连通试验落底式止水帷幕的实施效果分析

Analysis on the Effect of Cut-off Wall Based on Communicating Test

为查明某超大深基坑地下连续墙止水帷幕的隔水效果并反演地连墙的渗透系数,通过现场开展的7组连通试验,观测了各组试验井中地下水深随时间的变化,同时借助渗流分析软件Visual Modflow,以现场观测的井水位实测数据为依据,在软件中开启和冻结对应的基坑降水井,通过不断调整地下连续墙渗透系数等参数,最终达到与现场连通试验一致的降深—时间曲线。结果表明:虽然落底式止水帷幕无法完全阻隔坑内外水力通道,但可以延长地下水从坑外涌入坑内的渗流路径,从而大幅度减缓坑内外水位的下降速率,可见该工程的地连墙渗透系数满足施工需求。

In order to find out the water separation effect of the diaphragm wall of a super deep foundation pit and invert the permeability coefficient of the diaphragm wall, the change of groundwater depth with time in each group of test wells was observed through 7 groups of connection tests carried out on site. At the same time, with the aid of the seepage analysis software Visual Modflow, based on the measured water level data of the field observation wells, the corresponding foundation pit dewatering well was opened and frozen in the software, by continuously adjusting the permeability coefficient of diaphragm wall and other parameters, the final time depth curve is the same as that of connection test. The results show that although the water conservancy inside and outside the pit cannot be completely blocked by the cut-off wall, the seepage path of groundwater flowing into the pit from outside the pit can be prolonged, so as to significantly slow down the falling rate of the water level inside and outside the pit. It can be seen that the permeability coefficient of the diaphragm wall of the project meets the construction demand.