摘 要

我国滨海地区走在改革开放的前沿，滨海地区的建设对于完善我国沿海的经济布局，扩大对外贸易，改善国家经济结构有着非常重要的战略意义。高速公路的建设情况可以体现出国家和地区的交通发展水平，甚至可以反映出经济的整体状况。在滨海地区，软土地基会对高速公路的建设造成极大的不良影响，为了避免这些影响，必须对软土地基进行加固处理。软土地基主要的处理方法有置换法、排水固结法、化学加固法、碾压法和夯实法等。这些软土地基的处理方法极大地推动了我国滨海地区高速公路事业的发展，因此对滨海地区软土地基的处理效果进行研究与评价具有非常重要的意义。

本文总结了软土的性质与特点，归纳了各类软土地基处理技术的国内外研究概况，并以滨海地区高速公路某路段为工程背景，采用有限元分析软件对滨海地区软土地基的处理进行了有限元模拟分析，比较了CFG桩复合地基和水泥土搅拌桩复合地基的处理效果。之后对CFG桩复合地基的加固效果进行深入研究，分析了CFG桩的桩间距、桩长、桩土模量比和垫层模量等因素对CFG桩加固效果的影响。

本文并不仅描述了软土地基处理的各种方法，还在结合许多学者研究成果的基础上对规律进行了探究，通过对数据的分析和处理，找出了桩体、土体的几何、物理参数变化对桩土应力影响的一般规律。

关键词：软土地基;水泥土搅拌桩;CFG桩;复合地基;有限元分析

Evaluation of Foundation Treatment Effect in Coastal Soft Soil Area

ABSTRACT

China's coastal areas are at the forefront of reform and opening up. The construction of coastal areas is of great strategic significance for improving the economic layout of China's coastal areas, expanding foreign trade, and improving the national economic structure. The construction of expressways can reflect the level of traffic development in the country and the region, and even reflect the overall state of the economy. In the coastal area, the soft soil foundation will have a great adverse effect on the construction of the expressway. In order to avoid these effects, the soft soil foundation must be reinforced. The main treatment methods for soft soil foundation include displacement method, drainage consolidation method, chemical strengthening method, rolling method and tamping method. These soft soil foundation treatment methods have greatly promoted the development of expressway industry in China's coastal areas. Therefore, it is of great significance to study and evaluate the treatment effect of soft soil foundation in coastal areas.

This paper summarizes the nature and characteristics of soft soil, summarizes the research situation of various soft soil foundation treatment technologies at home and abroad, and uses the finite element analysis software to deal with the soft soil foundation in coastal area. The finite element simulation analysis was carried out to compare the treatment effects of CFG pile composite foundation and cement-soil mixing pile composite foundation. Afterwards, the reinforcement effect of CFG pile composite foundation is studied in depth. The effects of pile spacing, pile length, pile-soil modulus ratio and cushion modulus on the reinforcement effect of CFG piles are analyzed.

This paper not only describes the various methods of soft soil foundation treatment, but also explores the law based on the research results of many scholars. Through the analysis and processing of the data, the geometry and physics of the pile and soil are found out. The general rule of the influence of parameter changes on pile-soil stress.

Key words: soft soil foundation; cement-soil mixing pile; CFG pile; composite foundation; finite element analysis

目 录

1 绪论……………………………………………………………………………………………………………1

1.1 研究背景……………………………………………………….....……………………………………1

1.2 软土的特性…………………………………………….………………………………………………1

1.2.1 软土的概念…………………………………….………………………………………………1

1.2.2 软土的物理性质……………………………….………………………………………………2

1.2.3 软土的蠕变性质……………………………….………………………………………………2

1.3 地基处理方法的研究现状…………………………….………………………………………………3

1.3.1 地基处理方法概述…………………………….………………………………………………3

1.3.2 复合地基技术………………………………….………………………………………………4

1.3.3 板桩结构体系理论…………………………….………………………………………………6

1.4 地基沉降的研究现状………………………………….………………………………………………7

1.5 本文主要的研究内容………………………………….………………………………………………9

1.5.1 存在的问题及不足…………………………….………………………………………………9

1.5.2 主要研究内容…………………………………...……………………………………………10

2 滨海地区处理公路软土地基效果分析………………………..……………………………………………11

2.1 工程背景…………………………………………………...…………………………………………11

2.1.1 工程地质概况…………………………………………………………………………………11

2.1.2 工程地质条件…………………………………………………………………………………11

2.1.3 水文地质条件…………………………………………………………………………………13

2.2 有限元仿真分析技术的说明………………………………...………………………………………13

2.3 水泥土搅拌桩复合地基的有限元模拟………………………...……………………………………13

2.3.1 建立几何模型…………………………………………………………………………………13

2.3.2 计算结果输出…………………………………………………………………………………15

2.4 CFG桩复合地基有限元模拟……………………………………..…………………………………19

2.4.1 建立几何模型…………………………………………………………………………………19

2.4.2 计算结果输出…………………………………………………………………………………21

2.5 小结…………………………………………………………………...………………………………26

3 CFG桩复合地基的加固效果研究……………………………………………...……………………………27

3.1 桩间距变化分析…………………………………………………………...…………………………27

3.1.1 CFG桩的物理力学性质变化分析…………….………………………………………………28