Research On Parametric Method Of Optimizing The Structure And Joint Load Bearing Of Symmetrical Y Type Crescent-rib Steel Bifurcation

Underground pipe can take advantage of the surrounding rock to bear part of the internal water pressure, so it can reduce the thickness of the steel liner, save steel and less affected by external conditions. In addition, when power tunnel hole line is long, in order to reduce construction costs and reduce excavation of earth, the bifurcation is often inevitably used to carry out a joint water supply. Therefore, underground steel bifurcation is widely used in large and medium hydropower station in China. When underground steel bifurcation is in the actual operation, steel liner, concrete and surrounding rock withstand the internal water pressure commonly, but the current design methods mostly use approximation algorithm specification provides, in accordance with stress condition of the straight section of steel pipe to have a rough estimate of the forces that can be shared in the bifurcated pipe section, or making underground steel bifurcation stress allowable value appropriately raise a certain percentage than steel bifurcation. Although algorithm specification provides considers some of the shared role of the surrounding rock, but it doesn’t take into account the shape characteristics of steel bifurcation, nor take into account the effect of the initial gap and coefficient of rock resistance. The calculation is rough, and it can’t truly reflect the forces of various parts of steel bifurcation.Finite element program has a unique advantage in solving the analysis of the mechanical properties of complex structures. In the study of steel bifurcation model and stress, it can fully take into account the geometric characteristics and force deformation of the structure and compared with conventional methods calculation results is closer to the actual situation. Therefore, more and more scholars use the finite element program to study the deformation and force condition of steel bifurcation. Since structure of the steel bifurcation is complex, modeling process is cumbersome and it need to repeat a lot of work when analysis and optimization of structure. Therefore, it is particularly important for steel bifurcation parametric modeling and analysis.In this paper, according crescent steel bifurcation shape design theory and contact nonlinear finite element theory, using ANSYS finite element program, by setting the contact element, simulation of the joint bearing of steel bifurcation and rock, it implements the simulation of normal operation of underground steel bifurcation. At the same time, making full use of ANSYS’s APDL function, it implements the parametric modeling, automatic mesh division of steel bifurcated, solving the load and outputting the results directly in the software. After obtaining steel bifurcation simulation results, the results need to be analyzed. According to the forces of the structure, it could be optimized through change the parameters of the steel bifurcation shape. Further, in consideration of the surrounding rock to share internal water pressure, it conducts the sensitivity analysis of parameter(the initial gap and coefficient of rock resistance) affecting steel bifurcation force.In this paper, steel bifurcation model is reasonable,and parametric modeling and analysis process is simple, it can save a lot of work, improve work efficiency, have great practical value.