岩溶地区隧道底部围岩的破坏研究

ROCK MASS COLLAPSE RESEARCH OF THE BOTTOM OF THE TUNNEL IN KARST REGIONS

在岩溶地区施工时,经常会出现围岩塌陷的问题,特别当岩溶洞穴与隧道间的岩层厚度较薄时。隧道施工时,若围岩突然崩溃塌陷,将造成巨大的经济损失,甚至人员伤亡。文中建立的隧道模型存在于岩溶洞穴之上,并基于上限定理用解析解的方法研究了模型中隧道围岩突然崩溃塌陷的问题。基于解析解得到塌陷面的形状,研究岩体参数对岩体塌陷面的影响,并用数值模拟的方法与研究的解析解法进行比较,来验证评估方法的有效性。比较结果显示研究算法与数值模拟的结果非常吻合,表明研究提出的方法是有效的。

Local collapse of the surrounding rock often occurs during tunnel construction in a karst area,particular⁃ly when the rock pillar between the tunnel and the karst cave is very thin.The collapse of the surrounding rock in tunnel construction often leads to great economic loss or even loss of life.To predict the collapse of rock mass where a tunnel is excavated above a karst cave,an analytical expression of the collapse surface is derived from variational calculation in the framework of the upper bound theorem.Based on the analytical solutions,the shape of the collapse surface is plotted to investigate the effects of rock parameters on the collapse surface of the rock mass where a karst cave exists beneath a tunnel.According to the changing law of the collapse surface varying with the distance be⁃tween tunnel and cave,the calculation formula of the minimum safety thickness for preventing the collapse of rock pillar is derived.By comparing the analytical solutions with numerical solutions,the analytical solution matches up with the numerical solution very well,indicating that the analytical method proposed in this paper is valid.