路基不均匀沉降对车辆和轨道动力响应的影响

以经典车辆-轨道耦合动力学为基础,推导了考虑重力的板式轨道相关结构振动方程,结合多刚体的车辆系统动力学模型,建立了考虑重力的车辆-板式轨道垂向耦合分析模型,提出了通过路基反力变化模拟路基不均匀沉降的具体方法,并对模型和方法进行了必要的验证.利用该模型研究了行车速度及路基不均匀沉降(包括路基不均匀沉降幅值、路基不均匀沉降波长等)对系统动力响应的影响.研究表明:随着行车速度和路基不均匀沉降幅值的增加,系统响应均相应增加,路基不均匀沉降对车辆运行影响的控制性指标应以舒适性指标为主、安全性指标为辅;随着路基不均匀沉降波长的增加,系统动力响应存在一个先增加后减小的过程,路基不均匀沉降的敏感波长与混凝土底座的长度有关.

Effect of Subgrade Differential Settlement on Dynamic Response of Vehicle and Slab Track Vertical Coupled System

Based on the theory of vehicle-track coupling dynamics, vibration differential equations of rail, track plate and concrete footing in slab-track system are deduced considering gravity of track structure. Combined with the vehicle dynamics model of multi-rigid-bodies, vehicle and slab track vertical coupled dynamics model is established considering track structure gravity. The method of controlling subgrade reaction force is put forward to analyze the dynamic response of vehicle- slab track system induced by a wide range of subgrade differential settlement, and the coupled model and control method are verified to be accurate and reliable. Factors of subgrade differential settlement affecting system dynamic response, including driving speed, magnitude of the settlement and wavelength of the settlement, are analyzed, and the result shows as follows: the dynamics response increases with the driving speed and the magnitude of the settlement, and the comfort index should be treated as the primary index which is more important than safety index when facing differential settlement. Along with the wavelength of settlement increasing, the relative response shows a process of first increasing and then decreasing, so there exists a sensitive wavelength of the differential settlement which is related with the length of concrete base.