循环荷载条件下岩石节理剪切特性及宏细观机理研究

Study on the shear characteristics and macro scopic mechanism of rock joints under cyclic loading conditions

  • 摘要: 隧道及地下储库等岩体工程在循环荷载条件下,围岩性能逐渐劣化易引起大变形及塌方等灾害,研究岩石节理剪切特性及宏细观机理对评估岩体工程在循环荷载条件下的服役安全性具有重要意义。采用高强石膏制备节理试件,开展恒定法向荷载条件下节理循环剪切试验,并结合有限元—离散元耦合数值模拟方法开展研究。结果表明:节理面粗糙度越大,峰值剪切强度越大;相同循环次数中峰值剪切强度随循环剪切位移的增大而减小。平均剪胀角随循环次数的增加呈现减小的趋势;相同循环次数中,平均剪胀角随循环剪切位移的增大而减小,随节理粗糙度的增大而增大。随着循环剪切的进行,应力演化过程会逐渐趋于稳定,裂纹数量随着循环剪切次数的增加而增多。

     

    Abstract: Under cyclic load conditions, rock mass engineering such as tunnels and underground storage is prone to large deformation and collapse due to the gradual deterioration of surrounding rock performance. It is of great significance to study the shear characteristics of rock joints and macro-mesoscopic mechanism for evaluating the service safety of rock mass engineering under cyclic load conditions. Joint specimens were prepared with high strength gypsum, cyclic shear tests were carried out under constant normal load, and the numerical simulation method of finite element and discrete element coupling was used. The results show that the greater the roughness of joint surface, the greater the peak shear strength. In the same number of cycles, the peak shear strength decreases with the increase of cyclic shear displacement. The average dilatancy angle decreases with the increase of the number of cycles. In the same number of cycles, the average dilatancy angle decreases with the increase of cyclic shear displacement and increases with the increase of joint roughness. With the progress of cyclic shear, the stress evolution tends to be stable, and the number of cracks decreases with the increase of cyclic shear cycles.

     

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