混凝土重力坝功能叠合区坝体应力计算方法探析

Computation method for stress analysis of the multifunctional section of concrete gravity dam

基于重力坝功能叠合区受力结构体系复杂、不易评价坝体应力安全的特点,以某水利枢纽工程的混凝土重力坝的安装间坝段为例,对坝体应力计算模型的建立、计算方法的选择以及计算结果进行了对比分析。分析计算过程中,采用材料力学方法在高水位工况坝体上游面出现了约0.1Mpa的拉应力,然后通过建立考虑结构整体受力的计算模型和采用有限元法计算,得出了所有工况坝体均处于受压状态的合乎标准要求的结果。研究表明,对于类似功能叠合区的特殊体型的大坝坝体应力分析计算,如果采用偏保守简化的计算模型和材料力学法进行计算,得出的计算结果过于保守,并影响安全评价结论;因此采用有限元方法,通过细化计算模型,进行更切合实际的受力分析,以便得出更加准确的大坝安全性评价结论。

Due to the structure complexity of the multifunctional sections of concrete gravity dam,its stress safety is difficult to be assessed by conventional method. By taking the case of a concrete gravity dam section with the connection of dam body and powerhouse erection bay,contrastive analysis was conducted on analysis models,computation methods and calculation results. From the calculation by the method of mechanics of material,0.1 MPa tensile stress occurred at the upstream surface of the dam upon high water level condition. But,when finite element method is employed with the calculation model of taking dam and erection-bay as an integrated structure,no tensile stresses developed in the whole dam section under all the working conditions. The research results show that: when simplified model and the method of mechanics of material are used for the stress analysis of complicated structures or dam section with special shape,too conservative results may be obtained. Therefore, the correct safety assessment conclusion may not be achieved. By application of FEM with the accurate computation models,real stresses of the structure could be obtained,and the results of safety assessment could be more reliable.