内水压力重复加载作用下蜗壳外围钢筋混凝土的损伤分析

本文分析了三峡电站某直埋式蜗壳结构在内水压力重复加载下的混凝土损伤演变规律和钢蜗壳以及钢筋的受力特性,分析中考虑了钢蜗壳与外围混凝土间的摩擦接触特性,采用弹塑性损伤模型来描述混凝土的受拉损伤特性。研究表明,在历经内水压力的多次加、卸载循环后,蜗壳外围混凝土的损伤程度及范围虽有一定的增加并导致混凝土强度和刚度的相应退化和降低,但经一定的循环次数后,钢衬和钢筋的应力以及混凝土的损伤分布范围和程度将保持稳定状态。蜗壳外围混凝土出现稳定的损伤后,钢衬和钢筋承担的内水压力比例将比线弹性分析结果增大,从而能进一步发挥钢结构的承载作用。

Damage analysis of reinforced concrete surrounding the spiral caseunder the action of repeated water pressure

The damage process and the stress characteristics of reinforcement and directly embedded steel spiral case under the action of repeated internal water pressure in one of the turbines of the Three Gorges Project are analyzed.The elastic contact between steel liner and surrounding concrete are taken into account and the plasto-elastic damage model is adopted to describe the tensile damage characteristic of concrete.The result shows that the extent of damage in concrete,Von Mises stress of steel liner and reinforcement will keep unchange after a certain number of loading-unloading cycles.When stable degradation occurred to concrete,the steel liner and reinforcement will bear more water pressure.