System Reliability Analysis for Seismic Stability of the Soldier Pile Wall Using the Conditional Random Finite-Element Method
Afshin Kalantari, A. Johari
Abstract
The stability of the retaining system under seismic conditions is an important aspect of safe design in earthquake-prone areas. In addition, this stability is highly dependent on soil uncertainty and failure mode contribution. On the other hand, imaging the borehole data directly into the analysis section and ignoring the known data by using unconditional simulation can lead to unrealistic results. Against this background, the current study presents a reliability analysis by incorporating geostatistical conditional simulations and a pseudostatic approach into the Finite-Element Method (FEM) MATLAB code to address the aforementioned issues. Then, the Sequential Compounding Method (SCM) is implemented to calculate the overall system reliability from a combination of the individual subsystem. Reliability analysis of a real case study reveals that compared with the Unconditional Random Finite-Element Method (URFEM), utilizing the Conditional Random Finite-Element Method (CRFEM) helps improve the mean value of the Factor of Safety (FS) against all failure modes by 7%–30%, while reducing the related standard deviation by 12%–43%. The results of system reliability show that bending moment and lateral displacement are the fundamental mechanisms in the static and seismic states. Moreover, implementing conditional simulation in seismic stability analysis offers a 16% and 43% reduction in the mean value and standard deviation of an unsafe distance from the excavation edge, accounting for less uncertainty in the slip surface location. Besides, according to the Coefficient of Variation (COV) of the failure modes, it is concluded that the FS against lateral displacement is chiefly affected by the soil heterogeneity compared with others, while shear force failure mode is less affected.