STRESS-PATH DEPENDENT SHEAR-STRENGTH OF SAND

Failure envelopes of sands arc often considered to be nonlinear depend ing both on relative density and stress level. Triaxial tests that wer e performed on clean alluvial-quartzitic Zbraslav sand were used for a nalyzing the form of the failure envelope. In addition to relative den sity and stress level, the stress path (tests with constant-cell press ure were compared with tests with constant-mean stress level) has been found to affect the shear resistance as well. Only tests with constan t-mean stress produce nonlinear-failure envelopes. Up to the peak-stre ss difference, no shear bands were observed. Rough platens were used t o simplify the procedure since the specimen's restraint was found not to affect the shear resistance for diameter to height ratio 1:2. The w riter uses the percolation theory to provide the physical interpretati on of the experimental results.