Investigation of Soil Arching under Cyclic Loading Using the Discrete Element Method

This paper presents an analysis of the soil arching effect associated with piled embankments under cyclic loading by developing a series of two-dimensional trapdoor discrete numerical models. After identification of the microparameters by a biaxial compression test, the numerical models were validated by comparing the numerical model and plane laboratory test results. The contact force characteristics, deformation behaviors, and porosity distributions under various embankment heights were analyzed. The numerical results showed that cyclic loading leads to the degradation of soil arching as characterized by the collapse of load transmission paths and their vertical distribution. The variability observed in the contact fabric further confirmed that degradation in the higher embankment mainly occurred in the upper layers. Increasing embankment height decelerated the increasing contact force of the portion above the trapdoor and thus retarded the process of degradation. The load-induced time-dependent surface settlement accumulated with increasing cycle numbers and varied with embankment height. With an increasing number of cycles, the deformation area in the lower embankment cases above the trapdoor shifted from a triangular pattern to a rectangular pattern, while the higher embankment still maintained a triangular pattern. Furthermore, the effects of the localized loading area, stationary support width, and trapdoor displacement on soil arching concerning the loading efficiency and surface settlement were evaluated.