全套管钻机成孔复合型桩基降水施工新技术

针对基坑降水量小,围护结构外侧改移管线密布且交通繁忙无布设降水井场地,以及漂石地层中管井成孔困难和工期紧的问题,借助全套管钻机在直径1m围护桩施工时提出了一种新的复合型桩基降水方法.结合勘察报告将桩身加长,在桩底填滤料形成汲水区,用副钢筋笼内配套水泵、滤管与围护桩钢筋笼连接,排水管和水泵电线置于PVC套管中,沿围护桩钢筋笼升至地面,汲水区上部用细砂将预施围护桩隔离.计算显示围护桩内水位降深3m时,引起单桩沉降为0.12mm,小于桩顶总沉降值的10％.采用本工艺降低了施工成本,经济效益明显.

Composite Pile Dewatering Construction New Technology of Hydraulic Casing Rotator Machine Drilling-holes

Because of small foundation excavation precipitation,pipeline densely covered on the outside of supporting structure and busy traffic,there isn’t dewatering well sites and drilling holes is hard in boulder formation and tight schedule.A new composite pile formation dewatering method is proposed which 1meter diameter supporting piles are drilled by hydraulic casing rotator machine.The piles body is extended with the survey report and filter material is filled in the bottom of piles to form water-absorbing area and an assistant reinforcing cage contains a pump and a filter tube which is welded to the supporting pile’ reinforcing stage.Water pipeline and wire are protected in the PVC casing which is along the reinforcing stage up to the ground.In the top of the water-absorbing area,sand is filled to separate the prepared constructing supporting pile.Calculations show that the settlement of single pile caused by dewatering is 0.12mm,when dewatering depth is 3m in a supporting pileless than 10% of the total settlement of the pile.The application of the technology reduces the construction cost and obtains economic benefit.