Numerical Advances in Understanding the Behavior of Gravity Retaining Wall during Seismic Motions

The response of gravity retaining walls during ground motion is still a challenging field. Recent developments in computational methods have opened the possibility of enhancing the understanding of the non-linear nature of soil-structure systems, e.g., earth pressure thrust acting on the retaining wall, translational and rotational movements, propagation of waves in the soil more realistically and quickly. Till today, Mononobe Okabe (MO) method (pseudo-static) is the most used analytical method because of its simplicity. However, there are many limitations and gives over-conservative results in terms of earth pressure thrust, and many literatures have already justified such a response. Several improved studies are already available, but very few have considered proper soil-structure interaction, real-time input earthquake data (not sinusoidal), and a sufficient number of earthquakes to evaluate the response acting on the wall during dynamic loading.

We seek contribution by analyzing the problem numerically using FE software Plaxis 2D and studying the behavior of retaining wall during seismic loading (range of a_max = 0.053g to 1.2g) in terms of acceleration, displacement, rotation, and earth pressure thrust of retaining wall. The main contribution observed is the acceleration was not uniform throughout the medium instead gets amplified up to around 0.6g and later gets attenuated with maximum amplification occurring at the top of the retaining wall followed by the top of backfill soil and base of the wall. The residual displacement and rotation showed an incremental trend with an increase in horizontal seismic coefficient (k_h). The earth pressure thrust obtained using numerical analysis was comparatively less than predicted by the MO method.

Keywords: Gravity retaining wall; Acceleration amplification response; Earth pressure thrust; Finite element method;