砂砾石地基上面板堆石坝变形和应力性状分析

Deformation and stress behaviours of concrete-face rockfill dam built on sand and gravel foundation

结合原型观测资料和数值方法分析和评价建于砂砾石地基上苗家坝面板堆石坝的变形和应力特性,进而总结砂砾石地基上面板堆石坝的行为特性并与典型大坝(修建于基岩上的面板堆石坝)结果进行对比分析。原型观测结果由大坝详细变形监测系统获得,覆盖大坝施工阶段、蓄水阶段和一年运行期。为了全面获得大坝施工期和运行期变形和应力特性,并对大坝长期变形进行预测,基于参数反演结果对大坝进行三维有限元分析。比较分析表明,大坝原型观测结果与数值计算结果吻合良好。苗家坝面板堆石坝变形和应力特性表现良好并趋于稳定。另外,对包括苗家坝在内的12个已建砂砾石地基上面板堆石坝实测变形进行了总结归纳分析并与典型大坝结果进行比较。结果表明,砂砾石地基对面板堆石坝行为特性具有显著影响,大坝沉降和面板挠度显著大于典型坝结果,且最大值位置呈现向下移动的趋势。

Behaviours of the Miaojiaba concrete-face rockfill dam （CFRD） built on fiver gravel foundation was evaluated by combining in-situ measurements and numerical analysis, and time variations and spatial distributions of its deformation and stress were examined and compared with those of normal CFRDs on rock foundation. Detailed field data were collected in this study using a deformation monitoring system for the stages of dam construction and initial reservoir filling plus one year period of normal operation. We also made 3D finite element simulations using back analysis of the model input parameters to assess the deformation and stress behaviours for these short stages and long-term operation. Comparison of the measurements and FEM simulations shows a good agreement between them. The main findings suggest that this dam is stable and performs well. This paper also presents a comparative analysis of CFRDs on fiver gravel foundation versus rock foundation, based on the deformation data of in-situ measurements of 12 CFRDs in service. The analysis shows that fiver gravels have a significant affect of dam deformation. In the case of river gravel foundation, settlement of the dam body and deflection of face slabs are much larger than those of normal dams and the locations of peak deformation move downward.