Risk Evaluation Research Of Tunnel Collapse Based On Fuzzy Theory And Numerical Analysis

During the construction of rock tunnel,the collapse is one of the most commom and harmful engineering accident,due to its unpredictable,Serious consequences,it causes great difficulty to tunnel engineering construction,especially when the tunnel goes through the fault fracture zone,it is more likely to occur collapse.Therefore,evaluation of the risk about the tunnel that goes through the fault fracture zone and doing numerical simulation of excavation by using FLAC3 D can be early warning of the risk about collapse,analyzes the deformation law of surrounding rock in the process of tunnel excavation,and provides a reference for the smooth construction of tunnel.It has important theoretical significance and engineering application value.This paper researches on the risk about collapse of surrounding rock tunnel risk evaluation model,the main contents are as follows:The research on the risk of tunnel status at home and abroad was reviewed,several cause of the collapse and the present situation of the treatment measures was summarized.The risk about collapse of tunnel was defined,88 tunnels material of collapse at home and abroad was collected.Through the data statistics and analysis,the grade of surrounding rock,bad geology,design and construction,hydrological condition and so on four primary risk factors of the primary risk factors was identified,and each factor contains a number of secondary risk factors.The collaps risk evaluation model of tunnel that goes through the fault fracture zone was established based on Fuzzy theory.By using fuzzy statistics and assignment method,the membership degree of each risk factor was determined.The influence of various factors on collapse weight value was obtained base on AHP method.The probability of collapse risk ranks and collapse consequences was calculated by Fuzzy comprehensive evaluation method.Combined with specification,the collapse risk grade of different surrounding rock section was obtained.Combined with the example of one tunnel that goes through fault fracture zone in southwest,the collapse risk evaluation model was verified in this paper,the calculation result of analysis is agree with the realities of situation.the effevtiveness of the model is verified.With the numerical simulation of the construction of tunnel that goes through fault fracture zone,the stress and displacement change rule was analyzed.The analysis show that the vault area of fault fracture rock zone appears obvious ground arch during excavation,the stress of arch foot part changes sharply,it has a plastic zone in the vault area of the grouting circle.it is possibile that the tunnel occurs collapse.It is necessary to improve the support parameter of this section,and prevent the collapse occur.