Statistical Rule Of Surrounding Rock Pressure Of Road Tunnels And Reliability Analysis Of Tunnel Lining

Many uncertainties in the tunnel engineering make people doubt the traditional method of ensuring the reliability of the structure with the safety factor. The accuracy of engineering uncertainty is contradictory with the accuracy of computing technology, and it may cause the design of lining structure to deviate from the actual. This article is written in order to understand the mechanism of the surrounding rock pressure and lining structure of highway tunnel and explore the reliability of the lining structure.The paper is based on Xingfen Expressway in Xingtai. The statistical characteristics and distribution of surrounding rock pressure were analysised. Erviceability limit state,which is used to determine whether the structure is failure. At the same time, with the measured value of surrounding rock pressure as one of the lining structure load, the load-structure method is adopted to analyze the lining structure. Then, Monte Carlo method and response surface method were used to analyze the reliability of the lining structure. the numerical analysis of the certainty and the uncertainty based on the random parameters were compareds.Therefore,some conclusions can be acquired:(1) Overall, with the increase of the surrounding rock level, the measured value of the pressure of surrounding rock shows an increasing trend. The overall distribution of surrounding rock pressure is generally in the range of 0~1.6MPa. Generally speaking, the measured surrounding rock pressure value is greater than 20 k Pa, less than 720 k Pa; After the pressure box is installed, the measured value of surrounding rock pressure is shown as the growth model of “fast growth, slow growth, basic stability and fluctuation”. The fluctuation is influenced by the engineering disturbance; The surrounding rock pressure has certain randomness and uneven distribution along the excavation contour line, but it is not difficult to find that there is often considerable pressure of surrounding rock on the arch shoulder.(2) From the result of deterministic numerical analysis, the arch shoulder is the most dangerous part of the lining structure of the YK80+383 section(?-grade) of Huangyanzi tunnel. the junction of Inverted arch and arch foot is the most dangerous part of the the ZK76+262 section(V-grade) of Zhaizigou tunnel followed by arch shoulder. The section bending moment has the greatest influence on the lining structure.And the axial force is conducive to the relaxation of tension caused by bending moment, so it has a certain effect on the stability of the two lining structure.(3) From the non deterministic numerical analysis, the simulation results are no longer a specific value, but a range.Through the Monte Carlo method and response surface method, the failure probability of components and the correlation between input and output variables can be obtained. Through the failure probability is very small, it can be seen that the lining structure of YK80+383 section(?-grade) and the lining structure of the ZK76+262 section(V-grade) of Huangyanzi tunnel is reliable. The moment and the parameters of the cross section presents a linear correlation to some extent.