Dynamic Reliability-Based Design of Slopes in Spatially Variable Soils Based on an Inverse FORM

Reliability-based design (RBD) of slopes is a classic problem in geotechnical engineering. The objective is to find an optimal slope angle that meets the safety requirement for a given target reliability index (or target failure probability). Many probabilistic methods have been adopted in RBD to account for uncertainties involved in slopes, but they are often criticized for the low computational efficiency as numerous deterministic slope stability analyses are inevitably required. Meanwhile, few research studies had focused on the dynamic RBD of slopes when more site exploration data are progressively collected. To address these issues, this paper proposes a framework of the dynamic RBD of slopes. A cohesive slope is investigated as an example to illustrate the proposed method. First, the non-Gaussian random fields of soil shear strength parameters are discretized using the midpoints method based on the prior statistics, and the preliminary reliability-based design of slope angle is carried out using an inverse first-order reliability method (IFORM). Then, the Bayesian Updating with Structural reliability method (BUS) is employed to conduct the probabilistic inverse analyses of soil parameters with more available site-specific data. At last, the updated design of slope angles meeting the target reliability index can be acquired based on the IFORM. The results show that the proposed methodology can obtain a reliable informational design of slope angle with increasing site-specific data and can act as a practical and effective tool for the dynamic RBD of slopes in spatially variable soils.