岩溶隧道围岩破坏过程中应力、应变发生极为复杂的变化,研究起来极为困难,究其破坏本质是内部能量转化。为直观和准确地分析围岩灾变过程,以重庆轨道交通27号线中梁山隧道为依托,基于能量守恒原理,推导出围岩应变能密度、弹性应变能密度和耗散能密度计算理论,开发并验证了能量密度可视化程序。基于开发的程序分析地铁隧道底部存在溶洞时,不同的溶洞与隧道底部边距工况下,围岩内部能量密度演化规律与围岩塑性区分布、最大主应力、竖向位移、水平位移的对应关系。结果表明:开发的能量密度可视化程序可以较好地模拟隧道围岩在开挖过程中的能量演化规律;围岩耗散能密度分布与塑性区分布基本一致,耗散能密度分布区域贯通时隧道发生破坏;围岩周围的弹性应变能密度分布与最大主应力分布相关,弹性应变能密度突然释放时隧道发生破坏;隧道与溶洞的距离对围岩竖向位移影响较大,水平位移较小;隧道围岩破坏本质上是能量驱动的结果。

It is extremely difficult to study the extremely complicated changes of stress and strain in the destructive process of surrounding rock in karst tunnels. The essence of its destruction is the internal energy transformation. In order to intuitively and accurately analyze the peripheral rock damage process, based on the Zhongliangshan Tunnel of Chongqing Rail Transit Line 27, the calculation theory of peripheral rock strain energy density, elastic strain energy density and dissipation energy density are deduced based on the principle of energy conservation, and the energy density visualization program is developed and verified. Based on the developed program, the correspondence between the evolution law of internal energy density of surrounding rock and the distribution of plastic zone, maximum principal stress, vertical displacement and horizontal displacement of surrounding rock under different working conditions of different distances between the cave and the bottom of the tunnel in the presence of a cave at the bottom of the subway tunnel is analyzed. The results show that: The developed energy density visualization program can better simulate the energy evolution of the surrounding rock in the excavation process; the distribution of dissipated energy density in the surrounding rock is basically the same as the distribution of the plastic zone, and the tunnel will be damaged when the area of the dissipated energy density distribution passes through; the distribution of the elastic strain energy density around the surrounding rock is related to the distribution of the maximum principal stress, and the tunnel will be damaged when the elastic strain energy density is suddenly released; the distance of the tunnel from the cavity has a significant influence on the vertical displacement of the surrounding rock; the distance of the tunnel from the tunnel bottom has a significant influence on the vertical displacement of the surrounding rock. The distance between the tunnel and the cavern has a greater effect on the vertical displacement of the surrounding rock, and the horizontal displacement is smaller; the destruction of the tunnel surrounding rock is essentially the result of energy-driven.