Two-dimensional finite element based parametric analysis of south portal slope, Rohtang Tunnel, India

摘要

Slope failures associated with large-scale displacements and high strains in geomaterials have often resulted in large loss of life and properties in the Himalayan terrain. These slope failures bear a substantial relation to high-intensity rainfall events [1]. One such slope is located at south portal of Rohtang tunnel, numerous slope failures due to the effect of fluctuating water table and rainfall events had already occurred. This paper describes variation in strength reduction factor (SRF) by a two-dimensional finite element based numerical modelling under four dominate strength reduction parameters. A total of one thirty-five analysis has been performed to obtain SRF values considering two sets of parameters. Three type of rocks constituting the slopes are Phyllitic quartzite, Quartzitic phyllite and Migmatite gneiss. Physico-mechanical behaviour of these rocks are investigated as per ISRM and BIS standards. The role of pore water pressure, joint inclination, slope angle and water table within the slope and its effect on failure is discussed in this paper.