Research On Surrounding Rock Classification And Monitoring Measurements On NATM Construction On Dabieshan Tunnel

Currently,the mainstream method of tunnel construction is the New Austrian Tunnel Method.The theoretical foundation of the New Austrian Tunneling Method is that the self-supporting capability of wall rock is brought into full play to the protect the original intensity of wall rock of the tunnel as much as possible.To allow deformation of the wall rock but unlikely to bring about relaxing destruction. Meanwhile,it can also grasp the wall rock and prop up as well as protect the dynamic tunnel out of shape in time,in order to keep dynamic balance between the deformation of wall rock with structure supporting oppose energy which restraines the deformation.The paper takes the case of Dabieshan in MaWu highway,to analysis the condition of the specific wall rocks in tunnel and its deformation process when constructing,then finding the deformation disciplinarian of the tunnel under its wall rocks condition,in order to accumulate construction experiences and data for similar projects.What has been done in this paper is:1),Tell the research status about the theoretical foundation of the New Austrian Tunneling Method and its monitoring measurement.Meanwhile,the paper recapitulates two ideas about the method to determine the stability of wall rock:One is estabilishing precise mathematic or mechanical models to simulate the whole condition of the construction wall rocks and the process of the construction,then making a determine directly.Another one is to take the whole wall rocks as a overall system,then evaluating the stability of the wall rocks by using statistics and probability theory.There is seven main methods:mechanical analysis method, numerical value calculating method,artificial intelligence method,wall rock grading method,reliability analysis method,monitoring measurement inverse analysis method.2),Citing Bieniawski's RMR geomechanics classification system,build a method which can be used in this engineering and can estimate the wall rocks' classification of the tunnel quickly and exactly in construction site,then using it to the wall rocks classification in Dabieshan tunnel.At the same time,on this basis,it obtains a wonderful purpose through making supporting design to every grade factor.Hope it can provide some beneficial suggestion and elicitation to other similar projects.3),Sing large-scale finite element analysis software ANSYS to simulate the process of tunnel excavation and support,choosing the typical geological cross section under two different wall rocks,including theâ…£-class wall rock andâ…¢-class wall rock. Establishing geological generality model,Make an exact evaluation to the deformation and stability of the wall rocks by using the two-dimensional elastic-plastic Mohr-Coulomb model.The result of the numerical simulation shows that the support effect science is effective.4),Summarize and analyse deformation disciplinarian in the tunnel construction by using the result of the monitoring measurement in Dabieshan tunnel.And find out some kinds of deformation disciplinarians and the deformation total value range about the crown settlement and hole convergence in Dabieshan tunnel.Then,using the regression analysis to build the sketchy relationship between level rock and deformation.