Triaxial direct shear property and permeability change of interface between high-performance concrete and claystone with water injection and chemical leaching

Abstract

The mechanical properties and permeability change of the interface between barrier rock and concrete are essential to the load-carrying capacity and sealing performance evaluation of radioactive waste repository. This paper is devoted to investigating the mechanical property and permeability change of the concrete-claystone interface during the triaxial direct shear process in the context of repository tunnels. The cemented interface was firstly characterized by a high-resolution optical microscope. With the help of the triaxial test system and a self-designed direct shear device, a series of triaxial direct shear tests with water injection was carried out to study the hydromechanical characteristics and permeability change of the interface during shear at different confining pressures. The permeability evolution and shear strength of the interface under the influence of chemical dissolution were also investigated. The results show that the shear strength of the interface samples decreased by 21.8% due to water injection and decreased by 35.5% due to chemical leaching at the confining pressure of 12 MPa concerning its natural dry state. The permeability of the interface decreases at the beginning and then increases slightly when subjected to chemical leaching by ammonium nitrate solution. The results are beneficial to the safety evaluation of the claystone-hosted repository.