高地应力软岩隧道塌方成因和治理措施分析

基于某新建高地应力软岩铁路隧道工程,运用MIDAS GTS与ANSYS有限元软件,对二台阶三部开挖法的应力与变形特点进行了分析。结果表明:初支与二衬施作的时间间隔、循环进尺的长度、上下台阶的距离的合理选择是保证高地应力软岩隧道安全施工的重要因素。高地应力软岩隧道的二衬不仅作为对初支的加强和安全储备,且承受软岩的流变压力,流变压力在二衬施做的初期增长迅速,后期变缓趋于平稳。二台阶三部开挖工法施工中,应注意右下台阶的开挖稳定、合理的循环进尺及台阶距离能够保证高地应力软岩隧道的施工安全。

On Collapse Causes of Soft Rock Tunnel with High Geostress and the Control Measures

In relation to a new railway tunnel project in soft rock with high geostress, this paper analyzed the stress and deformation characteristics in two-bench three-step excavation with Midas GTS and ANSYS software. The results show that, proper selection of the time interval of initial supporting and secondary lining, the length of advance per round and the distance between the upper and lower bench, is important to guarantee the safe construction of soft rock tunnel with high geostress. The secondary lining herein, as the further reinforcement to the initial supporting and the safety margin, suffers from the soft rock’s rheological pressure which will increase rapidly at the beginning of the construction of secondary lining, then slow down and tend to be steady later. In the two-bench three-step excavation, the attention should be paid to stable excavation of the lower right bench, with the aid of proper advance per round and bench distance, may guarantee the safety in construction of soft rock tunnel with high geostress.