Technical Study Of Information-based Design And Construction On The Xuefengshan Tunnel

In recent ten years, to satisfy the necessity of society, the extra long highway tunnel was developing rapidly. Because the tunnel length was increasing and the geological conditions became more and more complicated, we have to use information construction and science construction, and need effective feedback from measurement with new science and technology. In order to improve the construction method and enhance the construction speed in term of safety and quality, we used the Xuefengshan tunnel as background, made full use of theoretical analysis, numerical simulation and experimentations, etc. We researched the method of measuring the convergence of surrounding rock quickly, the back analysis of the initial ground stress field and the parameter of surrounding rock, the estimate of the structure stability, the pre-support in the weak surrounding rock condition, the optimum time to construct the secondary lining in composite linings, and the optimum analysis of the support parameter of different surrounding rock. The main results are as follows:(1) We back analyzed the deformation data of typical cross-section of different surrounding rock, and gained the initial ground stress field and the mechanics parameter of surrounding rock.(2) We adopted the three dimension finite element program to calculate and analyze the mechanics effect in the construction progress. The surrounding rock's mechanics parameter and initial ground stress field can be used together with the result of the back analysis and the geological survey data, to evaluate the stability of the tunnel in construction. We chose the typical cross-section, on basis of the measure data of the surrounding rock's stress and the contact pressure between the initial lining and the secondary lining, adopted load structure model and structure-analysis software to analyze the stability of early support and the secondary lining.(3) The research of the pre-support style of the weak surrounding rock in Xuefengshan tunnel was mainly carried out in form of studying the principle of the pre-support in theory, adopting numerical method to simulate the mechanics effect of the pre-support, studying the pre-support construction technology combining with the practice of the construction.(4) Taking the tunnel's surrounding deformation as the control criterion, we determined the construction time of the secondary lining through the characteristic curve method. Firstly, we chose representative section to analyze the characteristic curve of surrounding rock and primary support according to different surrounding rocks, then we took advantage of the secondary lining structure characteristic to analyze supporting curve. With the two curves, the deformation data and project analogy, we could determine the optimum time of the secondary lining construction..(5) Based on the gotten construct monitoring section, we chose two representative sections to measure the contact pressure between primary support and secondary lining. If it kept stability for a long time, we could know the characteristics of the secondary lining, so we could get the inner force by calculation and analysis and evaluate the secondary lining's reliability under long term load application.(6) The optimization of different surrounding rock parameters and the range of optimization: the local optimization of lining form, the thickness optimization of primary support and secondary lining, the optimization of anchor's length and distribution, the optimization of steel grid's form and interval, and so on.