高寒地区碾压混凝土重力坝防渗体研究

Design of the Anti-seepage System for Roller Compacted Concrete Gravity Dam in Extreme Cold Area

奋斗水库所处地区全年最冷月平均气温仅有-17.9℃、极端温度甚至达到-44.1℃,年际施工期间极易造成混凝土坝体内毛细孔隙所含水体不断发生冻融转化,引起毛细孔隙局部塑性变形、增大孔径,长时间运行容易导致毛细孔隙相互贯通、串联,引起强烈渗透,致使整体崩解破坏。基于奋斗水库碾压混凝土重力坝分别开展常态混凝土、变态混凝土以及沥青混凝土防渗体系设计,并着重综合比较各方案施工工艺、造价、工期以及层间防渗效果,通过现场实测,变态混凝土方案施工便利、水泥用量小、防渗效果好、工程造价低,适用于奋斗水库。

The roller compacted concrete gravity dam in Fendou Reservoir is located in the extreme cold area that the lowest monthly average temperature is - 17.9℃ and the extreme temperature even reaches - 44.1℃. During the dam construction over years, water freezing and thawing inside the capillary pores in the dam body would continuously oc- curs, which leads to plastic deformation and aperture expansion of the capillary pores. Inter-penetration and inter-con- nection of the capillary pores due to long time operation could cause serious seepage and even the overall disintegration failure. Thus, three different anti-seepage system schemes for the dam are compared, including the normal concrete scheme, distorted concrete scheme and the asphalt concrete scheme. The construction technology, cost, construction pe- riod, and interlayer seepage prevention performance are compared in detail. Analysis and the in-situ measurement show that the distorted concrete scheme is of certain advantages such as the construction convenience, small cement amount, good anti-seepage performance and lower cost. Thus, the distorted concrete scheme is selected for the dam.