高速列车荷载下饱和土地基三维动力响应分析研究

The train-induced environmental pollution is becoming more serious. The suitable theoretical model of the ground is essential for the accurate prediction of the train-induced environmental vibrations. In light of this, the saturated poroelastic soil model is widely used in the research for its advantage of taking the coupling effects between the soil skeleton and pore water into consideration. This project is aimed to develop the three-dimensional finite element method for the investigation of the dynamic response of the saturated soil media subjected to high-speed train load, through developing the saturated soil element basing on Biot's theory and applying multi-transmitting boundary on the boundary of saturated soil model. The developed method can overcome the shortage of the analytical method and the 2D finite element method for their disability to dealing with the problem concerning complex circumstances. On the basis of this method, the vehicle-bridge interaction element, beam element, solid element, spring-damper element and lumped mass element are added to establish a finite element analysis model for the vehicle-elevated bridge-saturated ground system. 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 ground subjected to high-speed trains will be revealed. The vibration levels and its attenuation in the ground will be predicted. The implement of this project can supply a new method for the investigation of the train-induced ground vibration and theoretical guidelines as well as technical supports for the control of the environment pollutions caused by high-speed trains. Thus, it has important application prospect in the engineering practice and will bring significant social benefits.

高速列车引起的环境振动污染问题日益显著。选择合适的地基理论模型是准确预测列车引起地基振动的关键。饱和土体模型因能考虑列车荷载下地基中的水土耦合作用而被广泛采用。本项目拟开发基于Biot理论的饱和土体单元，并在地基模型边界处运用多次透射人工边界实现高速列车荷载下饱和土地基的三维有限元模拟，以克服现有解析法和二维有限元方法在涉及复杂情况时的不足，为进一步研究饱和土地基动力响应问题提供有效方法。在此基础上，结合车桥耦合单元、梁单元、实体单元、弹簧-粘壶单元和集中质量单元建立车体-高架桥-饱和土地基三维有限元分析模型，并通过现场实测验证分析模型的正确性。揭示高速列车-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与传播距离。本项目的实施能为高速列车引起的环境振动研究提供新的手段，为解决高速列车引起的环境污染提供理论指导与技术支持，具有重要工程应用价值与显著社会效益。

高速列车引起的环境振动污染问题日益显著。本项目基于Biot理论的饱和土体单元，并在地基模型边界处运用多次透射人工边界实现高速列车荷载下饱和土地基的三维有限元模拟，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。本项目利用建立的车体-高架桥-饱和土地基三维有限元分析模型系统研究了高速列车引起的环境振动，取得的主要成果包括：(1)建立了适用于饱和土体两相介质动力计算的多次透射人工边界条件(MTF)，解析推导并验证了MTF的反射系数，确定了MTF中视波速取值，给出了MTF的数值稳定措施。（2）建立了基于Biot动力控制方程的饱和土体二维以及三维有限元求解器，与解析解对比验证了求解器的正确性，建立了移动荷载—饱和路基分析模型，研究了不同荷载速度下的饱和地基土骨架和孔隙水的瞬态振动位移。（3）建立了列车轮对—轨道结构—高架桥梁周期叠合梁分析模型，研究了列车运行速度下的轮轨接触力以及轨道结构动力响应，重点分析了轨道板对轮轨接触力以及箱梁动力响应的影响；（4）研究了不同列车速度和振动频率下的饱和地基自由场振动响应，明确了地基振动速度以及孔压的传播和衰减规律。(5)另根据结合工程背景与研究情况，本项目对地铁列车引起的地基振动预测及减、隔振措施等相关方面进行了拓展研究。本项目的实施能为高速列车引起的环境振动研究提供新的手段，为解决高速列车引起的环境污染提供理论指导与技术支持，具有重要工程应用价值与显著社会效益。发表论文11篇，其中SCI论文9篇；编写专著1本，获软件著作权1项。