Method for determination of shear strength of soil (Badarpur Sand) with a maximum particle size of 4.75 mm in drained conditions using Direct Shear Test apparatus. It is a Floating Box type test in which upper half box is floating due to application of vertical loading resulting in lateral confinement thus generating sufficient friction which holds the upper half of shear box. In the shear box test, the specimen is not failing along its weakest plane but along a predetermined or induced failure plane i.e. horizontal plane separating the two halves of the shear box. This is the main drawback of this test. Moreover, during loading, the state of stress cannot be evaluated. It can be evaluated only at failure condition. Also, failure is progressive.

1. 1
Department of Civil Engineering, IIT Delhi
Submitted By:
Abhinav Kumar
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Soil Engineering Lab
REPORT TITLE (06)
Direct Shear Test

2. 2
Objective: Method for determination of shear strength of soil (Badarpur Sand) with a maximum
particle size of 4.75 mm in drained conditions using Direct Shear Test apparatus.
Apparatus:
1. Direct Shear Test Apparatus-
Loading Frame, Weights, Proving Ring, Micrometer Dial Gauge, Sample Trimmer or Core Cutter,
Stop Watch, Balance, Spatula, Straight Edge, Shear box grid plates, porous stones, base plates,
loading pad and water jacket shall conform to IS: 11229-1985.
(a) Upper and lower parts
of shear box coupled
together with two pins.
(b) Grid plates - 2 pairs
(c) Stone plates
(d) 4 Base plate
(e) Top plate
(f) Loading pad, and the
balance of 1 kg capacity,
sensitive to 0.1 g.
2. Weights - for providing the
required normal loads.
Testing methods and Procedures:
1. Specimen Preparation (Remoulded)
Cohesionless soil (Badarpur Sand) with relative density 70% was 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.
2. Undisturbed Specimen -Specimens of required size shall be prepared
from the undisturbed specimen collected from field in accordance with
IS: 2720 (Part 1)-1983.
3. Consolidated Drained Test-The shear box with sample and perforated
grid plates and porous stones was fitted into the load frame. After
application of normal stress which is done in increments [ IS: 2720 (Part
15)-1986, the sample was allowed to consolidate. When the consolidation
has completely occurred, the shear test should be done at such a slow
rate that at least 95 percent pore pressure dissipation occurs during the
test in this calculated time factor. 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 were made on
separate specimens of the same density at different normal stresses.
Shear Box Assembly

3. 3
4. Strain controlled direct shear machine consists of shear box, soil container, loading unit, proving ring,
dial gauge to measure shear deformation and vertical deformation. A proving ring is used to indicate the
shear load taken by the soil along the shearing plane.
Calculations:
1. From the calibration chart of the proving-ring, the loads corresponding to the load dial readings
obtained during the test was 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 (Ac) = Ao(1 - (δ/3))
where,
Ao = initial area of the specimen in cm2
and
δ = displacement in cm.
2. The longitudinal displacement at a particular load was either noted directly from the strain dial
readings or calculated as the product of the corresponding time reading and the strain rate, allowing for
the compression of the proving-ring, where applicable. The stress longitudinal displacement readings
were plotted and the maximum stress and corresponding longitudinal displacement together with the
normal load applied during the test recorded.
3. The maximum shear stress and the corresponding longitudinal displacement and applied normal stress
were recorded for each test and the results were presented in the form of a graph in which the applied
normal stress is plotted as abscissa and the maximum shearing stress is plotted as ordinate to the same
scale. The angle which the resulting straight line makes with the horizontal axis and the intercept which
the straight line makes with the vertical axis shall be reported as the angle of shearing resistance and
cohesion intercept respectively.
4. i. Shear Stress = (Proving ring reading x Proving ring constant)/Acorrected
ii. Horizontal displacement = (Horizontal dial gauge reading) x (Least count of horizontal dial gauge)
iii. Vertical displacement = (Vertical dial gauge reading) x (Least count of vertical dial gauge)
5. Shear stress at failure needs to be calculated for all three tests performed at three different normal
stresses to plot the failure envelope.

4. 4
Load
(kN)
Comp.
Division
0 0
0.3 141
0.6 282
0.9 425
1.2 567
1.5 712
1.8 856
2.1 1002
2.4 1145
2.7 1291
3 1438
Direct Shear Test Assembly
0
200
400
600
800
1000
1200
1400
1600
0 1 2 3 4
Comp.
Division
Load (kN)
Calibration for Proving Ring No- 15927
Proving Ring
Loading Yoke
Counter Weight
Vertical Dial Gauge
Lever Arm
Holding Screw
Horizontal Dial Gauge
Frame
Motor

5. 5
Data Table
DIRECT SHEAR TEST
Soil Weight 160 gm
Proving Ring
No. 15927
Length (L) 60 mm
Width (B) 59.90 mm
Normal Load
(kN): 0.17970
Least Count
of
Height (h1) 36.5 mm
Normal Stress
(kPa): 50 PR (mm) 0.002
h2 9.2425 mm Soil Type :
Badarpur
Sand VDG (mm) 0.002
Sample
Thickness
(H) 27.26 mm Density(gm/cc) 1.633 HDG (mm) 0.002
Vertical
Dial
Guage
Horizontal
Dial Guage
Proving
Ring
Reading
Horizontal
displ.
(mm)
Vertical
displ.
(mm)
Cummulative
Divisions of
PR
SF
(kN)
Shear
Stress
(KPa)
15.00 0.00 0.00 0.00 0.000 0.00 0.00 0.000 0.000 0.0000
15.03 25.00 11.00 0.05 -0.006 11.00 0.02 6.512 0.130 -0.0002
15.05 50.00 20.00 0.10 -0.010 20.00 0.04 11.860 0.237 -0.0004
15.04 75.00 28.00 0.15 -0.008 28.00 0.06 16.632 0.332 -0.0003
15.03 100.00 33.00 0.20 -0.006 33.00 0.07 19.634 0.391 -0.0002
15.01 125.00 38.00 0.25 -0.002 38.00 0.08 22.647 0.450 -0.0001
14.99 150.00 42.00 0.30 0.002 42.00 0.09 25.073 0.497 0.0001
14.98 175.00 46.00 0.35 0.004 46.00 0.10 27.508 0.545 0.0001
14.95 200.00 50.00 0.40 0.010 50.00 0.11 29.950 0.592 0.0004
14.93 225.00 53.00 0.45 0.014 53.00 0.11 31.801 0.628 0.0005
14.88 250.00 56.00 0.50 0.024 56.00 0.12 33.658 0.663 0.0009
14.84 275.00 58.00 0.55 0.032 58.00 0.12 34.919 0.687 0.0012
14.80 300.00 61.00 0.60 0.040 61.00 0.13 36.788 0.722 0.0015
14.75 325.00 63.00 0.65 0.050 63.00 0.13 38.059 0.746 0.0018
14.71 350.00 65.00 0.70 0.058 65.00 0.14 39.334 0.770 0.0021
14.65 375.00 67.00 0.75 0.070 67.00 0.14 40.613 0.793 0.0026
14.58 400.00 68.00 0.80 0.084 68.00 0.14 41.290 0.805 0.0031
14.52 425.00 70.00 0.85 0.096 70.00 0.15 42.578 0.829 0.0035
14.47 450.00 72.00 0.90 0.106 72.00 0.15 43.869 0.852 0.0039
14.40 475.00 73.00 0.95 0.120 73.00 0.16 44.555 0.864 0.0044
14.33 500.00 74.00 1.00 0.134 74.00 0.16 45.243 0.876 0.0049
14.26 525.00 76.00 1.05 0.148 76.00 0.16 46.546 0.900 0.0054
14.20 550.00 77.00 1.10 0.160 77.00 0.16 47.240 0.912 0.0059
14.13 575.00 78.00 1.15 0.174 78.00 0.17 47.937 0.924 0.0064
14.05 600.00 78.00 1.20 0.190 78.00 0.17 48.020 0.924 0.0070
13.99 625.00 79.00 1.25 0.202 79.00 0.17 48.720 0.935 0.0074
13.93 650.00 80.00 1.30 0.214 80.00 0.17 49.423 0.947 0.0079
13.85 675.00 80.00 1.35 0.230 80.00 0.17 49.509 0.947 0.0084

6. 6
13.78 700.00 80.00 1.40 0.244 80.00 0.17 49.596 0.947 0.0090
13.71 725.00 81.00 1.45 0.258 81.00 0.17 50.304 0.959 0.0095
13.64 750.00 81.00 1.50 0.272 81.00 0.17 50.392 0.959 0.0100
13.56 775.00 82.00 1.55 0.288 82.00 0.17 51.104 0.971 0.0106
13.47 800.00 82.00 1.60 0.306 82.00 0.17 51.194 0.971 0.0112
13.42 825.00 83.00 1.65 0.316 83.00 0.18 51.909 0.983 0.0116
13.32 850.00 84.00 1.70 0.336 84.00 0.18 52.628 0.995 0.0123
13.26 875.00 84.00 1.75 0.348 84.00 0.18 52.721 0.995 0.0128
13.18 900.00 84.00 1.80 0.364 84.00 0.18 52.814 0.995 0.0134
13.14 925.00 85.00 1.85 0.372 85.00 0.18 53.538 1.006 0.0136
13.07 950.00 84.00 1.90 0.386 84.00 0.18 53.002 0.995 0.0142
13.00 975.00 84.00 1.95 0.400 84.00 0.18 53.097 0.995 0.0147
12.95 1000.00 84.00 2.00 0.410 84.00 0.18 53.191 0.995 0.0150
12.87 1025.00 84.00 2.05 0.426 84.00 0.18 53.287 0.995 0.0156
12.81 1050.00 84.00 2.10 0.438 84.00 0.18 53.382 0.995 0.0161
12.76 1075.00 84.00 2.15 0.448 84.00 0.18 53.478 0.995 0.0164
12.69 1100.00 83.00 2.20 0.462 83.00 0.18 52.936 0.983 0.0169
12.65 1125.00 83.00 2.25 0.470 83.00 0.18 53.032 0.983 0.0172
12.55 1150.00 82.00 2.30 0.490 82.00 0.17 52.487 0.971 0.0180
12.53 1175.00 83.00 2.35 0.494 83.00 0.18 53.224 0.983 0.0181
12.45 1200.00 81.00 2.40 0.510 81.00 0.17 52.035 0.959 0.0187
12.38 1225.00 82.00 2.45 0.524 82.00 0.17 52.773 0.971 0.0192
12.32 1250.00 81.00 2.50 0.536 81.00 0.17 52.224 0.959 0.0197
12.25 1275.00 81.00 2.55 0.550 81.00 0.17 52.319 0.959 0.0202
12.19 1300.00 81.00 2.60 0.562 81.00 0.17 52.415 0.959 0.0206
12.13 1325.00 81.00 2.65 0.574 81.00 0.17 52.511 0.959 0.0211
12.07 1350.00 80.00 2.70 0.586 80.00 0.17 51.957 0.947 0.0215
12.02 1375.00 80.00 2.75 0.596 80.00 0.17 52.053 0.947 0.0219
11.97 1400.00 80.00 2.80 0.606 80.00 0.17 52.149 0.947 0.0222

7. 7
Soil
Weight 160 gm
Proving Ring
No. 15927
Length (L) 60 mm
Width (B) 59.90 mm Normal Load (kN): 0.35940 Least Count of
Height
(h1) 36.5 mm
Normal Stress
(kPa): 100 PR (mm) 0.002
h2 9.2425 mm Soil Type :
Badarpur
Sand VDG (mm) 0.002
Sample
Thickness
(H) 27.26 mm Density(gm/cc) 1.633 HDG (mm) 0.002
Vertical
Dial
Guage
Horizontal
Dial
Guage
Proving
Ring
Reading
Horizontal
displ.
(mm)
Vertical
displacement
(mm)
Cummulative
Divisions of
PR
SF
(kN)
Shear
Stress
(KPa)
20.00 0.00 0.00 0.00 0.000 0.00 0.00 0.000 0.000 0.0000
20.01 25.00 18.00 0.05 -0.002 18.00 0.04 10.656 0.107 -0.0001
20.02 50.00 32.00 0.10 -0.004 32.00 0.07 18.976 0.189 -0.0001
20.03 75.00 44.00 0.15 -0.006 44.00 0.09 26.135 0.260 -0.0002
20.05 100.00 55.00 0.20 -0.010 55.00 0.12 32.724 0.326 -0.0004
20.05 125.00 64.00 0.25 -0.010 64.00 0.14 38.143 0.379 -0.0004
20.05 150.00 72.00 0.30 -0.010 72.00 0.15 42.983 0.426 -0.0004
20.05 175.00 79.00 0.35 -0.010 79.00 0.17 47.241 0.468 -0.0004
20.05 200.00 86.00 0.40 -0.010 86.00 0.18 51.514 0.509 -0.0004
20.05 225.00 92.00 0.45 -0.010 92.00 0.20 55.202 0.545 -0.0004
20.05 250.00 96.00 0.50 -0.010 96.00 0.20 57.699 0.568 -0.0004
20.05 275.00 101.00 0.55 -0.010 101.00 0.21 60.807 0.598 -0.0004
20.05 300.00 104.00 0.60 -0.010 104.00 0.22 62.720 0.616 -0.0004
20.04 325.00 108.00 0.65 -0.008 108.00 0.23 65.243 0.639 -0.0003
20.03 350.00 111.00 0.70 -0.006 111.00 0.24 67.170 0.657 -0.0002
20.01 375.00 112.00 0.75 -0.002 112.00 0.24 67.891 0.663 -0.0001
19.98 400.00 116.00 0.80 0.004 116.00 0.25 70.436 0.687 0.0001
19.96 425.00 118.00 0.85 0.008 118.00 0.25 71.774 0.699 0.0003
19.93 450.00 120.00 0.90 0.014 120.00 0.26 73.115 0.710 0.0005
19.91 475.00 124.00 0.95 0.018 124.00 0.26 75.683 0.734 0.0007
19.87 500.00 125.00 1.00 0.026 125.00 0.27 76.425 0.740 0.0010
19.84 525.00 127.00 1.05 0.032 127.00 0.27 77.781 0.752 0.0012
19.80 550.00 128.00 1.10 0.040 128.00 0.27 78.530 0.758 0.0015
19.77 575.00 129.00 1.15 0.046 129.00 0.27 79.280 0.764 0.0017
19.73 600.00 130.00 1.20 0.054 130.00 0.28 80.033 0.770 0.0020
19.68 625.00 133.00 1.25 0.064 133.00 0.28 82.023 0.787 0.0023
19.65 650.00 134.00 1.30 0.070 134.00 0.29 82.784 0.793 0.0026
19.60 675.00 137.00 1.35 0.080 137.00 0.29 84.785 0.811 0.0029
19.57 700.00 138.00 1.40 0.086 138.00 0.29 85.553 0.817 0.0032
19.53 725.00 140.00 1.45 0.094 140.00 0.30 86.945 0.829 0.0034
19.50 750.00 140.00 1.50 0.100 140.00 0.30 87.097 0.829 0.0037

8. 8
19.45 775.00 141.00 1.55 0.110 141.00 0.30 87.873 0.835 0.0040
19.41 800.00 142.00 1.60 0.118 142.00 0.30 88.652 0.841 0.0043
19.35 825.00 143.00 1.65 0.130 143.00 0.30 89.434 0.847 0.0048
19.32 850.00 143.00 1.70 0.136 143.00 0.30 89.592 0.847 0.0050
19.28 875.00 143.00 1.75 0.144 143.00 0.30 89.751 0.847 0.0053
19.24 900.00 143.00 1.80 0.152 143.00 0.30 89.910 0.847 0.0056
19.19 925.00 143.00 1.85 0.162 143.00 0.30 90.070 0.847 0.0059
19.16 950.00 144.00 1.90 0.168 144.00 0.31 90.861 0.852 0.0062
19.11 975.00 144.00 1.95 0.178 144.00 0.31 91.023 0.852 0.0065
19.06 1000.00 144.00 2.00 0.188 144.00 0.31 91.185 0.852 0.0069
19.02 1025.00 143.00 2.05 0.196 143.00 0.30 90.714 0.847 0.0072
18.97 1050.00 144.00 2.10 0.206 144.00 0.31 91.512 0.852 0.0076
18.92 1075.00 142.00 2.15 0.216 142.00 0.30 90.403 0.841 0.0079
18.89 1100.00 142.00 2.20 0.222 142.00 0.30 90.566 0.841 0.0081
18.84 1125.00 142.00 2.25 0.232 142.00 0.30 90.729 0.841 0.0085
18.81 1150.00 142.00 2.30 0.238 142.00 0.30 90.893 0.841 0.0087
18.76 1175.00 141.00 2.35 0.248 141.00 0.30 90.416 0.835 0.0091
18.72 1200.00 141.00 2.40 0.256 141.00 0.30 90.580 0.835 0.0094
18.69 1225.00 139.00 2.45 0.262 139.00 0.30 89.457 0.823 0.0096
18.67 1250.00 137.00 2.50 0.266 137.00 0.29 88.330 0.811 0.0098
18.60 1275.00 136.00 2.55 0.280 136.00 0.29 87.845 0.805 0.0103
18.59 1300.00 135.00 2.60 0.282 135.00 0.29 87.358 0.799 0.0103
18.55 1325.00 135.00 2.65 0.290 135.00 0.29 87.518 0.799 0.0106
18.52 1350.00 134.00 2.70 0.296 134.00 0.29 87.029 0.793 0.0109
18.50 1375.00 133.00 2.75 0.300 133.00 0.28 86.538 0.787 0.0110
18.45 1400.00 130.00 2.80 0.310 130.00 0.28 84.741 0.770 0.0114

9. 9
Soil
Weight 160 gm
Proving Ring
No. 15927
Length (L) 60 mm
Width (B) 59.90 mm Normal Load (kN): 0.53910
Least Count
of
Height
(h1) 36.5 mm
Normal Stress
(kPa): 150 PR (mm) 0.002
h2 9.2425 mm Soil Type :
Badarpur
Sand VDG (mm) 0.002
Sample
Thickness
(H) 27.26 mm Density(gm/cc) 1.633 HDG (mm) 0.002
Vertical
Dial
Guage
Horizontal
Dial
Guage
Proving
Ring
Reading
Horizontal
displ.
(mm)
Vertical
dispL.
(mm)
Cummulative
Divisions of
PR
SF
(KN)
Shear
Stress
(KPa)
19.00 0.00 0.00 0.00 0.000 0.00 0.00 0.000 0.000 0.0000
19.03 25.00 13.00 0.05 -0.006 13.00 0.03 7.696 0.051
-
0.0002
19.04 50.00 22.00 0.10 -0.008 22.00 0.05 13.046 0.087
-
0.0003
19.05 75.00 35.00 0.15 -0.010 35.00 0.07 20.790 0.138
-
0.0004
19.07 100.00 49.00 0.20 -0.014 49.00 0.10 29.154 0.193
-
0.0005
19.09 125.00 62.00 0.25 -0.018 62.00 0.13 36.951 0.245
-
0.0007
19.11 150.00 73.00 0.30 -0.022 73.00 0.16 43.580 0.288
-
0.0008
19.13 175.00 84.00 0.35 -0.026 84.00 0.18 50.231 0.332
-
0.0010
19.14 200.00 95.00 0.40 -0.028 95.00 0.20 56.905 0.375
-
0.0010
19.15 225.00 104.00 0.45 -0.030 104.00 0.22 62.402 0.410
-
0.0011
19.17 250.00 114.00 0.50 -0.034 114.00 0.24 68.518 0.450
-
0.0012
19.18 275.00 122.00 0.55 -0.036 122.00 0.26 73.451 0.481
-
0.0013
19.19 300.00 131.00 0.60 -0.038 131.00 0.28 79.003 0.517
-
0.0014
19.19 325.00 139.00 0.65 -0.038 139.00 0.30 83.971 0.549
-
0.0014
19.21 350.00 145.00 0.70 -0.042 145.00 0.31 87.745 0.572
-
0.0015
19.21 375.00 154.00 0.75 -0.042 154.00 0.33 93.350 0.608
-
0.0015
19.21 400.00 159.00 0.80 -0.042 159.00 0.34 96.546 0.628
-
0.0015
19.21 425.00 168.00 0.85 -0.042 168.00 0.36 102.186 0.663
-
0.0015
19.21 450.00 174.00 0.90 -0.042 174.00 0.37 106.017 0.687
-
0.0015
19.21 475.00 180.00 0.95 -0.042 180.00 0.38 109.862 0.710
-
0.0015
19.21 500.00 185.00 1.00 -0.042 185.00 0.39 113.108 0.730
-
0.0015

10. 10
19.21 525.00 189.00 1.05 -0.042 189.00 0.40 115.754 0.746
-
0.0015
19.20 550.00 194.00 1.10 -0.040 194.00 0.41 119.021 0.766
-
0.0015
19.20 575.00 199.00 1.15 -0.040 199.00 0.42 122.300 0.785
-
0.0015
19.18 600.00 204.00 1.20 -0.036 204.00 0.43 125.591 0.805
-
0.0013
19.17 625.00 209.00 1.25 -0.034 209.00 0.44 128.893 0.825
-
0.0012
19.15 650.00 212.00 1.30 -0.030 212.00 0.45 130.971 0.837
-
0.0011
19.12 675.00 216.00 1.35 -0.024 216.00 0.46 133.675 0.852
-
0.0009
19.11 700.00 220.00 1.40 -0.022 220.00 0.47 136.388 0.868
-
0.0008
19.08 725.00 224.00 1.45 -0.016 224.00 0.48 139.111 0.884
-
0.0006
19.05 750.00 227.00 1.50 -0.010 227.00 0.48 141.222 0.896
-
0.0004
19.02 775.00 230.00 1.55 -0.004 230.00 0.49 143.340 0.908
-
0.0001
18.99 800.00 234.00 1.60 0.002 234.00 0.50 146.089 0.924 0.0001
18.97 825.00 237.00 1.65 0.006 237.00 0.50 148.223 0.935 0.0002
18.93 850.00 241.00 1.70 0.014 241.00 0.51 150.991 0.951 0.0005
18.89 875.00 246.00 1.75 0.022 246.00 0.52 154.397 0.971 0.0008
18.85 900.00 249.00 1.80 0.030 249.00 0.53 156.557 0.983 0.0011
0
20
40
60
80
100
120
140
160
180
200
0.00 0.50 1.00 1.50 2.00 2.50 3.00
Shear
Stress
(kPa)
Horizontal Displacent (mm)
Shear Stress vs Horizontal Displacement
50KPa 100KPa 150KPa
Badarpur Sand

11. 11
Normal stress (kPa) Shear stress (kPa)
50 53.538
100 91.51
150 146.20
Cohesion (C) 4.42 kPa
Angle of Shearing Resistance (Ø) 42.82°
y = 0.9266x + 4.4213
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
160.00
0 20 40 60 80 100 120 140 160
Shear
Stress
(kPa)
Normal Stress (kPa)
Shear stress vs Normal stress

12. 12
Individual Discussion:
1. The loading cap tilted downwards (as shown in fig) on the
motor side (opposite to proving ring) from where horizontal
displacement was applied, due to removal of the sand sample
from the gap created due to shearing of upper half and lower
half shear box.
2. It is a Floating Box type test in which upper half box is floating
due to application of vertical loading resulting in lateral
confinement thus generating sufficient friction which holds the
upper half of shear box.
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.00 0.50 1.00 1.50 2.00 2.50 3.00
Vertical
Displ.
(mm)
Horizontal Displ. (mm)
Vertical Vs Horizontal Displ. Curve
50 kPa 100 kPa 150 kPa
Tilting of Loading Cap

13. 13
3. In the shear box test, the specimen is not failing along its weakest plane but along a
predetermined or induced failure plane i.e. horizontal plane separating the two halves of the
shear box. This is the main drawback of this test.
Moreover, during loading, the state of stress cannot be evaluated. It can be evaluated only at
failure condition. Also, failure is progressive.
4. The angle of shearing resistance of sands depends on state of compaction, coarseness of grains,
particle shape and roughness of grain surface and grading. It varies between 28° (uniformly
graded sands with round grains in very loose state) to 46° (well graded sand with angular grains in
dense state).
5.
Soil Type Angle of Shearing Resistance
(Ø)
Cohesion (C)
Badarpur Sand 42.82° 4.42 kPa
Yamuna Sand 31.70° 18.9 kPa
6. Direct shear test is simple and faster to operate. As thinner specimens are used in shear box, they
facilitate drainage of pore water from a saturated sample in less time. This test is also useful to
study friction between two materials – one material in lower half of box and another material in
the upper half of box.
7. In general, loose sands expand and dense sands contract in volume on shearing. There is a void
ratio at which either expansion contraction in volume takes place. This void ratio is called critical
void ratio. Expansion or contraction can be inferred from the movement of vertical dial gauge
during shearing.
References:
1. IS: 2720 (Part 13):1986 Methods of test for soils: Direct shear test. Reaffirmed- 2016.
2. IS: 11229-1985.
3. IS: 2720 (Part 15)-1986
4. ASTM D 3080 - 04