Influence of intrinsic variability in anthropic slopes

Abstract

Anthropic slopes are common in constructing embankments and earth dams and forming open pit mines and fills, among others. However, these slopes artificially built sometimes could fail due to the variability of the soils, lack of expertise in determining the design parameters, and lack of knowledge of the soil's true behavior and construction methods, among others. To address these problems, physical models were made in a geotechnical centrifuge with similar characteristics to study the effect of variability. Subsequently, Monte Carlo simulations were performed using finite element models (FEM) with random geotechnical parameters for an elastic model with Mohr-Coulomb failure criteria. From these simulations, the influence of geotechnical parameters on the factor of safety and deformations was observed. The results show that the coefficient of variation obtained for the factor of safety was less than the coefficient of variation of the geotechnical parameters taken into account. This means that the coefficient of variation of the factor of safety is not the sum or the average of the coefficients of variation taken in the analysis. However, when the factor of safety is more or less constant, but the coefficient of variation of the parameters increases, the probability of failure may increase. This shows that a slope with a factor of safety greater than one can have a high probability of failure. In addition, low friction angle and low cohesion values tend to present more significant slope crest displacements.

Keywords:
Anthropic slopes; Monte Carlo simulations; Strength reduction method; Variability of geotechnical parameters