【作者】 申兆武；

【导师】 朱合华； 王卫东；

【作者基本信息】 同济大学 ， 结构工程， 2008， 博士

【摘要】 高层及超高层建筑(尤其是软土地基上的此类建筑)的桩基础和上部筏板可以形成桩筏基础。桩筏基础具有良好的承受载荷、减少平均沉降、调节差异沉降功能。本文拟采用共同作用的思路对桩筏基础分析方法进行研究,同时通过超高层建筑——上海环球金融中心桩筏基础实测进行验证,并引入计算机图形学中的Voronoi算法来考虑土层的横向不均匀性。本文开展的研究主要有以下内容:1)以修正的Poulos弹性理论解为基础,分析单桩、双桩、桩土、土土影响系数,进而计算桩土刚度。在桩土刚度的影响因素中,对桩长、桩径、土层压缩模量、泊松比等因素的具体影响进行研究。同时通过对实际工程中长短桩和后浇带问题进行分析,验证程序的有效性。2)Geddes弹性理论解把桩阻力分为:均匀分布侧阻力、三角形(线性增长)分布侧阻力和端阻力三种形式。本文对Geddes弹性应力解进行修正后,分析桩—桩影响系数,进行群桩分析,通过分析模型结构验证方法的合理性。并研究桩长、桩径、土层压缩模量等因素的对桩身刚度的影响。3)以Reissner厚板理论为基础,采用八结点等参元分析筏板结构,采用有限元软件ANSYS中壳元验证程序分析结果,进而分析板计算的影响因素。分析共同作用方法的特点,找到分析上部结构的简化方法,并应用到工程实际中。把共同作用的分析方法应用到中央电视台电视文化中心(TVCC)的工程分析中,验证程序的实用性。4)总结Voronoi图和其对偶图Delaunay三角形的定义和性质,同时分析其算法,主要研究间接法得到Voronoi图的算法。采用此算法分析一个理想模型考虑横向不均匀性与否的差别,同时分析转炉桩筏基础在考虑横向不均匀性与否的差别,总结考虑土层横向不均匀性与否的影响。5)采用共同作用的方法分析超高层建筑——上海环球金融中心桩筏基础的沉降、桩项反力、弯矩等项目,整理环球金融中心工程实测数据。通过精密水准仪测量筏板标高,由变化值得到沉降,绘制等值线图。采用桩顶压力盒和表面应变计测试桩项反力,分析其变化规律。利用钢筋应力计和混凝土应变计测量筏板钢筋和混凝土的应力、应变变化,同时用温度计测试筏板混凝土的温度,观测水化热的影响。采用孔隙水压力计和土压力盒测试孔隙水压力和桩间土的水土压力,分析桩土荷载的分担比。总结此类桩筏结构的规律,验证程序分析结果的有效性,为此类超高层建筑桩筏基础的设计总结经验。更多还原

【Abstract】 To the high-rise building and super high-rise building, especially sited in soft-soil ground, pile-raft can be formed by the pile foundation and the upper raft. Pile-raft foundation has right function that is big carrying capacity, reduce the average settlement and adjust the difference settlement and so on. In this paper, pile-raft foundation analysis method will be researched through the method of the interaction of superstructure, raft, pile and soil, and it will be validated by the super high-risebuilding------Shanghai Round-the-world Finance Center’s engineering measurementdata. At the same time, the Voronoi method in computer graphics will be applied to analysis the horizontal nonhomogeneous soil. The main research content is as follow:1) Calculating the single pile, double pile, pile to soil and soil to soil’s influence coefficient through the correction Poulos elastic theory solution, then the pile-soil stiffness will acquire. To the influencing factor of the pile-soil stiffness, it should be analyzed that is pile length, pile diameter, soil modulus of compression, Poisson ratio and so on. The program can be validated through the long-and-short pile and latter pouring belt analyzing in actual project.2) Based on the Geddes elastic stress solution, it can describe to the analytic solution, that is the pile end resisting force, linearity distribute and triangle distribute force coming form the pile side resisting force. Base on the solution, the pile-pile coefficient can calculate, so the group piles may analyze. The rationality of theory can be testified through the mode structure. At the same time, it should be analyzed the influence to the pile rigid, that is the factors, such as the pile long, pile diameter, soil modulus of compression and so on.3) Based on the Reissner thick plank theory, the raft plank has been analyzed by the 8-node isoparametric element. It will be verified by the analysis result ofthe universal finite element software------ANSYS Shell element. The plankcomputing influencing factor will be discussed. Through summarized the characteristic of interaction method, it will be found and applied in actual project that is the simplified analysis method for the superstructure. The program’s validation will be tested throng calculating the Beijing Television Culture Center (TVCC) engineering design. 4) Summarizing the definition, feature and algorithm of the Voronoi graph and its dual graph Delaunay triangle, the indirection algorithm to Voronoi graph will be researched. Based on this algorithm, it will be analyzed that is the difference result of considering the horizontal nonhomogeneous or not for the ideal model. At the same time, converter pile-raft foundation design will be analyzed. So the validation of considering horizontal nonhomogeneous will be summarized.5) Based on the interaction analyzing method, settlement, pile counterforce, moment and so on have been calculated for the Shanghai Round-the-world Finance Center’s engineering. It should be arranged this engineering’s measurement data. Contour chart will be plotted throng the precision gradienter measure the raft plank height mark and settlement from the difference. Taking the pressure cell on the pile and surface strain cell to measure pile counterforce, the variation law will be summarized. Taking reinforce bar stress gauge and concrete stress gauge to survey the change of raft reinforce bar and concrete stress, and taking thermometer to scale the raft concrete temperature to gain the influence of the heat of hydration. At the same time, adopting pore pressure gauge to scale the pore water pressure and taking soil pressure cell to measure the soil pressure, then the share scale of pile and soil among the pile will be analyzed. Summarizing the law of this kind of pile-raft foundation, the program is validation should be tested, so it will give some good experience to this kind of high-rise building’s pile-raft foundation analyses and design.更多还原