【作者】 于鹏；

【导师】 王建平；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2008， 硕士

【摘要】 疏桩基础是近年来提出并发展起来的一种新的桩基形式,它提出了用桩来补偿天然地基、改善天然地基的新构思。目前,疏桩基础在非饱和黄土地基中的应用与研究甚少。湿陷性黄土经过地基处理后有着比较高的承载特性。针对非饱和黄土地基开展疏桩基础的研究具有重要的理论意义和现实意义。论文对灰土挤密桩消除黄土湿陷性后疏桩基础的承载机理进行了较为系统的研究。首先从理论上分析了灰土挤密桩消除黄土湿陷性后疏桩基础的工作机理,然后通过对疏桩基础的三维非线性有限元分析,研究了疏桩基础中桩—土—承台相互作用机理、基础反力分布及分配规律和沉降变形特性。在此基础上讨论了疏桩率、桩基刚度和基础刚度变化时,对疏桩基础的承载特性和变形性状的影响。提出了针对疏桩基础运用不同疏桩率的“内强外弱”布桩方案,并将该方案与常规等距布桩方式作了比较。研究结果表明:疏桩基础可以有效地调匀桩顶反力,减小上部结构的次应力。疏桩基础较常规桩基础更能充分发挥单桩的极限承载力,使之达到桩土共同作用的目的,最大限度地发挥复合地基的承载力。研究成果为合理建立疏桩基础的沉降计算理论和设计方法提供理论依据,将促进疏桩基础在黄土地区的推广和应用。更多还原

【Abstract】 The sparse pile foundation is a new pile format which is put forward and developed in recent years. It brings forward a new idea that repairing and improving the natural foundation with piles. At present, the application and research of the sparse pile foundation is so little in unsaturated loess ground. Collapsible loess has good load-carrying properties after foundation treatment. The research of the sparse pile foundation in unsaturated loess ground is of momentous theoretical significance and current significance.The article has carried out comparatively systematic research on load mechanics about the sparse pile foundation which is eliminated collapsibility with lime-soil compaction pile. Firstly, it analyses the working mechanics of the sparse pile foundation theoretically. Then the article analyses the interaction mechanics of pile-soil-cushion cap, the distribution and rule of foundation reaction, the settling character in the sparse pile foundation through three-dimensional non-linearity finite element analysis. And it discusses the influence of load-bearing and deforming character for the sparse pile foundation, when the ratio of sparse piles and the stiffness of pile and foundation are changed. The article also puts forward a programme about "outside dispersed inside closed"with different range of piles for sparse pile foundation, and compares with normal equally spaced fashion for disposing piles. The results show that the sparse pile foundation can make the reaction of pile cap equably, reduce secondary stress of superstructure. The ultimate bearing capacity of pile can be fully exploited in the sparse pile foundation compared with normal pile foundation. The purpose of pile and soil interaction can be realized.And it can exploit the bearing capacity of composite foundation mostly.The research findings provide theoretical foundation for settlement calculation theory and design methodology for the sparse pile foundation, which can promote popularization and application for it in loess area.更多还原