【作者】 谷林涛；

【导师】 钱觉时； 殷永高；

【作者基本信息】 重庆大学 ， 材料学， 2002， 硕士

【摘要】 本论文采用实验室模拟试验与现场试验相结合的方法，系统研究粉煤灰-石灰-硫酸盐混凝土桩用于软土地基处理及其复合地基的主要性能，并从原材料、配合比、工艺等方面深入研究了各种因素的影响规律，通过化学分析和现代测试技术研究了粉煤灰-石灰-硫酸盐混凝土桩用于软土地基处理的加固机理，还针对粉煤灰-石灰-硫酸盐混凝土桩复合地基的特点给出了承载力的计算公式，最后通过实际工程应用展示了粉煤灰-石灰-硫酸盐混凝土桩用于软土地基处理的经济技术优势和社会环境效益。为了降低地下孔隙水含量，研究了粉煤灰-石灰-硫酸盐混凝土桩采用干料形态成型后吸水硬化的可行性与关键影响因素。分析了配合比、龄期及密实度对桩体强度的影响。由于粉煤灰-石灰-硫酸盐混凝土桩成型28天以后，其强度仍有较大的增长，因此结合具体工程条件可采用60天或90天龄期的抗压强度作为混凝土的强度判断依据。通过水化产物及长期力学性能的研究，发现粉煤灰-石灰-硫酸盐混凝土桩具有很好的耐久性，适用于软土地基的处理。桩体采用干料形态成型，密实度是影响桩体强度的关键，改善桩体密实度可以有效提高桩体的力学性质。现场研究采用了一种操作简单、移动方便、能耗低、体积小的施工设备，并给出了有关工艺参数，现场试验结果表明所采用设备和工艺工效高，特别适合于粉煤灰-石灰-硫酸盐混凝土桩的施工，有很广阔的工程应用前景。通过单桩静载荷原位试验和复合地基静载荷原位试验，显示了粉煤灰-石灰-硫酸盐混凝土桩的技术优势：不仅能有效发挥桩间土的承载力，同时自身强度较高，一般容易达到3MPa左右，而且粉煤灰-石灰-硫酸盐混凝土桩属于半刚性桩，使得桩与土的荷载分担比较均衡。桩体对地基除了有明显增强作用外，成型时的振动挤密与干料的吸水作用会使桩间土的物理力学性质得到明显改善，化学和微观分析还揭示桩体会游离出活性物质而对桩间土有化学加固作用，其化学作用随离桩距离的增大而逐渐减弱。相比于其他常用地基处理方法，粉煤灰-石灰-硫酸盐混凝土桩在施工过程中不仅对环境产生的污染较小，而且桩体材料可全部采用固体废渣，有非常明显的环境效益。更多还原

【Abstract】 It is investigated that the main properties of the concrete pile with FA(Fly Ash)-lime-sulfate system and its composite ground through al simulation experiment and site test. The influence of the raw material, mix proportion and technics were researched, and, the reinforce mechanism of FA-lime-sulfate concrete pile composition foundation is studied by chemistry analyzing and modern testing technology, and the calculating formula of bearing capacity of FA-lime-sulfate concrete pile composition foundation is provided. At last, the technological and economical superiority and society environment benefit of the FA-lime-sulfate pile are shown in the practical engineering. For reducing the water content of pore, the feasibility of drinking and cementing, and the key influence factors of drinking capability of FA-lime-sulfate system concrete pile molded in dry state are analyzed. Then the influence to the strength of mix proportion, period and density of pile are analyzed. Because the strength of the FA-lime-sulfate system still be developing after 28 days, it’s proposed that the 60 day’s or 90 day’s compressive strength can be used as the strength judgment standard. Based on the researching of hydration products and the long-term mechanics property, it’s discovered that the FA-lime-sulfate system has better duration property so as to be used in soft soil foundation treatment. When molding in dry state, it’s showed that the density is the main influence factor of the strength, which the mechanics property of pile can be increased by improving the density of pile.In the site investigation, we adopt a new machine to mold pile, which handling is easy, the moving is convenience, the power cost is low, bulk is small, and provided some relative technics parameter, The site result indicates that the work efficiency of such machine and technics is very high so as to fit to be used in FA-lime-sulfate concrete pile. Based on the single pile static load test and composite foundation static load test, the advantage of mechanics of FA-lime-sulfate concrete pile is shown, the pile is good to exert the mechanics of soil effectively. At the same time, it’s own strength is relatively high, commonly reach up to 3MPa, and FA-lime-sulfate pile is a half rigidity pile, so this make the pile-soil load participate be equilibria. When the pile possess reinforcment, it can improve the soil’s physics and mechanics property by the effect of extrusion-vibration and drinking. By chemistry and microcosmic analyzing, it’s recovered that the activity matter would dissociate out and<WP=6>have chemistry reinforce action to soil, and the effect is changed following the space to the pile. Compared with other foundation consolidation technic, the FA-lime-sulfate pile does less environmental pollution during construction, and its material can be composed of solid waste residue, so it has distinct environment benefit.更多还原