岳猛

摘要:随着社会的不断发展进步，深基坑建设项目的不断增多，当止水帷幕施工完毕后，重要的一环是基坑降水。

天津地区地下土层以粉土及粉质粘土为主，部分地区存在淤泥，目前普遍采用抽水管井和自渗井相结合的降水方法，地下水在重力作用下向管井内汇集，通过抽水泵排出。当其应用于渗透系数小的粘土、粉质粘土等弱透水层上时降水效果不理想，难以疏干，造成开挖出的土方含水量大，特别是为城市中心区的深基坑建筑，需要将开挖的土方晒干后才能外运，占用较大面积的场地，同时影响工期，部分项目为赶工期，不得不加大工程投入，在开挖出的含水量较高的土中加拌白灰，费时费力，本文向大家介绍另一种降水方法——真空井降水。

关键词: 真空井；降水；试验

Abstract: along with the development of social progress, deep foundation pit construction projects has increased, and stop water heavy curtain when finishing construction, the important part is the foundation pit dewatering.

Tianjin area with powder soil and underground soil layer silty clay is given priority to, part of the area in silt, the current widespread use of induction into the water and the combination of precipitation method, groundwater by gravity to within the casing well together, through the ChouShuiBeng eduction. When its application in the permeability coefficient of small clay, silty clay semi-permeable layer, the effect is not ideal precipitation, when hard, cause a big water content of the turkmen excavation, especially for the city center of the deep foundation pit construction, excavation will need the dry earth to sinotrans, occupy a large space, and to influence period, part of the project for cast time limit, have to increase the project investment, in the excavation of the moisture content of the soil a higher add mix lime, time-consuming, this paper introduce another precipitation method-vacuum well precipitation.

Keywords: vacuum well; Precipitation; test

中图分类号： P332.1 文献标识码：A文章编号：

一、 真空井降水原理：利用真空负压原理，用气压泵将抽水井进行抽真空，在地下土层中传递负压，利用大气压力加速地下水往井内汇集，提高排水效率及降水效果。

二. 真空井施工工艺：

1、工艺流程

设备进场→放线定位→钻孔→下护口管→终孔后冲孔→下井管→稀释泥浆→填砾→止水封孔→洗井→下泵抽水→做好排水管路及电缆路由→试验→正式抽水→配合开挖做好记录。

2、施工技术要求

满足“三通一平”条件后安排钻机进场，钻机安放稳固、水平。井管、砾料到位后开钻，要求整个钻孔孔壁圆整光滑，钻进时不允许采用有弯曲的钻杆。

钻进过程中保持泥浆比重，尽量采用地层自然造浆。……