Stability analysis of slope subjected to seepage forces considering spatial variability of soil properties

Abstract

The stability analysis of a saturated soil slope subjected to seepage flow generated by rapid water level drawdown is investigated in this paper by means of the limit analysis kinematic approach. The analysis takes into account the inherent spatial variability of soil strength and permeability properties. Adopting the framework of effective stresses for formulating the strength failure condition of the saturated porous medium, it is shown that the effect of seepage flow can be accounted for in the stability analysis by means of driving body forces computed from the gradient of pore pressure distribution. The hydraulic boundary value problem governing the water filtration velocity is addressed by resorting to a specific analytical variational approach, whose accuracy is assessed through comparison with finite element solutions. The impact of hydraulic-related parameters on the slope stability is first investigated within a deterministic framework. In the probabilistic stability analysis, soil cohesion, friction angle, and permeability are modeled as random fields that are numerically generated, making use of the Karhenum–Loéve Expansion. The Monte Carlo simulation method has been employed to evaluate the probability density function of the slope stability factor as well as associated overall failure probability. Numerical analyses have been performed with the aim to investigate the impact of some statistical parameters defining the distributions of strength and permeability on the slope stability conditions. Comparison of the simulation results with available numerical predictions pointed out the ability of the proposed stochastic limit analysis approach to accurately address the slope stability problem.