【作者】 姚志勇；

【导师】 程谦恭；

【作者基本信息】 西南交通大学 ， 地质工程， 2010， 硕士

【摘要】 桩-网复合地基处理软土具有施工速度快,对周围环境扰动小,工后不均匀沉降较小,且大部分沉降发生在施工期等特点,是一种有效的深厚软土地基处理形式。因此近年来在国内外获得广泛应用,目前已应用于高速公路基础处理、桥头跳车处理、铁路软基、油罐基础及工民建等。本文基于潮汕车站地区深厚软土的地基处理,采用统计分析、数值模拟的方法,研究潮汕软土的工程特性以及软土在无加固情况下变形规律、桩网复合地基的作用机理和沉降规律等。主要研究内容和成果如下：(1)对国内外桩网复合地基理论研究现状进行了总结,分析了桩网复合地基的组成及其机理。(2)基于潮汕车站地区典型地段软土的工程勘察资料,对其物理力学特性进行了详细的阐述,分析了潮汕地区软土的“三高三低”工程特性。(3)根据潮汕车站DK205+870断面路堤的特性,运用数值软件FLAC3D进行了不同模型下桩网复合结构荷载传递规律和沉降规律的分析。分析发现：①软土沉降量随填土高度的增加而增大。最大沉降发生在路基中心表层,最大侧向位移发生在坡脚下1Om处。②随着桩间距的增加,桩身轴力、桩侧摩阻力及负摩阻力影响深度都随之增大。桩帽对桩身轴力及桩侧摩阻力影响深度有限,超过一定深度,有无桩帽模型曲线基本重合。桩间距的减小和桩帽的设置能够减小地基面桩间土沉降。(4)针对国内尚无关于桩网复合地基设计规范,总结了国外关于桩网复合地基设计方法。更多还原

【Abstract】 Pile-net composite foundation is a method to improve the behavior of deep soft soil, and has been used broadly in highway embankment, railway embankment, and industral and civil construction recently.In this paper, based on the wide deep soft soil treatment project of the ChaoShan railway station area, statistical analysis and numerical simulation were used to study the engineering properties of soft soil, the deformation rules of non-supporting model, the action mechanism and deformation rules of the pile-net composite foundation, and so on. The main contents and results are as follows:(1) The previous methods dealing with pile-net composite foundation are outlined. The composition and mechanism of the pile-net composite foundation are summed up.(2) Base on the analysis of the physical and mechanical parameters of the ChaoShan deep soft soil, the following characteristics have been found:high water content, high void ratio, and high compressiblity, as well as low intensity, low permeability and low bearing capacity.(3) According to the characteristics of the embankment section DK205+870 of Chaoshan station, the pile-net composite foundation settlement rules and load transfer law of different models were studied using the numerical simulation software FLAC3D. It is concluded that:①the settlement of foundation distributes in bubble shape, and increases with the filling height increasing. The maximum settlement occurs at the center of the roadbed surface, and the maximum lateral displacement occurs at the place which is 10m lower than the toe.②The influence depth of axial force, skin friction, and negative skin friction increase with the pile spacing increasing. The influence of pile cap to axial force and skin friction is limited, presenting the law that, more than a certain depth, whether there is pile cap, the model curves will coincide. Reducing pile spacing and setting pile cap can reduce the settlement of soil among pile foundation.(4) Finally, the design methods for pile-net composite foundation are summed up.更多还原