Direct Shear Test - Soil Properties: Testing, Measurement, and Evaluation - page 381

Mass of oven-dried soil specimen (at end of test) plus can

182.58 g
Mass of can 46.28 g

[B] Shear Stress Data

Normal load on test specimen 20.6 lb

Rate of shear 0.05 in./min

Proving ring calibration 3,125 lb/in.

Shear (Horizontal)

Vertical Dial Displacement Reading Proving Ring Dial

Reading (in.) (in.) Reading (in.)

0 0 0

0.0030 0.025 0.0030

0.0050 0.050 0.0063

0.0070 0.075 0.0102

0.0080 0.100 0.0124

0.0090 0.125 0.0142

0.0095 0.150 0.0155

0.0100 0.175 0.0163

0.0100 0.200 0.0166

0.0110 0.220 0.0163

0.0115 0.240 0.0159

0.0115 0.260 0.0150

It is, of course, necessary to perform a direct shear test on two (prefer-
ably three) specimens from the same sample at different normal
stresses in order to evaluate the shear strength parameters. In this
example, however, actual data are shown for only one such specimen
tested.
All of the preceding data are shown on the form on pages 387 and
388. At the end of the chapter, two copies of this form are included for
the reader's use.
With these data known, necessary computations can be made as
follows:

[A] Specimen Parameters

The initial area A 0 and volume V 0 of the specimen are easily computed
as follows:

2

p D 0
4

2.50

p 1 2

4.91 in . 2

A 0

4

4.91 in. 3

V 0 H 0 A 0 1.00 4.91

1 21 2 1 21 2