断层角砾岩隧道开挖工法比选研究

Comparative Study on Excavation Methods for Tunnels in Fault Breccia

断层角砾岩结构松散,对隧道支护结构变形和受力有较大负面影响,科学选择开挖工法是确保隧道施工安全的重要前提。本文以马衙1号隧道为工程依托,结合实际地质情况借助有限元软件进行数值模拟并与现场实测数据对比分析,对断层角砾岩隧道开挖工法进行比选研究。基于受力和位移两个角度评估,采用CRD法及三台阶临时仰拱法进行开挖,马衙1号隧道位移及安全指标均能满足要求,而环形开挖预留核心土法存在一定安全隐患;工序层面,三台阶临时仰拱法避免了拆装临时中隔壁使得施工步序有所减少,既可安全施工又能降低成本,本工程推荐采用三台阶临时仰拱法施工。

The fault breccia has a loose structure,which has a significant negative impact on the deformation and force of the tunnel support structure,and the scientific selection of excavation method is an important premise to ensure the safety of tunnel construction.In this paper,based on the Maya No.1 tunnel project and combined with the actual geological situation,numerical simulations were carried out with the help of the finite element analysis software to compare and analyze the measured data in the field,and the selection of the fault breccia tunnel excavation method was studied.Based on the evaluation of stress and displacement,the CRD method and the three-bench temporary inverted arch method are used for excavation.Both the displacement and safety indexes of Maya No.1 Tunnel can meet the requirements.However,the reservation core soil of annular excavation method has some potential safety risks.From the process point of view,the three-bench temporary arch method is a safe and cost-saving method because it avoids the need to dismantle and install the temporary center tunnel and saves a certain number of construction steps.Therefore,it is recommended to use the three-bench temporary inverted arch method for this project.