高地应力互层软岩隧道支护方案与支护时机优化

Support Schemes and Optimization of Support Timing for Tunnels inInterlayers of Soft Rock under High Geo-stress

西部山区分布有大范围的层状地层,在地下洞室建设过程中大变形灾害问题突出,严重危及地下洞室的施工及运营安全。为探究高地应力作用下层状软岩隧道支护施工方案与合理支护时机,本文以甘肃尖山隧道为工程依托,设计了3种支护施工方案并考虑3种支护施作时机,运用FLAC3D软件计算分析各工况下隧道变形和支护结构受力并与实际监测结果进行对比。结果表明:(1)3种支护方案下,方案三对隧道变形控制效果最为明显且使得支护受力更为合理;(2)3种支护时机下,考虑到允许二衬承担一部分变形,故当隧道变形达到极限位移为90%时,隧道变形与支护受力最为合理;(3)数值结果均小于实际监测数据,两者差值在可接受范围之内。

There is a wide range of layered strata in the mountainous areas of the western part of China.During the construction of underground tunnel chambers,the problem of large deformation is prominent,which seriously endangers the construction and operation safety of underground tunnel chambers.The purpose of this paper is to explore the construction scheme of the support of tunnels in the layered soft rock under high geo-stress,and the reasonable timing of the support.Taking Jianshan Tunnel in Gansu Province as the case,three supporting construction schemes are designed and three opportunities of support are considered in this paper.Furthermore,the tunnel deformation and supporting structure stress under various working conditions are calculated and analyzed by FLAC3D and compared with the actual monitoring results.The results show that:(1)Among the three support schemes,the third one has the most obvious effect on tunnel deformation control and makes the support stress more reasonable.(2)Considering that the inner lining is allowed to bear part of the deformation under the three support opportunities,the tunnel deformation and support stress are the most reasonable when the tunnel deformation reaches the limit displacement of 90%.(3)The results of numerical simulation are less than the actual monitored data,and the difference between them is within the acceptable range.