Experimental study on effect of temperature on shear behavior of saturated clays

The effect of temperature on shear behavior of saturated clays is investigated by means of the temperature-controlled triaxial tests. Two kinds of normally consolidated saturated clays are tested. The test program involves different heating and consolidation sequences and drained conditions. The influences of the temperature change on the shear strength, the stress-strain relationship, the excess pore water pressure response and the flow rule are analyzed. The experimental results show that the temperature change significantly affects the shear behavior of the clay, while the temperature effect on the shear behavior of the silty clay is negligible. An increase in temperature increases the undrained and drained peak strength, but the critical friction angle does not change. The excess pore water pressures built up during undrained shear of clay specimens at different temperatures are all found to be positive, and the volume changes under drained shear are always contractive. It implies the reason that the stress-strain softening behavior at high temperature is not shear dilatancy, which is usually used to explain the softening behavior of heavily over-consolidated clays. The temperature effect on the shear behavior is also relevant with the temperature-stress path. The undrained shear strength of the specimen subjected to heat after consolidation is smaller than that of the specimen first heated. After a temperature cycle, the undrained shear strength increases markedly.