Question

Problem 3 (10 points):A set of three drained triaxial compression tests is performed on a uniformly graded angular sand. The major and minor principal stresses at the beginning (σ1c and ơ3c) sand end of the tests (c'lf and ơ'3r) are provided in the table below. The end of the test corresponds to a failure condition in the soil. Draw Mohr circles for each test, and plot the failure envelope. σ'sc (kPa) 50 100 200 o'e (kPa) 50 100 200 σ'3f (kPa) 50 100 200 ơ'if (kPa) 250 420 770 The sand that was tested was observed to be uncemented and cohesionless, like beach sand, prior to testing. Did you find that the sand exhibited a cohesion intercept? If so, do you think the cohesion intercept is reasonable given the observation that the sand has no cohesion when it is unconfined? Explain a hypothesis for why a cohesionless sand might exhibit a non-zero cohesion intercept based ona set of laboratory tests

Answer 1