DARSHAN INSTITUTE OF ENGINEERING & … file5 unconfine compression test(ucs) 18 6 consolidation test...

D E P A R T M E N T O F C I V I L E N G I N E E R I N G Page 1

DARSHAN INSTITUTE

OF

ENGINEERING & TECHNOLOGY

RAJKOT

SOIL MECHANICS

LAB MANUAL- 2150609

DEGREE CIVIL ENGINEERING

SEMESTER –V

Name of student

Roll No

Enrollment No

Department of Civil Engineering

Geotechnical Engineering Laboratory

Darshan Institute of Engineering and Technology Rajkot


INDEX

SR.

NO. TITLE

PAGE

NO. DATE SIGN.

1 FREE SWELLING INDEX 1

2 STANDARD PROCTOR TEST 3

3 DIRECT SHEAR TEST 7

4 CBR TEST 12

5 UNCONFINE COMPRESSION TEST(UCS) 18

6 CONSOLIDATION TEST 21

7 TRIAXIAL TEST 30

8 AUGER BOARING /SAMPLING 34

SOIL MECHANICS LAB MANUAL (2150609)

IS: 2720- 40 1.0 FREE SWELLING INDEX


SCOPE:

This standard (Part 40) covers the method for Free swell Index of soils. [As per IS: 2720

(Part 40) -1986 (Reaffirmed 2011)]

APPARATUS:

Sieve – 425 micron 1S Sieve.

Glass Graduated Cylinders - Two, 100-ml Capacity (see IS: 878-1956).

PROCEDURE:

Take two 10 g soil specimens of oven dry soil passing through 425 micron IS Sieve.

Each soil specimen shall be poured in each of the two glass graduated cylinders of

100 ml capacity.

One cylinder shall then be filled with kerosene oil and the other with distilled water

up to the 100 ml mark. After removal of entrapped air (by gentle shaking or stirring

with a glass rod), the soils in both the cylinders shall be allowed to settle. Sufficient

time (not less than 24 h) shall be allowed for the soil sample to attain equilibrium

state of volume without any further change in the volume of the soils.

The final volume of soils in each of the cylinders shall be read out.

CALCULATION:

The level of the soil in the kerosene graduated cylinder shall be read as the original

volume of the soil sample &, kerosene being a non-polar liquid does not cause swelling

of the soil. The level of the soil in the distilled water cylinder shall be read as the free

swell level. The free swell index of the soil shall be calculated as follows:

Free swell index, percent =𝑽𝒅−𝑽𝑲

𝑽𝑲×100

Where,

Vd =the volume of soil specimen read from the graduated cylinder containing distilled

water, and

Vk =the volume of soil specimen read from the graduated cylinder containing kerosene.

Figure: Free Swelling After 24 Hr.


IS: 2720- 40 1.0 FREE SWELLING INDEX


Value of free swelling index =

Conclusion:

Signature:


IS: 2720 -7&8 2.0 LIGHT/HEAVY COMPACTION TEST (PROCTOR TEST)


OBJECT:

Determination of the relation between the water content and the dry density of soils

using light/heavy compaction.[As per IS: 2720 (Part 7&8) -1980] (Reaffirmed 1987)

APPARATUS:

Sample Extruder (Optional)

Container Tray or pan Balances

Oven Trowel and spatula Spoon 10 kg sensitive to 1 g and other of capacity 200 g sensitive to 0.01 g

Steel Straightedge - Mixing Tools

Metal Rammer Mould

A representative portion of air-dried soil material about 5 kg of material passing a 4.75-

mm IS Sieve shall be taken.

PROCEDURE:

Obtain a sufficient quantity of air-dried soil and pulverize it. Take about 5 kg of soil

passing through 4.75 mm sieve in a mixing tray.

Weigh the mould with base plate and apply grease lightly on the interior surfaces. Fit

the collar and place the mould on a solid base.

Add water to the soil to bring its moisture content to about 8% and then mix it

thoroughly using the trowel until the soil gets a uniform color.

For light compaction, compact the moist soil in three equal layers using a rammer of

mass 2.6 kg and having free fall of 31 cm. Distribute the blows evenly, and apply 25

blows in each layer. Ensure that the last compacted layer extends above the collar

joint. Alternatively for heavy compaction, compact the soil with 25 blows per layer,

in five equal layers with a rammer of mass 4.9 kg and 45 cm free fall.

Rotate the collar so as to remove it, trim off the compacted soil flush with the top of

the mould, and weigh the mould with soil and base plate.

Extrude the soil from the mould and collect soil samples from the top, middle and

bottom parts for water content determination. Place the soil back in the tray, add 2%

more water based on the original soil mass, and re-mix as in step 3. Repeat steps 4

and 5 until a peak value of compacted soil mass is reached followed by a few samples

of lesser compacted soil masses.

Calculate the bulk density of each compacted soil specimen.

Calculate the average moisture content of the compacted specimen and then its dry

density.

Plot the dry densities obtained as ordinates against the corresponding moisture

contents as abscissa, draw a smooth compaction curve passing through them, and

obtain the values of maximum dry density (MDD) and optimum moisture content

(OMC).




On the same graph, plot a curve corresponding to 100% saturation, calculated from

Where,

S = degree of saturation,

Gs = specific gravity of solids, and

Ƴw = unit weight of water. CALCULATIONS:

Bulk Density –γb in g/ml, of each compacted specimen shall be calculated from the equation:

Ƴ𝐛 =𝐌𝟐 −𝐌𝟏

𝐕𝐦

Where,

Ml = mass in g of mould and base;

M2 = mass in g of mould, base and soil; and

Vm = volume in cm3 of mould.

The dry density, γdin g/cc, shall be calculated from the equation:

Ƴ𝒅 =𝟏𝟎𝟎 Ƴ𝒃

𝟏𝟎𝟎 + 𝐰

Where,

w = water content of soil in percent.

γb= Bulk Density g/cc

γd= Dry Density g/cc

The dry densities, 𝛾𝑏 obtained in a series of determinations shall be plotted against the

corresponding moisture contents w (%). A smooth curve shall be drawn through the

resulting points and the position of the maximum on this curve shall be determined.




REPORTING OF RESULTS:

The dry density in g/cc corresponding to the maximum point on the moisture

content/ dry density curve shall be reported as the maximum dry density to the

nearest 0.01.

DETERMINATION OF WATER CONTENT – DRY DENSITY RELATION USING

LIGHT/HEAVY COMPACTION

COMPACTION TEST (PROCTOR TEST) [IS:2720-PART 7&8 – 1980, RA 1987]

Type of test (Standard/ Modified proctor test)

Volume of mould (cm3) (1000cm3/2250cm3)

TEST 1 2 3 4 5

Container no.

Empty weight of container

Container + wet soil(gm)

Container+ dry soil (gm)

Mass of mould(gm)

Mass of mould + compacted soil (gm)

Mass of compacted soil, Wt.(gm)

Bulk density (g/cc)

Average water contentw (%)

Dry density (g/cc )

Dry density at 100% saturation (g/cc )

RESULT SUMMARY (after plotting a graph)

Maximum Dry Density……………gm/cc

Optimum Moisture Content……………%




Conclusion:

Signature:


IS: 2720 - 13 3.0 DIRECT SHEAR TEST


SCOPE:

Determination of shear strength of soil with a maximum particle size of 4.75 mm in

untrained, consolidated untrained and consolidated drained conditions [As per IS: 2720

(Part 13) -1986 (Reaffirmed 2011)].

APPARATUS:

The shear box grid plates, porous stones, base plates, and loading pad and water jacket

shall conform to IS: 11229-1985.

The apparatus required for the test is as follows:

1. Loading Frame, Proving Ring - Force measuring of suitable capacity, fitted with a

dial-gauge accurate to 0.002 mm to measure the shear force.

2. Micrometer Dial Gauges – Accurate to 0.01 mm. One suitably mounted to measure

horizontal movement and the other suitably mounted to measure the vertical

compression of the specimen.

3. Sample Trimmer or Core Cutter, Stop Clock, Balance - Balance of I kg capacity

sensitive to 0.1 g.

PREPARATION OF SPECIMEN:

Undisturbed Specimens - Specimens of required size shall be prepared in accordance

with IS: 2720 (Part I)-1983.

Remolded Specimens

a. Cohesive soils may be compacted to the required density and moisture content, the

sample extracted and then trimmed to required size. Alternatively, the soil may be

compacted to the required density and moisture content directly into the shear box

after fixing the two halves of the shear box together by means of the fixing screws.

b. Cohesion less soils may be tamped in the shear box itself with the base plate and grid

plate or porous stone as required in place at the bottom of the box.

The cut specimen shall be weighed and trimmings obtained during cutting shall be used

to obtain the moisture content. Using this information, the bulk dry density of the

specimen in the shear box shall be determined.




PROCEDURE:

Undrained Test -The shear box with the specimen, plain grid plate over the base plate

at the bottom of the specimen and plain grid plate at the top of the specimen should be

fitted into position in the load frame.

The serrations of the grid plates should be at right angles to the direction of shear the

loading pad should be placed on the top grid plate. The water jacket should be

provided so that the sample does not get dried during the test.

The required normal stress should be applied and the rate of longitudinal

displacement/shear stress application so adjusted that no drainage can occur in the

sample during the test. The upper part of the shear box should be raised such that a

gap of about I mm is left between the two parts of the box.

The test may now be conducted by applying horizontal shear load to failure or to 20

percent longitudinal displacement, whichever occurs first. The shear load readings

indicated by the proving ring assembly and the corresponding longitudinal

displacements should be noted at regular intervals.

CALCULATIONS AND REPORT:

If necessary, the vertical compression, if any, of the soil specimen may be measured to

serve as check to ensure that drainage has not taken place from the soil specimen. At

the end of the test, the specimen should be removed from the box and the final moisture

content measured. A minimum of three (preferably four) tests shall be made on separate

specimens of the same density.

From the calibration chart of the proving ring, the loads corresponding to the load dial

readings obtained during the test should be calculated.

The loads so obtained divided by the corrected cross-sectional area of the specimen gives

the shear stress in the sample. The corrected cross-sectional area shall be calculated

from the following equation:

Corrected area = Ao (𝟏 − 𝜹

𝟑 )

Where, Ao = initial area of the specimen in cm2, and

𝛿 = displacement in cm.




Direct shear apparatus

Arrangement of sample in direct shear apparatus




PROFOMANCES FOR RECORDING DST TEST RESULT:

SOIL SPECIMEN MEASUREMENTS

Dimensions: Area of Specimen:

Initial wet mass of soil specimen: Volume of Specimen:

Water content:

Final wet mass of specimen:

Water content at sear zone:

PREFORMA FOR RECORDING SHEAR STAGE

DIRECT SHEAR TEST [IS: 2720-PART 13-1986, RA 2011]

Specimen no. -

Depth- Size of box(cm)- Mass of soil (gm)-

Rate of strain - Area of box (cm2)- OMC - %

Type of test - Volume of box(cm3)- MDD - gm/cc

Normal stress applied (kg/cm2)- Density of soil(kg/cm3) -

Least count of disp. dial gauge (mm/div.)- Proving ring constant (kg/div.)-

Dial gauge reading

Proving ring

reading

(1)

Horizontal load

(Kg)

(2)

Shear stress

(Kg/cm2)

(3)

Normal stress

(Kg/cm2)

(4) Horizonta

l dial

gauge

Vertical

dial

gauge

Remarks-




From the graph

C = …………………….. Kg/cm2

Φ = ……………………... °

Conclusion:

Signature:

Shea

r st

ress

(kg

/cm

2)

Normal stress (kg/cm2)

BOX SHEAR TEST


IS: 2720 - 16 4.0 DETERMINATION OF CALIFORNIA BEARING RATIO OF SOIL


SCOPE:

Determination of California Bearing Ratio (CBR) of undisturbed soil specimens obtained

from the field and also remoulded specimens of the soil compacted in the laboratory

both by the static and dynamic method, and in the soaked and unsoaked state.[As per

IS: 2720 (Part 16) -1987 (Reaffirmed 2011)].

APPARATUS/EQUIPMENT:

The apparatus required for the test is as follows:

1. Moulds with Base Plate, Stay Rod and Wing Nut -Spacer Disc Metal Rammer - As

specified in IS: 9198-1979.

2. Expansion Measuring Apparatus -.Weights - This shall conform to 4.4 of IS: 9669-

1989.

3. Loading Machine -Penetration Plunger - This shall conform to 4.4 of IS: 9669-1980.

To use a plunger of greater length, a suitable extension rod may be used.

4. Dial Gauges - Two dial gauges reading to 0.01 mm.

5. Sieves - 47.5-mm IS Sieve and 19-mm IS Sieve [see IS: 460 (Part 1)-1978].

Sieves - 47.5-mm IS Sieve and 19-mm IS Sieve [see IS: 460 (Part 1)-1978].

PREPARATION OF TEST SPECIMEN:

The test may be performed:

a) On undisturbed specimens, and

b) On remoulded specimens which may be compacted either statically or dynamically.

Soil Sample -The material used in the remoulded specimen shall pass a 19-mm IS

Sieve.

Allowance for larger material shall be made by replacing it by an equal amount of

material which passes a 19-mm IS Sieve but is retained on 4.75-mm IS Sieve.

Statically Compacted Specimens – The mass of the wet soil at the required moisture

content to give the desired density when occupying the standard specimen volume in the

mould shall be calculated, A batch of soil shall be thoroughly mixed with water to give

the required water content. The correct mass of the moist soils shall be placed in the

mould and compaction obtained by pressing in the displacer disc, a filter paper being

placed between the disc and the soil.

Dynamically Compacted Specimen – For dynamic compaction, a representative sample

of the soil weighing approximately 4.5 kg or more for fine-grained soils and 5.5 kg or

more for granular soils shall be taken and mixed thoroughly with water. If the soil is to

be compacted to the maximum dry-density at the optimum water content determined in

accordance with IS: 2720 (Part 7)-1980 or IS: 2720 (Part 8)-1983, the exact mass of soil

required shall be taken and the necessary quantity of water added so that the water

content of the soil sample is equal to the determined optimum water content.




PROCEDURE:

Test for Swelling:

A filter paper shall be placed over the specimen.

Weights to produce a surcharge equal to the weight of base material and pavement to

the nearest 2.5 kg shall be placed on the compact soil specimen.

The whole mould and weights shall be immersed in a tank of water allowing free

access of water to the top and bottom of the specimen.

The tripod for the expansion measuring device shall be mounted on the edge of the

mould and the initial dial gauge reading recorded.

This set-up shall be kept as such undisturbed for 96 hours.

Noting down the readings everyday against the time of reading.

A constant water level shall be maintained in the tank throughout the period.

At the end of the soaking period, the final reading of the dial gauge shall be noted, the

tripod removed and the mould taken out of the water tank.

The free water collected in the mould shall be removed and the specimen allowed

draining downward for 15 minutes. Care shall be taken not to disturb the surface of

the specimen during the removal of the water.

The weights, the perforated plate and the top filter paper shall be removed and the

mould with the soaked soil sample shall be weighed and the mass recorded.

PENETRATION TEST:

The mould, containing the specimen, with the base plate in position, but the top face

exposed, shall be placed on the lower plate of the testing machine.

To prevent upheaval of soil into the hole of the surcharge weights, 2.5 kg annular

weight shall be placed on the soil surface prior to seating the penetration plunger

after which the remainder of the surcharge weights shall be placed.

The initial load applied to the plunger shall be considered as the zero load when

determining the load penetration relation.

Load shall be applied to the penetration plunger so that the penetration is

approximately 1.25 mm per minute. Reading of the load shall be taken at

penetrations of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 4.0, 5.0, 7.5, 10.0 and 12.5 mm The

maximum load and penetration shall be recorded it if occurs for a penetration of less

than 12.5 mm.

About 20 to 50 g of soil shall be collected from the top 30 mm layer of the specimen

and the water content determined.




Load v/s penetration curve

CALCULATION:

Load Penetration Curve:

The load penetration curve shall be plotted.

Bearing Ratio:

California bearing ratio = 𝑃𝑇

𝑃𝑆 X 100

Where,

PT = corrected unit (or total) test load corresponding to the chosen penetration from the

load penetration curve, and

PS = unit (or total) standard load for the same depth of penetration as for PTtaken from

Table.

REPORT:

The CBR value shall be reported correct to the first decimal place.




PERFORMA FOR CALIFORNIA BEARING RATIO TEST :

CALIFORNIA BEARING RATIO TEST [IS: 2720-PART 16-1987] Project No./Sample No. _________

CBR Casting Date _________

CBR Testing Date _________

Volume of CBR Mould(cm3)_________

(Dia. 15.0 cm x Height 12.5 cm)

Surcharge (kg)_________

Proving Ring /Load cell counts _________

Height-of-Sample_________

Method of Compaction __________

Field Dry Density __________

(gm/cm3)

Minimum Dry Density __________

(gm/cm3)

OMC(%) __________

Field Moisture (%) __________

MDD (gm/cm3) __________

Natural Moisture (%) __________

Percentage of soil friction above 19 mm (Replaced) = _______%

1. Compaction Density at (MDD/FDD/RD )= _______ gm/cm3

2. Desired Moisture Content =_______%

3. Weight of oven Dried soil Required for a Mould =_______ gm

4. Water to be added to Air Dry soil Taken to get Desired Moisture = _______ gm

5. Expansion Ratio = ((df-ds)/h)x100 = ________%

ds=_______ mm df=_______ mm h=_______ mm




MOISTURE CONTENT

BEFORE SOAKING AFTER SOAKING

Moisture Can no 1 2 3 1 2 3

Can + wet weight

Can + dry weight

Weight of water (gm)

Weight of container (gm)

Weight of dry soil (gm)

Moisture content

Average

CBR Readings

1 2 3

Penetration in

(mm)

Proving Ring (Red)

Corrected Load in

(Kg/cm2)

Proving Ring (Red)

Corrected Load in

(Kg/cm2)

Proving Ring (Red)

Corrected Load in

(Kg/cm2)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

4.0

5.0

7.5

10.0

12.5




From Graph

Correction CBR at 2.5 mm

CBR at 5 mm

CBR-1

CBR-2

CBR-3

Average CBR

Conclusion:

Signature:

Load

on

plu

nge

r(kg

)

Penetration(mm)

CBR TEST


IS: 2720 - 10 5.0 UNCONFINED COMPRESSIVE STRENGTH


OBJECT AND SCOPE:

The object of the experiment is to determine the unconfined compressive strength of

clayey soil using controlled strain. The purpose of the test is to obtain a quantitative

value of compressive and shearing strength of soils in an untrained state. The test may

be performed on both undisturbed and remolded soil specimen.

MATERIALS AND EQUIPMENTS:

I. Compression device of any suitable type

II. Sample ejector

III. Strain measuring dial gauge with 0.01 mm graduations

IV. Stopwatch

V. Oven

VI. Balance

VII. Miscellaneous equipment, such as specimen trimming and curving tools,

remolding apparatus, moisture cans, etc.

VIII. Split moulds 3.5 cm diameter and 7 cm long (or 3.75 cm diameter and 7.5 cm

long)

TEST PROCEDURE

Preparation of Test Specimen

I. Undisturbed cylindrical specimen may be cut from the bigger undisturbed

sample obtained from the field. A wire saw may be used to trim the ends parallel

to each other. a lathe or trimmermaybeusedtotrimthespecimentocircularcross-

section.Alternatively, fieldsample may be obtained directly in a thin sampling

tube having the same internal diameter as the specimen to be tested. The split

mould is oiled lightly from inside and the sample is then pushed out of the tube

into the split mould. The split mould is opened carefully and sample taken is

out.

II. Remolded sample may be prepared by compacting the soil at the desired water

content and dry density in a bigger mould, and then cut by the sampling tube.

Alternatively, remoulded specimen may be prepared directly in the split mould.




Compression Test

1. Measure the initial length and diameter of the specimen.

2. Put the specimen on the bottom plate of the loading device. Adjust the upper plate to

make contact with the specimen. Set the load dial gauge and the strain (compression)

dial gauge to zero.

3. Compress the specimen until cracks have definitely developed of the stress strain

curve is well past it speak or until a vertical deformation of 20 percent reached. Take

the load dial readings approximately at every 1 mm deformation of the specimen.

4. Sketch the failure pattern; measure the angle between the cracks and the horizontal,

if possible and if the specimen is homogeneous.

UNCONFIND COMPRESSION TEST MACHINE

Tabulation of observed data

Initial diameter or specimen D0:

Initial length (L0):

Initial area (A0) :

Initial density:

Initial water content:




Determination of Unconfined Compressive Strength

Sr. No.

Elapsed time

(min.)

Load (Kg)

Deformation (cm)

Strain (%)

Area A

(cm2)

Stress (kg/cm2)

1

2

3

4

5

6

7

8

Calculation:

The axial strain ∈is determined by the following equation:

∈= ∆𝑳𝑳

Area = 𝑨𝟎

𝟏−∈

Where:

∆L = Change in specimen, as read from the strain dial.

L= Initial length of specimen.

Conclusion:

Signature:


IS: 2720 - 15 6.0 DETERMINATION OF CONSOLIDATION PARAMETERS


OBJECT AND SCOPE:

To determine the compressibility i.e., consolidation characteristics of a soil by one

dimensional consolidation using consolidometer apparatus.

THEORY

Consolidation of soil is the process of compression by gradual reduction of pores under

a steady applied pressure. The main purpose of the consolidation test is to obtain soil

data required for predicting the rate and amount of settlement of structures. The data

can also be used to develop void ratio (e) versus pressure (p) curve generally for cohesive

soil.

The void ratio (e) of a soil specimen under any applied pressure (p) may be computed

using the following relationship, e=𝐻−𝐻𝑠

𝐻𝑠

Where,

H = Height of soil specimen at the end of each pressure increment (cm)

Hs = equivalent height of solids (cm), which is determined as follows:

Hs = 𝑊𝑠

𝐺×𝛾𝑤×𝐴

Where,

Ws= dry weight of the specimen

G = specific gravity of the solid particles

𝛾𝑤= unit weight of water (g/cc)

A = cross-sectional area of the soil specimen (cm2)

PREPARATION OF TEST SPECIMEN

1. UNDISTURBED SOIL SAMPLE

Clean, dry and lubricate the consolidation ring from inside with silicon

grease. Then weigh it. Record it as (W1) g.

Preparation from a block (undisturbed) sample

Sometimes, the soil sample from field is also collected as blocked mass. In that case,

cut a sample disc with two plain faces parallel to each other having its diameter and

thickness each at least 10mm greater than that of the consolidation ring. Hold the

consolidation ring vertically with cutting edge downwards and place it on the

prepared disc of the undisturbed soil sample. Using the ring as a template, trim off




the excess soil around the cutting edge. Gently, press the ring downwards with

minimum force required until the soil protrudes into the ring by about 5 mm above

its top. Cut the soil at the level of the-cutting edge of the cutter of the consolidation

ring. Trim the excess soil flush with top and bottom edges of the ring, using straight

edge. Remove the small interfering inclusion if any, during trimming process and fill

the cavity completely with the soil from the cuttings. Avoid the excessive remoulding

of the soil surfaces. Keep a portion from the trimmings/cuttings for determination of

initial moisture content and specific gravity. Weigh the ring with the specimen.

Record it as (W2)g.

PREPARATION FROM A TUBE SAMPLE

To push the sample directly into the consolidation ring, hold the ring firmly about 5

mm above the sample tube keeping the cutting face downwards. By means of a

hydraulic jack, eject the sample gently and steadily out of the tube so that it

introduces into the ring. During the process, continue trimming the specimen

carefully from outside the consolidation ring to reduce friction. Finally trim and

flush the soil sample with the ends of the consolidation ring.

2. REMOLDED SPECIMEN

Prepare the soil sample by compaction method in a compaction mould. The

compaction efforts (number of blows required for each layer) may be determined by

trial and error if the test is to be performed at desired moisture content and density,

other than optimum moisture content and maximum dry density. Place the

consolidation ring on a glass plate with the cutting edge upwards. Press the

remoulded soil into the ring by suitable means. Flush the soil specimen with the top

end of the ring and weigh. Alternatively the soil specimen may also be intruded into

the consolidation ring as explained.

Dynamically compacted specimen

Weigh the consolidation ring. Attach extension collar to the ring and place it on the

base plate. Prepare about 300 g wet soil for desired water content and density.

Calculate the volume of the ring including collar thickness (For a 60 mm dia. 30

mm total height (including 20 mm soil sample height), volume = 84.86 cm2) and the

required quantity of soil. Place this soil in the ring and compact by 2.6 kg rammer

or by any other suitable tool, to the total thickness including that of collar (30 mm).

Detach the extension collar and trim the excess soil flushing with the ring ends to

make the thickness of the specimen as 20 mm. Weigh the ring with compacted soil.

Statically compacted specimen

Prepare the soil specimen by mixing required quantity of water to about 300 g dry




soil. Leave the mix for about 5-6 hours. Keep a small quantity of this mix for

moisture content determination. Place the ring on the base plate and attach the

extension collar to it. Weigh the required quantity of the processed mix of wet soil to

obtain the desired test density when compressed to 84.86 cm2 volume. Place gently

the soil into the consolidation ring. Compress this apparatus by means of a suitable

pressing device. Detach the extension collar and trim the soil flushing with the edge

of the ring.

APPARATUS:

Consolidation Ring

Porous Stone

Consolidation cell

Dial Gauge/LVDT

Loading Ram

Set of weights

Consolidation test




PROCEDURE

Soak the porous stones in water and place the bottom porous stone on the base of

the consolidation cell. Keep a filter paper over the stone. Attach guide ring to one

or both ends of the consolidation ring containing soil specimen (as required) and

place it gently on the porous stone. Place another filter paper on the top of

specimen and keep upper porous stone and loading point. Adjust a steel ball in the

groove of the loading cap to provide uniform loading on the specimen.

Place this whole arrangement properly in position in the loading device. Check and

adjust the loading beam and the counter balancing system. Level the loading beam

with the help of a spirit level. Clamp the dial gauges in position for recording the

compression/swelling of the soil specimen. Read the initial dial reading and place a

0.05kg/cm2seating pressure on the pan of weight hanger. Connect the base plate

of the consolidation cell to water reservoir bymeans of rubber/plastic tubing for

saturating the soil specimen. Allow the saturation of the specimen for 24 hrs. Or

more to attain an almost constant dial gauge reading.

Select appropriate sequence of pressures to be applied. It is customary that the

pressure applied at any loading stage is twice that of the proceeding stage

pressure. The test, therefore, may be carried out for loading sequence, to apply

pressure on the soil specimen in the range of 0.125, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0

and 16.0 kg/cm2. However some other combination of loads may also be taken as

per Table 8.1. The maximum pressure to be applied should be more than the

effective vertical pressure envisaged due to in-situ over burden and the proposed

structure to be constructed on that soil.

Take the dial gauge readings after application of each load according to a time

sequence i.e. total elapsed such as 0.25, 1.00, 2.25, 4, 6.25, 9, 12.25, 16, 20.25,

25, 36, 49, 64, 100, 144, 196, 225, 256 minutes and thereafter 24 hours. A period

of 24 hours is generally sufficient for completion of primary consolidation of the soil

specimen for a particular load. A longer time. May be required in case of hard soil.

i.e., soil containing clay particles 25% or (N) SPT values= 30 or qu i.e. unconfined

compressive strength> 4.0 kg/cm2). With the help of the above time sequence it is

easy to plot the specimen thickness against square root of time or logarithm of time.

If the object of the study is to obtain pressure-void ratio relationship only, the time

versus dial gauge readings may be avoided and record only the final dial gauge

reading for each load increment after 24hours.

After completing the dial gauge observations at maximum pressure, release the

applied pressure to zero (0.05 kg/cm'' seating pressure) and leave the soil specimen

to swell by water for 24 hours. Record the final reading of the dial gauge. If




required, the loads may be reduced in stages and time-swelling readings may also

be taken accordingly.

Remove the seating load (0.05 kg/cm') and dismantle the consolidation ring. Wipe

off water from the ring and remove filter papers from both the ends of the specimen.

Weigh the ring and record it as (W') g with the specimen and then place it in a

container and dry in an oven (105°- 110°C).Alternatively push the soil specimen out

of the ring carefully so that no soil particle is lost, weigh the specimen and dry.

After drying, weigh the ring with the specimen and record it as (W3) g. Determine

the specific gravity of the soil from the dried specimen. Place the porous stones in a

container filled with water and boil for about 20-30 minutes and then clean to

remove any soil particle therein for their further use.

OBSERVATION DATA

Details of Soil Sample

Measurements of container ring:

Diameter (interior) of container =

Area of container =

Initial thickness of soil sample =

Specific gravity of soils =

Equivalent height of solid, Hs =

Least count of Dial gauge =

Wet density =

Dry density =




Moisture Content

Weight of container ring, W1 (g) =

Weight of container ring + Wet soil: W2 (g) =

Weight of container ring + Dry soil: W3 (g) =

Weight of dry soil: Ws (g) =

Weight of water (g) =

Moisture content (%) =

Degree of saturation: S = w*G/e =




Pressure: p (kg/cm2)

Elapsed

time: t

(min)

√𝒕

Displacement (mm)




Applied

pressure: p

(kg/cm2)

Final

displacement

(mm)

Change in

displacement

(mm)

Thickness

of soil

sample

(H)

Equivalent

ht. of voids

( H –Hs)

Void ratio

𝐇 − 𝐇𝐬 𝐞 =

𝐇𝐬

Conclusion:

Signature:


IS: 2720 - 11 7.0 DETERMINATION OF SHEAR STRENTH PARAMETER BY TRIAXIAL TEST


OBJECT AND SCOPE:

Determination of shear strength parameters of soils under triaxial loading conditions.

Apparatus

Triaxial cell,

Compression machine,

Cell pressure application system,

Pore pressure measuring device,

Volume change measuring device,

Proving ring,

Deformation dial gauge,

Split mould,

Trimming knife,

Rubber membrane,

Membrane stretcher,

Rubber „O' rings,

Balance,

Apparatus for moisture content determination

TRIAXIAL APPARATUS




CU test




UU Test

Procedure:

Prepare a test specimen of necessary diameter and length, and measure its

weight. Place a rubber membrane around the specimen using the membrane

stretcher.

De-air the out let line at the pedestal of the triaxial base, place on it stop as

saturated porous stone with a filter paper disc, and then position the soil

specimen with the membrane stretcher around it. Put a loading cap on the

specimen top, and seal the membrane on to the bottom pedestal and the top cap

with the rings.

Assemble the triaxial cell with the loading ram initially clear of the top cap. Fill the

cell with water, raise the water pressure to the desired value, and maintain the

pressure constant. Raise the platform of the compression machine to bring the

ram in contact with the seat on the top cap.

Set both the proving ring dial gauge and the deformation dial gauge to zero, select

an axial strain rate, and verify that the cell pressure remains constant.

For undrained shearing of saturated samples, either close the outlet valve at the

base of the cell or connect it to a pore pressure transducer. For drained shearing

of saturated samples, connect the outlet to a burette for volume change

measurements.

Apply axial compression load and take readings of the proving ring at intervals of

0.20 mm vertical deformation till the peak load has been passed, or till the strain

reaches 20% of the specimen length. Record also burette or pore pressure

readings, as applicable.

Remove the axial load, drain the water from the cell, remove the specimen, make a

sketch of the failure pattern, and take soil samples for water content




determination.

Repeat the test on identical soil specimens under different cell pressures.

Conclusion:

Signature:


ASTM D1452 8.0 AUGER BOARING /SAMPLING


BORING METHODS OF EXPLORATION

The boring methods are used for exploration at greater depths where direct methods

fail. These provide both disturbed as well as undisturbed samples depending upon the

method of boring. In selecting the boring method for a particular job, consideration

should be made for the following:

The materials to be encountered and the relative efficiency of the various boring

methods in such materials

The available facility and accuracy with which changes in the soil and ground water

conditions can be determined

Possible disturbance of the material to be sampled The different types of boring

methods are:

Displacement boring

Wash boring

Auger boring

Rotary drilling

Percussion drilling

Continuous sampling

DISPLACEMENTBORING

It is combined method of sampling & boring operation. Closed bottom sampler, slit cup,

or piston type is forced in to the ground up to the desired depth. Then the sampler is

detached from soil below it, by rotating the piston, & finally the piston is released or

withdrawn. The sampler is then again forced further down & sample is taken. After

withdrawal of sampler & removal of sample from sampler, the sampler is kept in closed

condition & again used for another depth.

FEATURES

Simple and economic method if excessive caving does not occur. Therefore not

suitable for loose sand.

Major changes of soil character can be detected by means of penetration resistance.

These are 25mm to 75mmholes.

It requires fairly continuous sampling in stiff and dense soil, either to protect the

sampler from damage or to avoid objectionably heavy construction pit.




WASH BORING

It is a popular method due to the use of limited equipments. The advantage of this is

the use of inexpensive and easily portable handling and drilling equipments. Here first

an open hole is formed on the ground so that the soil sampling or rock drilling

operation can be done below the hole. The hole is advanced by chopping and twisting

action of the light bit. Cutting is done by forced water and water jet under pressure

through the rods operated inside the hole.

India the “Dheki” operation is used, i.e., a pipe of 5 cm diameter is held vertically and

filled with water using horizontal lever arrangement and by the process of suction and

application of pressure, soil slurry comes out of the tube and pipe goes down. This can

be done up to a depth of 8m –10m (excluding the depth of hole already formed

beforehand).Just by noting the change of colour of soil coming out with the change of

soil character can be identified by any experienced person. It gives completely disturbed

sample and is not suitable for very soft soil, fine to medium grained cohesionless soil

and in cemented soil.

WASH BORING




AUGERBORING

AUGARS

This method is fast and economical, using simple, light, flexible and inexpensive

instruments for large to small holes. It is very suitable for soft to stiff cohesive soils and

also can be used to determine ground water table. Soil removed by this is disturbed but

it is better than wash boring, percussion or rotary drilling.

This method of boring is not suitable for very hard or cemented soils, very soft soils, as

then the flow into the hole can occur. This method is also not suitable for fully

saturated cohesionless soil.

ROTARY DRILLING

Rotary drilling method of boring is useful in case of highly resistant strata. It is related

to finding out the rock strata and also to access the quality of rocks from cracks,

fissures and joints. It can conveniently be used in sands and silts also. Here, the bore

holes are advanced in depth by rotary percussion method which is similar to wash

boring technique. A heavy string of the drill rod is used for choking action. The broken

rock or soil fragments are removed by circulating water or drilling mud pumped

through the drill rods and bit up through the bore hole from which it is collected in a




settling tank for recirculation. If the depth is small and the soil stable, water alone can

be used. However, drilling fluids are useful as they serve to stabilize the bore hole.

Drilling mud is slurry of betonite in water. The drilling fluid causes stabilizing effect to

the bore hole partly due to higher specific gravity as compared with water and partly

due to formation ofmud cake on the sides of the hole. As the stabilizing effect is

imparted by these drilling fluids no casing is required if drilling fluid is used.

This method is suitable for boring holes of diameter 10cm, or more preferably 15

to20cm in most of the rocks. It is uneconomical for holes less than 10 cm diameter. The

depth of various strata can be detected by inspection of cuttings.

ROTARY DRILLING SYSTEM

PERCUSSION DRILLING

In case of hard soils or soft rock, auger boring or wash boring cannot be employed. For

such strata, percussion drilling is usually adopted. Here advancement of hole is done by

alternatively lifting and dropping a heavy drilling bit which is attached to the lower end

of the drilling bit which is attached to the cable.




Addition of sand increases the cutting action of the drilling bit in clays. Whereas, when

coarse cohesionless soil is encountered, clay might have to be added to increase the

carrying capacity of slurry.

After the carrying capacity of the soil is reached, churn bit is removed and the slurry is

removed using bailers and sand pumps. Change in soil character is identified by the

composition of the outgoing slurry. The stroke of bit varies according to the ground

condition. Generally, it is 45-100 cm in depth with rate of 35-60 drops/min.It is not

economical for hole of diameter less than 10cm. It can be used in most of the soils and

rocks and can drill any material.

PERCUSSION DRILLING

One main disadvantage of this process is that the material at the bottom of the hole is

disturbed by heavy blows of the chisel and hence it is not possible to get good quality

undisturbed samples. It cannot detect thin strata as well.




CONTINUOUS SAMPLING

The sampling operation advances the borehole and the boring is accomplished entirely

by taking samples continuously. The casing is used to prevent the caving in soils. It

provides more reliable and detail information on soil condition than the other methods.

Therefore it is used extensively in detailed and special foundation exploration for

important structures.

It is slower method and more expensive than intermittent sampling. When modern

rotary drilling rigs or power driven augers are not available, continuous sampling may

be used to advantage for advancing larger diameter borings in stiff and tough strata of

clay and mixed soil.

In the Boston district, corps of Engineers has made faster progress and reduced cost by

use of continuous sampling in advancing 3-inch diameter borings through compact

gravelly glacial till, which is difficult to penetrate by any boring method.

SOIL SAMPLINGS AND SAMPLERS

Soil Sampling In general soil samples are categorized in to 2 types of samples.

Disturbed samples: The structure of the soil is disturbed to the considerable degree by

the action of the boring tools or the excavation equipments.

The disturbances can be classified in following basic types :Change in the stress

condition, Change in the water content and the void ratio, Disturbance of the soil

structure, Chemical changes, Mixing and segregation of soil constituents The causes of

the disturbances are listed below: Method of advancing the bore hole, Mechanism used

to advance the sampler, Dimension and type of sampler, Procedure followed in

sampling and boring. If all the constituents are present in the sample which represents

the same soil type from any place, then it is called a representative sample. In the

remolded sample the engineering properties get changed due to remoulding

Undisturbed samples: It retains as closely as practicable the true in-situ structure and

water content of the soil. For undisturbed sample the stress changes cannot be avoided.

No change due to disturbance of the soil structure, No change in void ratio and water

content, No change in constituents.




The following Different types of samplers:

Standard split spoon

Piston samplers Piston type sampler

Preservation of samples

Shelby tube etc.

Standard split spoon sampler

Open Drive Sampler Piston Sampler Shelby Tube

DIFFERENT TYPES OF SAMPLER

Date post:	06-Sep-2018
Category:	Documents
Upload:	trinhdung
View:	216 times
Download:	0 times

DARSHAN INSTITUTE OF ENGINEERING & … file5 unconfine compression test(ucs) 18 6 consolidation test...

Documents