特高砂砾石面板坝流变效应及面板防裂措施

针对高面板坝后期变形导致的面板破坏问题,采用大型室内试验测定了大石峡筑坝料流变力学特性,重点研究了后期流变效应对坝体、防渗体应力变形的影响。评估了各期面板浇筑前坝体沉降速率,复核了面板浇筑前预沉降时间的合理性。研究结果表明,该坝各期面板浇筑前设置的预沉降期可将坝顶沉降率控制在5mm/月以内。大坝蓄水运行后面板应力,尤其是轴向应力,较初次蓄水增加明显,存在挤压破坏的风险。论证了在面板受压区设置柔性缝的面板应力改善措施,结果表明该工程措施对削减面板轴向压应力效果明显。总体上,250m级的特高砂砾石面板坝坝体和防渗体应力变形能满足安全控制要求,通过合理的工程措施可保证大坝施工与运行安全。

Rheologic Effect and Crack Prevention Measures of Super High Sand Gravel Face Dam

Aiming at the problem of the slab damage caused by the rheological effect of dam material in high CFRDs, the large-scale indoor test was used to determine the rheological mechanical properties of the dam materials of the Dashixia dam. The impact of the rheological effect on the stress and deformation of the dam body and the anti-seepage body was mainly studied. The settlement rate of the dam before pouring slab was evaluated, and the pre-settling time before slab pouring was reviewed. The results show that the pre-settling time can control the settlement rate of the dam to below 5 mm/month successfully. During the dam operation, the stress of the slab, especially the axial stress, is obviously increased compared with the initial impoundment. There is a risk of crush damage. The flexible joints in the compression zone was proposed to reduce the slab stress. The measures have obvious effects on reducing the axial compressive stress. In general, the stress and the deformation of the 250 m high sand gravel dam can meet the requirements of safe control, and reasonable construction measures can ensure the dam construction and operation safety.