前坪水库大坝应力变形及抗水力劈裂研究

Study on Stress Deformation and Anti Hydraulic Fracturing of Qianping Reservoir Dam

心墙土料与坝壳砂卵砾石料、堆石料模量差别较大,为研究大坝心墙拱效应对心墙的应力变形及抗水力劈裂的影响,根据大坝材料分区及坝基地质情况,考虑施工填筑及蓄水过程分级加载,采用非线性邓肯-张模型对大坝应力变形进行研究分析,对前坪水库心墙的应力变形、抗水力劈裂进行分析。计算结果表明,坝体应力和变形分布符合一般规律,坝体最大竖向沉降发生在1/2～2/3坝高范围内,考虑心墙拱效应后,心墙抗水力劈裂是安全的。同时,结合已建工程经验,在大坝易出现裂缝部位可采取填筑高塑性土等工程措施,防止因裂缝而引发集中渗流破坏,避免心墙与基岩面产生裂缝。

The modulus of core wall soil is different from that of sand gravel androckfill. According to dam material division and dam foundation geology condition, considering the staged loading of construction and storage process and analysis of stress and deformation of dams by using nonlinear Duncan-Chang model, the deformation, stress and hydraulic fracturing safety of the core wall were analyzed to study the effect of arch effect of dam core wall on stress deformation and anti hydraulic fracturing of core wall. The calculation results show that the stress and deformation distribution of the dam conform to the general law. The maximum value of vertical settlement of dam is in the range of 1/2-2/3 dam height. Considering the arching effect of the core wall, the hydraulic fracturing of the core wall is safe. At the same time, combined with the experience of the existing projects, some engineering measures, such as filling high plastic soil, are adopted to prevent the core wall and the bedrock from being damaged by concentrated seepage or by contact scouring in the face of the core wall and the bedrock surface, in view of the easily occurring cracks in the dam.