强渗透深覆盖层基坑排水及混凝土施工方法

Methods of drainage and concrete construction of foundation pit with strong permeability and deep overburden layer

深溪沟水电站河床式厂房4号主机坝段地基为强渗透深覆盖层,基坑深窄且排水困难。针对施工场地狭窄、基坑内渗水量大等一系列问题展开深入研究。通过对强渗透深覆盖层基坑特征和基坑上、下游渗水来源进行分析,确定的施工总体思路为"上水上排,下水下排"。将下游集水井放在建筑物基础以外,不占用4号机第4坝块的浇筑部位,同时完成4号机右侧下游第3,4坝块基础混凝土施工部位的封闭。经过后期固结灌浆处理,钻孔取芯资料显示,混凝土质量满足设计要求。

Strong permeability and deep overburden layer are existed in deep and narrow foundation pit for monolith of No. 4 unit of Shenxigou Hydropower Station and concrete construction will be carried out in narrow and drainage - difficult pit. The research is conducted on narrow construction field and large seepage amount in foundation pit etc. By analysis on the strong permeability and overburden layer of the foundation pit and seepage sources from upstream and downstream of the pit, the construction scheme is determined, including drainage method. The collecting well is placed outside the foundation of structure, which does not occupy the casting site of the 4th dam section of No. 4 unit and close construction site of foundation concrete of the 3rd and 4th dam sections on the lower right side of No. g unit.