Permanent Displacement Based Seismic Design Chart for Cantilever Retaining Walls

The primary aim of this paper is to suggest a suitable design procedure using a seismic sliding displacement based chart for the design of cantilever retaining walls. Permanent displacement based design chart have been proposed by Franklin and Chang for slopes and have been used by Richards and Elms for the seismic design of gravity retaining walls. Engineers have been using the same chart for seismic design of cantilever retaining wall without understanding the implications of such considerations and hence may result in unreliable design. The suitability of design procedure to be adopted would depend upon its closeness with the actual mechanism taking place. Experimental investigations have witnessed the formation of a V-shaped wedge in the backfill of cantilever retaining walls. The Double wedge model computes displacements considering the formation of this wedge and its relative movement with the wall during seismic loading. The upper bound curve has been developed on the basis of Double wedge model by analyzing 153 earthquakes for four different heel-length to height ratio and compared with Franklin and Chang’s chart. The procedure followed for the development of this chart has been explained in the paper. This study has been performed to understand the suitability of Franklin and Chang’s chart for the design of cantilever retaining walls. A suitable design procedure has been suggested on the basis of the V-shaped mechanism for the seismic design of cantilever retaining wall.