Three-dimensional Finite Element Analysis And Research Of Prestressed Concrete Spiral Case For Hydropower Station

With the national water conservancy and hydropower industry booming,all sizes of hydropower stations have been building,the hydropower plant research is also increasingly deep.The spiral case is one of the important components of the hydropower plant,the choice of form is very important.For the water head is not too high water head,the concrete spiral case has the advantage of saving steel,reducing costs,from the economic considerations is undoubtedly the preferred spiral case material.However,for large and medium-sized hydropower stations with a head about 40 m,the strength of concrete is slightly insufficient.Therefore,it is the focus of this paper to improve the strength of the spiral case so that it can adapt to the higher head of the hydropower station.In this paper,a concrete hydropower project is taken as an example to analyze the stress,strain and fracture characteristics of concrete spiral case,high-strength concrete spiral case,strip steel spiral case and prestressed concrete spiral case,and the results are compared,Get the following conclusions:(1)This paper briefly introduces the research status of three-dimensional finite element technology in spiral case calculation,and introduces the application of the existing prestressed spiral case in practical engineering.The finite element software ANSYS was used to establish the fan-shaped model with several sections of the spiral case part of the hydropower station.The stress and strain of several different types of spiral case were analyzed.(2)The stress of the concrete is larger than that of the ordinary concrete spiral case,and the stress of the reinforced concrete is reduced,and the deformation of the structure is effectively controlled.In the aspect of cracking,the crack load is obviously improved,and the same reinforcement The maximum crack width is smaller than that of the common spiral case,but at the lower reinforcement ratio,the maximum crack width can not meet the requirements of the specification and can not achieve the purpose of reducing the amount of steel.(3)In the spiral case,the steel lining is a kind of traditional reinforcement means.The calculation results show that the steel lining is not obvious in the sharing of the internal water pressure.The pressure of the concrete is different from that of the ordinary concrete spiral case,but because of the structure,So that the allowable value of the maximum crack width in the specification is increased,so that the amount of the steel bar can be reduced under the premise of satisfying the structural crack resistance requirement.(4)The experience of using the prestressed anchor cable to improve the volute force in the existing project is limited,the finite element calculation and the simulation model test results show that the prestressed anchor cable has obvious effect in improving the structural force,and can meet the requirements of the anti-Crack performance under the premise of reducing the reinforcement rate.This method has a wide application prospect for the concrete spiral case with a head about 40 m in size and close to the model.Finally,the research results of this paper are summarized,and the follow-up work is prospected.