原料厂软土地基堆载预压中的计算与优化设计

发布时间：2018-06-14 06:36

本文选题：软土地基 + 堆载预压　；参考：《武汉轻工大学》2013年硕士论文

【摘要】：在我国的广大地区都分布着软土，其具有天然含水率高、天然空隙比大、渗透系数小、压缩系数高、抗剪强度低等特点。工程建设中经常会遇到软土地基，天然的软土地基往往不能满足建筑物对地基的承载能力越来越高的要求，一些软弱地基或特殊土地基在完成地基处理之后才可使用。从上世纪五十年代国内外开始运用堆载预压的方法加固软土地基，堆载预压法可以说是伴随着土力学一起发展的。早期在提出了太沙基固结理论后，土力学发展史上迎来了一个重要里程碑时刻，此后就开始广泛的运用在实际工程中。后来由于Biot固结理论的提出及计算机技术的快速发展，有限单元法等一些数值计算方法的引入，使得堆载预压加固软土地基土的技术得到了很大的发展。本文首先对堆载预压法的相关内容进行了简单的介绍，并对太沙基、Biot固结理论以及在Biot固结理论中常用的几种本构模型进行了回顾。然后总结分析了三种主要的抗剪强度理论。并根据魏西克(Vesic)圆柱孔扩张理论，将饱和软黏土当作一种Tresca弹塑性材料，参考挤土桩法在软土中所产生的弹塑性扩张应力解答为例，分别根据挤土过程中在塑性区和弹性区不同的应力解析表达式，推导得出挤土过后地基土的应力增长表达式，定量分析了挤土对地基土抗剪强度增长的影响，，考虑挤土效应对地基稳定性的影响并进行了计算分析。最后结合某工程中原料厂采用堆载预压的方法对软土地基加固进行研究。堆载容易引起堆载范围内软土较大的沉降和水平侧移，从而改变了邻近建筑物地基土体的应力状态，使邻近建筑物地基发生破坏。文中对堆载预压使可能会对邻近堆取料机轨道地基产生破坏的问题进行分析和解决。运用数值计算的方法模拟堆载预压处理原料厂软土地基的过程并进行分析和计算，提出了设置应力隔离桩的改进方法对原设计进行优化。
[Abstract]:Soft soil is distributed in the vast areas of our country. It has the characteristics of high natural moisture content, large natural void ratio, small permeability coefficient, high compression coefficient and low shear strength. Soft soil foundation is often encountered in engineering construction. Natural soft soil foundation often can not meet the requirement of higher and higher bearing capacity of building. Some soft foundation or special soil foundation can be used only after the foundation treatment is completed. Since 1950s, the method of surcharge preloading has been used to reinforce soft soil foundation, and the surcharge preloading method can be said to be developed along with soil mechanics. After putting forward the theory of Terzaghi consolidation in the early stage, the history of soil mechanics ushered in an important milestone moment, and then it began to be widely used in practical engineering. Later, due to the development of Biot consolidation theory and the rapid development of computer technology, and the introduction of some numerical methods such as finite element method, the technology of surcharge preloading to reinforce soft soil foundation has been greatly developed. In this paper, the relative contents of surcharge preloading method are briefly introduced, and the consolidation theory and several constitutive models commonly used in Biot consolidation theory are reviewed. Then three main shear strength theories are summarized and analyzed. The saturated soft clay is regarded as a Tresca elastoplastic material according to the theory of Vesic's expansion of cylindrical holes, and the solution of the elastoplastic expansion stress produced by the compaction pile method in the soft soil is taken as an example. According to the different analytical expressions of stress in plastic zone and elastic zone during soil compaction, the stress growth expression of foundation soil after compaction is derived, and the influence of compaction on the increase of shear strength of foundation soil is analyzed quantitatively. The effect of compaction on the stability of foundation is considered and calculated. Finally, the reinforcement of soft soil foundation is studied by the method of surcharge preloading in a raw material factory. It is easy to cause large settlement and horizontal lateral displacement of soft soil in the range of heap-loading, thus changing the stress state of the foundation soil of adjacent buildings and causing damage to the foundation of adjacent buildings. This paper analyzes and resolves the problem that the pile load preloading may cause damage to the track foundation of the adjacent heap-extractor. The numerical method is used to simulate, analyze and calculate the process of surcharge preloading treatment of soft soil foundation in raw material plant, and an improved method of setting stress isolation pile is put forward to optimize the original design.
【学位授予单位】：武汉轻工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU472.33

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