广州南沙港区真空预压加固饱和吹填土试验研究及数值仿真

发布时间：2018-05-26 00:20

本文选题：分级真空排水预压法 + 塑料排水板　；参考：《重庆交通大学》2014年硕士论文

【摘要】：关于真空排水预压加固软土地基的方法，现在的研究颇多，，对真空排水预压的加固机理和设计计算以及施工都有相关的规范出版了，但是关于真空排水预压法的研究脚步还在继续前进。学者们为了找到更加完善的真空排水预压方法不懈努力。真空排水预压法加固软土地基还有许多问题需要深入研究，比如影响真空排水预压法加固过程中出水量的因素以及解决办法等。鉴于此，本文主要通过室内模型试验对影响真空排水预压法加固过程中出水量的因素之一（塑料排水板的包裹滤膜）进行研究，研究表明：（1）从真空排水预压法的应力路径方面看，一次性加荷方式的真空排水预压法适用于渗透系数较大的土体；而分级加荷的真空排水预压法对渗透系数较小的土体（如粘土）更加有效。（2）分级真空排水预压法加固新近饱和吹填土模型试验表明，真空度随着深度的增加而逐渐减小，与一次性加载的真空排水预压法具有相同的规律。（3）根据分级真空排水预压法加固新近饱和吹填土模型试验过程中出水量、真空度、孔隙水压力、泥面沉降量的监测可以得知采用尼龙网100目作为排水板包裹滤膜获得的加固效果最好。真空排水预压分级加载的荷载等级应该是20KPa，40KPa，60KPa，80KPa。以这种等级加载，应该能使土体的排水量更加大，土体含水率更加的低，加固完成后应该能够获得更加好的加固效果。（4）通过分级真空排水预压法加固新近饱和吹填土的室内模型试验，综合分析可知，采用100目尼龙网作为塑料排水板包裹滤膜的加固效果比采用150目的尼龙网和200目的尼龙网作为塑料排水板包裹滤膜的加固效果要好，所以本文建议在实际工程中能够采用100目尼龙网作为塑料排水板的包裹滤膜。（5）通过分级真空排水预压法的室内模型试验，采用新型排水体（在砂袋内部插入塑料排水板作为竖向排水通道）进行加固，获得了很好的加固效果，可以进行现场试验进行验证。（6）通过大型有限元软件abaqus对真空排水预压法加固砂井地基进行模拟，根据模拟后的砂井地基平均固结度和砂井地基孔隙水压力消散可以得出，采用100目尼龙网作为包裹滤膜的地基平均固结度要大，并且其固结度增长速率和孔隙水压力消散速率较快。与室内模型试验相比较具有相同的结论。
[Abstract]:There is a lot of research on the method of strengthening soft soil foundation by vacuum drainage preloading, and some related codes have been published for the reinforcement mechanism, design calculation and construction of vacuum drainage preloading. But the research on vacuum drainage preloading is still advancing. Scholars make unremitting efforts to find more perfect vacuum drainage preloading method. There are still many problems to be studied in the consolidation of soft soil foundation by vacuum drainage preloading method, such as the factors that affect the water output in the process of strengthening by vacuum drainage preloading method and the solutions, and so on. In view of this, this paper mainly through the indoor model test to study one of the factors that affect the water output in the consolidation process of vacuum drainage preloading method (plastic drainage plate coated filter membrane), the study shows that: 1) from the point of view of stress path of vacuum drainage preloading method, vacuum drainage preloading method with one-off loading method is suitable for soil with large permeability coefficient; The vacuum drainage preloading method with graded loading is more effective for the soil with small permeability coefficient (such as clay). (2) the model tests on the consolidation of newly saturated filled soil by the staged vacuum drainage preloading method show that the vacuum degree decreases gradually with the increase of the depth, which has the same rule as the vacuum drainage preloading method. According to the method of graded vacuum drainage preloading, the water output, vacuum degree, pore water pressure during the model test of newly saturated filled soil are strengthened. Monitoring the settlement of mud surface shows that the best reinforcement effect is obtained by using Nylon mesh 100 mesh as the filter membrane wrapped with drainage board. The loading grade of vacuum drainage preloading grade should be 20 KPA 40 KPA or 60 KPA / 80 KPA. With this grade loading, the displacement of soil should be increased, the moisture content of soil should be lower, and the reinforcement effect should be better. (4) the indoor model test on the consolidation of newly saturated filled soil by the method of graded vacuum drainage preloading, and the comprehensive analysis shows that, The reinforcement effect of 100 mesh nylon mesh as plastic drainage plate wrapped filter membrane is better than that of 150 purpose nylon net and 200 purpose nylon net as plastic drainage board wrapped filter membrane. Therefore, it is suggested that 100 mesh nylon mesh can be used as the wrapping membrane of plastic drainage board in practical engineering. 5) through the indoor model test of the graded vacuum drainage preloading method, a new type of drainage body (plastic drainage board is inserted into the sand bag as a vertical drainage passage) is used to reinforce it, and a very good reinforcement effect is obtained. It can be verified by field test. (6) the consolidation of sand well foundation by vacuum drainage preloading method is simulated by finite element software abaqus. According to the average consolidation degree of sand well foundation and pore water pressure dissipation of sand well foundation after simulation, it can be obtained. The average consolidation degree of the foundation with 100 mesh nylon mesh as the encapsulated membrane is large, and the increase rate of consolidation degree and the dissipation rate of pore water pressure are faster. The conclusion is the same as that of indoor model test.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU472.33

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