【作者】 马远刚；

【导师】 杨春和；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2010， 博士

【摘要】 自平衡测试技术作为一种高效、先进的静载测试技术,在国内外得到了广泛的认可和应用,但对荷载箱埋设位置、测试数据等效转换和承载能力确定方法需进一步研究。另外进行试验的目的是为设计提供计算参考,现在工程试验基本都是作的单桩,并不能详细反映群桩的工作性状,提供的试验数据只是进行宏观的评价,并不能将其直接引入到全桥计算分析中去。本文主要从自平衡测试技术及群桩基础计算模型的改进入手,主要创新性成果如下：(1)根据不同已知条件,对荷载箱埋设位置的确定方法进行研究,并引入基于孔形检测的桩侧粗糙程度系数和桩端承载力折减系数,对相似模拟试验法中的桩侧阻力和桩端阻力进行修正,从而更为准确的计算荷载箱的位置。(2)随着超长桩在桥梁工程中的应用越来越多,为避免导管在穿越荷载箱时出现卡管现象,设计适用于超长桩试验的荷载箱,并获得国家专利。提出一种直接在工程桩上进行承载力测试的荷载箱设计,保证试验后桩身质量并有效传递轴力和弯矩。(3)提出一种新的自平衡试验数据简化等效转换方法,它考虑自平衡加载方式下底层荷载箱以上桩体的压缩量及其转换后桩顶加载方式下的压缩量,对等效转换的桩顶位移进行附加压缩量修正,并给出了单层及双层荷载箱计算公式；考虑桩侧摩阻力向下传递而引起的桩端位移,提出基于改进荷载传递函数的等效转换法,较准确地模拟基桩的荷载传递机理,符合基桩实际受力状况。(4)研究成果已成功应用于国内外大型桥梁大吨位试桩工程中,为提供了设计参数实测值,并对桩基优化进行了计算分析。(5)在神经网络和遗传算法理论的基础上,提出基于改进遗传神经网络的多参数反演方法,并采用MATLAB编制了反分析程序；(6)以桩侧接触面切向刚度、桩端接触面法向刚度和接触面与桩周土摩擦特性比值系数作为反演参数,利用自平衡测试数据进行反分析；根据反演结果进行基于单桩静载试验的群桩基础竖向承载特性计算,将群桩基础以位移边界的形式加入到桥梁结构整体计算模型中去,为上部结构-桩-土相互作用计算提供了以实测数据为基础的计算模式；(7)在总结本文研究工作的基础上,就本研究内容应该深入研究的方向和亟待完善的方面进行展望。更多还原

【Abstract】 As an efficient, advanced static loading test technology, self-balanced test method at domestic and abroad has been widely approvaled and applied, but the load-box laying position, equivalent conversion method of test data and determination of bearing capacity needs to furtherly study.In addition the testing purpose is to provide calculation reference for design, the current tests which are mostly made of single pile and the bearing performance of pile groups can not be fully reflected, providing test data is only macro evaluation, and it can’t be directly introduced into the calculation and analysis of the whole bridge. Based on the improvement of self-balanced test technology and pile group calculation model, the main innovative achievements of this article is as follows.(1) Research the methods for determining the install location of load-box according to different known conditions, and amend the side friction and end resistance of similarity analogue test technology unsing side roughness factor based on pile hole-shaped test and the pile end bearing capacity reduction factor for more accurate calculating load box location.(2) With the super-long piles in bridge engineering, design the dedicated load-box for super-long pile to avoid stucking the tube through the load-box, and obtains the national patent. A load-box for taking load test in working-pile is designed, to ensure the pile quality and effective transmission of axial force and bending moment.(3) A new simplication equivalent conversion method of self-balanced test data is proposed, which considers the compression of upper pile under self-balancing load mode and the top load mode to amend pile top displacement for additional compression, and gives formula for calculating the load-box location of single-layer and double-layer. A equivalent conversion method based on improved load transfer function is proposed, which considers the pile end displacement caused by side friction, it more accurately simulates the load transfer mechanism of pile, in line with the actual pile status.(4) Research results has been successfully applied to large-tonnage Pile of domestic and foreign bridge projects, to provide the measured values of design parameters, and optimize the calculation of pile foundation.(5) According to the neural network and genetic algorithm put forward multi-parameter inversion method based on improved genetic neural network, and prepare a back-analysis program using MATLAB.(6) To take the pile-side contact surface tangential stiffness, pile-end contact surface normal stiffness and the ratio factor between contact surface and soil for friction characteristics as the inversion parameters, make back-analysis using self-balanced test data; under the inversion results are based on static load test for single pile the vertical load-bearing characteristics of group pile foudation is calculated, and take the group pile foundation into the bridge structure model in the form of displacement boundary, to provide a calculation pattern based on measured data for considering the upper structure-pile-soil interaction terms.(7) To conclude this research work and forcast the direction that should be in-depth study and the aspects that need improvement.更多还原