Transmission of Tensile Stress Wave Across a Nonlinear Deformable Rock Joint: A Theoretical Investigation

ABSTRACT Seismic waves can possess a significant tensile component, and the compressive component of the stress wave will be transformed to tensile stress upon reflection at a free surface. Despite this, limited attention has been given to the propagation of tensile stress wave across rock joints. This study presents a theoretical investigation into the tensile stress wave propagating across a rock joint. To address joint nonlinear deformation under tension, a nonlinear displacement discontinuity model is formulated for tensile stress wave propagation across a rock joint by incorporating the inverse hyperbolic model, displacement discontinuity model and method of characteristics. The theoretical outcomes exhibit strong alignment with those derived from the modified split Hopkinson tension bar tests using long high‐performance mortar bars, proving the validity of the proposed theoretical formulation. The findings reveal waveform distortion of the transmitted wave when the rock joint experiences high stress levels that trigger the nonlinearity of joint deformation, particularly close to the tensile strength of rock joints. The transmission of tensile stress waves is notably influenced by the nonlinear deformational parameters, for example, initial tensile stiffness and joint tensile strength, and the characteristics of the incident waves (including amplitude and frequency). These results offer initial insights into the transmission of tensile stress waves across rock joints, offering valuable implications for understanding the fracture and pulverization of rocks experiencing transient tensile stress induced by fault rupture.