城市道路路基中砂袋垫层地屏障的减振与耗能研究

Aiming at the environmental vibration induced by vehicle loads on urban road, taking sandbag cushion as a barrier in road subgrade, the vibration reduction mechanism and effectiveness of sandbags are studied utilizing a method of combining theoretical analysis, numerical simulation and experiment. First, the vibration reduction model for sandbags resting on a poroelastic half-space soil medium under vehicle loads will be established by regarding pavement as a plate, and by regarding sandbags as viscoelastic bodies which have certain stiffness and damping. According to the vehicle loads and the pavement supporting force provided by combined sandbags, the plate governing equation expressed by vertical displacement is derived. The displacement expressions of pavement and poroelastic soil surface are obtained in terms of contact conditions between the pavement and the sandbags. The influence of structure parameters of sandbags, poroealstic soil characteristics, and fluid-solid coupling effect on reduction effectiveness is systematically analyzed. Then using the discrete element method, the energy dissipation equations of a single sandbag will be established, and the energy dissipation process of every part of the sandbag under vertical cyclic loading condition will be simulated. Furthermore, the indoor model and field tests are carried out to investigate vibration reduction function of sandbags and to verify the theoretical analysis. This project will reveal the vibration reduction mechanism of sandbags in road subgrade. Meanwhile, the influence law of structure parameters of sandbags and soil characteristics on vibration reduction will be presented. The research results will provide the scientific foundation for design and application of sandbags as barriers.

针对车辆荷载作用下城市道路的环境振动问题，以砂袋垫层作为路基中振动隔离体，研究其减振机理和效果。通过建立饱和土路基中砂袋垫层在车辆荷载作用下减振模型，将路面看作一薄板，每个砂袋视作具有一定刚度和阻尼的粘弹性体，根据作用在薄板上车辆荷载、砂袋组合单元所提供给路面支撑力，导出以竖向位移表示的薄板控制方程，再根据砂袋垫层和路基土体接触条件，得到道路和土体表面位移表达式，分析砂袋垫层结构几何参数、饱和土体流-固耦合效应等对砂袋垫层减振影响。利用离散单元法，通过建立砂袋单体减振过程中的能量耗散方程，模拟竖向循环荷载条件下袋子本身及袋内砂颗粒的能量耗散及其作用过程。通过对砂袋垫层进行室内外试验，进一步研究砂袋垫层的减振性能，并验证理论分析的准确性。项目预期将揭示饱和土路基中砂袋垫层的减振机理，得出砂袋垫层结构几何参数和土体特性等对减振效果的影响规律，可以为砂袋垫层设计和应用提供理论科学依据。

针对车辆荷载作用下城市道路的振动问题，以砂袋垫层作为路基中振动隔离体，研究其减振机理和效果。通过建立路基中砂袋垫层在车辆荷载作用下减振模型，将路面看作一薄板，每个砂袋视作具有一定刚度和阻尼的粘弹性体，根据作用在薄板上车辆荷载、砂袋垫层和路基土体接触条件，推导出路面和砂袋垫层的位移和振动速度表达式，从理论上解释了砂袋垫层的减振机理。利用离散单元法，模拟竖向循环荷载条件下袋子及袋内砂颗粒的能量耗散及其作用过程, 分析了砂袋的内力功和外力功的变化情况。通过对砂袋垫层进行试验，发现中砂袋垫层中加速度衰减最快，细砂袋次之，粗砂袋最慢。铺设砂袋垫层后，振动可比铺设前衰减40%。项目揭示了路基中砂袋垫层的减振机理和对减振效果的影响规律，可以为砂袋垫层设计和应用提供理论科学依据。