白鹤滩水电站移民区高填方工程现场监测与分析

Settlement Monitoring and Analysis of High Filling Project for Resettlement Area of Baihetan Hydropower Station

摘要:

为了保障高填方地基的稳定性和后期使用的安全性，开展了白鹤滩水电站高填方工程沉降变形的现场监测，分析了原地基和填筑体在施工期及竣工后的沉降规律，探讨了填筑高度、地基综合压实度、时间和水位变化对高填方地基沉降的影响。结果表明，以砾石填料为主的高填方工程，原地基和填筑体对总沉降均有较大贡献，其中原地基沉降占总沉降量的39.7%，填筑体沉降占总沉降量的60.3%。适当提高地基综合压实度是控制地基沉降的有效措施。使用不同拟合模型预测了高填方地基的沉降，结果表明指数模型能够较好反映此类高填方工程的沉降变形规律。水库蓄水引起填筑区域地下水位上升，土体发生的瞬时湿化变形占总体湿化变形量的60.9%。孔隙水压力的增长和消散主要受地下水位和填筑荷载的影响，填筑施工期孔压增量与上覆荷载增量呈线性关系，其孔隙水压力系数等于0.021，土体在填筑期间始终处于稳定状态。竣工后超静孔隙水压力逐渐消散，地基开始固结沉降。

Abstract:

In order to ensure the stability and the serviceability of high filling foundations， the field monitoring of the high filling project of Baihetan Hydropower Station is introduced， and the settlements of the original foundation and the filling are analyzed in this paper. The influencing factors such as the height of filling， compaction degree， time， and variation of groundwater on the settlement are discussed. The results indicate that the settlement of the high filling project with gravel filler is caused by the original foundation and the compression of the filling. The settlements of the original foundation and the filling account for 39.7% and 60.3% of the total settlement， respectively. The proper increase of foundation compaction degree is an effective measure to control the foundation settlement. Different fitting models are used to predict the settlement of high fill foundations， and it is found that the exponential model can successfully predict the settlement of the high filling project. The impoundment in the reservoir causes the groundwater level in the filling area to rise， and the instantaneous wetting deformation of the soil accounts for 60.9% of the total wetting deformation. The increase and dissipation of pore water pressure are mainly affected by groundwater level and filling load. A linear relationship between the magnitude of excess pore water pressure and the filling load is observed and the coefficient is 0.021， indicating that the soil is stable. The excess pore water pressure gradually dissipated after completion.