既有落底式止水帷幕对新建基坑降水的影响

近年来，落底式止水帷幕（如落底式地下连续墙）在武汉市深基坑工程中广泛使用。许多地铁车站基坑的降水工程中采用了落底式止水帷幕止水+管井降水的思路，取得了较好的工程效果。但在某些换乘车站的建设上，新建地铁车站的降水设计是未考虑既有车站的落底式帷幕的，这种既有帷幕对新建基坑的影响可能无法忽视。本文使用Visual Modflow渗流数值模拟软件，研究了在典型的长江一级阶地水文地质模型基础上建立的8种工况，探讨了既有帷幕对新建基坑的降水影响。研究表明：新建基坑中最大、最小降深均随着既有帷幕和新建基坑的距离的增加而呈现先变大后变小的趋势。

THE INFLUENCE OF EXISTING DROP WATERPROOF CURTAIN ON THE DEWATERING OF NEW FOUNDATION PIT

In recent years, the drop waterproof curtain(such as bottom-stopping diaphragm wall) has been widely used in deep foundation pit engineering in Wuhan. In many subway station foundation pit dewatering projects, the idea of the drop waterproof curtain stopping water+pipe well dewatering is adopted. However, in the construction of some transfer stations, the dewatering design of the new subway station does not consider thedrop waterproof curtain of the existing station, and the influence of the existing curtain on the new foundation pit may not be ignored. In this paper, Visual Modflow seepage numerical simulation software is used to study 8 working conditions established on the basis of typical first-grade terrace hydrogeological model of the Yangtze river, and the influence of existing curtain on the dewatering of new foundation pit is discussed. The results show that the maximum and minimum depth reduction in the new foundation pit tend to increase first and then decrease with the increase of the distance between the existing curtain and the new foundation pit.