水轮机蜗壳不同埋设方式的座环受力特性研究

Study on the mechanical characteristics of stay ring under different embedding of spiral case in concrete

基于接触非线性理论,考虑蜗壳与垫层及外围混凝土的接触滑移,对三种典型埋设方式的蜗壳结构进行三维有限元仿真分析,主要研究座环结构的受力特性。计算结果表明,不同埋设方式下各构件承担的扭转力比例不同,钢管承担的扭转力比例在保压方案下最大,座环承担的扭转力比例在垫层方案下最大,混凝土承担的扭转力比例在直埋方案下最大。软垫层和预压缝隙的存在降低了流道系统的强度和刚度,使得直埋方案座环扭转变形最小,垫层方案次之,保压方案最大。另外,充水保压蜗壳采用仿真算法,能够给出蜗壳和座环真实的变形和应力状态,计算结果准确合理,更加符合工程实际,应该在充水保压蜗壳结构的设计和研究中推广采用。

This paper studies the mechanical characteristics of stay ring through a three-dimensional FEM analysis of spiral case structure that is embedded in concrete in three typical manners.The nonlinear contact theory is adopted to model the contact slippage between the spiral case and its surrounding concrete.The results show that the torsional force ratio（TFR） of each member of the structure is different in the three embedding schemes,the TFR of the steel pipe is the greatest in preloading filling scheme,the TFR of the stay ring is the greatest in cushion layer scheme,and the TFR of surrounding concrete is the greatest in complete bearing scheme.Soft cushion layer and initial gap can reduce the strength and stiffness of the steel structure.In terms of the torsional deformation of stay ring,preloading filling scheme ranks the highest,cushion layer comes the second,and complete bearing ranks the lowest.FEM simulations of the construction and operation processes of preloading filling spiral case can reveal the real behaviors of stresses and displacements of the spiral case and the stay ring.The FEM results are reasonable and accurate.Such a method should be widely adopted in design and study of preloading filling spiral case structure.