Effect of 2-D Random Field Discretization on Failure Probability and Failure Mechanism in Probabilistic Slope Stability

摘要

This paper investigates, using the random field theory and Monte Carlo simulation, the effects of random field discretization on failure probability, pt, and failure mechanism of cohesive soil slope stability. The spatial sizes of the discretized elements in random field Ax, Ay in horizontal and vertical directions, respectively, are assigned a series of combinational values in order to model the discretization accuracy. The pf of deterministic critical slip surface (DCSS) and that of the slope system both are analyzed. The numerical simulation results have demonstrated that both the ratios of Δy/λ_y (λ_y = scale of fluctuation in vertical direction) and Δx/λ_x (λ_x = scale of fluctuation in horizontal direction) contribute in a similar manner to the accuracy of pf of DCSS. The effect of random field discretization on the pf can be negligible if both the ratios of Δx/λ_x and Δy/λ_y are no greater than 0.1. The normalized discrepancy tends to increase at a linear rate with Δy/λ_y when Δx/λ_x is larger than 0.1, and vice versa for pf of DCSS. The random field discretization tends to have more considerable influence on the pf of DCSS than on that of the slope system. The variation of pf versus λ_x and λ_y may exhibit opposite trends for the cases where the limitstate functions of slope failure are defined on DCSS and on the slope system as well. Finally, the pf of slope system converges in a more rapid manner to that of DCSS than the failure mechanism does to DCSS as the spatial variability of soil property grows from significant to negligible.