基于行车试验的高铁路基面动应力幅值概率分布规律及设计值研究

Probability distribution law and design value of dynamic stress amplitude on subgrade surface under high-speed railway train load

高速列车荷载作用下路基动应力的大小直接影响到路基沉降变形及长期动力稳定性,现很多高铁线路路基动力响应数据仍处于“信息孤岛”状态,信息共享不充分和综合再分析不够,较难获得更具普遍意义和价值的路基动应力响应规律。鉴于此,采用现场实测、调研收集和数理统计分析的方法研究高速列车荷载作用下路基面动应力大小及概率分布规律,探讨《高速铁路设计规范》中路基面设计动应力幅值计算公式的适应性,并提出高铁路基面设计动应力幅值的计算公式。主要结论如下:(1)高铁无砟、有砟轨道路基面动应力幅值均服从正态分布,并统计获得了其特征值(均值μ、标准差δ,“3δ规则”的上下限值);(2)路基面动应力幅值与列车速度的关系:对于高铁无砟轨道,当v≥150km/h,路基面动应力幅值基本保持不变;当v≥150km/h时,动应力幅值随速度线性增加。对于高铁有砟轨道,动应力幅值随速度增大而线性增加。高速无砟、有砟轨道路基面动应力幅值的速度影响系数α分别为0.0015和0.0012;高铁无砟铁路轴重系数β=0.074,约为普通和高速有砟铁路β值的1/3~1/2;(3)提出高铁无砟、有砟轨道路基面设计动应力幅值计算公式分别为σ_(dl)=0.119P,v<150km/h,σ_(dl)=0.119P[(1+0.0015(v-150)],v≥150km/h(无砟)和σ_(dl)=0.27P(1+0.0012v)(有砟)。研究成果可为高铁路基设计参数取值提供参考及其设计动应力幅值计算公式的修订提供依据。

The settlement and long-term dynamic stability of earthworks are directly and significantly affected by the subgrade dynamic stress under high-speed train load.The data of dynamic stress amplitude(DSA) from the field test and the published literatures were obtained and analyzed by mathematical statistics.Probability distribution of DSA was studied and formula of design dynamic stress amplitude in Code for Design of High Speed Railway was discussed.The new calculation formula of design dynamic stress amplitude was presented.The main conclusions are as follows:(1) The distributions of DSA for subgrade surface of ballasted and ballastless track obey the normal distribution,and the characteristic values such as mean value,standard deviation and the upper/lower limits are statistically obtained.(2) For high-speed railway of ballastless track,when v<150 km/h DSA of subgrade surface basically remains constant,while when v≥150 km/h it increases linearly with the increase of speed.For high-speed railway of ballasted track,DSA increases linearly with the increase of speed.In addition,the speed influence coefficients α of DSA are 0.0015 and 0.0012,respectively,for subgrade surface of high-speed railway of ballastless and ballasted track.The axial load coefficientβ for ballastless track is 0.074,which is about 1/3~1/2 that of ballasted track.(3) The calculation formulas of design dynamic stress amplitude σ_(dl) can be expressed as follows:For ballastless track,v<150 km/h,σ_(dl)=0.119P;v≥150 km/h,σ_(dl)=0.119P[(1+0.0015(v-150)].For ballasted track,σ_(dl)=0.27P(1+ 0.0012v).