Reliability analysis of rapid drawdown of an earth dam using direct coupling

This paper combines seepage analysis with limit equilibrium analysis to investigate the safety of an earth dam over time and during drawdown. The numerical investigation is accomplished by directly coupling the deterministic software packages Seepage/W and Slope/W with the StRAnD reliability software. The first-order reliability method is employed in reliability analysis. Sensitivity analyses reveal that saturated hydraulic conductivity (k(s)), friction angle (phi') and cohesion (c') are the random parameters with the greatest contribution to failure probabilities. The cumulative effect of random saturated hydraulic conductivity (mainly) makes critical times and critical slip surfaces significantly different in the probabilistic and deterministic analyses.