008, drainage is often a crucial remedial measure due to

the important role played by pore-water pressure in reducing shear strength. Because

of its high stabilization efficiency in relation to cost, drainage of surface water and

ground water is the most widely used, and generally the most successful stabilization

method. For the long term uses, the drains must be maintained to it continue to

function.

Kyōji Sassa, 2008 stated that the surface water is diverted from unstable

slopes by ditches and pipes. Drainage of the shallow ground water is usually achieved

by networks of trench drains. Drainage of the failure surfaces, on the other hand, is

achieved by counterfort or deep drains which are trenches sunk into the ground to

intersect the shear surface and extending below it. In the case of deep landslides, often

the most effective way of lowering groundwater is to drive drainage tunnels into the

intact material beneath the land slide.

3.3 RETAINING STRUCTURES

3.3.1 Introduction

Structures that holds back earth is called retaining wall. Retaining wall used to

stabilize soil and rock from down slope movement or erosion and provide support for

vertical or near-vertical grade changes. It means the function of a retaining wall is to

resist the lateral thrust of a mass of earth on one side and sometime the pressure of

subsoil water. In many cases the wall may also be required to support vertical loads

from a building above.

There are varieties of structure used to retain soil and/or water for both

temporary or permanent works as illustrated below. Mass Concrete or Masonry walls

rely largely on their weight for stability against overturning and sliding. They are un-

reinforced so their height must be limited to ensure internal stability of the wall in

bending and shear when subjected to the leteral stresses. They are typically not more

than 3m high. Providing a minimum slope of 1:50 on the front face avoids the illusion

of a vertically wall tilting forwards.

Reinforced concrete wall is more economical with reinforced enabling the

stem and base sections to be designed as cantilevered structural elements. Overall

stability is provided by an adequate base width and the weight of backfill resting on

the base slab behind the stem.

3.3.2 TYPES OF RETAINING WALL

According to Buzzles.com, the build of retaining walls consists of materials like

masonry, stone, brick, concrete, vinyl, steel or timber. Certain areas have topography

that varies from slightly rolling to mountainous. For such areas, retaining walls allow

the construction of steps or level areas. Retaining walls had been used by ancient

Roman civilization in the construction of roads. Their extensive use can be found in

many castles in Europe as well. Since then, there were many types of retaining wall

construction which have been used and improvised over time. Several of the types of

retaining walls has been described below.

3.3.2.1 Gravity Walls.

Gravity walls are any coherent structures that rely solely on its mass and

geometry to resist the earth pressure farces acting on it. Modular gravity walls rely

on weight, depth. Wall batter and inter-unit shear strength to achieve greater wall

heights as indicated in the gravity wall design. These depend mostly on their own

weight for stability. This type of retaining wall has wide bases and usually a rigid

construction.

1. Masonry Walls

A masonry wall is a wall made from materials which have

traditionally been cemented together with the use of mortar. Masonry

walls can have a wide variety of shapes, looks, and feels. Some are low

and broad, while others are thin and tall, and they can include varying

sizes of material for more visual interest, or uniformly shaped and sized

material for a more regular look. When designing masonry walls, people

need to think about how the wall will be used, the level of reinforcement

which may be necessary, and the desired aesthetic look of the wall and

surrounding environment.

Figure 3.3a: Examples of masonry wall

2. Gabion Walls

Gabion wall is a retaining wall made of rectangular containers or

basket fabricated of heavily galvanized wire, which are filled with

stone and stacked on one another, usually in tiers that step back with

the slope rather than vertically. The most common civil engineering

use of gabions is to stabilize the slopes against erosion. Other uses of

gabion walls are include retaining walls, temporary floodwalls, to

filter silt from runoff, for small or temporary or permanent dams,

river training, channel lining. (Wikipedia- Gabion)

Figure 2: Gabion Wall – Source from www.maccaferri-

northamerica.com

3. Crib Walls

Crib walls are constructed by interlocking individual boxes made

from pre-cast concrete or metal members and sometimes made from

timber for temporary works. The boxes filled with crushed stone or

coarse granular materials to create a free-draining structure. The

units are spaced so that the fill material is contained within the crib,

is not affected by climatic change and acts in conjunction with the

crib work to support the retained earth. Crib walls should not be used

for retaining slopes which are liable to slip. (Hunt, R. E., 1986)

Figure 3: pre-cast crib wall. (Crib wall at Paradise Road

Interchange)

– Source from www.infolink.com.au.

4. RC Walls

Reinforced concrete cantilever walls are the commonest modern

form of gravity wall. Either an L-shaped or an inverted T-shaped

cross-section is formed to produce a vertical cantilever slab, simple

cantilever, some utilizing the weight of backfill on the heel portion of

the slab, are suitable for walls up to 6 in height, for grater height,

counter fort walls or buttressed walls can be used. It is to improved

resistance to sliding a downward-projecting key is often incorporated

into the base.

Figure 4: Cantilever wall –Source from m.concretenetwork.com

5. Counterfort Wall

Counterfort walls are cantilever walls strengthened with counterforts

monolithic with the back of the wall slab and base slab. The

counterforts act as tension stiffeners and connect the wall slab and

the base to reduce the bending and shearing stresses.

(www.sbe.napier.ac.uk)

Counterforts are used for high walls with heights greater than 8 to 12

m. They are also used for situations where high lateral pressures

occur, e.g. where the backfill is heavily surcharged. Counterforts

should be designed as cantilevers of T-section and the wall stem as a

continuous slab. The design should transfer the main part of the earth

thrust from the slab to the counterfort. (www.sbe.napier.ac.uk)

Figure 5: Counterfort wall.

Source from m.concretenetwork.com

6. Buttressed Walls.

It is similar to counterfort walls except that the vertical braces are placed

on the wall instead of along the back. The vertical braces or stiffeners act

as compression braces. They are used for tall walls, but are not as

common as counterfort walls. (www.sbe.napier.ac.uk)

3.3.2.2 Embedded Walls

Embedded walls are constructed from contiguous or interlocking

individual piles or diaphragm wall-panels to form a continuous structure.

Embedded walls may be cantilever, anchored or propped. These are

constructed around the basement perimeter before excavation commences,

occupying minimal space but providing support to the soil and ground

water both in the permanent condition as the final structural basement

wall. They also support to vertical loads such as the external columns and

walls of a building.

1. Driven Sheet-Pile Walls

Sheet pile retaining walls are usually used in soft soils and tight spaces. Sheet

pile walls are made out of steel, vinyl or wood planks which are driven into the

ground. For a quick estimate the material is usually driven 1/3 above ground,

2/3 below ground, but this may be altered depending on the environment.

Taller sheet pile walls will need a tie-back anchor, or "dead-man" placed in the

soil a distance behind the face of the wall, that is tied to the wall, usually by a

cable or a rod. Anchors are placed behind the potential failure plane in the soil.

(Wikipedia-retaining wall)

This type of retaining wall used particularly for temporary works, in

habour structures and in poor ground. It has different material types including

timber. For cantilever walls up to 3m high and pre-cast concrete used for

permanent structure.

Figure 3.3.d: Sheet pile

Source from Courtsey H.B. Fleming

Sheet pile walls are constructed by:

i. Laying out a sequence of sheet pile sections, and ensuring that sheet

piles will interlock.

ii. Driving (or vibrating) the individual sheet piles to the desired depth.

iii. Driving the second sheet pile with the interlocks between the first

sheet pile and second "locked"

iv. Repeating steps 2 & 3 until the wall perimeter is completed

v. Use connector elements when more complex shapes are used.

2. Braced or Propped Walls.

Braces, props, shores or struts are placed in front of the wall. The lateral

deflection and bending moment are reduced, and embedment may not be used.

Furthermore, in wide excavations framed shores or raking shores are used.

3. Contiguous Bored-Pile Walls

Contiguous bored pile are formed from a single or double row of piles

installed in contact with each other in very close proximity. The alternate piles

are first drilled and placed and then a casing guide is used to drill alternate pile

holes.

Figure 3.3e : Contiguous bored pile

Sources http://www.purkelly.com/contiguous-piling.html

4. Secant Bored-Pile Walls

The wall is formed from bored piles, usually about 1 m diameter

piles are drilled in a row at closer spacing than the pile diameter and

the concrete placed. While the concrete are still weak,(after 2/3

days), the intermediate holes are drilled along a parallel, but slightly

offset, line so that these holes cut into first piles.

5. Diaphragm Walls

The principal of a Diaphragm Wall is to construct a retaining wall

within a slot excavated in the ground. Once completed the diaphragm

wall can be used as a retaining wall for a multitude of applications,

for example basement walls, earth retaining wall, water storage tank,

cut off walls, etc.

Figure 8; Diaphragm wall construction

source from www.bachy-soletanche.com.sg

6. Anchored Earth

There are several forms of anchored earth wall. In essence, any wall

which uses facing units tied to rods or strips (of any material) which

have their ends anchored into the ground is an anchored earth wall.

To aid anchorage, the ends of the strips are formed into a shape

designed to bind the strip at the point into the soil.

These anchor ends of the strips can take one of many forms. It

is important to realize that anchored earth walls act in a

fundamentally different manner to reinforced soil walls. With

anchored earth the resistance of the strips to movement is controlled

by their end anchor. In contrast, the reinforcing strips used in

reinforced soil, are found fully into the soil mass along their full

length.

Figure 9: Anchored earth

source from www.retainingsolutions.com

7. Reinforced earth walls

It consists of frictional backfill laid and rolled in layers between

which placed either reinforcing strips or geotextile mesh. It used in

retaining walls, sea walls, dock walls, bridge abutments, earth dams

and in numerous temporary works.

8. Soil nailing

An in situ reinforcement method in which steel bars or angles or

other metallic elements are driven in or grouted in drilled holes. Soil

nailing is typically 3m to 5m long and at spacing of 0.5-2 inch, the

facing is often simply a layer of shot Crete or gunite that primarily

used for temporary works, but suitable for same permanent structures

with non-corrodible nails.

Figure 10: Soil Nailing

Source from forum.skyscraperpage.com

9. Ground anchors

Ground anchor is tendons formed of rods, crimped bars or expending

strip elements are pressure – grouted into drilled holes, used as tic-

backs for sheet-pile walls, rock faces, tunnels and mine works.

3.3.3 FUNCTION OF RETAINING WALL

The function of a retaining wall is to form a nearly vertical face through

confinement and strengthening of a mass of earth or other bulk material. Besides,

the function is to strengthen the mass of earth or other bulk material such as

steep slope can be formed. In both cases, the purpose of constructing such

structures is to make maximum use of limited right of way. The difference

between it is that a wall uses a structural facing whereas a steep reinforced slope

does not require a structural facing. Reinforced slope typically use a permanent

erosion control matting with low vegetation as a slope to prevent erosion.

3.3.4 FAILURE OF RETAINING WALLS

The common failures of retaining wall are:

Stability failure

a. Overturning.

b.   Sliding.

c. Bearing capacity

Figure 11: stability Failure

Source from www.ce-ref.com

Structural failure

a. Bending or shear failure of stem.

b. Bending or shear failure of heel

c. Bending or shear failure of toe.

d. Bending or shear failure of key

Figure 12: Structural failure

Source from www.ce-ref.com

All items above should be considered in designing a retaining wall. There is also a rotational

stability failure that is not normally checked except when a retaining wall is located on a

slope

Chapter 4

SOIL IMPROVEMENT

4.0 DEFINITION

In the dredging industry soil improvement is typically implemented:

To prevent excessive settlement of reclaimed land when it is being utilized for

construction purposes such as roads, airport, bridge, and other foundations.

To enhance the soil stiffness in order to prevent liquefaction and subsequent

damage to structures in seismic-sensitive regions.

To enhance the shear strength of the soil to prevent slip failure.

To immobilize or stabilize contaminants in dredged soil in order to eliminate

environmental impacts.

Besides, soil improvement techniques vary depending on the characteristic of the soil.

Some technique is applied to consolidate existing loose subsoil and some are

specifically for compaction of newly reclaimed soil.

Furthermore, soil improvement is also applied to improve the mechanical

characteristic of contaminated soft soil by immobilizing heavy metal and other soil

contaminants. Many techniques have been developed to consolidate contaminated

sediment such as dewatering the sediment to reduce the quantity of soil, or combining

the sediment with additives, such as mixing sediment with cement which allows the

recycle use of the sediment as construction and or reclamation material.

4.1 SOIL IMPROVEMENT METHOD

Soil improvement technique have been widely used to improve or to change

properties of soil deposits for the purpose of strength increase, settlement control,

seepage control and reducing liquefaction potential under seismic loadings. There are

many factors which affect the effectiveness of a soil improvement method. Some of

the most important factors are:

The objectives of treatment or improvement and the intended use of the

treated ground.

The extent of improvement , including area, depth and total volume of soil to

be treated.

Soil type and properties.

Availability of materials such as sand, gravel or admixture.

Environmental factors.

Local experience and practice.

Time schedule.

Cost

The soil improvement methods which are suitable for the soft soil in Malaysia may be

classified as follows:

I. Geometrical Methods

When the moment of force causing the failure or the settlement is reduced, the

geometrical method has three technique such as:

a) Floating foundation

Floating foundation is a special type of deep foundation where the

weight of the structure is balanced by the removal of soil and

construction of an underground basement.

Figure 1: the example floating slab for foundation wall

b) Light Weight Fills

Because both stability and settlement of foundation depend on the load

applied to the foundation soils, problem foundation soil can often be

improved by simply reducing the load and, therefore, the stress on the

foundation. For building, bridge, and tanks, such as approach is rarely

feasible because it entails a complete redesign of the structure. On the

other hand, for embankment on soft foundations, reduced stress is a

viable design alternative, especially if it involves lightweight fills

materials. Various type of lightweight material that have been used in

embankment include wood bark, and sawdust, bailed peat, fuel ash,

slag, etc ; cellular concrete, expanded clay or shale and others.

Figure 2: Diagram of Highway 12 Passing Lanes and Shoulder Widening

c) Pressure Berms

Pressure berms are used on roads and for dykes where stability is

unsatisfactory. The method is based on building a counterweight that

prevents the embankment from sliding outwards.

The height and width of the pressure berm depend on the density of the

material as well as the shear strength and depth to firm bottom. In

general, any material may be used, which makes the method simple

and inexpensive. The use of pressure berm is very common in

building objects where there are problems with surplus soil and rock.

II. Mechanical Method

This method used where the shear strength is increased or the compressibility

is reduced by reducing the water content of the soil. This method have four

typ[e if technique such as:

a) Preloading(often combined with vertical drains to increase the

consolidate rate)

The prefabricated vertical drain (PVD) with preloading method was

considered the most feasible treatment option for the project based on

the depth of treatment, cost, time available for preloading and other

consideration. The objective of using vertical drain with preloading

technique is to accelerate the rate of consolidation and to minimize

future settlement of the treated area under the future dead and live

loads. Preloading increases the bearing capacity and reduces the

compressibility of weak ground by forcing soft soil to consolidate.

Soil improvement works is carried out in such a way that a specified

degree of primary consolidation is designed to be attained within the

desired time frame by improving the soil drainage system.

1) Preloading

The idea of preloading consists of first loading the foundation

layer such a manner and over a well-chosen area so that the

settlement related to this preloading already, either completely

or to a large extent, constitute the initial expected deformation

for the final construction (Van Impe, 1989). Preloading, with

or without vertical drains is only effective in causing

substantial pre-emptive settlement if the total applied load

significantly exceeds the pre-consolidation pressure of the

foundation material (Hausmann, 1990).

Soil stresses and pore water pressure are increased by the extra

weight, the pore water pressure temporarily. If the excess pore

water is then expelled, only the increased effective stresses

remain. The initial effective stresses after preloading may thus

increase considerably, leading to soil improvement during

construction.

2) Vertical drain

II.1 History of vertical drains

The American engineer D.J Moran first proposed the use of

sand drains as a means for deep stabilization in 1925. The

first practical sand drain installation were constructed in

California a few years later (Holtz et al, 1991).

In the last 20 years, a new frontier seems to have opened for

vertical drains. A large number of prefabricated drains

have appeared on the market. This competition has

decreased the cost of the drains appreciably. Installation

procedures too have improved and rapid installation to

depths up to 60 meters can now be achieved at rates of 1

m/s. Currently vertical drains are the most common form

of deep ground treatment in this region and their application

are vast in projects such as roads, railways, port, airport and

various other infrastructure projects.

II.2 Function of Vertical drains

In order to reduce, in cohesive layers, the time required to

reach a high degree of consolidation under preloading,

improved drainage should be used in the form of

prefabricated vertical drains (Van Impe, 1989).

The primary use of prefabricated vertical drains is to

accelerate consolidation to greatly decrease the settlement

time of embankment over soft soils such that the final

construction can be completed in a reasonable time with

minimal post construction settlement. By doing so the

vertical drains also accelerate the rate of strength gain of the

in-situ soft soils. Furthermore, vertical drains decrease the

amount of surcharge or preload material required to achieve

a settlement in a given time. Without installing vertical

drains, bearing failures may occur during placement of the

fill and settlement of soft soil may extend over many years,

Due to the high efficient drain installation methods,

preloading combined with vertical drains has become an

economic alternative to the installation of other ground

improvement methods (Hausmann, 1990).

Vertical drain accelerates primary consolidation only,

because significant water movement is associated with it.

Secondary consolidation causes only very small amounts of

water to drain from the soil and as a such secondary

settlement is not speeded up by vertical drains. Vertical

drains are particularly effective where a clay deposit

contains many thin horizontal sand or silt lenses (so –called

micro layers).

Prefabricated vertical drains are band shaped (rectangular

cross-section) products consisting of a geotextile filter

material surrounding a plastic core. The size of the

prefabricated vertical drain is typically 10 cm wide by 3 to

4 mm in thickness (BO et al, 2003). The material consists

of a plastic core formed to create channels which are

wrapped in a geotextile filter (Schaefer, 1997). The main

function of the filter of the vertical drain is to ensure that

fine particles cannot pass through and clog the drainage

channels in the core (Hansbo, 1981).

II.3 Properties of Prefabricated Vertical Drains

Prefabricated vertical drains consists of a core and filter

sleeve which are made of polymers. The dimension of the

drain is normally 100 mm wide and 3-4 mm thick. The

performance of vertical drain is affected not only by the

drain itself but also by the type of soil and the installation

method (Bo et al, 2003). The filter interacts with the soil

and the properties of it control the entry of water into the

drains. The method of installation used requires for the

vertical drain to posses a certain tensile strength to sustain

the tensile stresses subjected to it during the installation

process.

II.4 Type of vertical drains

There has many different types of vertical drain and

generally they can be divided into:

a. Sand drain

The drain is normally placed in a triangular or in

rectangular pattern at a spacing of 1.0 to 1.5m between

the drains. A standard pile driving rig is often used for

the installation of the sand drains as illustrated.

A large diameter steel pipe or casing is utilized which is

driven down the soil. The bottom of the pipe is usually

closed by a trap door thereby displacing the soil during

the driving jetting and pre-drilling can be used to reduce

the disturbance of the soil during the installation of the

drains.

The casing is filled with sand of suitable gradation

before the casing is retrieved after the driving. The

gradation of the sand had to be such that it functions as

a filter. At the same time the permeability had to be

high enough so that the loss of hydraulic head through

the drain will not be excessive. Otherwise the

effectiveness is reduced.

The maximum length of the drains is about 30 meters.

A 0.3 meters to 0.5 meters thick surface drainage layer

or blanket is usually placed over the ground surface

before the construction of the fill and the installation of

the drains. The largest particle size of the granular soil

in the drainage layer is normally 60mm since large

stones will interfere with the installation of the drains.

The drainage layer will also increase the bearing

capacity so that the relative heavy machines required for

the installation of the drains will not bog down in the

underlying soft clay.

The drain diameter ha s a relatively small influence of

the consolidation rate since the effectiveness of the sand

drains depend mainly on the spacing of the drains.

Commonly the drain diameter is in range of 300-

500mm.

Sand drains have almost been completely replaced by

band drains partly due to the high installation rate and

the resulting savings in time and costs and partly due to

the high efficiency of the band drains due to the

relatively small disturbance of the soil during the

installation of the drains.

Figure 3: Typical sand drain installation

b. Pre-fabricated band-shape vertical drains

Prefabricated vertical drains are band-shaped with a

plastic core wrapped by a filter sleeve. The plastic core

provides channels for the discharge of water provides

strength during installation and resistance to crushing

from the soil pressure at depth. The function of outer

filter sleeve is to ensure that fine particles are not able

to pass through and clog the drainage channels in the

core. The size of drains is usually 100mm width and

the thickness varies between 2 and 7mm.

A thin walled steel pipe is used for the installation of

band drains. The drains anchored in the soft soil by an

anchor plate at the bottom of the drain when the closed

end mandrell is withdrawn. The maximum length of the

drains may even exceed 40m. The installation rate is

high. Up to 4000 to 5000m can be installed per rig per

10 hour day. A vibratory hammer might be required to

penetrate a thick sand layer. Jetting has also been used.

b) Deep Compaction using blasting

Deep compaction using blasting is the process of detonating small

charges within loose cohesion less soils for the purpose of

densification.This technique immediate and long term surface

settlement. Settlement can be 2-10 percent of treated strata thickness.

Penetration resistance will increase slowly with time for several weeks.

Dense zones may be loosened during blasting.

The design consideration such as below:

i. Charges should be placed at approximately ½ -3/4 of desired

depth of compaction.

ii. Spacing of detonation holes should be between 5-15m.

iii. Successive coverage’s are separated by hours or days.

iv. Individual charge 1-12kg, the amount of total explosive is 89-

150g/m3of treated soil.

v. Soil closet to the surface will be poorly compacted and may

need compaction by another method or removal.

vi. The compaction resulting from blasting is a function of the

initial relative density.

Figure 4: deep compaction technique using blasting

iii) Physical and Chemical method

The method used when the shear strength is increased and the compressibility of soft

clay is reduced by altering the clay such as freezing or by mixing the soil with lime,

cement or other methods.

1) Ground stabilization

2) Electro-osmosis

3) Freezing

iv) Structural Method

This method used where structural elements such as geofabric,piles or stone columns

are used to reinforce the soil or to transfer the load to an underlying less

compressible stratum or layer.

1) Deep Compaction using Vibration Compaction and Dynamic compaction

1.1 Vibro compaction

Vibro-compaction is a deep compaction ground treatment technique for

densifying granular soils in-situ by means of a vibrating probe, or "vibroflot".

Shown below, the vibroflot is a long, slender, hollow tube of cylindrical shape,

consisting of two parts.  The lower part, termed the vibrator, is connected by

means of a special elastic energy coupling to the upper follow tubes.  The

vibrator houses two components, including a 150 Kw electric motor in the

upper part, to drive an eccentric weight in the lower compartment.  Capable of

1,500 to 1,800 revolutions per minute, the vibrator develops an unbalanced

(centrifugal) force of 30 to 50 tones, creating vibrations in a horizontal plane.

Follow tubes are custom made to length to suit the required penetration

depth.  The total weight of the vibroflot is adjustable by using a combination

of heavy and lightweight follow tube sections.  In compaction operation, the

vibroflot is freely suspended from the crane and the vibrator gyrates about the

vertical axis with a maximum (peak-to-peak) displacement of 23 to 32mm. 

The design of the elastic coupling, or vibration isolator, allows the follow

tubes to remain nearly stationary while the vibrator is in motion.

Under the influence of simultaneous vibration and saturation, loose

particles are rearranged into a more compact state, improving the engineering

properties of the treated profile.  In general, vibro compaction is suitable for

granular soils with silt contents up to 10 %.

Sequentially depicted below, the vibroflot first penetrates under its

own weight and vibrations, with the jetting action of water or compressed air. 

After reaching the desired treatment depth, the vibroflot is extracted at 0.5m

intervals while maintaining vibration energy at each increment until the power

consumption rises to the specified maximum.

Figure 5: the technique of vibro compaction

Figure 6: Step of vibro compaction

1.2 Dynamic Compaction

Soil densification by dynamic compaction (DC), also called "heavy tamping"

is a well-known compaction method. The method was "rediscovered" by

Menard, who transformed the crude tamping method into a rational

compaction procedure. Soil is compacted by repeated, systematic application

of high energy using a heavy weight (pounder). The imparted energy is

transmitted from the ground surface to the deeper soil layers by propagating

shear and compression waves types, which force the soil particles into a

denser state. In order to assure effective transfer of the applied energy, a 1 to

2 m thick stiff layer usually covers the ground surface. Pounders can be

square or circular in shape and made of steel or concrete. Their weights

normally range from 5 to 25 tons and drop heights of up to 25 m have been

used. Heavier weights and larger drop heights have been used for compaction

of deep soil deposits, but are not very common.

Dynamic compaction is carried out in several passes. During each pass,

the weight is dropped repeatedly in a predetermined grid pattern. The

distance between the compaction points is normally decreased in the

subsequent passes and compaction is carried out in-between the previously

compacted points. The final pass, also called "ironing pass", usually

performed with low compaction energy, is carried out with a reduced drop

height. The objective is to densify the superficial soil layers without

remoulding the already densified deeper layers. Mayne (1984) presented a

detailed description of the dynamic compaction method.

Although the dynamic compaction method appears to be very simple,

it requires careful design of the compaction process. The densification effect

is strongly influenced by the dynamic response characteristics of the soil to

be compacted, but also by the underlying soil layers. Usually, extensive

compaction trials are needed to optimize the compaction process with respect

to the required energy for achieving specified densification criteria. A major

limitation of dynamic compaction is the lack of monitoring and quality

control during the production phase. However, for research purposes, the

pounder can be equipped with sensors to monitor the applied energy and to

record the dynamic response of the soil layer.

Figure 7: dynamic compaction technique

2) Geotextile

Geotextiles are permeable fabrics which, when used in association with soil, have

the ability to separate, filter, reinforce, protect, or drain. Typically made from

polypropylene or polyester, geotextile fabric come in three basic forms such as

woven (looks like mail bag sacking), needle punched 9looks like felt), or heat

bonded (looks like ironed felt).

Geotextile composites have been introduced and products such as geogrids and

meshes have been developed. Overall, these materials are referred to as

geosynthetics and each configuration. Geonets, geogrids and other can yield

benefits in geotechnical and environmental engineering design.

Figure 7: the example of geotextile

3) Grouting

This series of This series of schematics illustrates the

general procedures in the bottom-up

technique of compaction grouting.

The first step, shown here, is to install

grout pipes using drilling or driving

techniques.

The mortar-like grout, injected through

the pipes, displaces the surrounding

soil. The grout pipe is then lifted some

distance (0.3 to 1.5 m), and the

injection process is repeated.

Injection in "stag Injection in "stages"

continues until the target layer has been

treated. Grouting can stiffen and

strengthen the soil layer by increasing its

density, increasing the lateral stresses,

and acting as a reinforcement. Grouting

may also be used to produce controlled

heaving of the ground surface to re-level

a structure that has been damaged by

differential settlements.

Chapter 5

CASE STUDY: EARTHWORK FOR HIGHWAY

CONSTRUCTION.

5.1 CASE STUDY INFORMATION

The name of this project is the Privatisation of Highway from KL to Kuala Selangor (KLS

Highway). This project start in October 2008 and the expected date to finish is April 2011.

The main contractor that has been awarded to this concession project is Mudah Jaya

Corporation Berhad. The total cost of this project is about RM 958 Million. The construction

of this highway is on the 30 km length. The company that has appointed as to do the

concession is KL- Kuala Selangor Expressway Berhad in 30 years before it will hand to

government. This project is under the federal government and implemented by Ministry of

Prime Work.

Foto 5.1a : Site of Highway Construction

5.1.1 SITE LOCATION

his project took place in the (Package 1) Assam Jawa to Kudang

Foto : Highway KL-Kuala Selangor in construction

5.2 EARTHWORK FOR HIGHWAY CONSTRUCTION

The main purpose of this study is to look in details on the earthwork for highway construction

in how the method statement is done, the specification, the scope of work and also the

machinery involved.

1. Sequent of work

a) Survey setting out

Setting out of the Works (e.g. control stations, level pegging etc )is important

in preliminaries works and also done since in design process to get known the level

of the highway and to decide how many quantity of soil need to be cut and fill

based to Mass Haul Diagrams. These lines or points will be referenced to enable

their re-establishments as construction proceeds. Original Ground Level (OGL)

survey will be checked on site and verified against the construction drawing

progressively after the site clearing for any discrepancies.

The surface of construction area is measure and can produce it in 3D View to

get clearer visual. From this view, the main contractor in this turnkey project is

able to design on themselves and decide on which level to start the excavation. To

saving the cost and to reduce the consumption of time, the contractor has design

the level of excavation by using Mass Haul diagrams where there are no imported

and disposed soil needs for this construction. The amount of soil to be cut is

actually enough to fill in the low-lying area.

b) Site Clearences.

Site clearance means removing all the buildings and facilities from a site

Decommissioning is the process related to decontaminating and removing

buildings or other structures and clean-up is concerned with ground remediation of

contaminated land. Site clearance is, therefore, a combination of decommissioning

and cleans up. Site clearance involves the removal of walls, hedges, ditches, and

trees, other vegetation and services from the site. It can also involve the clearance

of fly-tipped materials.

The machinery that used in site clearance is excavator to remove the vegetation.

The man power also need by using chain saw for the removing the stump. After

that, the works continue by disposing of top soil with average 150 mm deep to

remove unsuitable material such as rubbish, grass and ect.

Removing the vegetation Site removed from vegetation

Disposed of top soil

c) Earth Excavation

The excavation for earthwork in highway construction for this project actually

contains the slope excavation and normal excavation. All of this work is refers to

Mass Haul diagrams before an excavation can start. It is important to get know

how deep of soil need to be excavate for each area by using cut and fill technique.

Figure : Mass Haul Diagrams

In this earthwork excavation, there are two major locations that was the

working area, where the Cutting Area and Filling Area are took place.

i) Cutting Area ii) Filling Area

i. Cutting Area.

These areas involve an excavation work in order to cut the slope before it

can be fill in the other area. In this cutting area, the height of soil need to

be excavated is 12 m from original ground level (OGL). For the

excavation method, there are using 7number of excavator model PC 300 to

excavate.

Besides, there were also using blasting technique to dispose unfilled material

such as rock and ballast according the procedure and approval from the S.O.

Unfilled Material need to be blasting

Otherwise, the details of the operation shall be modified and a written

statement of the explosives used, the method of loading and the method of

stemming shall be modified until the results obtained in pre-splitting

operations are satisfactory in relation to the character of the material being

pre-split. Drill holes for pre-splitting shall be spaced at centre not exceeding

three feet and shall be drilled as near to the design slope lines and as parallel to

one another as possible.

Explosive charges placed in slope-drilled holes shall be uniformly spaced

along the length of hole and shall be as light as possible to effect clean

splitting of the rock along the plane of the slope and to minimize the fracturing

of the remaining rock face or cut.

Methods of Excavation

The excavator from model PC 300 is used to excavate the soil. This is

important to identify and monitor the cut quantity before start the excavation.

There are also needs to make sure the ground is free from sub surface water.

The PC 300 excavator, use the bucket to excavate and put the soil at the back of tipper lorry.

After the tipper lorry full loaded with material, it will hauling the material to the filling area

ii. Filling Area.

In the filling area, the height of soil need to fill is 6m. The tipper lorry will

dump the soil within this place, while the bulldozer used to spread the

material.

Foto : Bulldozer spreading the soil

After that, the soil is remain at it place while waiting to dry. Vibro

compactor is used to compact the soil.

Foto : Vibro compactor used to compact the soil.

5.3 SPECIFICATION OF MACHINERY

Here is the specification of the machinery used in the earthwork from excavating, loading,

hauling, spreading and compacting.

1. Excavating

Excavator

Model CATERPILLAR PC 300

Specification - 7 roller track frame

- 52’’- 2.38 YD. Bucket/ 1.3 m3

- 10 300 hours

- 4 tons

Estimate

Output

- 1400m3

2. Hauling

Tipper LorryModel CATERPILLAR 769B

Specification - 20 ton/ 21.4 YD

-Supplemental steering

- 29.5r25 tires

- 13326 hours.

Estimate

Output

75 load/ 6m3 per bucket

3. Spreading

Bulldozer

Model CATERPILLAR D6R XL Bulldozer

Specification -2001 Cat D6R XL

- 6352 hours

-40% uc

-Ripper valve

- EROPS Cab/air SU tilt blade

Estimate

Output

2000m3/ 2m3 per bucket.

4. Compaction.

Vibro- compactor

Model CAT CS323C Vibratory Compactor

Specification - CAT 3020 Engine

- 12,700 Ibs

- 12 tons

- 48’’ Smooth drum.

Estimate

Output

300mm deep compaction

Chapter 6

CASE STUDY: Slope Retaining Structure

6.0 Introduction

Before beginning any necessary works regarding the construction of the road, the

slope between the road and the palm oil plantation must be retained in order to prevent any

slope failures during and after construction when the road is used. The most appropriate

method was to use the concrete slope retaining structure method. This is a very simple and

fast method of retaining a slope and is proven to be very affective and is widely used as a

slope retaining structure.

This method involves the use of steel reinforced concrete as a retainer to avoid the slope from

collapsing or failing. This structure will be anchored onto the slope using steel cable anchors

to solidly placing the concrete structure onto the slope.

Photo 6.0a: The slope retaining structure

6.1 Method of Construction

The construction of this slope retaining structure is a fast process that can be

completed in a day depending on the length and size of the slope. In this case, it is 6m

in height and about 1km long. The construction process involves a couple of

procedures which is reinforcement bar placing, anchoring the steel cable anchors,

placing the drainage pipe and concreting the slope.

1. Placing anchors

In order to keep the retaining wall from seperating with the slope, anchors are

embedded into the slope in a horizontal fashion. The anchors include steel cables

attached to the retaining wall and anchorred by a steel block inside the slope. This

provides counterforce towards forces trying to seperate the retaining wall from the

slope. This is a crucial step in the construction of slope retaining structures as it is the

key element in providing a retaining structure that is durable to withstand horizontal

and verticle forces due to ground movement.

2. Reinforcement bar placing

Before installing the reinforcement bar panels, concrete screed is applied onto

the slope to allow a more efficient mix of concrete later on to be poured. The concrete

screed helps to prevent water from the concrete batch from entering the soil.

The next step is to place the reinforcement bars onto the slope. This is done to

strengthen the concrete when it is poured onto the slope. The reinforcement bar is

placed on the slope by using wood pickets as a support for hanging the reinforcement

bars in place against the slope.

Photo 6.1a: The reinforcement bar mounted on a wooden picket

3. Installing drain pipes

Drain pipes made from steel are embedded into the slope with both ends

sealed to prevent any soil or unwanted materials from trapping inside the pipe. These

drain pipes function as a dewatering method for the slope to prevent any moisture

build up in the slope that would damage the retaining wall. It is installed throughout

the whole span of the retaining wall and at the bottom will be constructed a drainage

for the water that flows out of the pipes.

Photo 6.3: The PVC pipes used in the dewatering system

The pipes are embedded into the soil of the slope. The outer hole must be covered by

any means necessary to avoid concrete from entering the pipe when the concreting

process begins. This is to assure the pipe has a clear hollow passage to allow its use as

part of the dewatering system.

Photo ?.4: The pipes that are embedded into the slope

4. Concrete pouring

The concreting process is done after the reinforcement bars are finished being

placed. It is a fast process which involves the use of a concrete mix pumper called the

gunite machine. It functions as a concrete pumper with using a hose to pump concrete

towards the surface of the slope. This involves 2 labors, 1 being supended on the

slope using a rope while in charge of pouring cement onto the slope and another labor

to control the gunite machine. The concrete will dry off as soon as it’s been poured.

Photo 6.5: The concrete being pumped onto the slope surface

Advantages

1. This method is a fast method compared to any other retaining wall methods.

2. Includes a dewatering system that enhances its strength for long periods of time

and prevents moisture build up in the slope.

3. Simple and cheap method that requires only few labors and with lesser materials

and machinery compared to other methods.

Disadvantages

Being built beside the road, this retaining wall is prone to damage if any collision

occurs onto it because

Chapter 7

CASE STUDY : PREFABRICATED VERTICAL DRAIN

1. The machine is setup and place at the construction site. The equipment will be install

at plant.

2. Before installed in the ground, steel plate or clamp will be installed at the end point of

the geosynthetic. This plate to fix it in the ground and not pull up after the process

complete.

The geosynthetic or vertical drain

The worker installed the steel plate at end point of vertical drain

3. The geosynthetic will be placed inside the mandrill and will be vibrated to install in

the ground at desired depth.

The mandrill installed in the ground

4. After it installed at the desired depth, the mandrill will be taken out from the soil and

left the geosynthetic inside the soil.

The mandrill has been taken out from the soil

Source: http://www.haywardbaker.com/services/wick_drains.htm

5. The geosynthetic will be cut off after about 2ft from the ground.

6. If when the geosynthetic install in the ground not enough, it will join with another

geosynthetic with only tape at the joint of the geosynthetic.

7. The process of installing prefabricated vertical drain will be repeated from step 1 to 6

for another prefabricated vertical drain.

The completed of prefabricated vertical drain

2. STONE COLUMN

Compacted granular or stone columns are constructed in soil to increase the load-bearing

capacities or drainage capabilities of the native soil.

1. The machine is setup and place at the construction site.

The view of machine place at the construction

2. A vibratory probe is penetrated down into the soil to the desired depth. This will

create cavity or hole along the probe. During the penetration is use water jet, the water

jets are adjusted in such a way that an annular space or hole remains open around the

vibrator and it's extension tubes.

The vibrator penetrates the soil with water jet

The figure show the vibrator penetrate the soil with water jet

Source:

http://www.groundimprovement.ch/Ground_Improvement_Solutions/Stone_Columns.html

3. As the probe is incrementally withdrawn, the cavity is filled with granular material

that is compacted in place by the probe by moving the vibrator up and down. It is

using loader to transport the stone to the hole.

The stone is filled inside the hole

The figure show the movement vibrator for compaction

Source:

http://www.groundimprovement.ch/Ground_Improvement_Solutions/Stone_Columns.html

4. As the stones being added in the hole, the third process is repeated up to ground level,

leaving on completion a well compacted, tightly interlocked stone column surrounded

by soil of enhanced density.

Figure show the finishing of stone column

Source: http://n-six.blogspot.com/2009_06_01_archive.html

Figure show the compacted soil

Source:

http://www.groundimprovement.ch/Ground_Improvement_Solutions/Stone_Columns.html

5. The process of stone column will be repeated from step 1 to step 4 for another stone

column.

REFERENCES

Hungr O, Evans SG, Bovis M, and Hutchinson JN (2001) Review of the classification of

landslides of the flow type. Environmental and Engineering Geoscience, VII, 221-238.

Varnes D. J.: Slope movement types and processes. In: Schuster R. L. & Krizek R. J. Ed.,

Landslides, analysis and control. Transportation Research Board Sp. Rep. No. 176, Nat.

Acad. oi Sciences, pp. 11–33, 1978.

http://www.nationalatlas.gov/articles/geology/a_landslide.html

Kyōji Sassa, Paolo Canuti, 2008, Landslide- Disaster Risk reduction,

Buzzles.com Hunt, R. E., Geotechnical Engineering Analysis and Evaluation, 1986,

McGraw-Hill; BS8002: 1994

http://www.bachy-soletanche.com.sg/processes/processes-diaphragmwalling.htm

http://www.ce-ref.com/cant-rc-wall.htm

http://www.geoforum.com/knowledge/texts/compaction/viewpage.asp?ID=23

http://en.wikipedia.org/wiki/Geotextile

http://cee.engr.ucdavis.edu/faculty/boulanger/geo_photo_album/Ground

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