Case Study: Seismic Stability of Underwater Retaining Walls

The upstream end of a reservoir’s outlet structure is retained by 9 to 12m high retaining walls. The effect on retaining wall stability of a 3 to 4m thick layer of gravels deposited upslope of the walls, particularly retaining wall stability under seismic loading, has been assessed.

This paper details the method of stability analysis, modelling three-dimensional effects of the reservoir shoreline slope and wall geometries, modelling wall reactions, soil and hydrodynamic loads, and determination of seismic displacements. Different thicknesses of deposited surcharge material were modelled, as were different reservoir levels. Both drained and undrained conditions on the failure surface under earthquake loading were considered. Results are presented for stability, sensitivity, wall capacity and shoreline slope displacement.