Analysis of influence of shear rate on shear strength of sand under high stress

The direct shear strength tests of Fujian standard sand with 16 normal stress levels and 5 series of shear rate were carried out by using the super-high-pressure direct and residual shear testing system DRS1. The test results indicate that the shear strength of sand is influenced by both normal stress level and shear rate; and it has a close relation with particle crushing degree and particle rearrangement/reorientation state after particle crushing (coordinate number Nc). Shear rate has no influence on shear strength of sand under small normal stress; and the Mohr failure envelops are almost same to each other. But when normal stress is relatively large, the shear strength with faster shear rate become smaller; and the Mohr failure envelops show "deflexibility-rise" fluctuation cycle; so the shear rate should be considered in the strength analysis of sand under high normal stress condition.