A DISPLACEMENT PREDICTION METHOD FOR RETAINING WALLS UNDER SEISMIC LOADING

Mitsu Okamura and Osamu Matsuo

ABSTRACT: This paper describes a new calculation method for seismic displacement of retaining walls. A macroscopic failure surface and a plastic displacement potential in the general load space are considered in the method to evaluate the subgrade reaction force from foundation ground. The method is capable of calculating not only horizontal, vertical or rotational displacement alone, but also their combined effect. The method is validated through comparison with centrifuge test results of a gravity retaining wall with dense backfill sand subjected to strong base shaking. The calculated displacement components, that is vertical, horizontal and rotational displacement, at the end of shaking compared well with those measured. It also appeared that previously proposed conventional displacement calculation methods based on Newmark's sliding block analogy might underestimate the displacement. The assumption of the constant frictional coefficient may be responsible for this.
The proposed method is limited to retaining walls resting on soils where dramatic degradation of soil strength due to the generation of excess pore pressure does not occur.

Key words: shallow foundation, retaining wall, seismic displacement, bearing capacity, failure envelope, plastic potential (IGC: E8/E13)