摘 要

随着近些年来，城市地铁站的深基坑开挖面积、开挖深度都越来越大，在这样的现状背景下，地铁深基坑的施工将会不可避免遇到降水问题，而因降水产生的地铁深基坑施工安全事故，不仅会造成重大经济损失，也会引起不良社会影响和延误整个工程工期。因此，在地铁站施工中如何有效降水已成为深基坑工程重要课题。

本文首先阐述了地铁站深基坑深井降水基本概念，分析深基坑降水的研究目的意义和当前的研究现状。然后总结和分析常用深基坑深井降水设计方法，并结合武汉轨道交通7号线王家墩东站深基坑管井降水的工程实例，进行了基坑降水的相关设计计算，同时运用天汉降水软件对地铁站深基坑降水进行模拟分析，然后将模拟计算结果同工程监测结果进行比较分析，从而验证降水设计方案模拟结果符合现场实际的监测结果。

本文的创新点及难点：

1. 渗透系数K是通过现场抽水试验用选定公式反算得到，从而进行接下来涌水量的计算。特别对于较长基坑可根据水文地质分期分段进行抽水试验，从而可以得到各期各段的渗透系数。
2. 本次通过三种规范公式先试算出基坑涌水量Q，其中不同公式算出结果差别会较大，通过结合王家墩实际水文地质情况，得到最合理的基坑涌水量值的大小。

（3）落底式地下连续墙对基坑降水影响很大，需要对坑内外分别进行抽水试验，从而得到坑内外不同渗透系数K，其中理论上落底式地连墙是不漏水入基坑的，但实际会有地下水从缝隙和墙底渗入坑内。对于本次基坑场地需要调整坑内外渗透系数的大小，分别进行天汉软件降水模拟。

（4）运用天汉降水软件对深基坑降水进行模拟计算分析，通过软件绘制的水位降幅图和周围地面沉降量图，讨论在基坑中降水井工作时，基坑内外水位降值的变化情况，基坑周围沉降量的变化趋势情况，再分析降水结果是否满足降水设计要求，以及得到了沉降的相关处理措施。

（5）基于王家墩东站基坑降水设计，进行了降水井的数量和布置方式的讨论，其中降水井数量涉及降水优化问题，布置方式是讨论出合理的降水井布置，其中分析过程也是通过天汉软件进行的。本次降水设计还重点考虑了基坑分段开挖时需要分段降水，而此时基坑边界条件会发生改变，同时要考虑坑内降水区和未降水区的相互影响。此时天汉降水软件分析时，需要对坑内外渗透系数稍作调整，通过模拟出的降水效果图分析分段降水效果。

关键词：深基坑降水 降水井 布置方式 分段降水 模拟

Abstract

With the recent years, the depth of excavation area and the depth of excavation of urban subway stations are increasing. Under the background of this situation, the construction of subway deep foundation pit will inevitably encounter precipitation problem. Precipitation of subway deep foundation pit construction safety accidents, not only will cause significant economic losses, but also cause adverse social impact and delay the entire project duration. Therefore, how effective precipitation in subway station construction has become an important subject of deep foundation pit engineering.

In this paper, the basic concept of deep well dewatering in deep foundation pit of subway station is expounded, and the purpose and current research status of deep foundation pit precipitation are analyzed. Then, the design method of deep well drainage in deep foundation pit is summed up and analyzed, and the relevant design and calculation of the foundation pit is carried out with the engineering example of the deep foundation pit of Wangjiazun East Station of Wuhan Metro Line 7.At the same time, the precipitation of deep foundation pit in subway station is simulated by Tianhan precipitation software, and then the simulation results are compared with engineering monitoring results to verify that the simulation results of precipitation design are in line with the actual monitoring. And finally determine the precipitation design in line with the precipitation requirements.

The innovation and difficulty of this paper:

1. The permeability coefficient K is obtained by inversion of the selected formula by the on-site pumping test, so that the next gushing water is calculated. Especially for the longer foundation pit can be divided according to the hydrogeological section of the pumping test, which can be obtained for each period of the permeability coefficient.
2. In this paper, the water quality Q of the foundation pit is calculated by the three normative formulas. The difference between the different formulas will be larger. By combining the actual hydrogeological condition of Wangjiadun, the most reasonable foundation pit water is worth.
3. The subduction-type underground continuous wall has a great influence on the foundation pit, and it is necessary to carry out the pumping test respectively inside and outside the pit, and obtain the different permeability coefficients K.Which is theoretically down the wall is not leaking into the pit, but the actual groundwater from the gap into the pit. For this foundation pit site need to adjust the permeability coefficient inside and outside the pit size, the days of software precipitation simulation.
4. The precipitation analysis of deep foundation pit was carried out by using the precipitation technique of Tianhan, the water level drop map and the surrounding ground subsidence plotted by software.In this paper, the change of water level in the foundation pit and the change trend of the settlement around the foundation pit are discussed. The results of the precipitation meet the requirements of the precipitation design and the relevant treatment measures.
5. Based on the design of the foundation pit of Wangjiadun East Station, the number and arrangement of the discharge wells are discussed. The number of the wells is related to the optimization of the precipitation. The layout is to discuss the reasonable layout of the wells, and the analysis process is through the Tianhan software ongoing.The present design also takes into account the need for subgrade precipitation in the excavation of the foundation pit, and the boundary conditions of the foundation pit will change at the same time, and the interaction between the precipitation area and the non-precipitation area will be considered. At this time, the analysis of precipitation in the Han and Han Dynasties requires a slight adjustment of the permeability coefficient inside and outside the pit and the analysis of the precipitation by simulated precipitation

Key Words：Deep foundation pit precipitation; precipitation wells; layout method; section precipitation; simulation.

目录

第1章 绪论 1

1.1 概述 1

1.2 基坑地下水控制主要方法 1

1.2.1 明沟、盲沟排水 1

1.2.2 降水 2

1.2.3 截水与回灌 3

1.3 深基坑深井降水目前的研究现状 3