压路机激励下重载铁路路桥过渡段动力特性研究

以蒙华重载铁路某路桥过渡区为试验对象,开展压路机激励下过渡区的动力特性试验,研究过渡区动力响应的分布规律;建立考虑振动轮-路基耦合的动力分析数值模型,研究过渡区等效刚度分布及振动轮-路基面接触力变化特性。结果表明:随着路基深度增大,动应力扩散角逐渐减小,埋深0.2~3.0 m处扩散角在78.2°~55.0°,倒梯形过渡段动应力扩散角要大于一般路基扩散角;相比列车荷载,压路机激励引起的竖向动应力在路基中衰减更快,并且在基床表层中衰减最大;压路机驶离桥台方向的基床表层动侧压力系数为0.35~0.53,驶向桥台方向为0.24~0.36,倒梯形过渡段的动侧压力系数要小于一般路基段;过渡段路基等效刚度在74.8~87.2 kN/mm,随离桥台距离增大而呈线性减小趋势;振动轮激励过程中,过渡段内的振动轮-路基面最大接触力峰值比一般路基段大,且随着过渡区刚度差的增大而增大。

A study on dynamic characteristics of a subgrade-bridge transition section of a heavy haul railway under the excitation of a roller

Dynamic response field tests of a subgrade-bridge transition zone in the Menghua heavy haul railway were carried out to investigate the distribution of dynamic stress,dynamic displacement and vibration acceleration in the transition zone.Subsequently,a 3D FEM model considering the coupling vibration of roller-subgrade was established to study the equivalent stiffness distribution along the transition zone and the contact force response between the roller and subgrade surface.The results show that with the depth of subgrade increases,the diffusion angle of dynamic stress gradually decreases,the diffusion angle of the subgrade depth between 0.2-3.0 m is 78.2°-55.0°,and the diffusion angle of the inverted trapezoidal transition is larger than that of the general subgrade.Compared with the train load,the vertical dynamic stress caused by the excitation of the roller is attenuated faster in the subgrade and the attenuation is the largest in the surface layer.The dynamic lateral pressure coefficient in the surface layer is 0.35-0.53 in the direction of the roller leaving the abutment,and the direction toward the abutment is 0.24-0.36.The dynamic lateral pressure coefficient of the inverted trapezoidal transition is smaller than that of the general subgrade.The equivalent stiffness of the transition section is between 74.8-87.2 kN/mm,which decreases linearly with the distance from the abutment.During the vibration wheel excitation process,the peak of the maximum contact force of the roller-subgrade surface in the transition section is larger than that of the general subgrade section,and the maximum contact force peak of the transition section increases with the stiffness difference of the transition zone.