Effect of Shear Displacement Rate on the Internal Shear Strength of GCLs

A series of large-scale direct shear strength tests were conducted to evaluate the effect of shear displacement rate on the internal shear strength of reinforced GCLs. Specifically, the tests were conducted using shear displacement rates ranging from 0.0015 to 1.0 mm/min and using normal stresses ranging from 50 to 520 kPa. The peak internal shear strength was found to increase with decreasing shear displacement rates for high normal stresses, while the opposite trend was observed for low normal stresses. Interpretation of these results, involving indirect evaluation of shear-induced pore water pressures, is proposed to explain this apparently counterintuitive trend. In addition, a decreasing large-displacement shear strength was noted with increasing shear displacement rate for tests at all normal stresses. Future research is geared toward the verification of the trends in peak and large-displacement for other GCLs over a wider range of shear displacement rates.