Reliability Coupled Sensitivity-Based Seismic Analysis of Gravity Retaining Wall Using Pseudostatic Approach

Abstract

The stability of geotechnical earth structures is often affected by associated uncertainties present in geotechnical parameters, if they are not properly accounted for. The present paper aims at quantifying these uncertainties and proposes a modification factor, namely probabilistic risk factor (Rf) for each geotechnical random variable. A gravity retaining wall is analyzed by a pseudostatic method of analysis against four modes of failure namely, sliding, overturning, eccentricity, and bearing. The effect of variation of properties of backfill and foundation soil on stability of the wall for various earthquake conditions is analyzed. Rf simultaneously identifies the effects of Pf of a gravity retaining wall subjected to earthquake loading and also the sensitivity of geotechnical random variables on different modes of failure. The geotechnical random variables are modified by Rf and applied in design. It is observed that, apart from the seismic horizontal and vertical pseudostatic acceleration coefficients kh and kv, friction angle of backfill soil (φ1), and cohesion of foundation soil (c2) are the major guiding geotechnical parameters in stability analysis of the gravity retaining wall. Parametric studies are carried out for different combinations of kh, kv, and φ, and risk factors-based on the formulated approach are proposed for each case. Finally, design guidelines are proposed for different variations of random variables and earthquake conditions. A case study is also presented, which deals with the application of proposed risk factors to a series of 54 retaining walls in Hodogaya Ward and Naka Ward of the Yokohama municipality area in Japan.