Inversion Analysis Of Tunnel Rock Parameter Based On Monitoring And Numerical Simulation

With a larger number construction of mountain highway tunnel, it is particularly important to determine reasonable parameter of rock mechanics. Due to the complexity of rock mass media and construction factors, the majority of engineering analysis method is not possible. With the application of computer technology in rock mechanics and geotechnical engineering, rock mechanics theory and numerical methods have got the rapid development and application. However, due to the heterogeneity and discontinuity of rock material, rock mechanics calculation of input parameter is often difficult to determine. The labarary test and field local test using in engineering can not reflect the nature of rock mass, which will result in a great difference between theoretical analysis and the actual value. Anti-displacement analysis based on the measurement of displacement is one of effective means in determining numerical calculation parameter. According to the measurement data and monitoring information, a system,convenient,practical way of inversion analysis of rock parameter must be found, which will bring a significant cost-effective influence to tunnel construction, and also a good reference and guide to the design of tunnel construction.Basing on the currently under construction project of Malichang tunnel and the Xiluodu hydropower station 4# highway tunnel which has been completed, this paper use the way of direct inversion analysis to analysis the mechanical parameter of rock, under the result of tunnel monitoring, combined with the numerical simulation of tennel. The main content can be summarized as follows:(1) Rock parameter model is an important theory premise of the inversion analysis. If the model is not consistent with the actual situation, we can not make sure of the precise expression of mechanical medium behavior, no matter how the parameter is determined. This paper make a detailed introduction of elastic model and elastic-plastic constitutive model of rock mass.(2) Basing on the previous experience, we determine the elastic-plastic model for the anti-analysis medium model. At the same time, there have been determined elastic modulus and coefficient of lateral pressure as inversion parameters for the question from the impact of factors surrounding the extent of displacement.(3) Combined with two project entities, we first determine the scope of optimization parameter, then continuously optimize parameter to calculate the displacement of rock by golden section method, and then compare with the actual value. At last, after many rounds of selection and displacement calculation,there have determind elastic modulus and coefficient of lateral pressure and stress. As we examine the result by the monitoring of cross-section, there have been proved that the inversion parameter is accuracy and satisfied. The mothod of inversion analysis using in this paper is proved to be reliable.