Comparative study on response surfaces for reliability analysis of spatially variable soil slope

This paper focuses on the performance of the second-order polynomial-based response surfaces on the reliability of spatially variable soil slope. A single response surface constructed to approximate the slope system failure performance function G(X) (called single RS) and multiple response surfaces constructed on finite number of slip surfaces (called multiple RS) are developed, respectively. Single RS and multiple RS are applied to evaluate the system failure probability p (f) for a cohesive soil slope together with Monte Carlo simulation (MCS). It is found that p (f) calculated by single RS deviates significantly from that obtained by searching a large number of potential slip surfaces, and this deviation becomes insignificant with the decrease of the number of random variables or the increase of the scale of fluctuation. In other words, single RS cannot approximate G(X) with reasonable accuracy. The value of p (f) from multiple response surfaces fits well with that obtained by searching a large number of potential slip surfaces. That is, multiple RS can estimate G(X) with reasonable accuracy.