【作者】 陈俊；

【导师】 邹银生；

【作者基本信息】 湖南大学 ， 结构工程， 2006， 硕士

【摘要】 在分析国内外相关研究成果的基础上,本文主要研究竖向荷载作用下考虑上部结构影响的桩筏基础桩顶反力及沉降特性,并在此基础上探讨了变刚度调平设计的原理、方法和步骤。在前人研究成果的基础上,本文研究了层状地基中桩与桩、桩与土相互作用的内在机制。采用剪切位移法,利用递推原理导出桩顶柔度系数的计算公式;采用分层地基模型计算土体单元之间的相互作用,从而获得承担竖向荷载桩土支撑体系的柔度矩阵近似解析公式,进而得到桩土支撑体系刚度矩阵。本文上部结构采用空间杆单元,每个节点有六个自由度;筏板采用在经典薄板理论基础上利用广义协调元方法建立的薄厚板通用单元,每个节点有三个自由度;桩土支撑体系每个桩节点或土节点只有一个自由度。针对该情况,本文提出了一种简单可行的耦合方法,将上部结构刚度矩阵、桩土支撑体系刚度矩阵和筏板刚度矩阵进行耦合,形成共同作用方程并编制共同作用分析程序。利用上述共同作用分析方法和共同作用分析程序,做了如下研究工作:(1)筏板设计参数对桩筏基础桩顶反力及沉降特性的影响;(2)桩设计参数对桩筏基础桩顶反力及沉降特性的影响;(3)在上述分析研究的基础上,阐述了变刚度调平设计的原理、方法和步骤。理论研究表明:桩距、桩长、桩径及筏板厚度的变化对桩筏基础桩顶反力及沉降特性有很大影响,特别是筏板厚度和桩距的变化对桩筏基础沉降差影响甚大。算例分析表明:桩筏基础通过变刚度调平设计后,可以有效减小桩筏基础的沉降差,从而减小筏板的内力及上部结构的次应力,有效降低工程造价。更多还原

【Abstract】 On the basis of investigation on the related researching achievements home and abroad, this thesis puts emphasis on studying the counterforce on the pile head and the sedimentation characteristics of the piled raft foundation under the vertical loads, considering the superstructure’s effect. And then, this thesis probes into the principles, methods and processes of balance design method for variable-rigidity.Based on predecessor’s achievements, this thesis has studied the intrinsic interaction mechanism of pile-pile and pile-soil in the layered soil. With the shearing deformation theory and deductive theory, the calculational formulas of flexibility coefficient of the pile head can be obtained. The interaction of the soil elements is calculated according to the layered-soil model. Consequently, approximate analytical formulas of the flexibility matrix of piles-soil system, which undertake the vertical loads, come out. Owing to this, we can also get the rigidity matrix of piles-soil system.In this thesis, there are six arguments in each node of three-dimension pole element which is used to analyze the superstructure. With the classical the slab theory, the thin and thick slab universal element, which is composed with the general harmony unit method, is used to analyze the raft, and each node has three arguments. But there is only one argument in each pile node or soil node in piles-soil system. Therefore, an effective, simple and feasible coupling method is proposed in this thesis. That is to couple the three different rigidity matrixes of superstructure, raft and piles-soil system. Subsequently, the interaction equations and its analysis programs come into being.With the applications of above interaction analysis method and its analysis programs, the following works are studied in this thesis,(1) Study on the effects of the design parameters of the slab, which affect the counterforce on the pile head and the sedimentation characteristics of the piled raft foundation.(2) Study on the effects of the design parameters of the piles, which affect the counterforce on the pile head and the sedimentation characteristics of the piled raft foundation.(3) The principles, methods and processes of Balance Design Method for Variable-Rigidity were expatiated on the basis of above studies.The theoretic studies show that the variation of span, length and diameters of piles,更多还原