Mechanical properties of clay under large shear displacement conditions

By employing a ring shear apparatus, shear tests were conducted to examine the mechanical properties of clay under large shear displacement conditions. Based on the test results, the effects of stress history and shear speed on the shear resistance of over-consolidated silty clay were studied. The following results were found: (1) The variation of shear strength is related with the preconsolidation history and the shear speed. (2) With shear speed increasing, the peak strength and the strength reduction after peak value become greater. The faster shear tests are more favorable to the slip surface formation that leads to the ultimate stable shear strengths. (3) The variations of shear resistance in the fast shear ring shear tests are mainly due to the structural changes in the shear zone, while the influence of pore water during fast shearing is negligible.