不良地质段双洞交叉开挖三维有限元分析

3D FEM analysis of excavating two intersecting tunnels in bad geology

积石峡水电站泄洪洞与导流洞交叉段形成了跨度为28m,高度为22m类似城门洞形的大断面洞室,该洞段围岩呈层状分布,且有一软弱夹层穿过拱顶,对洞室稳定极为不利。针对这一实际工程问题,确定了开挖方案和支护措施,采用三维非线性有限元分析了该处的围岩应力和变形随开挖进行的变化和围岩的稳定性,并考虑了位于拱顶的软弱夹层对交叉段洞室开挖围岩稳定的影响,对于其他类似工程,其结果具有良好的参考价值。

A large arch-wall-shaped cross-section with 28 m in span and 22 m in height formed in the Jishixia waterpower project when the spillway tunnel and the diversion tunnel intersect in bad geologic site. The surrounding rocks are distributed in layers and a weak intercalation goes through the top of a cross-section. To verify the schemes of excavation and supports,3D numerical simulation of excavating which tracks construction process is used to study the stresse and deformation distribution and the stability of the surrounding rocks. At the same time,the weak intercalation is taken into consideration. The results may have better reference values for similar projects in the future.