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深部岩体开挖过程中,能量的释放与耗散是导致围岩发生损伤破坏的重要诱因。针对深埋圆形隧洞爆破开挖,采用理论模型研究微差段间爆破荷载与地应力瞬态卸荷重复扰动及耦合作用下围岩应变能的变化规律,并基于弹性应变能判别准则计算围岩损伤范围。研究结果表明:在爆破荷载作用下,围岩应变能经历了先增大再减小最终趋于稳定的动态变化过程;在地应力的瞬态卸荷作用下,围岩应变能经历了先减小再增大最终趋于稳定的过程;二者耦合作用会进一步加剧围岩应变能动态调整过程,并且体现出更加明显的微差段间重复扰动效应,以开挖轮廓附近起爆的两圈崩落孔及周边孔最为明显。爆破荷载主要引起围岩张拉破坏,而地应力瞬态卸荷主要导致围岩压剪破坏,在二者耦合作用下地应力的存在会抑制爆破荷载引起的围岩张拉破坏,从而减小围岩的损伤范围。最后,采用锦屏二级水电站引水隧洞实测围岩损伤范围对理论计算方法的正确性进行了验证。
During the excavation of deep rock mass, energy release and dissipation are the important inducing factors of damage and destruction of surrounding rock. Aimed at the blasting excavation of the deep round tunnel, a theoretical model was used to study the variation of the transient energy of the transient unloading and the strain energy of the surrounding rock during the differential loading between the blasting load and the earth stress, and the surrounding rock strain energy was calculated based on the elastic strain energy criterion Rock damage range. The results show that under the action of blasting load, the surrounding rock strain undergoes a dynamic process of first increasing, then decreasing and finally stabilizing. Under the transient unloading of the earth stress, the strain of the surrounding rock undergoes the first decrease Small and then increase eventually stabilize the process; the coupling between the two will further aggravate the process of dynamic adjustment of the surrounding rock strain energy, and reflect the more obvious effects of repeated perturbation between the differential section to excavated contour near the initiation of two collapses Hole and the most obvious hole around. The blasting load mainly causes the tensile failure of the surrounding rock, and the transient unloading of the earth stress mainly results in the pressure-shear failure of the surrounding rock. Under the coupling action of the two, the existence of the ground stress will suppress the tensile failure of surrounding rock caused by the blasting load, Rock damage range. Finally, the correctness of the theoretical calculation method is verified by measuring the range of surrounding rock damage in the diversion tunnel of Jinping Hydropower Station.