A New Apparatus for Evaluation of Contact Erosion at the Soil–Structure Interface

Abstract

Abstract The interface between clay core-wall and concrete cut-off wall is one of the weakest parts of high earth and rockfill dams. An unsuitable design can cause contact erosion at the interface or shear failure surfaces, and eventually this will harm the safety of the dam. A new soil–structure contact erosion apparatus was developed for the evaluation of contact erosion at the interface under high stress, high hydraulic head, and large shear deformation. It consists of a soil–structure model base, a seepage pressure system, a confining pressure system, an axial pressure system, and a data acquisition system. The seepage pressure system simulates the seepage erosion effect at the interface, and the maximum seepage pressure is 2.0 MPa. The confining and axial pressure systems simulate the triaxial stress state of the interface and the large shear deformation of the soil structure; the maximum confining and axial pressures are 2.0 MPa and 4.0 MPa, respectively. The data acquisition system can monitor pore pressure dissipation and settlement. Two repeatable experiments on the interface between a kind of highly plastic clay and a concrete cut-off wall were conducted to verify the scientific utility of the new apparatus. The new apparatus was found to be capable of yielding fairly consistent results in repeatable experiments. The new apparatus will prove an effective tool for studying a reasonable connection form of concrete cut-off wall and core wall in high earth and rockfill dams.