针对现有的国内外研究成果均未考虑40 t轴重荷载作用下的隧道基底结构动力响应特征及累积损伤特性,利用有限元软件ABAQUS建立隧道-围岩耦合二维计算模型，结合隧底围岩累积损伤机制与隧底混凝土结构的损伤塑性特性，对行车速度为120 km/h、40 t轴重的重载列车荷载作用下单线有砟隧道隧底衬砌结构主要设计参数进行研究。结果表明：
随着列车轴重的增加，隧道底部围岩逐渐出现损伤，尤其当轴重为40 t时，隧底结构出现明显的损伤效果；改变矢跨比与填充层厚度对仰拱竖向位移影响不大，随着矢跨比的减小，仰拱结构拉应力在不断增大，且矢跨比分别小于1∶6和1∶7后，仰拱结构拉应力增大明显；随着填充层厚度增加，隧道仰拱结构拉应力不断减小，当填充层厚度大于1.3 m时，这种减小的趋势逐渐变缓；在关键参数建议取值条件下的隧底二次衬砌结构疲劳寿命均符合要求。
The dynamic response characteristics and cumulative
damage characteristics of the base structure under 40 t axle load had not been
considered in existing research results in China and abroad, hence, a twodimensional
numerical model of tunnelsurrounding rock coupling is
established by using software ABAQUS. Based on the cumulative damage mechanism
of the surrounding rock and the damage plasticity of the concrete structure at
the bottom of the tunnel, the main design parameters of the lining structure at
the bottom of the singletrack ballasted tunnel under
the load of heavyhaul train with the traveling speed
of 120 km/h and 40 t axle load are studied. The results show that: (1) With the
increase of train axle load, the surrounding rock at the bottom of tunnel is
gradually damaged, especially when the axle load reaches 40 t, the damage
effect of tunnel bottom structure is obvious. (2) The variations of the spantospan ratio and the thickness of the
filling layer affect the vertical displacement of the inverted arch little;
with the decrease of the spantospan ratio, the tensile stress of the inverted arch structure
continues increases, and when the spantospan ratios are less than 1∶6 and 1∶7, respectively, the tensile stress of the inverted arch structure
increases significantly. (3) With the increase of the thickness of the filling
layer, the tensile stress of the inverted arch structure of the tunnel continuously
decreases, and when the thickness of the filling layer is greater than 1.3 m,
the decreasing trend gradually slows down. (4) Under the condition of
recommended key parameters, the fatigue life of the tunnel bottom lining
structure can meet relevant requirements.
