Study On Surrounding Rock Mass Deformation And Stress Characteristics Of Supporting Structure Of TBM Tunnel In Bad Stratum

The regional engineering geology and hydrogeological conditions of the Barry BABEI TBM tunnel in Nepal are complex,and the bad strata are mainly expansive rock and fault fracture zone.In the construction,the swelling rock is faced with swelling of water and softening of rock mass,the stability of the surrounding rock of the fracture zone is poor,the stability of the rock is easy to break and the thickness of the pea gravel packing layer is uneven.A series of key technical problems such as the supporting force of the segment supporting structure affect the progress of the project.Based on the TBM tunnel in Nepal,this paper studies and summarizes the deformation of the surrounding rock and the stress characteristics of the supporting structure of the TBM tunnel through a large number of data investigation,literature review and theoretical analysis and numerical simulation.The main research contents are as follows:(1)Based on the characteristics of water swelling and water loss shrinkage of the expansive rock,the three-dimensional model of fluid solid coupling is established by the finite element software ABAQUS,and the influence of the swelling characteristics of the expansive rock on the deformation of the tunnel surrounding rock and the stress of the supporting structure under different depth of buried depth is studied.(2)Based on the joint distribution model,the stability of the surrounding rock,the stress characteristics of the supporting structure and safety are studied when the TBM tunnel passes through the fracture zone with different joint dip angles and different joints.It provides a reference for the safety and rapid construction of the tunnel.(3)To establish a three-dimensional model that can accurately reflect the interaction between the pieces of the pea gravel packing layer and the formation of the three layers.The influence of the thickness of the pea gravel packing layer on the stress characteristics of the support structure of the pea gravel packing layer is studied when the TBM tunnel is used as the supporting structure.