利用夯击地面变形估算夯后地基沉降及夯后地基性状的研究

发布时间：2018-05-26 08:44

本文选题：强夯法 + 地面变形　；参考：《江西理工大学》2013年硕士论文

【摘要】：工程实践表明,强夯法具有施工简单、加固效果好、使用经济等优点,因而被各国工程界所重视。但是,迄今为止,强夯的设计方法仍处于高度经验和定性的初级阶段。开展地面变形规律的研究对完善强夯设计理论、提高应用水平有着重要意义。夯后地基性状及夯后地基在特定工程荷载下的沉降是强夯设计的控制指标之一。在沉降控制方面,现行方法通常是以强夯后土体应达到的压缩模量值作为控制指标。由于强夯时地基经历了沿深度方向的压密,常处于不同程度的超固结状态,因此,夯后土的压缩模量只能在夯后通过检测来获取,是否达到要求也只能通过不同能量的试夯来确定,或采用偏于安全的方法来估测；而且由于加固效果随深度变化,用载荷试验确定的压缩模量并不具完全的代表性。另一方面,夯后地基的性状及夯后地基在工程荷载作用下的沉降与夯前土质有关,也与强夯时产生的压密量：即与夯击时产生的地面变形有关。基于这一思路,本文主要通过收集前人工程实测资料及实验经验,运用统计学、简化理论分析等方法处理了室内模型试验、现场实测及数值模拟相关数据,总结了夯后地面变形的研究现状；在相对加固程度基础上,研究了夯后砂土静探阻力随深度变化的结果,给出了一种定量估算夯后地基加固程度的概化模式及方程；在前人总结的竖向位移分布结论基础上,进一步做了归一化拟合,得出更简化的竖向位移及应变计算方程,结合夯后应变与夯前土性参数的关系,给出了用地面变形估算夯后土性指标的方程,并用相应算例做了计算；最后根据文中建立的夯前地基沉降与夯击地面变形的关系,给出了用强夯地面变形估算夯后地基沉降的方法,并初步探讨了夯后地基的变形模量和承载力的计算方法,可用于施工控制。课题来自导师的国家自然科学基金基于地面变形的强夯加固计算方法研究项目中的部分内容,即基于地面变形观测成果的夯后地基沉降计算方法研究和基于地面变形的施工控制方法的研究。研究内容包括利用夯坑深度和场地平均夯沉量进行沉降计算和夯后性状评价。文章最后分别通过具体的算例及工程实例验证了所建方程及模型的可行性与实用性,结果表明夯后地基性状及夯后沉降估算方程的建立为夯前强夯设计及施工控制提供了一种可靠、有效、便捷的途径。
[Abstract]:The engineering practice shows that the dynamic compaction method has the advantages of simple construction, good reinforcement effect and economical use, so it has been attached importance to by the engineering circles all over the world. However, up to now, the design method of dynamic compaction is still in the initial stage of high experience and qualitative. It is of great significance to improve the design theory of dynamic compaction and improve the application level by studying the law of ground deformation. The behavior of the compacted foundation and the settlement of the compacted foundation under specific engineering loads are one of the control indexes for the design of dynamic compaction. In the aspect of settlement control, the current methods usually take the compression modulus value of the soil after dynamic compaction as the control index. The compression modulus of the compacted soil can only be obtained by testing after compaction, because the foundation is compacted along the depth direction and is often in the state of overconsolidation in varying degrees during dynamic compaction. Whether or not we can meet the requirements can only be determined by means of different energy test compaction, or can be estimated by the method of partial safety, and because the reinforcement effect varies with depth, the compression modulus determined by load test is not completely representative. On the other hand, the behavior of the compacted foundation and the settlement of the compacted foundation under engineering load are related to the soil quality before compaction, and also to the compaction amount produced by the dynamic compaction, that is, the deformation of the ground caused by the tamping. Based on this idea, this paper deals with the related data of indoor model test, field measurement and numerical simulation by collecting the data and experience of previous projects, using statistics, simplifying theoretical analysis and so on. This paper summarizes the research status of ground deformation after compaction, studies the variation of static detection resistance of sand soil with depth on the basis of the relative reinforcement degree, and gives a general model and equation for quantitatively estimating the consolidation degree of foundation after compaction. On the basis of the conclusion of vertical displacement distribution summarized by predecessors, a more simplified equation for calculating vertical displacement and strain is obtained, which combines the relationship between the strain after compaction and the parameters of soil property before compaction. The equation of estimating soil property index after tamping with ground deformation is given, and the corresponding calculation examples are given, and finally, according to the relation between foundation settlement and ground deformation before tamping, the relation between ground settlement and ground deformation before tamping is established. This paper presents a method for estimating the settlement of the ground after compaction with dynamic compaction ground deformation, and preliminarily discusses the calculation method of deformation modulus and bearing capacity of the foundation after compaction, which can be used for construction control. Some of the contents of the research project of the National Natural Science Foundation of China based on the deformation of the ground in the research project of the dynamic compaction reinforcement method based on the deformation of the ground, That is to say, the calculation method of ground settlement based on ground deformation observation results and the construction control method based on ground deformation are studied. The research includes the settlement calculation and the evaluation of post-compaction behavior by using the depth of the ramming pit and the average tamping volume of the site. Finally, the feasibility and practicability of the established equations and models are verified by concrete examples and engineering examples. The results show that the establishment of foundation property and settlement estimation equation after compaction provides a reliable, effective and convenient way for the design and construction control of dynamic compaction before compaction.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU472.31

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