陈恺

摘 要：地铁建设工程降水复杂程度及处理难度远高于一般基坑降水工程。文章以北京地铁三号线04合同段平房村站～东坝中街站区间为例，对6～8m低渗透性粉细砂地层隧道内降水处理施工技术进行分析，在采取地面管井降水+深孔注浆等措施进行降排水后仍存在层间残留水情况下，通过采用水平真空降水井施工工艺完成了降水井套管封堵，在接入真空泵以后完成了本次抽水施工。

关键词：低渗透性粉细砂地层;地铁建设工程;水平真空降水井

中图分类号：TQ177.4        文献标识码：A 文章编号：1001-5922（2021）09-0177-04

Research on Construction Technology of Horizontal Vacuum Drain Well in Tunnel of 6～8m Low Permeability Fine Sand Formation

Chen Kai

（Beijing Rail Transit Construction Management Co.， Ltd.， Bei Jing 100068， China）

Abstract：The complexity and difficulty of dewatering in subway construction engineering is much higher than that in general foundation pit dewatering engineering. The article takes the interval between Pingfangcun Station and Dongbazhongjie Station on Contract 04 of Beijing Metro Line 3 as an example， for 6 to 8 m low permeability silty sand stratum tunnel construction technology in the precipitation were analyzed， and the ground tube well precipitation + deep hole grouting and other measures still exist after draining water interlayer residual water conditions， through the adoption of horizontal vacuum dewatering well construction technology completed the dewatering well casing seal， after the access to the vacuum pump has completed the construction of pumping.

Key words：low permeability silty sand formation; subway construction project; horizontal vacuum dewatering well

0 引言

北京地鐵三号线04合同段平房村站～东坝中街站区间位于东坝中路下方偏西侧呈南北向敷设;区间长1137m。覆土深12.7～17.8m，采用暗挖法施工。区间包含停车线大断面和标准断面，大断面长345m，大断面与标准断面净距3.11m。区间共设置3处施工竖井及横通道，其中1号、2号横通道兼作区间联络通道。

区间主体位于东坝中路下方偏西侧呈南北向敷设，东坝中路交通繁忙，地下管线敷设密集，区间存在9个一级风险源，其中整条区间需平行穿越3200m×2500m雨水箱涵、φ1000污水、φ500中压燃气、18根10kV电力管线，施工难度大、风险高。在区间隧道进行开挖时，减少对地面、管线的影响，是极为重要的[1-3]。

整个区间地质情况较为复杂，拱顶粉细砂层厚度6～8m，停车线大断面拱脚处、标准断面拱顶位于粉细砂层和砂质粉土交接部位，对应交界处存在层间水（局部具有承压性），粉细砂层渗透性差，施工现场采取地面管井降水+深孔注浆等措施进行降排水，但开挖掌子面仍存在层间残留水，致使施工难度增加，进度无法保证，存在掌子面易不稳定等安全隐患。……