论文总字数：69013字

摘 要

睿可电子科技有限公司江宁项目位于南京市江宁区秣陵街道紫金路与紫金二路的交汇处，基坑开挖面积约18447.98m²，支护周长约611m，2 层满堂地下车库，基坑开挖深度9.80~10.75m。 经勘察揭示，场地内土层主要有杂填土、粉质黏土、强风化闪长岩。场地地形平坦，各岩土层分布基本均匀，场地地下水为潜水层，潜水水位在地表以下1.0m处。

考虑基坑周边环境对支护结构变形的敏感性，本着“安全可靠，经济合理，技术可行，施工方便”的原则，基坑采用钻孔灌注桩的围护结构；水平向采用多道对撑、角撑结合边桁架的支撑体系，竖向采用临时钢立柱及柱下钻孔灌注桩作为水平支撑系统的竖向支承构件。整个平面布置简单、传力明确、受力合理。基坑四周钻孔灌注桩桩径为800mm，桩间距为1000mm。整个基坑由于土层基本为粉质黏土层，故不需要特别进行止、降水方案的设计，整个基坑采用坑内桩间挂网喷浆的方式止水，坑内集水明排的方式降水。

采用土压力极限平衡理论的朗肯土压力理论进行土压力计算：坑外迎土面的土压力取主动土压力，开挖面深度以下的土压力按三角形分布考虑，坑内开挖面以下背土面的土压力取被动土压力。对于地下水位以下的素填土、粉质黏土，采用水土合算的方法；对于地下水位以下的残积土、强风化闪长岩，采用水土分算的方法。

为了综合分析不同工况下支护结构的内力和变形情况，除手算外，还使用理正深基坑软件对基坑进行单元计算，使得设计更加合理与精确。

关键词: 深基坑 支护结构 排桩支护 钢筋混凝土内支撑

The Design of Deep Foundation Pit Support in the Fourth Affiliated Hospital of Nanjing Medical University

Abstract

Jiangning project of Ruike Electronic Technology Co., Ltd. is located at the intersection of Zijin road and Zijin Second Road, moling street, Jiangning District, Nanjing city. Project overview: The Jiangning project of Ruike Electronic Technology Co., Ltd. is located at the intersection of Zijin road and Zijin Second Road, moling street, Jiangning District, Nanjing city. The excavation area of the foundation pit is about 18447.98m2, the perimeter of the support is about 611m, and the excavation depth of the foundation pit is 9.80-10.75m. According to the survey, the soil layer in the site mainly includes miscellaneous fill, silty clay and strongly weathered diorite. The terrain of the site is flat, and the distribution of each rock and soil layer is basically uniform. The groundwater of the site is the phreatic layer, and the phreatic water level is 1.0m below the surface.

Considering the sensitivity of the surrounding environment of the foundation pit to the deformation of the supporting structure, and based on the principle of "safe and reliable, economic and reasonable, technically feasible, and convenient for construction", the foundation pit adopts the retaining structure of bored pile; the internal support system adopts the support system of multi-channel opposite support, angle support and side truss horizontally. The temporary steel column and bored pile under the column are used as the vertical support components of the horizontal support system. The whole plane layout is simple, the force transmission is clear and the stress is reasonable. The diameter of bored pile around the foundation pit is 800mm, and the spacing between piles is 1000mm. Because the soil layer of the whole foundation pit is basically silty clay layer, there is no need to carry out the design of stopping and dewatering.

The Rankine earth pressure theory of the earth pressure limit equilibrium theory is adopted for the earth pressure calculation: the earth pressure on the earth facing surface outside the pit is the active earth pressure, the earth pressure below the depth of the excavation surface is considered as a triangular distribution, and the earth pressure on the back surface below the excavation surface inside the pit is the passive earth pressure. For plain fill and silty clay below the groundwater level, the method of water and soil calculation shall be adopted; for residual soil and strongly weathered diorite below the groundwater level, the method of water and soil calculation shall be adopted.

In order to comprehensively analyze the internal force and deformation of the supporting structure under different working conditions, in addition to the manual calculation, the straightening deep foundation pit software is also used to carry out the unit calculation of the foundation pit, making the design more reasonable and accurate.

Key Words: Deep excavation project; Supporting structure design; Row pile support; Reinforced concrete internal support.

摘 要 II

Abstract III

第一章 设计方案综合说明 1

1.1 工程概况 1

1.1.1 基本概况 1

1.1.2 项目概况 1

1.1.3 场地周边环境条件 1

1.1.4 工程地质条件 1

1.1.5 水文地质条件 3

1.1.6 基坑支护设计参数 3

1.2 设计总说明 4

1.2.1 设计依据 4

1.2.2 设计原则 4

1.2.3 支护设计方案 5

1.2.4 计算工况 6

1.2.5 主要计算结果 7

1.2.6 设计成果 7

1.3 基坑及支护结构的监测 8

1.3.1 基坑及支护结构监测内容 8

1.3.2 基坑及支护结构监测要求 9

1.3.3 基坑监测警戒值 9

第二章 支护结构设计计算 10

2.1 设计计算 10

2.1.1 计算区段的划分 10

2.1.2 土压力系数计算 11

2.1.3 土压力计算 11

2.2 AB段支护结构计算 12

2.2.1 支撑轴力计算 13

2.2.2 嵌固深度及桩长计算 15

2.2.4 桩体内最大弯矩计算 16

2.3 AD段支护结构计算 18

2.3.1 支撑轴力计算 18

2.3.2 嵌固深度及桩长计算 21

2.3.3 桩体内最大弯矩计算 21

2.4 CD段支护结构计算 23

2.4.2 嵌固深度及桩长计算 26

2.4.3 桩体内最大弯矩计算 26

2.5 支护桩配筋 28

2.5.1 AB段支护桩配筋 28

2.5.2 AD段支护桩配筋 28

2.5.3 CD段支护桩配筋 29

第三章 支撑结构设计计算 31

3.1 冠梁计算 31

3.2 钢筋混凝土支撑设计计算 32

3.2.1 角撑计算 32

3.3 立柱及立柱桩设计计算 36

3.3.1 立柱计算 36

3.3.2 立柱桩验算 37

第四章 基坑止降水设计 38

4.1 基坑止水设计 38

4.2 基坑降水设计 38

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