30 t轴重下重载铁路隧道隧底结构疲劳损伤研究

Study on Fatigue Damage of Tunnel Bottom Structure of Heavy Haul Railway Tunnel under 30 t Axle Load

鉴于重载铁路隧底结构疲劳损伤现象较普通客货共线铁路更加明显,根据现场调查对重载铁路隧底结构病害进行分类,并确定了影响其疲劳损伤的主要因素为重载列车长时间大轴重碾压。依托张唐铁路双线重载铁路隧道大型现场原位激振试验,得到了Ⅲ、Ⅳ、Ⅴ级围岩条件下道床结构表面的轴重列车附加动荷载分布规律,利用Ansys Workbench仿真软件对重载铁路隧底结构损伤分布及疲劳损伤进行模拟,并结合试验所得道床和仰拱结构的动应力验证其计算结果的准确性,结果表明:将实测所得动压力时程曲线作为Workbench动力初始条件进行疲劳损伤计算具有客观性,计算得出:随着围岩条件降低,隧底结构损伤范围及损伤程度逐渐增加;在相同围岩级别30 t轴重条件下隧底结构损伤出现的时间由上至下依次递增,且损伤程度逐渐降低。研究成果可为重载铁路隧道运营期长期服役性能研究及疲劳寿命预测提供借鉴和参考。

The fatigue damage of the bottom structure of heavy-haul railway tunnels is more obvious than that of the conventional passenger and freight railway.The disease types at the bottom of heavy-haul railway tunnels were classified according to field surveys,and the main factor causing the fatigue damage was determined as long time running of heavy haul trains with heavy axle load.Based on the large-scale in-situ excitation test in the tunnel of the Zhangjiakou-Tangshan double-track heavy-duty railway,the distribution law of the additional dynamic load of the train with 30 t axle load on the surface of the track structure under the conditions of ClassⅢ,ⅣandⅤsurrounding rock was obtained.The damage distribution and fatigue damage of the bottom structure of heavy-load railway tunnel were simulated with Ansys Workbench simulation software,and the accuracy of the calculation result was verified by the test.The results show that it is objective to use the measured dynamic pressure time history curve as the dynamic initial conditions to calculate the fatigue damage.The damage extent and damage degree of the bottom structure increase with the decrease of surrounding rock conditions.Under the conditions of the same surrounding rock and 30 t axle load,the occurrence time of the damage increases from top to bottom while the damage gradually decreases.The research results can provide reference for the research of long-term service performance and fatigue damage prediction of heavy-haul railway tunnel.