软弱破碎围岩隧道施工数值模拟研究

Numerical Simulation of Weak Broken Surrounding Rock Tunnel

为研究软弱破碎围岩条件下隧道施工过程中围岩与支护受力变形特征,以某隧道工程为背景,利用ABAQUS分别建立隧道施工二维和三维有限元模型。模型力求与工程实际相符合,同时考虑了隧道实际的支护体系和地质条件,并模拟不同的施工工况,其中二维模型模拟隧道全断面开挖、初期支护完成和二次衬砌完成等工况;三维模型模拟隧道上、下台阶开挖、初期支护完成和二次衬砌完成等工况。通过模型计算,并与监控量测结果进行对比分析,揭示了该隧道支护和开挖过程中支护与围岩受力与变形特征。研究结果表明,有限元方法能够较好地预测隧道拱顶沉降;及时封闭初期支护能够有效地控制隧道围岩支护体变形,提高隧道稳定性;二次衬砌施做能够显著改善初期支护受力状态,使之应力分布较为均匀。

For the study of force and deformation characteristics of rocks of the tunnels in soft and fractured surrounding rocks during construetin supporting and surrounding g,2D and 3D finite element model are established by ABAQUS based on a tunnel project. The models are consistent with the actual situation of the engineering. Full-face excavation,initial support completion and secondary lining comple- tion construction conditions were included in 2D model;the up and lower bench excavation, initial support completion and secondary lining completion construction conditions were included in 3D model. The stress and deformation characteristics of tunnel supports and surrounding rocks were revealed by solving the finite element models and comparing the on-site monitoring results. The results show that, finite element method can be used to predict the tunnel crown settlements. Timely closure of initial support can be effectively controlled tunnel surrounding rock deformation and improve the stability of the tunnel. Construction of secondary lining can significantly improve the force state of initial support making it more uniform stress distribution.