基于车辆响应的无砟轨道路基不均匀沉降评价指标理论研究

路基不均匀沉降的合理评价对于保障高速铁路运营安全和指导线路养护维修至关重要。传统路基沉降评价多基于沉降幅值单一指标，缺乏对车辆运营速度、路基沉降波长的综合考虑。该文基于建立的精细化多车-无砟轨道-路基耦合动力学模型，分析了路基不均匀沉降下的车辆动力学响应特征以及运营速度、沉降波长及幅值对车辆响应的影响规律，在此基础上提出了沉降时变率指标用于路基不均匀沉降评价。结果表明:沉降时变率能融合车辆运营速度、沉降波长、波幅三者对高速列车动力学响应的共同影响。沉降二阶时变率和轮轨垂向力、轮重减载率安全性指标呈显著的线性映射关系；沉降一阶时变率和车体加速度等舒适性指标呈较为显著的线性映射关系；并提出了轮重减载率、车体加速度与沉降时变率的拟合公式。研究成果可为高铁线路设计和养护维修提供参考。

THEORETICAL RESEARCH ON EVALUATION INDEX OF UNEVEN SETTLEMENT OF BALLASTLESS TRACK SUBGRADE BASED ON VEHICLE RESPONSE

Reasonable evaluation of uneven subgrade settlement is key to ensuring the long-term safe operation of high-speed railways and guiding the meticulous maintenance and repair. Traditional roadbed settlement evaluation is mostly based on a single index of settlement amplitude, which lacks the comprehensive consideration of vehicle operating speed and subgrade settlement wavelength. A refined multi-vehicle-ballastless track-subgrade coupled dynamic model was established, and the dynamic response characteristics of vehicles under uneven settlement of subgrade were analyzed, which accounted for the influence of operating speed, settlement wavelength and amplitude on vehicle response. The time-varying rate of settlement index was proposed for the first time in the evaluation of uneven settlement. The results show that the time-varying rate of settlement can integrate the common effects of vehicle operating speed, settlement wavelength and wave amplitude on the dynamic response of high-speed trains. The second-order time-varying rate of settlement has an obvious linear relationship with the wheel-rail vertical force and the safety index of wheel load reduction rate; the first-order time-varying rate of settlement and the vehicle acceleration show obvious linear relationship. Finally, the fitting formulas of wheel load reduction rate, vehicle acceleration and time-varying rate of settlement were put forward respectively. The research results can provide a theoretical reference for the maintenance of high-speed railway lines.