Analysis On Surrounding Rock Stability And Liner Structure For Underground High Pressure Reinforced Concrete Branch Pipe

With the development of electric system, many pumped-storage power stations have been built, which are displaying the important effect in exchanging peak load to fill valley load, balancing the quantity of electricity of day and night, improving the flexibility and reliability of electric network. Building of hydraulic tunnels with high head and large diameter increase gradually, and the underground reinforced concrete branch pipe is adopted in more and more projects. This kind of structure is characterized by high internal water pressure, high outside water pressure and large diameter. For the complexity of the loads on branch pipe, there are many complex problems in analysising on the stability of surrounding rock and the design of lining.The state of research on underground reinforced concrete branch pipe, the design theory of underground reinforced concrete branch pipe and the numerical analysis on high-pressure branch pipe by ABAQUS are introduced in this paper. The ways for selecting lining form of underground high-pressure tunnels, the numerical analysis of surrounding rock stability, the numerical analysis of lining structure, the combined effect of surrounding rock with lining, the value of internal and outside water load, the rebar model of lining, the constitutive model of concrete and the method of these analysis process by the software of ABAQUS FEM are recited in this article. In this paper, the truss element and the spring element simulating the interaction of concrete lining and the surrounding rock are compared, the code formula and the concrete constitutive model for configuration rebar are compared and the reinforced bar stress and crack distribution is analyzed, some data and conclusions are gotten. Finally, the different work conditions such as the construction, operation, inspection on one pumped-storage power station project in Liaoning Province are analyzed by 3-D non-linearity FEM method; the surrounding rock stability and the stress-strain situation of branch pipe are studied; two different kinds of designing theory based on surface force and seepage body force of water load are analyzed; different calculation methods are draw out; the thickness of concrete lining and the quantity of rebar are designed by adopting simplified spring model. By above study, a few beneficial conclusions are gained, which provide a reference for design theory and method of an underground reinforced concrete branch pipe.