【作者】 颜（山献）；

【导师】 韩选江；

【作者基本信息】 南京工业大学 ， 岩土工程， 2003， 硕士

【摘要】 水泥搅拌桩作为一种地基加固新技术，具有许多优点。随着大量基础工程的建造， 搅拌桩的应用也越来越广泛。但由于其理论研究方面结合实际的滞后和不重视对施工经 验的提炼，制约了搅拌桩在实际工程中更广泛的应用和加速发展。 本文将结合实际工程，在室内外试验的基础上，研究打桩后桩间土力学性状的变化 规律，提出更加合理的搅拌桩复合地基承载力计算方法，推导出单桩桩侧摩阻力的理论 计算公式以及有效桩长的理论计算公式，最后采用有限元方法对单桩以及群桩进行数值 分析。论文的具体内容如下： 1．水泥搅拌桩加固商住楼软弱地基的现场试验研究。在单桩，单桩复合地基以及 双桩复合地基载荷板下具有代表性的截面处埋设压力盒，测得复合地基在加载过程中 桩，土应力随荷载的变化情况。根据实测数据，全面深入地分析总结了搅拌桩复合地基 在加载过程中的固结变形特征，桩土应力比变化规律，搅拌桩单桩承载力与桩间土承载 力实际发挥情况等规律，为搅拌桩的应用和理论分析研究提供了可靠的依据。 2．视搅拌桩桩体为均质弹性介质，推导了复合地基中单桩有效桩长的理论计算公 式；根据王启铜柔性桩桩侧摩阻力计算公式，以桩侧土与桩体协调位移为前提推导了柔 性桩桩侧摩阻力的计算公式；以基底接触应力均匀分布，桩体、桩间土均质为前提，讨 论了桩，土协同工作原理，从而得出复合地基桩、土荷载－变形特性，以及桩、土应力 比计算公式；结合本次试验，通过计算加载时桩体与土体的荷载分担情况以及在极限状 态下桩土承载力发挥值，提出考虑群桩效应的搅拌桩复合地基承载力计算公式。 3．建立多种模型。基于桩土共同工作原理，建立桩土共同作用模型，用有限元软 件对双桩承台，四桩承台以及九桩承台复合地基进行了数值计算。研究桩长、桩距、桩 体模量以及置换率对单桩承载力、桩间土承载力发挥值以及桩土应力比的影响程度，并 将计算结果与实测结果相比较。 4．考虑桩、土协同工作，提出搅拌桩复合地基优化设计及建议。为实用时保证桩 体和桩间土体能同时达到极限承载力为前提，通过改变褥垫层厚度与弹性模量实现调节 桩体与桩间土体的应力分配，从而达到优化设计的目的。进而为搅拌桩复合地基设计与 施工提供了新思路，提高了搅拌桩复合地基的经济性。更多还原

【Abstract】 Deep Mixing Pile is a new technique of reinforcing foundation which has a lot of advantages. With the construction of numerous foundation projects, the application of Deep Mixing Pile is more extensive. However, being sluggish in the theory and unmature in the construction management, the application and development of Deep Mixing Pile is restrained. In this dissertation, based on experiments, the mechanical behaviors of the soil between piles are studied. A more reasonable method computing the bearing capacity is presented. Theoretical formula is derived to compute the lateral frictional resistance of single pile. Finally, the numerical analysis for single pile and group piles are done by with FEM. The main contents are as follows: 1.Field tests of the reinforced foundation of commence and living building with Deep Mixing Pile. In a practice project, field test is done. The laws of the deformation characteristics in consolidation and the stress-ratio of pile are summed up with the monitoring data. It provides reliable basis for the application and the theoretical research of Deep Mixing Pile. 2. On the premise that the materials of the piles are uniformity, the theoretical computing formula of the effect length of the single pile in composite foundation has been deduced. Based on the formula which is used to compute the lateral resistance of single pile deduced by Wang Qitong, a formula is setup whose precondition is that the pile and the lateral soil directly around the pile deform in-phase. On the basis of that the contact stress of the foundation is equal ,a formula that can be used to conform the stress-ratio of the composite ground is set up, on the same time, the principles of the deformation harmony of the soil and the piles in the composite ground are also discussed. Combining with results of this test, a formula which can calculate the bearing capacity that considering the effect of group piles of the composite ground is also deduced. 3．Build model .The model of the interaction between piles and soil is built based on the interaction between piles and soil, the program is written with Fortran90 language. The stress ratio and load-transfer and information are researched through 2 piles group, 4 piles group and 9 piles group. The relationship between mechanic characteristics of composite ground and the length, the distance, elasticity modulus and replacement percentage of piles are discussed. The results of computing analysis has been contrast to the experimental data. 4．Considering the conformity of piles and soil, present propositions that can optimize更多还原