A series of three direct shear tests has been conducted on a certain saturated soil. Each test was performed on a 2.375-inch diameter, 1.00-inch tall sample. The results of these tests are as follows:

Test Number Normal Stress Shear Stress
1 2435 1656
2 4870 3571
3 7305 4578

Determine the friction angle and cohesion intercept.

Go to explaination for the details of the answer.

Explanation:

Angle of friction (friction angle) is a measure of the ability of a unit of rock or soil to withstand a shear stress. It is the angle (φ), measured between the normal force (N) and resultant force (R), that is attained when failure just occurs in response to a shearing stress (S).

The cohesion intercept is a used when we want to describe the shear strength soils. The definition is mainly derived from the Mohr-Coulomb failure criterion and it is used to describe the non-frictional part of the shear resistance which is independent of the normal stress.

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