基坑承压水涌水的降水施工分析及对下伏既有隧道变形影响

Analysis of dewatering construction of foundation pit confined water gushing and its influence on the deformation of underlying existing tunnel

基坑承压水涌水导致既有隧道变形是城市地铁建设的一个主要问题,为此,提出了附加荷载法预测基坑降水对下伏既有隧道变形的影响,并采用渗漏风险导向降水法处理深基坑承压水涌水。首先,假设土壤中不存在现有隧道,并计算上部基坑开挖和相关降水引起的现有隧道位置处的垂直卸载应力。其次,将现有的基础隧道简化为Paselnak地基模型上的弹性梁,以计算其竖向变形。深圳车公庙枢纽工程施工的预测结果与现场测量结果吻合良好,验证了该方法的有效性,这种分析方法可以为类似工程项目提供快速、准确的评价结果。

The deformation of existing tunnel caused by confined water inrush of foundation pit is a main problem in urban subway construction.Therefore,this study proposes the additional load method to predict the influence of foundation pit dewatering on the deformation of underlying existing tunnel,and uses the leakage risk oriented dewatering method to deal with the confined water inrush of deep foundation pit.Firstly,it is assumed that there is no existing tunnel in the soil,and the vertical unloading stress at the location of the existing tunnel caused by the excavation of the upper foundation pit and related precipitation is calculated.Secondly,the existing foundation tunnel is simplified as an elastic beam on the paselnak foundation mod el to calculate its vertical deformation.The predict-ed results of the construction of Shenzhen chegongmiao hub project are in good agreement with the field measurement results,which verifies the effectiveness of this method.This analysis method can provide fast and accurate evaluation results for similar projects.