Probabilistic Assessment of Seismic Response of Toe-Excavated Partially Saturated Hillslopes

Toe excavation of the hills is a common practice in the highlands of India for construction or extension of roadway projects. Landslides in such cut slopes occurs very often and have dire consequences on human lives, properties and communication network in the hilly regions. Rise in natural ground water level due to torrential rain during monsoon season and seismic activity are two most crucial factors responsible for most of these landslides in cut slopes. The customary stability assessment techniques for such cut slopes is based on deterministic method, where the stability is assessed with reference to a single safety measure commonly known as factor of safety. Nonetheless, due to uncertainty related to various geotechnical parameters, the standard deterministic approach may end up resulting in mismatched design solutions. This paper reports the seismic behaviour of cut slopes in the presence of water table for different seismic zones in India utilizing a probabilistic approach. The study also exhibits the influence of correlation coefficient, spatial variation of shear strength parameters and the coefficient of variation on the seismic response of the partially saturated cut slope. Furthermore, the study reports the effect of incorporation of uncertainty in water table location and pseudo-static earthquake forces on seismic response of the partially saturated cut slope. A nonlinear time-history analysis is also carried out to estimate the more realistic seismic behaviour of the partially saturated cut slope during earthquake.