Experimental study of the evolution of soil arching effect under cyclic loading based on trapdoor test and particle image velocimetry

Arching effect, which is a common phenomenon in any system involving soil–structure interaction, has been found to be inevitably affected by various factors, including loading conditions. This study investigated the evolution of arching effect induced by cyclic loading by conducting a series of tests using a trapdoor apparatus. The test box was instrumented to control the displacement of the moving gate and to record the variation of vertical stress distribution by using a set of dynamic load cells. Digital images were captured during tests and processed using particle image velocimetry (PIV) to determine the displacement field and hence to examine the variation of geometric features of arch and particle movements. The evolution process of arching effect, from the initial formation to the finial collapse, was identified. Depending on the analysis for the geometry appearance, displacement region, and variation of cyclic stresses, both stable and collapsed arches were observed. By increasing the amplitude of cyclic loading step by step, critical loading amplitude corresponding to the threshold of collapse of the arching effect was determined. Based on the results, the effects of trapdoor displacement, cyclic loading frequency, and filling height on arching effect are discussed.