The Study On Construction Technology Of The Big-Span Diversion Tunnel Of Water Power Engineering

In company with nonstop rushing of the long-span tunnel construction, a matterstation encounter more and more. For instance, the demand of the present design and construction code is already insatiability with the need of long-span tunnel engineering design and construction. And both domestic and foreign concerned research output is not too much to refer. So the engineering design and construction on long-span tunnel has definite blindness of the approve use for reference. Consequently, it was for the present urgency problem on that how about increase in advance quality on the engineering design and construction of the long-span tunnel. The key to solve this matter is making research direct towards on excavation and support course of the long-span tunnel. The excavation and support systematic mechanics character information of long-span tunnel sunounding rock under the course of different construction method is achieved to supply design basis and supervise for the big-span tunnel. For this reason, in the thesis, the reliable construction methods are studied and the numeric value on the construction method of the long-span tunnel is simulated. So this research nossesses not onlv theoretical value, but also imnortant engineering sense as well. The contents in this thesis are concluded as follows:1.Based on the research output of predecessor, in this thesis, some significant factors in tunnel construction have been present. The results show that some terms such as the importance of the engineering, geology and hydrologic conditions have critical role to employ which construction method in big span tunnel;2.To present the mechanics of soil and rock under static loading, elastic-plastic theory and some constitutive models have been declared. By the means of incremental elastic-plastic theory, the analysis model to simulate dynamic construction of underground structures was established, which provides theoretical basis for the subsequent works in the dissertation;3.Programe of finite element method (FEM) Plaxis 3D Tunnel is applied to study the big-span tunnel constrution. By take geology conditions and different construction method into consideration, many examples has been peformed to demonstrate tunnel and rock stability. Some favourable conclusions are assessed to improve the structure safty.4.In the Qing Jiang diversion tunnel of water power engineering, the bench cut method is applied and construction simulation is analysed. The result shows that it is competent when excavating tunnels in the disadvantageous condition of the soft ground, shallow depth and big span.