【作者】 郑鑫；

【导师】 陶夏新；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2007， 硕士

【摘要】 交通拥挤正成为制约我国城市发展的重要问题之一,发展城市轨道交通是一个有效的解决方案。轨道交通引起的环境振动与防治研究,越来越迫切地成为亟待解决的问题。用台阵观测方法反演城市轨道交通振源函数是一个崭新的课题,本文采用虚拟反演方法,给定振源函数,计算台阵各点的振动,再反演振源参数,比较结果和给定输入的差别,论证这个思路的可行性。首先,简化场地条件为弹性半空间单一覆盖层模型。利用传递矩阵法及Laplace-Hankel联合变换技术,推导出层间完全接触的弹性半空间单一覆盖层模型表面作用脉冲荷载时,覆盖层表面竖向位移场解析解。接着,详细阐述了数值化实现该解析解的方案,分五种情况考虑数值计算可能出现的问题,分别提出了解决方案,编制了Fortran程序。通过退化为弹性半空间问题,与经典解对比,验证了数值计算的准确性。然后,简要评述了遗传算法的研究历程及发展现状、基本遗传算法原理及其存在的问题。详细介绍了微遗传算法的要点和步骤,构造了反演的遗传策略,编制了振源反演计算程序,通过四个测试函数验证了整个反演程序的可靠性。最后,给定弹性半空间单一覆盖层具体的场地模型、三角脉冲振源模型和台阵布置的方案,计算了矩形台阵六个点的位移时程。分析了时程表达的信息,借助频率-波数谱分析,得到场地的频散曲线,与用频散方程得到的频散曲线对比说明计算的可靠性。利用微遗传算法虚拟反演振源参数,分别采用单点时程段、单点自功率谱、两点自功率谱联合、两点互功率谱与其中一点自功率谱联合作目标曲线反演振源参数,结果与给定输入脉冲的参数比对,表明反演结果稳定,效率较高;利用两个点的信息,反演结果更为稳定,反演效率高。论证了根据台阵各点的竖向位移时程构造适当的目标函数,反演准确的振源参数的思路是可行的。更多还原

【Abstract】 Traffic congestion is now one of the most important problems in city development of our country. An effective method to solve this problem is developing urban track traffic. Thus, study on environmental vibration and its prevention has been an urgent problem.Inversion of vibration source from urban track traffic by observed data on an array is a quite new idea. The virtual inversion is adopted in this dissertation, in the process, a vibration source function is given, and vibration on each point in the array is calculated then. Based on the vibrations at the array, the parameters of the source function are inversed and are furthermore checked with the given ones to validate the feasibility of this idea.Firstly, site condition is simplified as a model with single soil layer overlaid on elastic homogeneous half-space. The analytical solution of vertical displacement field on the surface of the model from pulse loading on the surface is derived by means of transfer matrix and Laplace-Hankel combined transform. In the derivation all layers contacted with each other completely. Afterwards, the numerical realization of the solution is introduced in detail, five possible problems in the process are discussed and the method to manage them is presented, and a Fortran program is compiled. The numerical result by degenerating the model into elastic half-space is checked with classical solution to validate the reliability of the calculation in this dissertation.Then, the evolution and the state-of-the art of Genetic Algorithm are reviewed briefly, as well as the principles and existing problems in the basic Genetic Algorithm. The gist and the procedure in the Micro Genetic Algorithm are introduced in detail, the generic strategy for inversion is designed, the program for inversion is also compiled. The reliability of the program is verified by four test functions.Finally, displacement time histories at six points in a rectangular array are calculated from the given site model with single soil layer overlaid on elastic half-space, given array layout and given triangular pulse input. The information in the time histories are analyzed, frequency dispersion curve at the site is acquired and is checked with those derived directly from frequency dispersion equation. Micro Genetic Algorithm is adopted in the virtual inversion of source parameters. Target curves are constructed respectively by the time history at a point, the auto-power spectrum at a point, the cross-power spectrum between a pair of points in the array. The results are checked with the given source parameters, and show a good stability and efficacy. The information on two points can improve the inversion results. As a conclusion, the idea to inverse traffic vibration source from the observation data at an array is feasible, if the target function is constructed well.更多还原