高碾压混凝土重力坝的失稳破坏机理和极限承载能力分析

Analysis on the failure mechanism of stability of high RCC gravity dam and its ultimate load bearing capacity

针对碾压混凝土坝的结构和施工特点 ,采用弹塑性有限元和不等比例降材料强度参数的方法 ,对高碾压混凝土重力坝的渐进破坏过程、破坏机理和极限承载能力进行了分析计算 ,结果表明 ,大坝的破坏失稳表现为沿RCC层面 (包括建基面 )的剪切滑移 ,或表现为从坝体下部下游侧RCC本体开始的大面积压剪屈服为主的与沿RCC层面剪切滑移的组合 ,它取决于大坝的断面形状和RCC层面与块体材料强度的组合情况。因此 ,在研究评价大坝的稳定安全程度时 ,除核算沿关键层面 (或建基面 )的抗滑稳定性外 ,还应考虑坝趾区块体的抗压剪能力。用不等比例降材料强度参数的方法揭示了碾压混凝土坝的破坏规律 ,且结果合理 。

According to the characteristics of the structure of RCC dam and its construction, the analysis and calculation have been made on the gradually failure process and mechanism and the ultimate load bearing capacity of high RCC gravity dam by using the elastic plastic finite element method and the unequal proportional reduction material strength parameter method The results have shown that the unstable failure of dam is a shear sliding along RCC bedding surface (including construction foundation base) or a composite of shear sliding along RCC bedding surface which is mainly caused by the large area compressive shear yield of RCC block body in the downstream side of the lower dam The latter depends on the composite of section shape of dam, the RCC bedding surface and block material strength Therefore, in the study and evaluation on the safety degree of the stability of dam, the compressive shear capacity of the blocks in the dam toe should be considered besides the stability against sliding along key bedding surface (or construction foundation base) should be checked The method of unequal proportional reduction material strength parameter has revealed the failure laws of RCC dam and its results are reasonable and tally with reality