Direct shear experiment on salt rock incorporating loading rate effect

Abstract

To investigate the shear behavior of salt rock under different loading rates, direct shear testing was conducted on high-purity salt rock obtained from Pakistan using a YZW-100 apparatus. The experimental results of the shear stress, deformation, and failure characteristics of the salt rock showed that the loading rate is an essential factor influencing the shear strength parameters of the rock. When the shear loading rate was increased, the cohesion of the salt rock significantly increased; however, the internal friction angle slightly decreased, nearly remaining unchanged. The shear failure mode of the salt rock manifested by shear stress-displacement curves tended to be ductile failure with increased normal force. The residual stress of the salt rock was large, indicating its high friction-bearing capacity. The dilatancy deformation was also subjected to shear loading. The fracture section of the salt rock exhibited visible local scratch marks. These experimental results are helpful for further understanding the failure mechanism of salt rock and the stability of underground gas storage under different gas injection and production scenarios.