充水保压蜗壳三维非线性仿真与承载力研究

Three-dimensional nonlinear simulation analysis and bearing capacity of preloaded filling spiral case

基于混凝土弹塑性损伤模型和接触非线性理论,采用仿真算法对充水保压蜗壳进行三维非线性仿真分析并对其进行超载计算,研究内水压力上升过程中钢蜗壳和钢筋应力、外围混凝土损伤区、机墩结构位移和座环变形的变化规律以及结构的超载能力。结果表明,内水压力达到保压值以前,钢蜗壳几乎处于单独承载状态,应力增加较快;在设计内水压力作用下,外围混凝土局部有较小范围的损伤,钢筋应力较小;超载系数大于1.1以后,外围混凝土的损伤区域和损伤程度迅速增大,机墩和座环的变形明显;但超载系数达到1.5时,蜗壳结构仍然具备一定的安全裕度。三维非线性仿真算法更加符合工程实际,应该在充水保压蜗壳结构的设计和研究中推广采用。

A three-dimensional nonlinear simulation was made for analysis of a preloaded filling steel spiral case and its overload computation on the basis of an elastoplastic damage model for concrete and the contact nonlinear theory.The analysis focuses on the behavior of spiral case under water pressure increasing,including stress and reinforcement,damage range of surrounding concrete,displacement of generator pier,and deformation of stay ring.The results show that the spiral case alone almost bears all the internal water pressure and its stress increases very rapidly before the internal water pressure reaches the design preloading value.When internal pressure reaches the design value,the damage range of surrounding concrete and the stress of reinforcement become very small.If the overload coefficient exceeds 1.1,the damage range and damage degree on the surrounding concrete increase rapidly,and the deformations of generator pier and stay ring are significant.The spiral case structure still has a certain margin of safety,however,even when this coefficient reaches 1.5.Three-dimensional nonlinear algorithm can produce a simulation closer to the real case,and it should be adopted in design and study of preloaded filling spiral case structure.