Safety Analysis Of Defective Tunnel Structure Based On Reliability Theory

In recent years,the construction speed of Chinese tunnels has continued to increase.From the perspective of the number,scale and construction speed of tunnels,China has become the country with the largest number of tunnels,the most complicated structure and the fastest development in the world.Due to the complex geographical conditions,diverse environmental climate,and rapid construction scale,the quality of design and construction cannot be fully guaranteed,and the disease problem is more prominent.A large number of existing research and engineering practices have shown that due to the interference of human factors in tunnel design,construction and operation,as well as the interaction between natural factors such as tunnel geological conditions,environmental climate and tunnel construction,and the interaction between the two,Tunnels are often accompanied by a variety of diseases of different forms and severity during their operation.In this paper,based on a certain coal-traffic railway tunnel as the project,based on the disease detection results of the tunnel structure,the software modeling analysis and reliability theory are used to analyze the tunnel structure performance.The main work and achievements are as follows:(1)The coal line inspection showed that the tunnel disease was insufficient for the thickness of the partial section.The data of disease detection results are analyzed and analyzed to provide a basis for subsequent structural stability analysis.(2)Modeling and analyzing the surrounding rock of Class IV and V of diseased tunnels based on the norm,using load structure method to analyze 8 dangerous sections and calculate the safety factor of disease parts.The results show that the safety factors of section ?a??b and ?a lining are less than the standard requirement 3.6,which do not meet the requirements of the specification,and the dangerous section position needs to be strengthened.(3)Applying reliability theory to the stability analysis of diseased tunnels,considering various uncertainties and random factors in the calculation process,a calculation method for reliability index of secondary lining of railway tunnels based on probability and statistics is proposed.Comparing the reliability index ? with the K calculated by the traditional method,it can be seen that the two are basically consistent in the overall trend,and can reasonably reflect the stress characteristics of the secondary lining structure of the railway tunnel,but the calculation of the reliability index ? In the process,considering the uncertainty of the parameters,the calculation results and the safety factor can reflect the safety state of the structure more realistically.(4)In the case of known target reliability indicators,it is feasible to use the inverse reliability theory for the stability calculation of diseased tunnel structures,which can avoid cumbersome debugging.The inverse reliability method can quickly and conveniently calculate the required design parameters,which has good theoretical value for guiding engineering practice.