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考虑巷道围岩在开挖过程中的动静力作用,提出了围岩松动区包含破碎区和塑性软化区两个部分。首先在围岩的瞬间卸载所产生的动力作用下,巷道周边围岩产生张拉裂隙破坏区,随后在原岩应力的静压作用下,产生拉剪复合破坏形成破碎区。塑性软化区是在原岩应力的静压作用下,随围岩变形的增大逐渐形成的。同时,根据弹性力学知识,得到巷道围岩由于开挖扰动和原岩应力作用引起的弹性应力场和位移场,提出了破碎区半径的求解方法。根据破碎区围岩应力的分布及残余强度理论,得到破碎区对塑性软化区的支撑反力,再利用塑性区的应力计算公式,得到了确定围岩松动区半径的计算公式。通过实例计算与实际监测对比表明,松动区的半径与现场实际观测到的结果吻合的较好。
Taking into account the static and dynamic forces during the excavation of the surrounding rock in the roadway, the loosening zone of the rock mass is proposed to contain two parts: the crushing zone and the plastic softening zone. Firstly, under the dynamic force generated by the moment unloading of the surrounding rock, the surrounding rock of the roadway generates a tensile fracture zone, and then the composite rock-shearing compound fracture is formed under the static pressure of the original rock stress to form a crushing zone. The plastic softening zone is formed under the static pressure of the original rock stress, with the deformation of the surrounding rock gradually formed. At the same time, based on the knowledge of elasticity, the elastic stress field and displacement field caused by excavation disturbance and original rock stress are obtained. According to the stress distribution and the residual strength theory of the surrounding rock in the crushing zone, the supporting reaction force of the crushing zone to the plastic softening zone is obtained, and the formula of the stress in the plastic zone is used. The formula to determine the radius of the rock loosening zone is obtained. The comparison between actual calculation and actual calculation shows that the radius of loosening area is in good agreement with the actual observed results in the field.