水电站蜗壳垫层参数优化研究OA

Cushioned spiral casings are widely used in large and medium-sized hydropower projects due to their advantages such as con-venient construction and low investment cost.The determination and optimization of cushion parameters are crucial in structural design.To solve the problems of complex parameter types and lack of optimization standards for spiral casing cushions in hydropower stations,a three-dimensional overall nonlinear model was established using the finite element method.Typical sections were selected to investigate the influences of common-node model versus friction model,interfacial friction coefficient,cushion elastic modulus and thickness on the mechanical characteristics of cushioned spiral casing structures.The results show that the friction model has excellent nonlinear simulation capability.Compared with the common-node model,the circumferential stress distribution of the surrounding concrete is more uniform,the water pressure bearing ratio of concrete in the full circumference decreases by 63.2%,and the average values of steel liner Mises stress and circumferential stress increase by33.1%and34.6%,respectively.When the interfacial friction coefficient and cushion elastic modulus decrease and the cushion thickness increases,the bearing capacity of the steel liner is better exerted,the stress state of the sur-rounding concrete is improved accordingly,the circumferential stress of concrete and the internal water pressure bearing ratio decrease,while the multi-directional stresses and displacements of the steel spiral casing increase.Under comprehensive consideration,the optimal cushion scheme yields a full-circumference internal water pressure bearing ratio of concrete of 14.89%,an average circumferential stress of the steel spiral casing of 54.46 MPa,and maximum circumferential and radial displacements of 0.45 mm and 0.58 mm,respectively.The research results can provide a reference for the optimal design of spiral casing cushion parameters.