应力波斜入射对岩体节理端部的影响

Influence of oblique incidence of stress wave on rock joint ends

岩体节理在受到应力波扰动时端部受力会发生不同程度的连续性变化,为具体分析这种动态变化与应力波入射角度之间的关系,引用岩石非线性法向本构关系与线性切向本构关系的组合模型以及相应的在P波斜入射节理的应力波传播方程,结合岩石断裂力学中Ⅰ、Ⅱ型裂纹尖端应力和位移场的相关理论,得出组合形式下的节理端部应力场和位移场随质点振速变化的计算公式。通过不同入射角的模拟脉冲信号作用对端部应力位移的变化分析:应力波斜入射节理导致节理端部上、下两侧应力与位移场非对称分布,随着入射波质点振速的增减变化,应力集中位置会出现变化;计算并整理模型中节理端部上、下两侧0.005 m位置的数据,节理法向刚度由入射波质点振速带来的变化直接影响到应力波的透射与反射,进而会导致端部的应力与位移出现滞后效应;节理端部横向位移值与入射角度并非单调变化,而竖向位移会随着入射角的增大呈现下降趋势。

When rock joints are disturbed by stress waves, the continuous stresses in joint ends change with various degrees of joints.To analyze the relationship between the dynamic change and the incident angle of stress wave, we introduce a combined model of the nonlinear normal normalised constitutive relation and the linear tangential constitutive relation of rock and the corresponding stress wave propagation equation of oblique incident joints in P wave oblique incidence joint. According to the theory of mode-I and mode-II crack-tip stress in fracture mechanics and the displacement field, a formula is obtained for calculating the stress field and displacement field with the change of the velocity of the joint in the combined form. This study investigates the effect of the simulated pulse signal with different incident angles on the simulation of stress and displacement at the end. Stress and displacement fields at the upper and lower ends of the joint present non-symmetric distribution under the oblique incidence of stress wave. With the increase and decrease of vibration velocity of the incident wave particle point, the position of the stress concentration changes. The data of 0.005 m position at the upper and lower sides of the joint end in the model are calculated, the change of joint normal stiffness bringing by the particle velocity of incident wave directly influences the transmission and reflection of stress wave, which leads to the lag of stress and displacement at the end of the joint. The lateral displacement and the incident angle do not change monotonically, but the vertical displacement decreases with the increase of incidence angle.