关键词: 应力集中, 椭圆型节理, 应力波传播, 法向刚度

Abstract: To analyze the stress concentration effect at rock joint ends under dynamic disturbance, a modified hyperbolic model of non-uniform joint normal stiffness distribution is introduced, based on the compression closure and elliptical shape characteristics of rock joints. Factors such as in-situ stress, joint inclination angle, and joint length are considered to compare and analyze joint surface stress and end stress concentration effect under P wave and SV wave disturbances. Results indicate that considering joint morphology, the closer to the joint ends, the greater the disturbance amplitude of the stress wave on the joint surface’s normal stress, and the reduction effect of joint on the stress wave diminishes, resembling the propagation effect in intact rock. The stress concentration effect at the joint ends is positively correlated with the compressive stress and shear stress on the joint surface, but the stress concentration effect at the joint end caused by compressive stress is more significant. Considering the characteristics of joint morphology, the fluctuation of stress concentration effect at the end with the incidence of stress wave is more obvious than that of ignoring the joint morphology, increasing the likelihood of damage. Therefore, considering the joint morphology is more conducive to the analysis of engineering safety. Under the same conditions, P wave primarily causes the change of normal stress on the joint surface, while SV wave primarily causes the change of shear stress. Analysis of the joint end extension point shows that as the incident angle of the stress wave increases, the effect of SV wave on the shear stress at the monitoring point weakens, while its effect on normal stress strengthens, opposite to the effect of P wave. The horizontal displacement is positively correlated with the normal stress value, and the vertical displacement increases with the increase of the shear stress. When the joint experiences tensile shear stress, normal stress in most end areas is tensile, whereas it is primarily compressive in the compressive shear state.

Key words: stress concentration, elliptical joints, stress wave propagation, normal stiffness