大锚锭超深基坑降水施工关键技术及监测分析

Key Technology and Monitoring Analysis of Dewatering Construction of Large Anchor Ingot Foundation Pit

临江富水超深基坑开挖是跨江大桥建设的重要组成部分,保证开挖时基坑和围护结构的稳定是目前的重大难题。本文以棋盘洲长江大桥南侧锚锭基坑为背景,该工程基坑面积大,地质条件复杂,属于大型深基坑,且开挖工况多变,并且周围居民密集、持力层岩面起伏大,承压水头高且距离抗洪大堤距离较近,所以为了兼顾保护周边环境,基坑的降水难度大大增加。针对该工程特殊的地理位置及工程重要等级,本文对该深基坑的支护及降水进行了设计,并计算得到基坑的涌水量,然后对降水井的数量和布置形式以及降水井的结构设计等方面进行了探讨,通过采用井点降水及分段抽水的措施,来保证基坑施工的安全性。同时对支护结构、基坑内外水位及周边建筑物沉降实时监测,并得出该种降水施工方案的关键点,为此后其他类似工程提供参考。

As an important part of the construction of the bridge across the river,it is a big problem to ensure the stability of the foundation pit and the retaining structure.This paper takes the south side of Qipanzhou Yangtze River Bridge as the background.The foundation pit of this project has a large area,complex geological conditions,belongs to a large-scale deep foundation pit,and the excavation conditions are variable.Moreover,the surrounding residents are dense,the rock surface of the bearing stratum fluctuates greatly,the pressure head is high and the distance from the anti-flood dike is relatively close.Therefore,in order to protect the surrounding environment,the foundation pit dewatering difficulty is greatly increased.In view of the special geographical location and importance level of the project,this paper designs the support and dewatering of the deep foundation pit,and calculates the water inflow of the foundation pit,then discusses the number and layout of the dewatering wells and the structural design of the dewatering wells,through the measures of well point dewatering and sectional pumping,to ensure the safety of the foundation pit construction.At the same time,real-time monitoring of supporting structure,water level inside and outside the foundation pit and settlement of surrounding buildings is carried out,and the key points of this dewatering construction scheme are obtained,which provides reference for other similar projects.