渐变流道混凝土结构施工期温度应力特性

Characteristics of temperature stress of concrete structure with gradual flow channel during construction period

水电站和泵站的流道结构中存在着各种形式的流线形结构,可以统称为渐变流道结构,工程经验表明,它们在施工期的应力发展特点不同于其他水工混凝土结构。以此类结构的某实际工程为研究对象,采用数值仿真计算方法,对不同约束形式影响下混凝土温度场和应力场的变化规律进行了深入分析。结果表明:当结构的两个端部均被约束时,产生的拉应力超过结构混凝土的抗拉强度,极易发生贯穿性裂缝;而任意一端被约束时与两端自由的应力状态差别不大。此外,由于粗端与细端断面尺寸相差较大,导致它们的温度场和应力场变化不同步,相位差约3个月。

There are various streamlined schemes adopted in the flow channel structures of hydropower stations and pumping stations,which can be generalized as gradient flow channel structures. Based on previous engineering experience,the stress development characteristics of the gradient flow channel structures are different from those of other hydraulic concrete structures during the construction period. The development regularity of the temperature field and the stress field regarding concrete structures of this kind,with different forms of constraints applied,is studied and analyzed in depth through numerical simulation calculation. The results show that when both ends of the structure are constrained,the tensile stress will exceed the tensile strength of the structure concrete,and the penetrating cracks will easily occur. Whereas the stress state of the structure with both ends free of constraints is not significantly different from that with neither end being restricted. In addition,due to the large difference in cross-sectional dimensions between the thick end and thin end,their temperature field and stress field do not develop synchronously and the phase difference is about three months.