强岩溶地区混凝土坝基基础处理施工技术

Construction technology of concrete dam foundation treatment in strong karst region

沙沱水电站坝基处于强岩溶地区,河床基础深层岩溶裂隙发育,在基坑开挖过程中出现多处渗漏涌水,导致基坑开挖和基础混凝土浇筑十分困难。在对渗漏通道进行深入勘查基础上,提出了有效的堵、排和基础处理技术措施,特别是通过对各种堵漏灌浆材料和工艺进行研究,采用膏浆、泵送沙浆并掺合一定微膨胀性材料等综合施工工艺技术,将塑性浆液大流量挤压入岩溶裂隙渗漏通道,堵漏效果显著,达到大坝基础处理要求,确保了工程进度目标,为类似工程的堵漏处理积累了成功经验。

The dam foundation of Shatuo Hydropower Station is in strong karst region,where the deep karst fracture under the river bed is developed. The excavation and grouting of foundation was difficult because the seepage and water burst occurred at many spots during the excavation process. The effective measures such as blocking or discharging and foundation treating were adopted through intensive investigation on the seepage passage. Especially,on the basis of the research on different blocking and grouting material and technologies,large volume of plastic slurry was pressed into the seepage passage of karst fracture by the comprehensive technique of paste slurry,pumping mortar and adding some slightly expansive material. The blocking effect is outstanding,which meets the requirement of dam foundation treatment and ensures the construction schedule.