较高土石坝膜防渗结构设计方法探讨

根据不同防渗体位置的土石坝受荷位移规律与土工膜受力变形特点,分析了坝内土工膜的变形机理,并以四川瀑布沟186 m的心墙堆石坝为例,提出了土工膜与土心墙联合防渗的思路及设计原则.分析表明:坝内绝大部分区域的土工膜能够承受坝体位移引起的变形,但在刚性锚固部位,由于“夹具效应”,土工膜可能会产生局部过大变形而发生破坏;对于高水头土石坝,土工膜尤其适用于存在缺陷的黏性土料心墙的联合防渗;四川瀑布沟186 m的心墙堆石坝,如果采用土工膜与土心墙联合防渗设计方案,则不仅可以提高防渗安全的可靠性,而且与原设计方案相比,技术上更先进,经济上更合理.

Design of impervious structure with geomembrane for high earth-rock dams

The mechanism of geomembrane deformation in earth-rock dams was analyzed according to the characteristics of stress and deformation of geomembrane as well as the law of earth-rock dam deformation under loads with impervious structures at different positions.Regarding to the core wall rockfill dam of 186m at Pubugou of Sichuan Province,an idea and design principle of united seepage control measure with geomembrane and earth core was proposed.It is pointed out that geomembrane in most regions of the dam body can withstand the dam deformation caused by the displacement of the dam body,but geomembrane in rigid anchoring regions may be damaged by intolerable deformation due to the "clamping effect",and that geomembrane is particularly suitable for united seepage control of high earth-rock dams with defective clay core.As a result,the adoption of united seepage control scheme with geomembrane and soil core for the rockfill dam at Pubugou can improve the reliability of seepage control,and it is advanced and economical as compared with the original design scheme.