摘要在经济的发展和人们对居住环境要求不断提高的前条件下，近年来，我国建筑行业得到飞速的发展。在城市中，地价很昂贵。因此，在建筑物向高度方向发展的同时，地下空间也成为了一个重要的发展方向。许多工程施工都会面临深基坑的问题，例如：高层及多层建筑的地下室，地下商场，地铁车站等。50800

基坑工程具有如下特点，如不可预见的因素多，工程量大，技术难度高。并且其安全可靠性受周边的环境影响。因此必须选择合适的支护方案。

在本次设计中对-8.00m深基坑选择了钻孔灌注桩+内支撑的支护体系，并采用深层搅拌桩止水，对桩及支撑的几何参数进行了设计和计算，并进行基坑稳定性的分析验算。

此外之外，考虑到地下水对施工的影响，还需选择合理的降水工艺。本工程采用轻型井点降水法来降低地下水位。

毕业论文关键词： 基坑 钻孔灌注桩 支护 降水

Abstract China's construction industry has reached rapid development under the condition of the economic development and the increasingly becoming higher and higher people’s requirements for living environments in recent years. And the price of ground is very expensive in the cities. And therefore，when the development of the building is towards to higher stories，the underground space has also become an important development direction. There are lots of constructions of the engineering will face the problem of deep foundation pit projects，such as underground shopping malls,，High-level and multi-storey building in the basement, underground garage and subway station and so on.

Foundation pit projects have some following features, such as many unforeseen factors, the large work quantity and the technical difficulty, so the surrounding environment will be affected by its security and reliability. Therefore we have to select the appropriate support scheme.

In this design, which the pit is -8.00 m deep, we take the bored piles and inner support system. We take the deep mixing pile in order to stop water 。We design and calculate the geometric parameters of the pile and anchor, analysis and check the pit stability.

In addition to this，considering the impact of underground water in the construction, we need to select a reasonable choice for the precipitation process. This engineering takes use of the light well point precipitation method to reduce the level of groundwater.

Keywords：pit   bored  piles  precipitation  support 

 目 录

第一章 绪论 1

1.1 概述 1

1.2 现状 1

1.3 基坑支护类型及其选择 2

1.4 优点及其不足 5

第二章 基坑支护设计综合说明 6

2.1工程概况 6

2.1.1结构概况 6

2.1.2基坑周边环境 6

2.2工程地质概况 6

2.2.1地形地貌 7

2.2.2工程地质条件 7

2.2.3水文地质条件 7

2.2.4基坑支护设计各层土层参数 8

2.3基坑支护的选型依据---- 8

2.4 方案选定 9

第三章 基坑支护方案选择 11

3.1设计依据 11