CFG桩处治饱和尾矿砂地基模型试验研究

发布时间：2018-05-24 10:21

本文选题：复合地基 + CFG桩　；参考：《长安大学》2014年硕士论文

【摘要】：CFG桩复合地基作为地基处理的主要手段之一，已经得到越来越广泛的应用。目前刚性基础下CFG桩复合地基已形成了相对完整的理论体系和设计方法，而柔性基础下CFG桩复合地基的理论分析和设计方法尚不成熟，尤其在尾矿库这种特殊地基上的处治技术在我国还处于空白阶段，因此有必要开展CFG桩处治饱和尾矿砂地基的沉降、承载力及孔隙水压力等特性的研究。本文通过对尾矿砂进行一系列基本物理实验，研究其基本物理性质，同时利用相似模型理论，依托现场工况开展CFG桩处理饱和尾矿砂地基的室内模型试验，在饱和尾矿砂中埋设位移计、孔隙水压力计、土压力盒等，，以便探索在上部加载变化的情况下，CFG桩复合地基的沉降、孔隙水压力、桩间土压力和桩顶压力的变化规律。试验结果表明，当CFG复合地基施加上部荷载时，在短时间内产生较大沉降变形，但随着时间的推移，桩的承载能力发挥出来，地基沉降量的变化不再显著，最终维持在一个较稳定的状态。在承受上部荷载的时候，土体中间位置相较于其他位置沉降更大。CFG复合地基的孔隙水压力随着深度的增加呈现出增大的趋势，但其变化幅度随着深度增加逐渐变缓，土体中心处的孔隙水压力随时间的变化较平稳。排水会导致孔隙水压力急剧下降并最终稳定。在分级荷载条件下复合地基模型的桩顶压力和桩底压力都随着上部荷载增加的不断增加，而桩间土的压力变化范围波动很大，缺乏规律性。加载过程中，桩土应力比持续上升，排水阶段对桩土应力比的影响显著，应力比值下降，说明桩间土承载力的增长幅度大于桩顶处。
[Abstract]:As one of the main methods of foundation treatment, CFG pile composite foundation has been used more and more widely. At present, CFG pile composite foundation under rigid foundation has formed a relatively complete theoretical system and design method, but the theoretical analysis and design method of CFG pile composite foundation under flexible foundation is still immature. Especially, the treatment technology of tailings reservoir is still in blank stage in our country, so it is necessary to study the settlement, bearing capacity and pore water pressure of saturated tailings foundation treated by CFG pile. In this paper, a series of basic physical experiments on tailings are carried out, and the basic physical properties of the tailings are studied. At the same time, by using the theory of similar model, the laboratory model tests of treating saturated tailings foundation with CFG piles are carried out under the field working conditions. Displacement gauge, pore water pressure gauge and earth pressure box are embedded in saturated tailings in order to explore the variation law of settlement, pore water pressure, soil pressure and top pressure of CFG pile composite foundation under the change of upper load. The experimental results show that when the upper load is applied on the CFG composite foundation, large settlement deformation occurs in a short period of time, but with the passage of time, the bearing capacity of the pile exerts its bearing capacity and the settlement of the foundation does not change significantly. Eventually, it is maintained in a more stable state. When bearing the upper load, the pore water pressure of the soil in the middle position is larger than that in the other places. The pore water pressure of the composite foundation increases with the increase of depth, but the variation range of the pore water pressure increases slowly with the increase of the depth. The pore water pressure in the center of soil is stable with time. Drainage can cause pore water pressure to drop sharply and eventually stabilize. Under the condition of graded load, the pile top pressure and pile bottom pressure of composite foundation model increase with the increase of upper load, but the variation range of soil pressure between piles fluctuates greatly and lacks regularity. During the loading process, the pile-soil stress ratio continues to increase, the drainage stage has a significant effect on the pile-soil stress ratio, and the stress ratio decreases, which indicates that the increasing range of soil bearing capacity between piles is greater than that of pile top.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1;U414.1

【参考文献】