【作者】 罗鹏飞；

【导师】 闫明礼；

【作者基本信息】 中国建筑科学研究院 ， 岩土工程， 2013， 博士

【摘要】 CFG桩复合地基技术通过二十余年的科研和工程实践,从最初应用于多层建筑发展到广泛应用于高层和超高层建筑地基处理,取得了显著的经济效益和社会效益。本文主要完成以下工作：1.完成模拟高低层连体建筑形成偏心荷载作用的室内模型试验,获得轴心荷载作用下天然地基、均匀布桩CFG桩复合地基基底反力可简化为均匀分布；偏心荷载作用下天然地基、均匀布桩CFG桩复合地基基底反力可简化为线性分布；偏心荷载作用下高层部位均匀布置长桩、低层部位均匀布置短桩的局部均匀布桩CFG桩复合地基基底反力可简化为局部均匀分布；“等变形”条件下(本文根据试验条件,当基础长度方向两端差异沉降小于某一较小数值时,即认为左右两端为变形相等的“等变形”状态)高层部位均匀布置长桩、低层部位均匀布置短桩的局部均匀布桩CFG桩复合地基,基底反力可简化为长桩区域高、短桩区域低的局部均匀分布,且按高层、低层部位复合地基的复合模量进行分配。2.基于以集中力表示的静力平衡方程,推导了多桩型复合地基承载力表达式；指出多桩型复合地基施工完成后的桩间土承载力提高系数,与土性、施工工艺和桩间距有密切的关系；提出不同布桩形式下,多桩型复合地基面积置换率的计算方法；提出多桩型复合地基计算变形时如何进行分区,各分区复合模量提高系数如何计算,以及如何进行分层,各分层复合模量如何进行计算,并给出多桩型复合地基变形计算的步骤；提出不同布桩形式下,多桩型复合地基的质量检测方法。3.针对目前天然地基、CFG桩复合地基变形计算中,存在压缩模量取值不当的问题,提出对固结试验结果进行拟合分析。在综合分析大量前人研究拟合固结试验结果成果的基础上,提出新的数学模型：e=c[exp(aNpbN)-1]+e0该数学模型除具有单调递减和呈“S”形的特点外,还满足边界条件：当压力p=0时,孔隙比e=e0,为天然孔隙比；当压力p→+∞时,孔隙比e=e0,为压密极限。本文运用最优化方法求得的各参数,具有唯一的确定值,并运用VC++编制了相关可视化程序。对大量固结试验结果的拟合分析表明,本文提出的数学模型对固结试验结果的拟合程度高,因而可直接运用本文提出的数学模型对固结试验结果进行拟合,可通过编制相关程序确定自重压力至自重压力与附加压力之和的压力段的压缩模量,实现人机对话,避免人为误差,达到提高变形计算精度的目的。更多还原

【Abstract】 CFG pile composite ground technology was applied in multistoried building at first, and developed to be applied in high-rise and super high-rise building widely through more than twenty years of scientific research and engineering practice. It is obtained remarkable economic and social benefit. This paper mainly finished the following:1. Adopted the large-scale indoor test to simulate the eccentric loading effect of connecting body of high-low rise building. Based on the results of the test, it is obtained that base reaction of natural foundation and uniform layout of CFG piles composite ground under axis loading can be simplified as uniform distribution, the base reaction of natural foundation and uniform layout of CFG piles composite ground under eccentric loading can be simplified as linear distribution, and the non-uniform layout of CFG piles composite ground under eccentric loading is non-linear distribution. The non-uniform layout of CFG piles composite ground under condition of equal deformation is non-linear distribution, which the end of long pile is higher and the end of short pile is lower, both can be simplified as uniform distribution, and it is distributed by the composite modulus of high-rise part and low-rise part.2. Based on static equilibrium equation expressed by concentrated force, the bearing capacity formula of multi-type-pile composite foundation was derived. It is pointed that the bearing capacity improvement factor of soil between piles is tight link with soil features, construction technology, and pile spacing. It is put forward that how to part the area, how to calculate the improvement factor of composite modulus, how to lay the soil along the depth and how to calculate the composite modulus of each layer when calculating the deformation of multi-type-pile composite foundation. The procedures of calculating the deformation of composite ground is also given.3. According to problem of selecting the incorrect compression modulus to calculate the deformation of natural foundation and CFG piles composite ground in currently, simulating the consolidation test results is put forward. Based on comprehensive analysis a lot of simulating mathematical models put by the previous, a new mathematical model is put forward as followding: e＝c[exp(-aNpbx)-1]+e0The above formula has the characters of satisfy the boundary conditions, monotone decreasing and showed the shape of "S". Each parameters of the formula have the unique value by the optimization method. A visual program is compiled by VC++computer language. It is indicated that the mathematical model put forward by this paper has high fitting degree, and better than models put forward by the previous according simulating a lots of compression modulus test results. It can apply the model put forward by this paper to simulate the compression modulus test results directly, in order to calculate the compression modulus of pressure section between gravity stress and the sum of gravity stress and additional stress. It is achieved the man-machine interaction, avoided human error, and improved the calculation accuracy of deformation.更多还原