| In the construction of tunnel engineering, one of the key problems is how to evaluate and guarantee the stability of tunnel. Fusong tunnel is the background for the thesis, which studies evaluation methodology of the analysis of tunnel stability under the complex condition by some methods, such as numerical simulation, strength reduction method, cross text design technique, and extremum difference analysis. This thesis intends to perfect the theoretical and methodology system of evaluation of tunnel stability, and it will be of great importance in tunnel design, safe construction, and the adjustment of support scheme. The main achievements can be summarized as follows:(1) The left hole of Fusong tunnel from ZK275+203 to ZK275+239 was numerically simulated in the present thesis. The thesis sequentially introduces the tunnel stability under two different construction processes which are double-side-wall heading constructing method and full face excavation method, tunnel stability under whether considering seepage, and tunnel stability under seismic effect. The result indicates that in the process of tunnel excavation, compared with the full face excavation method, using double-side-wall heading constructing method has greater advantages in controlling rock deformation. Existence of the seepage has a great influence on the stability of the tunnel. Connection part of the tunnel lining, especially arch springing is the weekness of seismic design of tunnel.(2) Studying the stability of the tunnel and destruction law under different conditions by strength reduction method. The result indicates that the minimum safety factors of Fusong tunnel in different conditions have great difference. Especially safety factor of tunnel is the smallest one in the presence of water, stability of tunnel is the worst, and more easily leads to tunnel collapse. The using of rock bolt support can greatly improves the stability of tunnel. Meanwhile, the difference of hoop spacing of anchor bolts will also lead to the difference of the increase of tunnel stability.(3) In order to solve the proplem of the role of the anchor stock can’t be give full play to and cannot be able to judge the strength of sensitivity of anchor stock factors, The thesis combines simulation of anchor effect and strength reduction method to do the analysis of sensitivity of anchor stock factors. After calculating many times, the thesis takes 2.5 as reduction coefficient, the role of the anchor stock can be give full play to, and we can judge the strength of sensitivity of anchor stock factors. The thesis sets the experimental scheme for geotechnical factors and anchor stock factors by using the. cross text design technique, and does sensitivity analysis for all the finite element results of orthogonal design. The result shows that the elastic modulus of rock soil and the circumferential spacing of anchor stock show the strongest sensitivity, that is to say, they have a strong influence on stability of surrounding rock. |
