集水明排与深井井点联合降水工程应用

摘要

沙特阿拉伯红海沿岸某大型深基坑开挖面积近50 000m2,最大开挖深度达15.75 m,要求最大水位降深达12.25 m.且场地60 m深度范围内均为砂层,渗透系数大,给基坑降水带来极大困难.根据传统降水设计理论,共需布设降水井52眼,降水井较多不但影响基坑开挖进度,且深井井管及水泵易受海水腐蚀,维护成本高.因此将深井井点优化至22眼,井距约40 m,基坑开挖至地下水位面时,沿坑底四周开挖集水沟、集水井,采用潜水泵直接排水.降水结果表明,集水明排与深井井点联合降水方案达到了预期降水效果,减少了降水对施工的干扰,可为该类地层基坑降水提供参考.%The excavation area of a large deep pit is nearly 50 000 m2 in Saudi Arabia close to the Red Sea.The maximum excavation depth is 15.75 m,and requiring maximum drawdown is 12.25 m.The depth of the site within 60 m is sand layer,the permeability coefficient is large,which brings great difficulties to the dewatering of foundation pit.According to the traditional theory of dewatering design,a total of 52 deep wells need to be laid.A large number of deep wells will affect the progress of excavation,and the deep well pipes and pumps are easy to be corroded by seawater,which can increase the maintenance costs.Therefore,the number of deep well is optimized to 22,and the well spacing is about 40 m.When the foundation pit is excavated to the groundwater level,the ditch will be excavated around the bottom of the pit,and the water will be drained by submersible pump.The results of the excavation show that the combined dewatering method of water catchment and deep well has achieved the expected dewatering effect,reduces the interference of precipitation on construction.It provides references for similar project of dewatering of foundation pit.