Experimental study on piping in sandy gravel foundations considering effect of overlying clay

摘要: The influence of the overlying clay on progression piping in sandy gravel foundation water-retaining structures is often neglected. In order to study this influence, an experimental investigation was conducted a laboratory-scale model. It discovered that critical hydraulic gradient and area tunnel increase when thickens. With thicker layer, erosion below layer occurs later, but, once starts, rate very high average velocity water seeping through cross-section increases rapidly due low deformability thick layer. Furthermore, it found complicated iterative process involving fine particles, clogging pores, flushing clogged pores. Two types have been identified piping: one causes advance upstream, other depth tunnel. results show important factor evaluating foundations structures.