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深埋圆形隧洞围岩的应力应变状态是深地下工程设计的重要参考依据。针对岩体内部的缺陷引起的应力集中和松弛,建立了局部附加应力与缺陷尺度和卸载时间之间的联系,得到圆形隧洞在卸载时围岩破坏前遵循的一系列方程,进而推导出围岩变形的解析积分表达式。将围岩应力应变的时间效应分为卸载阶段和应力松弛阶段,通过逐步逼近法分别求解了围岩的应力和变形的近似解析表达式。该近似解析式考虑了岩体内部缺陷处应力集中的影响和卸载的时间效应,可用来考察不同半径处缺陷应力集中和卸载快慢对应力变形状态的影响。计算表明,围岩内部在卸载过程中和卸载完成后均存在局部附加拉应力集中,围岩变形在卸载完成后仍会进一步增加。
The stress-strain state of the surrounding rock of the deep circular tunnel is an important reference for deep underground engineering design. Aiming at the stress concentration and relaxation caused by internal defects in rock mass, the relationship between local additional stress and defect scale and unloading time was established. A series of equations followed by the failure of surrounding rock during unloading were obtained, Analytic Integral Expression of Rock Deformation. The time effect of stress and strain of surrounding rock is divided into the unloading phase and the stress relaxation phase. The approximate analytical expressions of stress and deformation of surrounding rock are respectively solved by the step approximation method. The approximate analytic formula considers the influence of stress concentration and the unloading time effect in the internal defects of the rock mass, and can be used to investigate the influence of the stress concentration and the unloading speed on the stress and deformation state at different radii. The calculation shows that there is a local concentration of additional tensile stress during the unloading process and the unloading process, and the deformation of the surrounding rock will further increase after unloading.