土石坝超深混凝土防渗墙变形与受力分析

我国病险土石坝已开始应用超过60 m的超深混凝土防渗墙进行加固。受库水变化和帮坡加载等作用、基岩嵌固条件及墙体材料性能等影响,防渗墙受力复杂多变。结合花凉亭水库大坝除险加固工程,采用Biot固结理论和南水双屈服面弹塑性模型,对混凝土防渗墙在坝体内的变形与受力情况进行三维仿真分析。成果表明:坝体混凝土防渗墙受老坝帮坡加固和库水上升的影响较小;超深混凝土防渗墙建议适当提高抗压强度、降低弹性模量,以满足其受力和耐久性要求;对于非直线型大坝拐弯处的混凝土防渗墙,底部墙体应力会增大,可考虑增设钢筋等措施。研究成果可为超深混凝土防渗墙的设计提供借鉴。

Deformation and Stress Analysis of Extra-deep Concrete Cut-off Wall for Earth-rock Dam

Extra-deep concrete cut-off wall with depth over 60 m has been used for the reinforcement of dangerous earth-rock dams in China. The stress of cutoff wall is complex and changeable due to reservoir water level fluctua-tion,slope loading effect,the embedded condition of bedrock as well as the characteristic of wall materials. In this paper,the deformation and stress of concrete cut-off wall in dam body are analyzed by 3D simulation based on Shen Zhujiang's Double Yield Surface Model in association with Biot's consolidation theory. The hazard elimination and reinforcement project of Hualiangting reservoir dam is taken as a case study. Results reveal that the impact of the old dam reinforcement and the rising of water level exert small influence on the concrete cut-off wall. We recom-mend to enhancing compressive strength and reducing elastic modulus in order to meet the requirements for stress and durability;due to stress increment at the bottom of cut-off wall,we also recommend additional reinforcement for concrete cut-off wall of non-linear dam.