高水头下深厚覆盖层高土石围堰应力变形分析

乌东德水电站位于长江上游的金沙江,其土石围堰高74 m，河床砂卵石覆盖层厚70 m，上下游水头差达151 m，且设计在下游侧堰脚开挖70 m深的基坑，拟采用高86 m的混凝土防渗墙上接复合土工膜防渗。对该高水头下深厚覆盖层高土石围堰的应力变形特征进行了非线性有限元分析，模拟了堰体填筑、蓄水、下游侧降水与基坑开挖的过程，采用无厚度Goodman单元模拟堰体与防渗墙间的接触面。应力与变形分析的结果表明围堰的设计方案是可行的。此外，研究了覆盖层与围堰填料的参数，防渗墙的材料、厚度与墙底沉渣等因素的影响，对设计方案提出了建议。

Stress and deformation analysis of high earth cofferdam on deep subsoils under high water head

Wudongde Hydropower Station lies on the Jingsha River, which is located at the upstream of the Yangtze River. The earth rockfill cofferdam is 74m high; the boulder overburden layer of river bed is 70m deep; and the water head difference is 151m. A foundation pit with the depth of 70 m is planned to excavated at the toe of the cofferdam at the downstream side, and concrete wall( 86m high) with geomembrane on the top, the geomembrane has the depth of 43m. The stress and deformation characters of the cofferdam are analyzed by the nonlinear FEM. The processes of construction, the upstream water level,and the excavation in downstream side were modeled. The interface between filling material and the cut-off wall is modeled by Goodman element without thickness. Results of stress and deformation analysis indicate that the design scheme is feasible.Furthermore,the influences of the paramerters of the overburden layer, the influences of filling materials,and the influences of the material, the thickness and the bottom sediment of the cut-off wall are studied. Some suggestions obtained from analysis are presented for the design scheme.