30t轴重下隧底密实度对隧底结构受力的影响及隧底加固效果分析

Analysis of the Influence of Tunnel Bottom Compactness on Structure Stress and Strengthening Measures under 30t Axle Load Train

针对朔黄铁路某隧道隧底不密实病害,分析了隧底不密实病害的主要成因。提出采用聚氨酯树脂填充隧底吊空等不密实处以及固结虚砟的隧底加固方案。采用有限元软件ANSYS建立数值分析模型,以Ⅴ级围岩隧道为例,借助于现场实测30t轴重列车轮轨力时程曲线,分析隧底不同密实度以及加固后的隧底结构动力响应。结果表明:在取Ⅴ级围岩弹性模量的中值1.5GPa作为隧底密实度标准值的条件下,30t轴重列车通过隧底密实度仅为标准值的7%的隧道时,其隧底结构产生最大为1.05 MPa的拉应力,隧底结构的应力水平超过0.5ft(ft为计算混凝土抗拉极限强度,取2.01 MPa),从而导致隧底结构的疲劳问题;采用聚氨酯树脂对隧底结构加固后,隧底结构的应力水平降低至0.13ft,消除了疲劳破坏的隐患,而且隧底结构的振动加速度也得到明显的降低,验证了采用聚氨酯树脂的加固方案适宜于重载铁路隧底的加固。

In allusion to the disease that a certain tunnel bottom of Shuohuang Railway is not dense, the main causes for such disease were analyzed and the consolidation methods of filling the voids in tunnel bot- tom with polyurethane resin and consolidating the empty ballast were put forward. The numerical analysis model was established by the finite element software ANSYS. With the surrounding rock grade V tunnel as an example, by means of the field measured time history curve of the wheel-rail force of 30 t axle load train, the dynamic response of the tunnel bottom structure of different density and after strengthening was analyzed. The results show that, if the median of 1.5 GPa in the elasticity modulus of the surrounding rock grade V is regarded as the Standard value for the compactness of tunnel bottom, when 30 t axle load train passing through the tunnel with the bottom compactness of 7% standard value only, the maximum tensile stress of tunnel bottom structure is 1.05 MPa and the stress level exceeds 0. 5 ft （ ft is the calculated ultimate tensile stress of concrete and the value is 2.01 MPa）, which results in the fatigue problem of tunnel bottom structure. After the tunnel bottom has been strengthened by polyurethane resin, its stress level is reduced to 0.13 ft and the hidden danger of fatigue failure is eliminated. Moreover, the vibration acceleration is significantly reduced. The strengthening scheme with polyurethane resin has been validated suitable for the tunnel bottom of heavy haul railway.