Probabilistic analysis of an embankment under different rainfall events considering spatial variability of soil strength parameters

ABSTRACT: Studies have shown that embankments built with fine materials such as silt are more susceptible to extreme rainfall events than those built with coarse materials. In most of these studies, it was assumed that soil strength and hydraulic parameters such as unit weight, friction angle, cohesion, and hydraulic conductivity are random variables. However, soil properties and hydraulic properties can vary spatially within a soil profile. This has been shown by several researchers by carrying out stochastic analyses. Therefore, as a preliminary study, this research investigates the influence of spatial variability of soil strength parameters including cohesion, friction angle and unit weight on the probability of failure and a simplistic assumption of constant hydraulic conductivity throughout the soil profile is made. The probabilistic analysis is carried out for an extreme rainfall event. The results are compared with analyses in which assumption of random variable soil parameters is made. The results show a reduction in the value of the total probability of failure for the case with spatially variable soil strength parameters compared to the case with random soil parameters. The spatially variable case better describes the practical site condition.