筏板基础与刚—柔性桩复合地基共同作用分析

发布时间：2019-02-08 17:55

【摘要】：当天然地基承载力较差，无法满足建筑物的要求时，就必须对地基进行处理或采用桩基础来提高承载能力。通过增强或置换部分土体而形成的复合地基实现了由天然土体和增强体共同承担荷载，是一种较好的地基处理方式。随着地基处理技术的提高以及复合地基理论的发展，近年来出现了一种新型的复合地基形式，即刚-柔性桩复合地基。刚-柔性桩复合地基结合使用了刚性桩和柔性桩，再加上桩间土体的作用，共同来承受建筑物的荷载。土体相对较软，承载能力小，柔性桩可以补偿桩间土承载力的不足，提高原有土体的承载能力，刚性桩不仅对柔性桩起到护桩作用，，而且承受了较大的荷载并起到了控制沉降的作用。刚-柔性桩复合地基可以充分发挥各部分的承载能力以及减少工程造价，因而有着较强的应用前景。本文首先介绍了筏板基础下刚-柔性桩复合地基的组成以及各自的作用特点，讨论了荷载作用下桩、土的应力以及荷载分担情况，并比较分析了复合地基的复合模量的计算方法，进而求解沉降值。然后通过讨论筏板的分析模式、桩土的相互作用等关系，建立了筏板基础与复合地基共同作用的基本方程。为了研究在共同作用下各个组成部分参数对复合地基承载特性的影响，利用ANSYS有限元软件建立了筏板基础刚-柔性桩复合地基的模型进行计算分析。通过对比分析计算的结果数据，讨论各个参数对复合地基承载特性的影响程度，并据此探讨如何进行刚-柔性桩复合地基的优化设计分析。通过本文的研究工作得出，刚性桩模量对于沉降值影响不大但改变了应力分布；柔性桩模量的增大减少了差异沉降，可以改善各部分的荷载分担比；筏板基础模量对沉降及应力分布影响较小基本可以忽略，但其厚度增大提高了抗弯能力，减小了差异沉降；褥垫层的设置改善了应力的分布，其模量的提高减小了沉降但使刚性桩承担了更多荷载。在实际工程中可以利用这些规律，根据建筑物对承载力和沉降的要求，合理地采取布桩形式及选取参数，使这种复合地基得到更好的应用。
[Abstract]:When the natural foundation bearing capacity is poor and the requirements of the building cannot be met, the foundation shall be treated or the pile foundation shall be used to improve the bearing capacity. The composite foundation, which is formed by strengthening or replacing part of the soil, is a kind of good foundation treatment method to bear the load jointly by the natural soil body and the reinforcement. With the improvement of the foundation treatment technology and the development of the composite foundation theory, a new type of composite foundation, that is, the rigid-flexible pile composite foundation, has appeared in recent years. The rigid pile and the flexible pile are used in combination with the rigid-flexible pile composite foundation, and the action of the soil body between the piles is combined to bear the load of the building. The soil body is relatively soft and has small bearing capacity, and the flexible pile can compensate the deficiency of the bearing capacity of the soil between the piles, improve the bearing capacity of the original soil body, The composite foundation of the rigid-flexible pile can give full play to the bearing capacity of each part and reduce the project cost, so it has a strong application In this paper, the composition of the rigid-flexible pile composite foundation under the raft foundation and its function characteristics are introduced in this paper. The stress and load sharing of the pile and soil under the load are discussed, and the calculation method of the composite modulus of the composite foundation is also analyzed. The foundation of the raft and the foundation of the composite foundation are set up through the discussion of the analysis mode of the raft and the interaction of the pile and soil. In order to study the effect of various component parameters on the characteristics of the composite foundation, the model of the foundation of the raft-plate-rigid-flexible pile composite foundation is established by using the finite element software of ANSYS. The effect of each parameter on the characteristics of the composite foundation is discussed, and the optimization of the rigid-flexible pile composite foundation is discussed. The results of this paper show that the modulus of the rigid pile does not affect the settlement value but the stress distribution is changed, the increase of the modulus of the flexible pile reduces the differential settlement, and the parts can be improved. The load-sharing ratio; the influence of the base modulus of the raft plate on the settlement and the stress distribution is small and can be neglected, but the thickness of the raft plate improves the bending resistance and reduces the differential settlement; the arrangement of the mattress layer improves the distribution of the stress, the increase of the modulus reduces the settlement, but the rigid pile More load can be used in the actual project. According to the requirements of the building to the bearing capacity and the settlement, the form of the pile and the selection of the parameters can be reasonably adopted, so that the composite foundation can be obtained
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU470

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