特高面板砂砾石坝结构安全性论证

基于试验研究与数值计算分析,对新疆大石峡250 m级特高面板砂砾石坝结构安全性进行了论证。结果表明:压实后的砂砾石料有较高的变形模量、较小的流变和地震残余变形,大坝运行期坝体最大沉降仅为最大坝高的0.64%;设计地震用下坝体最大震陷量仅为最大坝高的0.40%;静、动力荷载作用下,面板周边缝的沉陷和张拉值均未超过国内外已建工程的最大实测值,周边缝的剪切位移虽然比国内外已建工程的最大实测值大,但中国在混凝土面板接缝止水结构与材料方面的技术储备已经能够满足其要求。因此,与相同高度的面板堆石坝相比,面板砂砾石坝变形安全控制的难度较小。需要指出的是,250 m级特高砂砾石坝的防渗面板在静、动力荷载作用下的轴向和顺坡向拉、压应力极值较高,有必要在面板周边缝和压性垂直缝两侧一定范围配置加强钢筋。

Evaluation of safety performance of extremely high slab-faced gravel dams

The structural safety performance of Dashixia concrete face gravel dam (CFGD), an extremely high CFGD in Xinjiang, is studied based on the large-scale triaxial experiments on dam materials and the detailed finite element method-based numerical analyses. Compacted gravel materials are found to exhibit high deformation modulus, small magnitude of creep and small magnitude of shaking-induced residual deformation. The maximum settlement of Dashixia CFGD during operation is evaluated to be about 0.64% of the dam height, while the earthquake-induced permanent settlement at the crest is about 0.40% of the dam height. The maximum settlement and tension of the peripheral joints do not exceed the maximum measured ones in the investigated existing cases. The shear displacement, on the other hand, is larger than all the measured ones in these cases. However, the advancement in sealing structures and materials achieved in China can already satisfy the need of CFGDs as high as 250 m. Therefore, it can be concluded that the difficulty in deformation control is relatively less compared with that of rockfill dams with similar height. What deserves special attention, on the other hand, is the high static and dynamic stresses in concrete slabs, both along the axial and slope directions. The reinforcements near some peripheral joints and the compressive vertical joints are necessary.