| In tunnel construction, it is of great significance to make use of the measured data of displacement of support in the evaluation of the safety of a tunnel. Based on the displacement-based method to assess the safety of primary support in tunnels under construction established before, the research work in this paper improves the theory. The previous study mainly dealt with the safety evaluation of primary support constructed with plain concrete and lattice-girder-reinforced shotcrete, as well as the influence of shrinkage, creep and temperature of shotcrete on the stability of a tunnel. This thesis focuses on the shape steel reinforced support, the creep of shotcrete, and the temperature field of primary support induced by heat of shotcrete hydration. This work in this paper makes the displacement-based method more accurate in the evaluation of the safety of tunnels. Research results are as follows:(1) Performance functions to a cross-section of the shape steel reinforced primary support are established, and formulas are derived to compute the internal forces of primary support through measured displacements.(2) Law of creep of shotcrete is studied by experiment. By comparing the value of experiment with the B3and GL2000model predicted values, the applicability of the two models, which are used to predict the shotcrete creep, are discussed. A new and more accurate model is obtained through modification of specified parameter of the GL2000model.(3) Temperature fields of the shotcrete support were simulated with the large three-dimensional finite element software ANSYS, and the temperature variation of the primary support is given. Based on the simulation, some suggestions on calculating the temperature deformation are given.(4) The reliability indexes of three tunnels are done through a computer program. The computed indices for the tunnels are all consistent with the in-situ situation, which proves the correctness of the research results. |
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