Study On Damage And Cracking Characteristics Of Tunnel Lining Subjected To Fault Creep Slip And Fortification Measures

Fault dislocation poses a major threat to the safety of the tunnel structure,and needs to be considered in advance in the exploration and planning stage.Starting from the fault dislocation mode,tunnel anti-displacement performance and fault-tunnel interaction,based on the concrete plastic damage model,the damage law of tunnel lining under the action of fault creep is analyzed,and a fine-zoned tunnel design method based on damage evolution is proposed.;Based on the cohesive force model,the cracking modes of the tunnels repaired separately and jointly repaired were compared,and the cracking laws of the tunnels under the dislocation of the deep-buried faults were revealed.On this basis,the effects of antidisplacement measures such as setting up segmented linings,deformation joints,and radial let-down layers are further studied.The main work and research results of the paper are as follows:(1)Using the method of literature research,the numerical simulation methods of tunnel lining concrete are compared and analyzed;starting from the interaction between fault dislocation and tunnel structure,it is determined that the concrete plastic damage model and cohesion model are used to characterize the tunnel under the effect of fault dislocation.The corresponding properties of mechanics.(2)The failure mode of the tunnel caused by fault dislocation is mainly affected by the fault attribute,dislocation mode and dislocation amount,and the support structure system.Based on the concrete plastic damage model,a three-dimensional tunnel reinforced concrete numerical mechanics model was established by the finite element method.Starting from the relative stiffness of surrounding rock and tunnel,taking the classification of surrounding rock as the main variable,combined with the characteristics of creep fault dislocation,the failure modes of the tunnel caused by strike-slip fault,normal fault and reverse fault dislocation,as well as shear,tension Mechanical characteristics of shear and compression shear actions.(3)Based on the cohesive fracture damage theory,a three-dimensional numerical model of tunnel-fault creep dislocation is established to analyze the characteristics of tunnel damage,cracking and crack propagation.By comparing the cracking and failure characteristics of separate and combined repair tunnels caused by fault dislocation,it provides a basis for judging the failure mode angle for the selection of separate and combined repair methods for cross-fault tunnels.To explore the cracking characteristics of deep tunnel lining under normal fault,reverse fault and strike-slip fault dislocation 10 cm.According to the different cracking characteristics,discuss the feasibility of zoning fortification and targeted measures.(4)Based on the mechanical response law of tunnel structures under the action of faults,the adaptability of fortification measures for tunnels across faults is studied.Analyze the way in which the deformation joints and radial compression support of the segmented tunnel function.The effects of lining segment length,deformation joint stiffness,annular joint form and radial yielding support on the anti-shifting performance of the tunnel are discussed.