高应力区大尺度隧洞开挖损伤区范围预测研究

Prediction of excavation damage zone of a deep tunnel with large size subjected to high in-situ stress

通过理论公式和数值模拟方法进行了高应力区大尺度隧洞开挖损伤区范围预测研究。当圆形隧洞开挖后,根据工程经验得到的破坏准则,结合隧洞周围的应力经典求解结果,可以推导出损伤区范围的理论公式,并且水平方向与竖直方向的范围能够直接得到,可以作为估测开挖损失区的实用方法。当把破坏准则与有限元方法结合,能够得到更为精确的损伤区分布,改变隧洞的形状与尺寸,得到主要结论如下:当初始水平应力小于竖直应力时,圆形隧洞的直径增大后,水平方向的开挖损伤区范围比竖直方向更大;隧道形状对开挖损伤区分布范围和特性有着显著影响,在相同地应力和围岩条件下,开挖相同面积的圆形和矩形隧洞,圆形隧洞的损伤区范围比矩形隧洞更小;3当矩形隧洞的宽高比增大后,开挖区附近出现拉应力,水平方向的损伤区范围最大。

The analytical and numeral methods are used to predict the excavation damage zone of a deep tunnel with large size subjected to high in-situ stresses. Based on an empirical damage criterion and the classical solutions of stress distributions around a circular tunnel, the range of excavation damage zone in the horizontal and vertical directions can be analytically determined, which can serve as a first-order approximation to estimate the range of excavation damage zone. By integrating the empirical damage criterion with the finite element models, more accurate range of excavation damage zone can be determined. The results show that the excavation damage zone is dependent on the tunnel shapes and sizes: (1) When the diameter of circular tunnel increases, the range of EDZ is larger in the horizontal level than that in the vertical level; (2) The circular tunnel is more economical and reasonable than the other one in the same area; (3) When the width/height of rectangle tunnel increases, there is tensile stress generated in the vicinity of excavation,and the range of EDZ is also larger in the horizontal level.