Experimental investigation on seepage erosion of the soil–rock interface

Abstract

Internal erosion under seepage flow affects the hydraulic and mechanical behavior of the soil, which is one of the most important factors of geological disasters. Due to that the soil–rock interface can be the potential preferential seepage channels commonly, the characteristics of erosion are more significant and hazardous at the soil–rock interface. In this study, a series of laboratory experiments are performed to investigate the failure mechanism and evolution of interfacial seepage erosion. The influences of two essential influence factors (i.e., the confining pressure and the roughness of the interface) are investigated by comparing the seepage velocity, hydraulic conductivity, failure hydraulic gradient, and failure hydraulic shear stress in experiments. Furthermore, the failure pattern of interfacial seepage erosion is particular investigated by the CT scanning. The interfacial seepage erosion tests indicate that the interfacial seepage erosion shows a three-phase progressive failure as the hydraulic gradient increases and the hydraulic conductivity decrease with the progress of suffusion in the initiation phase. The increase of confining pressure leads to the increase of failure hydraulic gradient. The results of CT scanning show that the roughness of the soil–rock interface significantly affects the size and shape of resulting zone of erosion.