The Reliability Of Underground Structure Considering Coupling Effect Based On Response Surface Analysis

This paper carried out the research to eliminate the deficiency of the reliability response surface modelling method which can not judge the importance of basic factors to structure state. Firstly, quadratic regression orthogonal composite design method was combined with inspection principle of lack of fit test and significance test. Then, the differentiate method of judging basic factors and quasi-birth items to the infection degree of structure feature value was constructed. As it implanted into the program that solving the equation of structure state for response surface, a new screening method for state function of complex structure was formed, which based on the principle of significance and could differentiate basic factors and quasi-birth items. In addition, the Matlab search method was used to optimize the calculating process of response surface reliability index. Sequentially, a new technology analysing response surface for complex underground structure with high efficiency was set up. At last, the operational process of the technology and the operating procedure were given out in detail through calculating the stable reliability of the surrounding rock of certain tunnel engineering. After the comparison with other methods was made, it found that the method presented in the paper have high efficiency and wide applicability.At first, taken the section K8+947 of Zhang Jia Jie Long Yang Road Tunnel for example, builded ANSYS (APDL) parameterization model, and based on the construction monitoring of the section K8+947, this paper analyzed the monitoring results and evaluated the stability of surrounding rock through the total deformation , the stable time of deformation and the deformation rate, and this paper applied the comparative analysis of nonlinear regression analysis and grey Verhulst model to predict the stable displacement value of the surrounding rock in the monitoring point. According to the basic theory of displacement back analysis, combined with the forecasting displacement value of the monitoring point, the paper used APDL parameterization model to obtain the rational parameter value of the surrounding rock for the section K8+947, and the result of back analysis could be availed to modify initial design proposal and serve as reference material of similar project.Secondly, an orthogonalization establishment method of structural state equation based on quadratic regression orthogonal combination design was introduced. The calculating programme based on Visual Basic was compiled. The basic idea is to use APDL parameterization model to solve feature value of structural state for every one-group of experiment design project, it was established by complicated non-linear optimization structural state equation between structural state feature value and basic factors through statistical screening and analytical calculation. And the section k8+947 applied this method to create structural state equation between tunnel vault sinking displacement and basic factors as the criterion to displacement under serviceability limit state after screening optimization.Finally, in terms of created structural state equation, the paper taken advantage of Matlab search method based on nonlinear programming, Matlab optimization method and traditional response surface JC method, and compiled corresponding reliability calculation program. Those methods was used for calculating tunnel reliability. The computed results of the above three methods that compared with the exact solution of Monte Carlo Method come to a conclusion: the three formers were able to avoid the problem of repeated structure numerical calculation in Monte Carlo method based on ANSYS probabilistic analysis. In addition, with respect to calculating accuracy and calculating efficiency, The two formers were compared with Monte Carlo Method and traditional response surface JC method to versify its applicability and feasibility.