刚性桩复合地基—基

发布时间：2018-01-09 19:00

本文关键词：刚性桩复合地基—基础—上部结构整体抗震性能的简化算法研究　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：刚性桩复合地基是二十世纪初形成的一种全新的地基处理形式,它可以使地基土和增强体相互协作共同承担上部结构传到地基上的荷载,从而增加地基的承载能力、减小基础和上部结构沉降;刚性桩复合地基具有施工简单快速、节省施工成本等特点,受到工程界人士的青睐,在工程中应用广泛。然而现在的工程界人士对刚性桩复合地基的工作原理还不太清楚,特别是对刚性桩复合地基抗震性能更是一无所知。实际工程设计时,往往忽略地震对复合地基性能的影响,这就有可能使上部结构存在安全隐患。目前对刚性桩复合地基-基础-上部结构整体抗震性能的研究,以模型试验和有限元数值模拟为主。模型试验需要耗费非常多的人力、时间和金钱,而数值模拟建模困难,工程设计中难以采用。本文针对上述问题,通过理论推导建立了一种刚性桩复合地基-基础-上部结构整体抗震性能的简化算法,大大降低了刚性桩复合地基整体抗震分析的难度,可应用于如今的工程设计中,提高了工作效率。本文主要从下面几点着手研究:(1)建立单桩复合地基-基础-上部结构的整体简化模型,分别推导各个部分的动力微分方程,然后根据整体模型的边界条件和各个部分的相互作用条件,得到整体体系地震响应的运动微分方程,并构造合适的差分格式求解动力微分方程,最终求得地震作用下整个模型的动力响应;(2)采用Matlab软件编制了单桩复合地基-基础-上部结构整体抗震分析程序,计算分析了单桩复合地基-基础-上部结构的地震动响应,并与已有研究成果进行对比,验证本文简化算法的可靠性。然后,根据并桩原则把群桩复合地基合并成单桩复合地基,建立刚性桩复合地基-基础-上部结构整体抗震的简化算法;(3)选取适宜的地震波研究刚性桩复合地基-基础-上部结构的抗震性能,分析各个部分在多遇和罕遇地震作用下的动力响应,通过对比发现,在多遇地震作用下,复合地基的减震作用不明显,上部结构的计算结果与不考虑复合地基时的计算结果差别不大;在罕遇地震作用下,复合地基的减震效果较为显著,上部结构的震动响应改变非常显著。(4)最后,研究褥垫层模量、厚度,刚性桩桩径、桩长,对整体模型抗震性能的影响。通过分析发现褥垫层厚度的改变对模型动力响应影响不大,增大褥垫层的模量既增大了桩顶和桩底的剪力又使桩身的弯矩有所增大,对桩身造成不利的影响;垫层模量增大时,上部结构的楼层最大位移和最大层间位移均变化较大。桩径越大,桩越短,上部结构位移越大,桩体的弯矩和剪力越大,但是增加到一定范围后逐渐的趋于稳定。
[Abstract]:Rigid pile composite foundation is a new type of foundation treatment formed at the beginning of 20th century. It can make the foundation soil and the reinforcement cooperate with each other to bear the load from the superstructure to the foundation. Thus, the bearing capacity of foundation is increased and the settlement of foundation and superstructure is reduced. Rigid pile composite foundation has the characteristics of simple and fast construction, saving construction cost and so on, so it is favored by engineers. It is widely used in engineering. However, the working principle of rigid pile composite foundation is not clear, especially the seismic performance of rigid pile composite foundation. The influence of earthquake on the performance of composite foundation is often ignored, which may make the superstructure have hidden danger of safety. At present, the seismic behavior of rigid pile composite foundation-foundation-superstructure is studied. Model test and finite element numerical simulation are the main parts. Model test requires a lot of manpower, time and money, but numerical simulation is difficult to model, so it is difficult to use in engineering design. A simplified algorithm for seismic behavior of rigid pile composite foundation-foundation-superstructure is established by theoretical derivation, which greatly reduces the difficulty of whole seismic analysis of rigid pile composite foundation. It can be applied to the engineering design of today and improve the working efficiency. This paper mainly studies the following points: to establish a simplified model of single pile composite foundation-foundation-superstructure. The dynamic differential equations of each part are derived, and then according to the boundary conditions of the global model and the interaction conditions of each part, the kinematic differential equations of the seismic response of the whole system are obtained. An appropriate difference scheme is constructed to solve the dynamic differential equations, and finally the dynamic response of the whole model under earthquake action is obtained. (2) the program of seismic analysis of single pile composite foundation-foundation-superstructure is compiled by Matlab software, and the seismic response of single pile composite foundation-foundation-superstructure is calculated and analyzed. And compared with the existing research results, verify the reliability of the simplified algorithm. Then, according to the principle of co-pile, the composite foundation of pile group is combined into single pile composite foundation. A simplified seismic algorithm of rigid pile composite foundation, foundation and superstructure is established. 3) selecting suitable seismic wave to study the seismic behavior of rigid pile composite foundation, foundation and superstructure, and analyzing the dynamic response of each part under the action of frequent and rare earthquakes, and finds out by comparison. Under the action of frequent earthquakes, the seismic absorption of composite foundation is not obvious, and the calculation results of superstructure are not different from those of the composite foundation without considering the composite foundation. Under the action of rare earthquake, the damping effect of composite foundation is obvious, and the vibration response of superstructure is very significant. Finally, the cushion modulus, thickness, rigid pile diameter and pile length are studied. Through the analysis, it is found that the change of cushion thickness has little effect on the dynamic response of the model. Increasing the modulus of cushion not only increases the shear force on the top and bottom of the pile, but also increases the bending moment of the pile body, which has an adverse effect on the pile body. When the modulus of cushion increases, the maximum floor displacement and the maximum interstory displacement of the superstructure vary greatly. The larger the pile diameter, the shorter the pile, the larger the displacement of the superstructure, the greater the bending moment and shear force of pile. But after increasing to a certain range, gradually tend to stabilize.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU435;TU352.11

【相似文献】