Safety Analysis Of Tunnel Under High Temperature Based On The Reliability Theory

With the development of city scale,as a fast transport subway can effectively alleviate the pressure of people's travel,followed by the number and frequency of accidents also increased,fire is one of the major accidents,because of its high risk aroused the attention of the parties.Due to the high temperature and high heating speed,the tunnel will cause serious damage to the bearing capacity of the structure,which will affect the reliability of the structure.How to accurately and quantitatively evaluate the reliability of the structure can provide a clear reference for tunnel lining fire prevention and post disaster repair.The reliability theory can be used to evaluate the safety degree of the structure quantitatively on the basis of considering the uncertain factors.Therefore,based on the previous research,this paper studies the reliability of the structure under the limit state of the shield tunnel under the fire:(1)Select the thermal parameters of the material,use ANSYS to establish the finite element model of the tunnel lining under fire,and analyze the variation law of the temperature field under the structure fire.(2)Based on the analysis of the change regularity of temperature field on the mechanical properties of materials with high temperature and deterioration,establish the structural bearing capacity calculation formula with the time by fire,combined with the modified method,considering the material degradation effect on the internal force distribution of building section load effect calculation formula with the time by fire,then a high temperature section under the failure function.(3)Based on Monte Carlo theory,the influence of various factors such as lining thickness,concrete strength,thickness of protective layer thickness and its variation coefficient on structural reliability is analyzed by MATLAB.(4)On the basis of reliability analysis,the influential factors is explored.From the actual situation,the tunnel structure fire protection optimization design is carried out.Relevant fire prevention suggestions are given.And the post disaster assessment model is established based on the reliability theory.