【作者】 马君伟；

【导师】 马崇武； 慕青松；

【作者基本信息】 兰州大学 ， 工程力学， 2007， 硕士

【摘要】 本文通过碎石桩实验来研究碎石桩在复合地基中的传力特性，运用颗粒物质静力学的有关知识对实验结果进行分析，并建立了碎石桩传力方式的二维模型。本小组运用自行设计的实验装置进行一系列室内试验，首次将颗粒物质静力学的相关理论与碎石桩研究相结合，通过测得桩底部压强随顶部荷载增加的变化规律来研究碎石桩的传力特性和破坏模式。从单桩的实验结果分析得出桩长是影响碎石桩传力方式的一个重要因素，桩长是否超过临界桩长是判断碎石桩传力方式的标准。同时，在不同的传力方式下，碎石桩将发生不同的破坏模式。从多桩的实验结果分析得到多桩的相互作用能够有效地减小临界桩长，使多桩中拱结构及早的形成，且更稳定。多桩的相互作用同样对底部压强产生影响，并且在不同的传力方式下，影响也不同。基于Janssen经典的“谷仓效应”理论，提出了碎石桩的二维模型，能够定性地反映单桩桩长超过临界桩长时底部压强的变化规律，但该模型不适用于桩长未达到临界桩长的情况，还需进一步进行研究。在论文的最后对碎石桩处理地基的实际工程提出了几点建议，希望能够对碎石桩复合地基的设计和施工有所帮助。更多还原

【Abstract】 This thesis studies the characters of the stress transferring in stone column composite foundation through experiments. Then the experiment results are analyzed by using the theory of mechanics of granular media. Finally, a 2-D model which describes the characters of the stress transferring in stone column composite foundation is built.We design the experiment equipments by ourselves, and carry out a series of experiments in laboratory. We combine the stone column research with the mechanics theory of granular media and study the character and failure model of stone column by measuring the pressure on the bottom of stone columns.By analyzing the experiment results of single column, we could get that the column length is one of the important factors which influence the stress transferring mode. Whether the length exceeds the critical length or not is the standard that differentiates the stress transferring modes. It also shows that the failure models are different in different stress transferring modes. The experiment results of multi-column show that the columns affect each other, which can minimize the critical length effectively and advance the arch structure’s formation. The arch structure in multi-column is more stable than that in single column. Also, the effect among columns will affect the bottom pressure and the influence will be different corresponding to the different stress transferring modes.Based on the theory of "granary effect" by Janssen, we build a 2-D model about the character of the stress transferring in stone column composite foundation. Our 2-D model can describe the transformation of the pressure on the bottom of single stone column when the length exceeds critical length. But it doesn’t suit the case when the length is shorter than critical length. Therefore, we need to do more research on this.At the end of this thesis, we offer some advices for engineering practices to assist stone column composite foundation design and construction.更多还原