PROBABILITY OF FAILURE OF CONCRETE RETAINING WALLS DUE TO EARTHQUAKES IN KANTO AREA, TOKYO

Safety of retaining structures contributes the safety of physical and social environment. In this study, procedure to estimate the safety of retaining walls against earthquakes is proposed. The retaining walls in different parts of Kanto area in Tokyo were selected and pseudostatic earth pressure acted on concrete retaining wall was calculated and seismic hazard of each wall was evaluated against strength of respective wall. Different failure mechanisms- overturning, sliding, shearing, bending were checked and results were found in terms of peak ground acceleration (PGA) in order to know resistance against earthquake ground motion. Considering the uncertainties in seismic behavior, ground response, wall design model or any assumed parameters, probabilistic approach is used for the evaluation of the safety of the retaining walls. Overturning mode is found to be more probable than the sliding mode of failure. Further, Mononobe-Okabe method appears to give conservative results. More and detailed information about uncertain parameters gives more reliable estimation of safety.