SOIL LABORATORYEXPERIMENT NO: 1

GRAIN SIZE DISTRIBUTIONS - SIEVE ANALYSISAIM:

To determine the percentage of gravel , sand and a conbined percentage of silt and clay.

APPARATUS:1. A set of specified sieves2. Balance

1

2

3

CALCULATIONS:- Weight of material retained in each sieve

% of retained = x 100 Weight of sample taken for the test

% of passing = 100 - % of retained

GRAPH:-

A semi log graph connecting particle diameter in mm and percentage of passing is plotted and the grain size distribution curve is obtained. From the grain size distribution curve percentage of gravel, coarse sand, medium sand and fine sand are calculated. Effective sizes D10, D30, D60 are calculated from the graph. Uniformity co-efficient Cu,Coefficient of curvature Cc and fineness modulus of the soil are found out. The approximate value of k (coefficient of permeability) is also calculated as

R= 100x (D10)2(Hayen william’s coefficient)

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INFERENCE:-

Uniformity coefficient Cu is a parameter indicating the range of distribution of grain size is a given soil specimen. If Cu is relatively range it indicates a well graded soil, if Cu is nearly equal to unity it means that the soil grains are of approximately equal size and the soil may be referred to as a poorly graded soil. In some cases a soil way has a combination of two or more uniformly graded fractions and this soil is referred to as gap graded.

The parameter Cc (coefficient of curvature) describes the shape of grain size distribution curve.

If Cu>6 and Cc- 1 to 3 (well graded sand)If Cu>4 and Cc- 1 to 3 (well graded gravel)D15 and D85 sizes are used for design of filters D50 size is used for correlation of

liquefaction potential of saturated granular soil during earthquakes.Filter criteria (D 15 of filter ) / ( D85 of base material ) < 4 to 5 (D 15 of filter ) / ( D15 of base material )

Sl.No.I.S. Sieve

Weight retained

(gms)

Cumulative weight

retained (gms)

Cumulative percentage

retained

Percentage passing

1 4.75 mm

2 2.36mm

3 1.18mm

4 600 µ

5 425 µ

6 300 µ

7 150 µ

8 75 µ

9 Pan

MODEL CALCULATION:1. Effective size of soil = D10

2. Uniformity coefficient (Cu) = D60 / D10

3. Coefficient of curvature ( Cc) =(D30) 2 / (D60 x D10)

4. Fineness modulus = (Total sum of cumulative % retained) / 100RESULT:1. Effective size of soil = 2. Uniformity coefficient (Cu) =

3. Coefficient of curvature ( Cc) =

4. Fineness modulus =

5

a) Coarse sand (4.75 mm to 2.00 mm) = %

b) Medium sand (2.00 mm to 0.425 mm) = %

c) Fine sand (0.425 mm to 0.075mm) = %

1. Gravel > 4.75 mm = %

2. Sand (4.75 mm to 0.075 mm) = %

3. Silt (0.075 mm to -0.002 mm) = %

4. Clay < (0.002 mm) = %

EXPERIMENT NO. : 2 GRAIN SIZE DISTRIBUTIONS – HYDROMETER ANALYSIS

INTRODUCTION: In I.S. specifications, the various fractions have the following limits of equivalent

particle diameter.

Gravel > 4.75 mm equivalent particle diametersSand 4.75 - 0.075 mm equivalent particle diametersSilt 0.075 – 0.002 mm equivalent particle diametersClay < 0.002 mm equivalent particle diameters

PARTICLE SIZE DISTRIBUTION USING HYDROMETER:

AIM:To determine the percentage of silt and clay in the given soil sample.

APPARATUS:

Hydrometer, measuring cylinder (1000 ml), high-speed stirrer, deflocculating agent, constant temperature bath, thermometer and stop watch.

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7

8

Correction to hydrometer readings:1. Meniscus correction (Cm)

Since soil suspensions are opaque, the true reading of the hydrometer at the bottom of the meniscus of the liquid cannot be obtained. In order to read the hydrometer at the top of the meniscus, a meniscus correction must be made. The meniscus correction is positive and added to the hydrometer reading.

2. Temperature Correction (M t)

Hydrometers are usually calibrated at 20oC and if the suspension is not at this temperature, a correction is necessary for the change in density of the liquid. The correction is added if the temperature is above the standard temperature and subtracted if below. Corrections are obtained from the temperature correction chart.

3. Dispersing agent correction (Cd )The addition of dispersing agent raises the specific gravity of the liquid and therefore

the correction has to be subtracted.For the standard concentration, the correction is 0.8.

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The corrected hydrometer reading ‘R’ is thus given by R = R h + Cm - C d + M t

Correction to height of fall:The correction is due to rise in level of suspension in the hydrometer jar due to the immersion of hydrometer. The effective depth ‘ H R ‘ corresponding to any reading of the hydrometer ‘Rh ‘ is obtained from the calibration chart of the hydrometer used. CALCULATIONS:

The observed data and computed quantities are recorded in the data sheet.The percentage by weight of particles smaller than the corresponding equivalent particle diameter ‘D’ is found from the formula.

% finer than D = 100 GsR ---------------- % W s (Gs – 1)

WhereWs = total dry weight of soil particles in 100 ml of suspension.

(50 – Weight of material retained in sieve no. 75 mm.Gs = Specific gravity of soil particlesand R = Corrected hydrometer reading.

The equivalent particle diameter ‘D’ in mm is obtained from the formula

D = 0.175 ( η HR / (G – 1) t mm Where, η = Viscosity of water in C.G.S. Units (Piece)H R = Effective height of fall in cmsGs = Specific gravity of soil particlesand t = observed time in minutes

DATA SHEET – HYDROMETER ANALYSIS

Gs =

Ws =

10

Meniscus correction (Cm ) = 0.5

Correction for dispersing agent (C d ) = 0.8

R = R h + C m + M t – 0.8 = R h + Mt - 0.3

% finer than D = 100 Gs R / Ws (Gs – 1)

D in mm = 0.175 ( η HR / (G – 1) t

TemperatureTo C

Elapsed time t

minutes

Observed hydrometer reading ( R h )

Temperature correction

( Mt )

Correctedhydrometerreading (R)

Viscosity(Poise)

Height of fall (H R )Cms

Equivalent particle diameter (Dmm)

%of particles finer than

the corresponding particle diameter ( -

75 basis)

½

1

2

3

815

30

60

120

240

1440

11

MODEL

CALCULAION:

RESULT:

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EXPERIMENT NO.: 3SPECIFIC GRAVITY OF SOIL GRAINS

AIM:To determine the specific gravity of the given soil sample.

1. (A) laboratory method using a density bottle:APPARATUS:

(i) A 50 cc density bottle with a perforated stopper(ii) A drying oven at 105 ْ c to 110 ْ c(iii) Analytical balance

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CALCULATIONS:-

(W2-W1)The specific gravity of soil grains at Tºc=(Gs @ Tºc) (W2-W1)- (W3-W4)

Specific gravity of water @Tºc

The specific gravity of soil grains is = x Gs @ Tºcreferred @27ºc (Gs @ Tºc) specific gravity of water @27ºc

DATA SHEETObservations Density bottle

Weight of density bottle /(W1, g)Weight of density bottle with soil (W2, g)Weight of density bottle + Soil + water (W3, g)Weight of density bottle + water (W4, g)Temperature of the test T ْ cSpecific gravity of distilled water G T

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MODEL CALCULATION:

RESULT:-

Specific gravity of soil grains at test temperature =

Specific gravity of soil grains at @27ºc =

1. (b) Field method using a psychomotor / volumetric flask:APPARATUS:

pychometer / volumetric flask and a counter balance sensitive it one grams.

DATA SHEET

ObservationsDensity bottle

Pychno meter

Volumetric flask

Weight of Volumetric flask / pychnometer (W1, g)Weight of Volumetric flask / pychnometer with soil (W2, g)Weight of Volumetric flask / pychnometer + Soil + water (W3, g)Weight of Volumetric flask / pychnometer + water (W4, g)Temperature of the test T ْ c

Specific gravity of distilled water G T

MODEL CALCULATION:

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The specific gravity is obtained from the following expression.Specific gravity (Gs) = (W2 – (W1) GT

-------------------------------------------------

(W2 – (W1) - (W3– (W4)

RESULTS:Specific gravity of the given soil (G) (Using density bottle) =Specific gravity of the given soil (G) (Using Pychno meter) =Specific gravity of the given soil (G) (Using volumetric flask) =

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EXPERIMENT NO.: 4RELATIVE DENSITY OF SAND

AIM:

To determine the maximum void ratio and the minimum density as well as minimum void ratio and the maximum density for the given sand.

APPARATUS:(i) A standard compaction mould without collar(ii) A funnel(iii) A straight edge(iv) A balance with weight.

DATA SHEET:

Diameter of the mould =

Height of the mould =

Minimum Density:

1. Volume of the mould, (Vt cm3 ) =

2. Specific gravity of sand, (Gs) =

3. Weight of mould (g ) =

4. Weight of mould + sand in loose state (g) =

5. Weight of sand in loose state (g) =

6. .Minimum density of the sand (g / cm3) =

(Ws / Vt)

7. Volume of the solids, ( cm3)

Vs = Ws / G =

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8. Volume of the voids, ( cm3)

(Vv = Vt – Vs) =

9. Maximum void ratio,

(e max = Vv / Vs) =

Maximum density:

10. Reduction in height of the sand

after tapping the sides (cm) =

11. Reduction in volume(Cm3 ) =

12. Reduced volume of sand

after tapping the sides (V1 cm3) =

(Total volume – Reduction volume)

13. Maximum density of the sand,

(Ws / V1) (g / cm3) =

14. Volume of solids, ( cm3)

Vs = Ws / Gs =

15. Volume of voids (Vv cm3) V1 – Vs =

16. Minimum void ratio,

emin = Vv / Vs =

Assuming a field void ratio in-between e max and e min (usually taken as (emax + emin) / 2)The density index or relative density can be calculated using the relation Relative density ID = (e max – e field) / (emax - emin)

INFERENCE: Based on the relative density of sand obtained. The denseness of the medium can be

inferred as per the following table.

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MODEL CALCULATION:

RESULT:

Soil: specific gravity:

1. Maximum density (g / cm3) =

2. Minimum void ratio ( emin ) =

3. Minimum density, (g / cm3) =

4. Maximum void ratio (e max ) =

EXPERIMENT NO.: 5ATTERBERG LIMITS TEST- DETERMINATION OF LIQUID LIMIT OF SOIL.

Aim:

To determine the liquid limit of the given soil.

Apparatus:

1. Liquid limit device with grooving tool,2. China clay disc3. Balance to weigh up to an accuracy of 0.01gm4. Spatula5. Container to dry the sample

Observations and calculations:Observations:

Soil: Specific gravity:

Weight of can (W0 ) (gm)

Weight of wet soil with can (W1) (gm)

Weight of dry soil with can (W2) (gm)

Weight of water (W2 – W1) (gm)

Weight of dry soil (W2 – W0) (gm)

Moisture content (W %)

Number of Blows (N)

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Graph:

A plot is made between the water content and number of blows in a semi log plot.

Calculation: (W2 – W1)

1. Moisture content W =------------------- x 100 (W2 – W0)

2. Liquid limit is directly found from the graph (corresponding to 25 blows)

(W2 – W1) 3. Flow index (If) = -------------------

Log (N2 / N1)

Where, W1, W2 = water content in % at N2 and N1 blows respectively

Results:Soil: Specific gravity:

Liquid limit of the soil =Flow index =

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EXPERIMENT NO: 5AATTERBERG LIMITS TEST- DETERMINATION OF PLASTIC LIMIT OF SOIL

Aim:To determine the plastic limit of the given soil.

Apparatus: 1. glass plate2. china clay disc3. balance4. container to dry the sample in oven

Observations:Soil: Specific gravity (G)

Weight of can (W0 ) (gm)

Weight of wet soil with can (W1) (gm)

Weight of dry soil with can (W2) (gm)

Weight of water (W2 – W1) (gm)

Weight of dry soil (W2 – W0) (gm)

Moisture content (W %)

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Calculation: (W1 – W2)

Determination of Moisture content W =------------------- x 100 (W2 – W0)

The average of the three moisture contents is taken as the plastic limit of the soil it is expressed to the nearest whole number.

Results:

Soil: Specific gravity:Plastic limit of the soil =

EXPERIMENT NO.: 5BATTERBERG LIMITS TEST- DETERMINATION OF SHRINKAGE FACTORS OF

SOIL.

AIM:To determine the following characteristic of the given soil.1. Shrinkage limit2. Shrinkage ratio3. Volumetric change4. Linear shrinkage

APPARATUS:Evaporating dish, spatula, stainless steel dishes, glass cup, three pronged plate and

mercury.

CALCULATIONS:

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The water content of the soil at the time it has been placed in the dish, expressed as a percentage of the dry weight of the soil, shall be calculated as follows:

W – Wo w = ------------ X 100

WoWhere,w = water content of the soil when placed in the dishW = Weight of wet soil pat obtained by subtracting the weight of shrinkage

Dish from the weight of wet pat and dish, and Wo = weight of dry soil pat obtained by subtracting the weight of the dish from the weight of the dry pat and dish.

Shrinkage limit:

The shrinkage limit (Ws) shall be calculated as follows:

Ws = w ( ( V Vo) / Wo ) X 100

Where,

Ws = shrinkage limitw = water content of wet soilWo = weight of oven dried soil patV = volume of the wet soil patVo = Volume of the oven dried soil pat

Shrinkage ratio:The shrinkage ratio R shall be calculated as follows:

WoR = ------

Vo

Volumetric shrinkage : The volumetric shrinkage (Vs) shall be calculated as follows:

Vs = (w – Ws) R

Linear shrinkage:The linear shrinkage (Ls) shall be calculated as follows:

Ls = 100 [1 – { 100 / (Vs + 100) }] in %

Shrinkage index (Is) : Wp - Ws

Where Wp = plastic limit of the soil.

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Specific gravity (Gs):The specific gravity of the soil solids (Gs) may also be calculated from the data

obtained in the test by the following formula1

Gs = -------------------1 / R – Ws / 100

REMARKS:

Obtained is to be reported rounded off to the nearest whole number. If any individual

value The test shall be repeated at least three times for each soil sample and the average of

the values thus varies from the average by more than + 2 %, it shall be discarded and the test

to be repeated

1 Trial No. 1 2 3

2 Shrinkage dish No. 1 2 3

3 Weight of empty shrinkage dish (g)

4 Weight of mercury filling the dish (g)

5 Volume of dish = volume of wet soil pat, Weight of mercury filling the dish / 13.6, ( Vccs)

6 Weight of shrinkage dish + wet soil pat (g)

7 Weight of wet soil pat (g)(Weight of shrinkage dish + wet soil pat) - Weight of empty shrinkage dish)

8 Weight of shrinkage dish + dry soil pat (g)

9 Weight of oven dried soil pat (Wo, g)(Weight of shrinkage dish + dry soil pat) - weight of empty shrinkage dish

10 Water content of the wet soil pat,(W) % =

(Weight of wet soil pat - weight of oven dried soil pat) / weight of oven dried soil pat)

11 Weight of mercury displaced by dry soil pat + weight of evaporating dish (g)

12 Weight of evaporating dish (g)

13 Weight of mercury displaced by oven dried soil pat (g) =(Weight of mercury displaced by dry soil pat + weight of evaporating dish (g) - weight of evaporating dish

14 Volume of dry soil pat (Vo) ccs =Weight of mercury displaced by oven dried soil pat / 13.6

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MODEL CALCULATION:

RESULT:

Soil: Specific gravity:

Shrinkage limit =

Shrinkage ratio =

Volumetric shrinkage =

Linear shrinkage =

CONSISTENCY LIMITS: Liquid limit – natural water content1. Consistency index (CI) = ------------------------------------------- Liquid limit - plastic limit

2. Liquidity index (LI) Natural water content – plastic limit Or = -------------------------------------------------- Water plasticity ratio (IL) liquid limit – plastic limit

Plastic characteristics

Plasticity index (IP)Toughness index ( IT) = -------------------------- Flow index (IF)

Consistency classification:

Plasticity index Plasticity

0

1-5

5-10

10-20

20-40

> 40

Non plasticity

Slightly plasticity

Low plasticity

Medium plasticity

High plasticity

Very high plasticity

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CI + LI = 1 Plasticity index (Ip)

Activity ratio (Ac) = ------------------------------------- Percent finer than 2 microns

Undisturbed (qu)Sensitivity of clay (St) = ------------------------------ Remoulded ( qu)

Sensitivity Classification / type Remarks

<1

1-4

4-8

8-15

>15

Insensitive

Normal clays( low and

medium sensitive)

Sensitive

Extrasensitive

Quick clays

---

Honey comb structure

Honey comb of flocculated

structure

Flocculants structure

unstable

Relative between shrinkage limit and swelling type of soils

CI LI Consistency

Unconfilled compression

strengthQa in KN / m2

1.00 – 0.75

0.75 – 0.50

0.50- 0.25

0.25 – 0.00

0.0 – 0.25

0.25 – 0.50

0.50- 0.75

0.75 – 1.00

Stiff

Medium

Soft

Very soft

Very stiff

Hard

100-200

50 – 100

25-50

< 25

200-400

> 400

Ac soilty classification

<0.75

0.75 – 1.25

>1.25

Inactive clay

Natural clay

Active clay

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Swelling potential (Sp)

Sp = 60 K Ip2.44

K = 3.6 * 10 -5 for clay content between 8 to 6.5 %

Relation between Sp and Ip

EXPERIMENT NO.: 6DETERMINATION OF MOISTURE- DENSITY RELATIONSHIP USING STANDARD PROCTOR TEST.

AIM:To determine the moisture content – dry density relationship of the given soil under light

compaction.

APPARATUS:1. Proctor’s compaction mould with base and extension cellar2. Standard rammer3. Balance and Weights.

Swelling typeShrinkage limit(Wl)%

Non – critical

Marginal

critical

>12

10-12

< 10

Sp Ip Expansitivity

<1.5

1.5- 5

5 -25

> 25

0-15

15-35

35-55

>55

Low

Medium

High

Very high

27

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CALCULATION:a) Wet density, ( γwet g / cc) = W2 – W1

---------------------------Volume of the mould

Dry density ( γdry g / cc) = (wet density) / (1+ w / 100)

Where,W2 = weight of mould with moist compacted soilW1 = weight of empty mould

And w = water content, percent

Plot the ‘dry density – moisture content’ curve and determine the optimum moisture content and the maximum dry density.

b. Zero air voids curve:The line showing the dry density as a function of water content for soil containing no air voids is called the zero air voids curve and established by the equitation.

Dry density ( γdry) = Gs γ w / ( 1 + w G)Where, Gs is the specific gravity of the soil particles.

DATA SHEET

Mould no. =

Volume of mould, (v, cm3) =

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Weight of empty mould with out collar (W1, gms) =

Trial No. 1 2 3 4 5

Weight of mould with compacted wet soil (W2, gms)

Weight of empty mould with out collar

Weight of the compacted moist soil(W2 – W1) gms

Wet density ( γwet g / cc)

Moisture content, w %

Dry density ( γdry, g / cc)

MOISTURE CONTENT DETERMINATION:

Trial No. 1 2 3 4 5

Can no.

Empty can weight (gms)

Weight of can with wet soil (gms)

Weight of can with dry soil (gms)

Weight of water (gms)

Weight of dry soil (gms)

Moisture content (w %)

ZERO AIR VOIDS CURVE:

Specific gravity Gs =

30

Moisture content (w) 5 % 7.5 % 10 % 12.5 % 15 % 17.5 %

Dry density = Gs γ w / ( 1 + w Gs)

MODEL CALCULATION:

RESULT:

Soil: specific gravity:

a. From the plotted dry density – moisture content curve report the following1. Optimum moisture content =2. Maximum dry density (g / cc) =3. Void ratio at maximum dry density =

b. Plot the zero – air void curve also in the same graph.

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EXPEREIMENT NO.: 7PERMEABILITY DETERMINATION - CONSTANT HEAD METHOD

AIM:To find out the coefficient of permeability of the assigned soil using a constant

head permeameter.

APPARATUS:Universal permeameter with accessories.

CALCULATIONS:The coefficient of permeability ‘k’ of the soil calculated from the relation.

k = (Q L) / At h

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Where,k = Co efficient of permeability of soil (cm / sec )Q = Total discharge in time ‘t’ (cm3 / sec)A = Area of sample perpendicular to the direction of flow of water (cm2)L = Length of the sample (cms)H = Head causing flow ( cms )

‘k’ is normally expressed in cm / sec. the other terms in the equation should be obtained in proper units.

If the soil sample is sand, compare the ‘k’ value of sand, with the value obtained by Hazen’s equation for filter sands (i.e.) k = 100 (D10 )2 , where ‘ k’ is the permeability in cm / sec. and D10 is the ten percent size expressed in cm.

DATA SHEET

Constant head permeability test

Dimensions of the permeameter =

Area of the sample (cm2 ) (A) =

Volume of the sample (V) ccs =

Weight of the sample filling the mould (Ws grams) =

Specific gravity of the soil (Gs) =

Volume of solids, Vs = (Ws / Gs) ccs

Volume of voids (Vv = V – Vs) ccs =

Void ratio, e = Vv / Vs =

Length of the sample, (L, cms ) =

Head causing flow, (h, cms) =

Viscosity of water at 27 ْ c ( μ 27 ) poise =

Temperature of the test, T ْ c =

Viscosity of water at T ْ c ( μ T ) poise =

Trialno.

Time ‘t’ in sec.

Quantity of water

collected Q.cs

‘K’ at T ْ cCm / sec

k 27 = kT x μ T / μ 27

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kT (average) =k27 (average) =

MODEL CALCULATION:

RESULT:

Soil: Specific gravity:

k27 =

Void ratio =

EXPERIMENT NO: 7 APERMEABILITY DETERMINATION -FALLING HEAD METHOD

AIM:To determine the coefficient of permeability (K27 in cm / sec) of fine grained soils like

silt and clay having low permeability.

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APPARATUS:Permeameter with accessories.

35

CALCULATIONS:The coefficient of permeability of the soil can be calculated from the calculation.kt = {2.303 a L log 10 ( ho / h1 ) } / At

Where, kt = coefficient of permeability in cm / sec at temperature T ْ c a = Area of cross section of the stand pipe (cm2)

L = Length of the specimen in cmA = Cross sectional area of specimen in cm2

t = time in seconds for the head to fall from ho to h1

ho = head at the beginning of test (cms)h1 = head at time t (cms)‘k’ is usually expressed at a standard temperature of 27 ْ ْْ ck27 = kT x ( μT / μ27 ) Where,k27 = coefficient of permeability at 27 ْْ ckT = coefficient of permeability at T ْْ c

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μt = coefficient of viscosity at T ْْ c μ27 = coefficient of viscosity at 27 ْ c

DATA SHEET:

Variable head permeability test:Dimensions of the permeameter =

Area of the sample (A, cm2) =

Area of the stand pipe (a, cm2) =

Volume of the sample (V cm3) =

Weight of the sample filling the mould (Ws, gms) =

Specific gravity of the soil sample, Gs =

Volume of the solids, (Vs = Ws / Gs) cm3 =

Volume of voids, (Vv = V – Vs) cm3 =

Void ratio (e = Vv / Vs) =

Length of sample (L, cms) =

Viscosity of water at 27 ْ c ( μ27 ) = 8.55 Millie (poise)Viscosity of the water at T ْ c (μT ) =Temperature of the test, T ْ c =

Trial No. Initial head ho, cmsFinal head at time t1 h1 cms

Time in seconds

t1

‘kt’ at the temperature of

the test

1.

2.

3.

4.

Average of kt

( μt )k27 = kt (average) x ------------------ cm / sec

( μ27)MODEL CALCULATION:

37

RESULT:

Soil: specific gravity:

k27

Void ratio

EXPERIMENT NO: 8DETERMINATION OF SHEAR STRENGTH PARAMETERS- DIRECT SHEAR

TEST ON COHESIONLESS SOIL

38

APPARATUS:Direct shear test apparatus with the necessary accessories.

39

CALCULATION:The angle of internal friction, φ can be computed from the plot of ‘ultimate shear

strength’ Vs ‘normal stress’, using the relation.t = σ tan φIn which t = shear stress.

DATA SHEETDIRECT SHEAR TEST ON COHESIONLESS SOIL

Soil sample =

Specific gravity of soil, (Gs) =

Weight of dry soil used, (g) =

Dimensions of sample = 6 cm x 6 cm x 2 cm

Void ratio, (e) =

Proving ring calibration

I division =

Trial no. 1 2 3 4 5

Normal stress σ ,Kg / cm2

Proving ring dial reading at failure

Shear force at failure (kg)

Ultimate shear stress σ ,Kg / cm2

MODEL CALCULATION:

RESULT:

Soil: specific gravity:Ultimate friction angle φ ult =Void ratio ‘e’ =

40

41

EXPERIMENT NO. 8A

DETERMINATION OF SHEAR STRENGTH PARAMETERS- UNCONFINED COMPRESSION TEST ON COHESIVE SOIL

AIM:To determine the unconfined compressive strength of soil.

APPARATUS:Unconfined compression tester (motorized) with the necessary accessories.

42

CALCULATION:The stress strain curve of the specimen is plotted and using the same

relationship as before the unconfined compressive strength of the sample is determined.

DATA SHEET:Unconfined compression test (using load frame)

Soil =

Dimensions of the sample = 3.81 cm dia

43

8.57 cm length

Volume (cm3) =

Area (initial), (Ao cm2) =

Moisture content (W %) =

Dry density (g / cm3) =

Degree of saturation, (S) =

Proving ring calibration 1 division =

Deformation dial calibration 1 division =

Deformation (No. of divisions x)

Strain in (mm)

1 – v A=Ao / (1 – v) (cm 2)

Proving ring readings (No.of division)

Load (P) in (Kg)

Stress = P / A(Kg/ cm2)

MODEL CALCULATION:

RESULT:Soil: specific gravity:

Dry density (g / cm3) =

Moisture content (w % ) =

Degree of saturation (S) =

Unconfined compressive strength (g / cm2) =

Shear strength (c) ( g / cm2) =

Consistency qu

Consistency qu (unconfined compressive strength in KN/m2 c=( qu / 2)

HardVerystiff

>400200-400

44

StiffMediumSoftVery soft

100-20050-10025-50<25

EXPERIMENT NO.: 8B

DETERMINATION OF SHEAR STRENGTH PARAMETERS- TRIAXIAL COMPRESSION TEST

Aim:To determine the effective stress parameters of Φ and C of a soil.

Apparatus:1. Compression machine

45

2. Triaxial cell3. Specimen mould, rubber membrane, membrane stretcher, rubber binding strips

and porous stones

DATA SHEETSample data:Area: Length of the sample:

Machine data:Loading rate: Proving ring constant:

Data of testing:S.No. Pressure applied

Kg /cm2 s3

Proving ring dial

Deviator load Deviator

Total normal stress

46

reading Pstress

kg / cm2

dkg / cm2 s1

Result:

The stress parameters =

Cohesion of the given sample C =

And angle of internal friction of the given sample.

EXPERIMENT NO.: 09

ONE DIMENSIONAL CONSOLIDATION TEST (DETERMINATION OF COEFFICIENT OF CONSOLIDATION ONLY)

AIM:To find the co efficient of consolidation of the given remolded clay sample ( by square root fitting method and log fitting method) under a pressure increment from 0 to 0.5 T / S. ft.

47

APPARATUS:Consolidometer with the necessary accessories.

SECURE ROOT FITTING METHOD:CALCULATIONS:

Co efficient of consolidation Cv is calculated using the relation

T 90 H 2

Cv = ---------- T 90

48

Where,

T90 = time for 90% consolidation = 0.848H = effective drainage path in cm

= height of sample-----------------------

2

And t 90 = time required seconds for 90% compression obtained from square root plot.The primary compression ratio, ‘r’ can be calculated using the relationship.

10---- (d s - d 90)9

-----------------------------------d 0 - d f

Where,d s = Corrected zero pointd 0 = Compression dial reading at 0 % consolidationd s = Compression dial reading at zero timed f = Final dial reading

‘LOG t ‘ FITTING METHOD:Co efficient of consolidation C v is calculated using the relationship.

T50 H2

C v = ----------------- t 50

Where,T50 = time factor for 50% consolidation

= 0.197H = effective drainage path in cm

= height of sample--------------------

2T50 = time required in seconds for 50% compression obtained from ‘log t’

Plot.The primary compression ratio ‘r’ cn be calculated using the relationship

d s - d 100

R = ---------------------d s – d f

Where,d 100 = compression dial reading at 100%

Primary compression by log fitting methodd s = Corrected zero pointd 0 = Compression dial reading at zero timeAnd d f = Final dial reading

When the sample is subjected to different pressure increments, the void ratios can be calculated at the corresponding pressure ranges. The slopes of the e – log p curve is called the compression index (Cc) where Cc is given by

eo - e C c = - -------------------------

49

_ log 10 (s / s0)

where eo - initial void ratio corresponding to initial pressure s0 ْand

e – void ratio at increased pressure _ ْ ْ s

DATA SHEET

CONSOLIDATION TEST

Soil sample:

Dimensions of ring = 3” dia and 1” height

Load on hanger = 5 lbs

Load on sample = 55 lbs (lever arm ratio 1: 11 )

Consolidating pressure = 0 to 0.5 T / ft2

Date =

Starting time =

Least count of deformation dial =

Elapsed time ‘t’ in minutes

√t (min) Dial gauge reading

0

¼

1

2.25

4

6.25

9

12.25

16

20.25

25

50

30.25

36

49

64

81

100

121

144

169

1440 (24 hours)CALCULATION:

1. Weight of Consolidometer base +

Ring along with bottom porous plate (W1 g) =

2. Weight of Consolidometer base + ring +

Wet soil along with the

Bottom porous plate (W2 g) =

3. Weight of wet soil, (W2 – W1 ) g =

4. Moisture content (w %) =

5. Weight of dry soil

(W2 - W1) X 100

-------------------------- (g) =

100 + w

6. Specific gravity (Gs) =

7. Volume of solids V s cc (5) / (6) =

Volume of solids

8. Height of solids ----------------------- =

Area of solids

9. Height of voids (initial) =

10. Height of voids (final) =

11. Initial void ratio (e 0 ) =

12. Final void ratio (e f) =

51

13. Dial reading corresponding to initial height =

14. Dial reading corresponding to final height =

15. Initial height of sample =

16. Final height of sample =

17. Average height of sample during the test =

‘ √t ‘ Fitting method ‘ Log t ‘ fitting method

T 90 = 0.848 t 50 = 0.197

√t 90 = t 50 =

t 90 =

H =

t 90 = C v =

H = d 0 =

C v = d s =

d 0 = d 100 =

d s = d f =

d 90 =

d f =

MODEL CALCULATION:

52

RESULT:

Soil: specific gravity:

Co efficient of consolidation C v cm 2/ sec ‘√t ‘ Fitting method = ‘Log t ‘fitting method =

Primary compression ratio ‘r’:‘√t ‘ Fitting method =

‘Log t ‘fitting method =

EXPERIMENT NO.: 10FIELD DENSITY TEST -CORE CUTTER METHOD

Aim:To determine the dry density and dry unit weight of in-situ soil by core cutter.

APPARATUS:1. Cylindrical core steel core cutter 150mm long and 10cm internal diameter with a

wall thickness of 3mm beveled at one end,2. Steel dolly 2.5cm high and 10cm internal diameter with wall thickness of 7.5mm,3. Steel rammer of weight 9kg,4. Balance,

53

5. Moisture cans.

54

55

DATA SHEET

1. Weight of the core cutter + wet soil gm =

2. Weight of the core cutter only gm =

3. Volume of the core cutter in cm3 =

4. Wet density gm / cm3 obs.(2/3) gms/ cm3 =

5. Wet unit weight kN/m3 ( obs. 4 )x 9.81 =

6. Moisture content % =

7. Dry density gm / cm3 obs.(4)/ (1+w) =

8. Dry unit weight kN/m3 obs.(7)x9.81 =

RESULT:

1. Wet density gm / cm3 =

2. Wet unit weight kN/m3 =

3. Dry density gm / cm3 =

4. Dry unit weight kN/m3 =

56

EXPERIMENT NO: 10AFIELD DENSITY TEST -SAND REPLACEMENT METHOD

AIM:The object of this experiment is to determine the dry density of natural or compacted

soil on the field by ‘sand replacement’ method.

APPARATUS:Sand pouring cylinder, calibrating container and metal tray.

57

DATA SHEETField density test

Volume of cone and bulk density of sand:

1. Weight of sand pouring cylinder = W1

2. Weight of sand pouring cylinder with sand = W2

3. Weight of sand pouring cylinder with

Sand after filling the cone = W3

4. Weight of sand filling the cone = W2 – W3

5. Weight of sand pouring cylinder with sand

After filling the cone and calibrating can = W4

6. Weight of sand filling the cone

And calibrating can (2) - (5) = W2 – W4

7. Weight of sand filling the can only

(6) - (4) = (W2 – W4) – (W2 - W3)

8. Volume of can (10 cm dia and 12.5 cm deep)=

9. Bulk density of sand (7) / (8) =

10. Volume of cone (4) / (9) =

58

Field density:11. Weight of sand pouring cylinder with sand (2) =

12. Weight of sand pouring cylinder with

Sand after filling the cone and hole =

13. Weight of sand filling the cone (4) =

14. Weight of sand filling the hole

(11) - (12) - (13) =

15. Volume of hole, (14) / (9) =

16. Weight of empty cans =

17. Weight of cans with soil taken from the field=

18. Weight of soil taken from the field =

19. Weight of soil retained on 4.76 mm sieve =

20 Weight of wet soil passing 4.76 mm sieve =

21. Volume of material retained on 4.75 mmSieve (19) / Absolute density Of + 4.75 mm Material (assume a density Of 2.65 g / cm3 for + 4.75 mm sieve) =

22. Volume of material passing 4.75 mm sieve (15) – (21) =

23. Moisture content of (4.75 mm material(W %) =

24. Weight of dry soil passing 4.75 mm sieve (20) X 100

-------------------- = 100 + w

25. Dry density of soil (on – 4.75 mm basis).(24) / (22) =

26. Total dry weight of soil(19) + (24) =

27. Dry density of soil (on over all basis) (26) / (15) =

28. Percentage of + 4.75 mm material (19) ---------- X 100 = (26)

59

MODEL CALCULATION:

RESULT:

1. Field density of soil (-4.75 mm sieve basis) (g / cm3) =

2. Field density of soil (Over all basis) (g / cm3) =

3. Percentage of + 4.75 mm size material =

4. Moisture Content of material passing 4.75 mm sieve =

60