Hydraulic Calculation And Structural Analysis Of A Hydropower Station Surge Tank

Surge tank is the most important component in diversion type hydropower station building,it is also used in pumped storage power stations and water supply projects.The design has a direct impact on the safe operation of such projects.The hydraulic calculation and structural analysis is the most important content in the design.In this paper,the whole design process are expounded,especially for the hydraulic calculation and analysis of surge shaft structure,and summarizes the rules for future reference in design of surge tank,used a water diversion type hydropower station surge tank which is in Fengjie County of Chongqing City as an example.In the case of no setting surge tank in the diversion system of hydropower station,the water hammer pressure of water diversion system under three conditions is calculated.The calculation results show that the surge shaft set in power plant pressure channel is the most feasible plan.Stable sectional area of surge chamber was calculated used the Thomas criteria.The water level fluctuation of the surge chamber under six conditions is calculated by the analytic method.The highest surge water level and lowest surge water level are obtained,provide the basis for the design of surge shaft section size and height.The surge shaft structure is analyzed by using the method of structural mechanics and numerical analysis method.By using the thin cylinder and plate theory,well bore and floor structure of the surge shaft is analyzed,the internal force distribution and the change rule of the surge tank is got.By using the finite difference method calculate software FLAC3 D,five stage static three dimensional numerical simulation analysis is carried out,in the excavation process of the surge tank and after the completion of normal operation.The result of structural analysis shows that: the bottom of the shaft is compressed and the axial stress and radial stress are the biggest at the bottom,the location stress of 0~7m in the lower part of the shaft is larger,the stress changes rapidly along the elevation of the wellbore;bottom edge compression,outer edge tension,the inner edge of the bottom compression stress is large;these areas should be strengthened monitoring,have good protection measures.The calculated stress values are larger than those obtained by numerical analysis,because some assumptions are made in the calculation of structural mechanics.The numerical analysis method shows its good characteristics in simulation load,shape and adjacent parts,so it is more practical.