基坑变形监测及地下水的处理

结合南昌某建筑基坑，介绍了基坑支护结构水平位移和沉降监测点的布设、观测方法、监测数据处理等，并根据监测结果，发现可能发生危险的先兆，判断工程的安全性，防止工程破坏事故的发生；并以施工监测的结果指导施工，进行信息化反馈优化设计。由于基坑开挖后地下水丰富，坑内局部出现涌水、涌砂，导致电梯井等加深部位不能开挖到位。在基坑外部排水能力有限等情况下，提出了在电梯井的四周用旋喷桩形成止水帷幕、井底用旋喷桩封底的方法。实践表明：在旋喷桩施工完成后1 d即可垂直开挖电梯井，并没有渗水，取得了良好地加固效果和经济效益。

Deformation monitoring and groundwater treatment of excavations

Combined with a building foundation pit of Nanchang, the retaining and protecting structure of foundation excavation, the horizontal displacement, the settlement monitoring points’ disposal, observation methods and monitoring data processing, are described. Based on the results of monitoring, it would forebode the danger, estimate the safety of engineering and avoid the happening of engineering accident.The construction was supervised with the monitoring results; and the information feedback was optimized designed.There were groundwater inflow and sand inflow due to the abundance of groundwater after the excavation, which made the deeper part such as the elevator shaft pit can’t be excavated to the right location. A method that is forming a waterproof wall around the elevator shaft pit and back covering the bottom of well with jet grouting was brought forward for the limited drainage ability around the excavation. The results show that the elevator shaft pit could be excavated uprightness one day after the construction of jet grouting and there was not water yielding, which brought on favorable reinforced effect and economy benefit.