EPS Seismic Buffers for Earthquake Load Attenuation against Rigid Retaining Walls

Expanded polystyrene (EPS) geofoam is an ideal material to construct seismic buffers to reduce earthquake-induced loads against rigid retaining wall structures. The paper provides a synthesis of published work by the writers on both experimental and numerical simulation work on EPS seismic buffers. Proof of concept is first demonstrated using a series of 1 m-high models placed on a shaking table. The tests showed that for the geofoam materials employed, a reduction in peak dynamic loads as great as 40% was possible compared to the rigid wall case. Next, a FLAC computer model was developed to simulate the experimental results. The validated model was then used to carry out a parametric analysis to investigate the influence of wall height, EPS geofoam type, thickness, stiffness, and excitation record on seismic buffer performance. One of the important outcomes of this research is that the practical quantity of interest to attenuate dynamic loads using a seismic buffer is the buffer stiffness defined as K = E/t (E = elastic modulus, t = thickness). For the range of parameters investigated in this study, K ≤ 50 MN/m³ was observed to be the practical range for the design of these systems to attenuate earthquake loads.