The Discuss Of Tunnel Structure And Construction In Xigeda Soil

As an important part of buildings in hydropower station, the working behavior and stability of surrounding rock of tunnel is a strikingly important problem, and will influence the safe operation of the project. However, as the structure underground, the surrounding rock is widely different. It is necessary to select the appropriate method of design and construction. Xigeda soil is widely distributing in Panzhihua-Xichang region. Which was formed in very early age. Along Tiezhaizi faultage, from Ertan and Tongzilin waterpower station to Daqiao reservoir in Mianning County, then to dam foundation of Yele station, the workshop locality of Liziping station and Caluo region, is more and more younger and the concretion of ground is better. The waterpower station researched in the thesis is located in the region. The author has completed the following work: (1) Based on the research of forerunner, the author takes the test of the Xigeda soil. Through experimentation, the physical parameters are gained, which are the reference of design of the structure and construction. . (2) The distribution of inner force is achieved through analysis of tunnel structure with traditional method. And the thickness of the material used and the scalar of reinforcing steel bar are calculated. Then the security of structure is judged based on probability. (3) Through analysis of structure with linear-elastic FEM, the working behavior of lining numerically simulated in case of internal pressure, external pressure and several elastic modulus of surrounding rock, and so on. And based on the case of internal pressure, the scalar of reinforcing steel bar is calculated. (4) Being optimum to lining thickness, the structure becomes reasonable and economic. (5) At present, the traditional theory and FEM are extensively applied. The comparation of the two result shows that the stress value by the former calculation is larger than the value by the latter. Because the traditional theory is based on the premise, however, FEM can well simulate the figure, the load and the resisting effect of surrounding rock in different place. It is suggested that FEM is used in big design as the assistant of the traditional theory. (6) Under the function of ground stress field, nonlinear FEM is used to study and analysis the stress of tunnel lining and plastic distribution, according to the feasible excavation model and timbering form. The conclusion is gained that it is necessary to take timbering measures when tunnel is built in Xigeda soil. (7) The primary design of tunnel construction in Xigeda soil is accomplished. Some measures to landslide are summarized in the thesis.