列车-高架桥-饱和土地基三维耦合振动研究

The traffic-induced environmental pollution is one of the seven major public environmental nuisances in the international world. The accurate understanding of the ground vibration mechanism under moving loads is essential for the control of excess ground vibrations. Based on Biot's theory, the saturated soil element with 8 nodes is developed.Combining the multi-transmitting boundary at the boundary of saturated soil model,the three dimensional simulation of the dynamic responses of the saturated poroelastic media subjected to moving loads can be realized with finite element method. The influnences of the couping effects between the soil skeleton and pore fluid on the moving-load induced ground vibrations are investigated. On the basis of proposed method, the vehicle-bridge interaction element, beam element and solid element are added to firstly establish a finite element analysis model for the vehicle-elevated bridge-saturated soil system. The dynamic responses of the elevated bridge and the ground to the high-speed trains are predicted，and the accuracy and feasibility of this model will be verified by the in-situ tests. The vibration mechanism of elevated bridge as well as the saturated soil medium subjected to high-speed trains will be revealed, and the vibration levels and attenuation of the saturated poroelastic half-space will be predicted. The present research can supply a new method for the investigation of dynamic responses of saturated poroelastic media, which can promote the development of soil dynamics discipline. Furthermore, the theoretical guidelines as well as technical supports will be provided for the control of the environment pollutions caused by high-speed trains. Thus, it has important application prospects in the engineering practice and can bring significant social benefits.

交通荷载引起的环境振动被列为国际七大环境公害之一。正确认识交通荷载下地基的振动机理以及传播衰减规律，是有效控制地基振动的关键。本项目基于Biot理论开发u-w格式三维8结点饱和土体单元，并结合饱和土地基多次透射人工边界实现移动荷载下饱和土地基动力响应的三维有限元模拟；研究移动荷载下饱和土地基中水土两相耦合作用对饱和土地基振动特性的影响。在此基础上，结合车桥耦合单元、梁单元及实体单元首次建立车体-高架桥-饱和土地基三维有限元分析模型，获得实际列车荷载作用下高架桥与饱和土地基的振动响应，并通过现场实测对研究模型的进行验证；揭示列车-高架桥结构-饱和土地基系统的耦合振动机理，预测高架桥铁路引起的地基振动大小及传播距离。研究成果能丰富饱和土地基动力响应研究手段，对土动力学的发展具有重要理论意义，同时为解决高速列车引起的环境振动问题提供理论指导与技术支持，具有重要工程应用价值与显著的社会效益。

高速列车引起的周边环境振动污染被列为国际七大环境公害之一。近十年来，国家投资数万亿用于高速铁路建设，我国高速铁路建设举得了举世瞩目的成就。然而我国高铁快速发展导致沿线振动污染问题日益严重，目前我国在环境振动控制方面缺乏相应的控制标准以及基础技术积累，这些问题都有待进一步深入研究与解决。建立合适的高架铁路振动预测模型为准确预测列车引起地基振动的关键。本项目采用饱和多孔介质模型来模拟地基，开发了基于Biot理论的饱和土体单元，并提出了适用于移动荷载的饱和土地基多次透射人工边界，使得人工边界条件满足稳定性且透射效率最高条件，进而实现移动荷载下饱和土地基动力响应的有限元准确高效模拟。克服了现有解析法和二维有限元方法在涉及复杂情况时的不足。轨道系统模拟为双层梁系统，求解了不同移动速度点荷载作用下的轨枕动反力频谱，进而采用模态叠加法和Newmark隐式积分法计算轨道结构动力响应。群桩基础与饱和土成层半空间的动力响应问题通过容积法进行求解，以获得群桩基础在饱和土地基中阻抗函数。上部轨道结构与群桩基础通过箱梁橡胶支座处竖向力平衡和竖向位移连续实现耦合，进而建立列体-高架桥-饱和土地基三维有限元单元分析模型，现场实测表明该模型能较为准确的预测高架铁路引起的地基振动响应，并揭示了高速列车-高架桥结构-饱和土地基系统的耦合振动机理与振动传播规律。此外，本项目建立了列车减隔振理论分析模型，评估了隔振沟、枕木胶垫等振动控制措施的振动控制效果,研究揭示减隔措施对列车引起的高频振动具有显著效果。本项目系统研究了高架铁路引起饱和土地基振动机理与传播规律，并评估了减隔振措施的减振效果，研究成果为解决高架铁路引起的环境污染问题提供理论指导与技术支持，具备良好的工程应用前景与社会效益。本项目研究已发表论文7篇，其中第一或通讯作者SCI论文5篇；参加国际学术会议2次，做大会主题报告1次。