水垫塘反拱底板极限荷载非线性有限元计算

为分析水垫塘反拱底板的极限荷载及失稳模式,以某大型水电站在建拱坝为例,通过ANSYS软件,采用非线性有限元方法考虑不同拱块之间的摩擦接触效应及水荷载的随机性,分析不同位置若干拱块同时受径向荷载情况时的敏感性。计算发现单个拱块受径向荷载时中间拱块的极限荷载最大,向两边逐渐减小。中间拱块受径向荷载时底板的失稳模式相似,受力拱块沿径向拔出并带动两侧相邻拱块旋转,而边缘拱块受径向荷载时,边缘拱块自身会绕着一侧的拱块旋转;多个拱块受径向荷载时,受力拱块相邻的组合比拱块间隔的组合危险,若受径向荷载的拱块中有边缘拱块,边缘拱块会最先失稳。研究结果表明,中间部位拱块的极限荷载大于两边拱块的极限荷载,且由于反拱底板跨度较大,拱效应不明显,受力拱块位移破坏不会波及整个底板,只会影响到受力拱块相邻的拱块。研究成果可为工程实践提供参考。

Nonlinear Finite Element Method of Ultimate Load of Inverted Arch Floor of Plunge Pool

In order to analyze the ultimate load and instability mode of the invert arch floor of plunge pool, taking a large-scale hydropower station under construction as an example, through ANSYS software, the nonlinear finite element method is used to consider the friction contact effect between different arch blocks and the randomness of water load, and the sensitivity of several arch blocks at different locations under radial load is analyzed. It is found that the ultimate load of the middle arch block is the largest when a single arch block is subjected to radial load, and gradually decreases to both sides. When the middle arch block is subjected to radial load, the instability mode of the bottom plate is similar. The stressed arch blocks pull out along the radial direction and drive the adjacent arch blocks on both sides to rotate, while when the edge arch block is subjected to radial load, the edge arch block itself will rotate around the arch block on one side. When multiple arch blocks are subjected to radial load, the combination of adjacent stressed arch blocks is more dangerous than the combination of separation of the arch blocks. If there are edge arch blocks in the arch blocks subjected to radial load , the edge arch will lose stability first. The research results show that the ultimate load of the middle part of the arch block is larger than that of the two sides of the arch block, and the arch effect is not obvious due to the large span of the inverted arch bottom plate. The displacement failure of the stressed arch block will not affect the whole floor because of the large span of the inverted arch floor and the obscure arch effect. The research results can provide reference for engineering practice.