Stability analysis of non-homogeneous soil slopes under rainfall conditions

Abstract

Natural slopes are non-homogeneous in the form of stratifications or variation in different material properties and hydraulic conditions with depth because of various geological formations and climatic conditions. Even in case the of uniform stratification, variations of different hydraulic properties like saturated permeability, and unsaturated permeability function with depth make the slope non-homogeneous in nature. Many slopes have failed due to rainfall infiltration. Presence of a ground water level (GWL) divides the slope into saturated and unsaturated zones. In the unsaturated zone, the matric suction significantly contributes to enhanced shear strength. Under rainfall conditions, rainwater infiltration occurs leading to the rise of ground water levels as well as the pore water pressures. The rise of pore water pressures in the unsaturated zone leads to shallow failure of slopes under infiltration conditions due to the reduction in suction levels and thereby the shear strength. Behaviour of non-homogeneous slopes will be different from that of homogeneous slopes, particularly under rainfall conditions, which may lead to failure under critical situations.