Shaking table tests on the seismic performance of a flexible wall retaining EPS composite soil

Abstract

A series of shaking table tests were designed and conducted to study the seismic performance of an inverted T-shape cantilever retaining wall with an anti-sliding tooth at the base using EPS composite soil as backfills. For comparison, the same wall model retaining Nanjing fine sand was simultaneously excited. The macro phenomena and seismic behaviors of two wall–soil systems are depicted in detail and analyzed. The displacement mode of the non-sliding flexible retaining wall and distribution characteristics of dynamic earth pressure acting on the wall back retaining two types of backfills are emphasized. The testing results show that, as a kind of backfill, Nanjing fine sand has a greater peak ground acceleration (PGA) than EPS composite soil under the kinematic interaction between wall and soil, while the difference in the inertial force of the retaining wall itself is not obvious. As the input peak base acceleration increases, Nanjing fine sand which possesses the compaction strength gradually transforms from the global shearing deformation to the wedge sliding deformation, while EPS composite soil with a cemented strength exhibits the block shearing deformation mode under all excitations. The tested retaining walls with the rotation displacement are non-sliding flexible walls. The dynamic deformation mode of backfills is closely related to the inertial interaction between wall and soil, which results in a significant difference in the dynamic earth pressure increment distribution between the walls retaining two types of backfills. The dynamic earth thrust in the retaining wall-Nanjing fine sand system (WSS) has a nonlinear relation with PGA, and the action position approximated 2/3 wall height. A linear relation is more suitable for retaining EPS composite soil and the corresponding action position is about 1/3 wall height. The retaining wall-EPS composite soil system is shown to have a better seismic performance in contrast to WSS. The Seed and Whitman method with 100% PGA is recommended to predict the dynamic earth thrust on the wall retaining EPS composite soil.