Constitutive modeling of earthquake-induced slides on clays along slip surfaces

The paper first proposes and validates a constitutive model simulating the change of resistance along a slip surface of clay for both the undrained and drained cases. The proposed model is based on (a) the critical state theory and (b) the assumption that the critical state changes once failure is reached, in terms of the further shear displacement. Under undrained conditions, the proposed model simulates the excess pore pressure generation and, subsequently, the continuous change of resistance along the slip surface from its initial value to the peak strength and then, at large displacement, the residual value. The latter can be measured in constant-volume ring shear tests. Then, the developed constitutive model is implemented in the multi-block sliding system model for the prediction of the triggering and deformation of slides. The improved model is applied at the well-documented Fourth Avenue landslide of the 1964 Alaska earthquake.