多基坑深层承压水降水引起地表沉降规律研究

Study on the law of formations settlement induced by dewatering in deep confined aquifer in multiple excavations

基于上海某地铁换乘枢纽工程,借助Geo Studio2007数值分析软件,针对上海地区第二层承压水降水及其引起地层沉降进行数值模拟.考虑了两种多基坑排布形式,两个独立基坑和坑中坑;设置了两个控制变量,承压含水层厚度M和基坑间距D.研究表明,对于两个独立基坑,在降压井影响区域内,地表沉降量随着承压含水层厚度的增加而先增加后减小,在影响区域外,地表沉降量随着承压含水层厚度的增加而增加;随着基坑间距的增大,目标基坑和相邻基坑内部的地表沉降均减小.对于坑中坑,在降压井影响区域内,地表沉降量随着承压含水层厚度的增加而减小,在影响区域外,地表沉降量随着承压含水层厚度的增加而增大;随着外侧地下连续墙与深坑距离的增加,深坑内部的地表沉降量呈现先增大后减小的现象.

A numerical simulation is carried out on dewatering in the second confined aquifer and the formations subsidence based on the underground complex engineering of a Shanghai metro junction hub. By utilizing the element numerical software Geo Studio2007, two array modes of multiple excavations are considered, with two control parameters, thickness of confined layer and distance of excavations. It shows that in the case of two independent pits, as the thickness of confined aquifer turns larger, the surface settlement increases first and declines later within the affected area of dewatering well, but raises monotonically outside the area. With the distance of excavations extending, the settlement declines both in the target pit and neighboring pit. As to the case of pit small in pit larger, the surface settlement shows a decrease and increase respectively within and without the affected area of dewatering well. Furthermore, there exists a feature of raise and down for the settlement in the center pit with a prolongation of the distance between the outside diagram wall and the center pit. The achievements of this paper will provide certain aids and references for engineering problems in soft areas as dewatering in deep confined water in multiple excavations.