Failure Mechanism And Method Of Anti-Dislocation Of Mountain Tunnel Through Active Fault

In order to solve the key scientific problems in the seismic field of mountain tunnel engineering,this paper carries out depth and systematic research on failure mechanism and method of anti-dislocation of mountain tunnel through active fault.The specific research contents are as follows:The hazard analysis for tunnel engineering of active fault is carried out.From the standpoint of engineering earthquake damage analysis,the correlation between fault and tunnel earthquake damage is studied and the evaluation method of earthquake rupture is put forward.Theoretical analysis of failure mechanism of tunnel through active fault is launched by analytical method and numerical method.In order to carry out further research on failure mechanism of tunnel through active fault,the theoretical calculation method and the physical model test are adopted.Based on the research results of tunnel failure mechanism,comprehensive consideration of many factors,research on the anti-dislocation method of the mountain tunnel through active fault is developed.The effectiveness and correctness of the anti-dislocation method are verified by various verification methods.On the basis of the correlation between active fault and tunnel engineering,the potential damage type and damage degree of tunnel can be evaluated.The dislocation of the engineering site can be estimated by the quantitative evaluation method of fault fracture parameter。The fault rupture influence range and tunnel longitudinal fortification range can be determined by longitudinal distribution of dislocation in active fault zone.By the study of the failure mechanism of the tunnel through active fault,the failure principle of the mountain tunnel in the fault dislocation can be obtained.Based on the above research results,the targeted anti-dislocation measures of the tunnel through active fault can be put forward in consideration of multifaceted factors.The main research contents and results are summarized as follows:(1)The study on earthquake damage of Wenchuan earthquake and other typical earthquakes is carried out.Tunnel earthquake damage phenomenon is analyzed from the standpoint of engineering seismic damage.By classifying the earthquake damage and concluding the degree of earthquake damage,the correlation between active fault and engineering earthquake damage and the weak part of the tunnel structure are analyzed.By sorting and analyzing several different types of earthquakes in the western regions of China including Wenchuan and Ya’an earthquake,the regression relation of seismic magnitude and seismic fracture parameters is established.(2)Based on the analytical method of bedrock of Okada,the amount of dislocation of the upper surface of bedrock is calculated by the geometric parameters of the fault and the parameters of the rock and soil properties.The bedrock perpendicular to one side of fault-based method for calculating the width of the longitudinal strong deformation zone in the fracture zone is proposed.According to the properties of the surrounding rock,the relevant parameters in the formula are calibrated and corrected,and the formula is verified by numerical simulationa Theoretical analysis on failure mechanism of tunnel through fault is research from two aspects of theoretical calculation method and numerical analysis method based on different faults and tunnel parameters.(3)By the large scale physical model test,taking the tunnel through reverse fault as an example,destructive research test is carried out.Based on the analysis of deformation,stress and failure of the mountain tunnel under the condition of.the stick slip and dislocation of the reverse fault,the failure mechanism of the mountain tunnel through the active fault is studied.(4)From the basic principles of fortification,the magnitude of earthquake and the amount of dislocation,fortification distance of tunnel through active fault,optimization of tunnel structural form of anti-dislocation and quantitative setting method of longitudinal anti-dislocation combined deformation joint aspects,the research on the method of anti-dislocation of tunnel through active fault is carried out respectively.And the structural form of anti-dislocation combined deformation joint suitable for different tunnel positions is put forward.(5)Numerical simulation,laboratory model test and engineering field test are carried out for the proposed anti-dislocation method of tunnel through active fault.The effectiveness and correctness of the anti-dislocation method are verified by the verification results.