路桥过渡段基床填料膨胀诱发无砟轨道上拱规律研究

Heave response of ballastless track induced by subgrade filler swelling in bridge-subgrade transition section

无砟轨道路基膨胀诱发钢轨上拱是高铁建设运营面临的常见病害之一,路桥过渡段是路基膨胀病害的高发路段,为研究高铁路桥过渡段路基膨胀后钢轨上拱分布及路基结构变形规律。以一处典型过渡段路基膨胀工点为例,通过现场监测和室内试验判别轨道上拱情况及路基膨胀层位,并通过数值模拟计算研究路基基床膨胀对过渡段路基结构的影响规律。研究结果表明:水流下渗与基床填料中的蒙脱石作用是导致填料发生膨胀的主要诱因;桥梁对路基膨胀引起的钢轨上拱具有明显的阻隔效应,临近桥台侧钢轨上拱变化范围明显小于远离桥台侧;路桥过渡段基床填料膨胀率为0.08%时,钢轨上拱量达到无砟轨道钢轨上拱可调节临界值4 mm;临近桥台侧钢轨轴向应力峰值远大于远离桥台侧。

The rail heave induced by the swelling of the ballastless track subgrade is one of the common diseases faced by the construction and operation of the high-speed railway.The bridge-subgrade transition section is a high incidence position of the subgrade swelling disease.In order to study the distribution of the rail heave and the deformation law of the subgrade structure after the subgrade swelling in the bridge-subgrade transition section of the high-speed railway,a typical transition subgrade swelling site was taken as an example.The on-site monitoring and laboratory tests were used to find out the track heave situation and the subgrade swelling position.The effect law of subgrade swelling on the bridge-subgrade transition section structure was studied by numerical simulation calculation.The following results are obtained.The infiltration of water flow and the effect of montmorillonite in the subgrade filler are the main causes of the swelling of the filler.The bridge has a significant barrier effect on the rail heave caused by the swelling of the subgrade,and the range of the rail heave near the side of the abutment changes significantly smaller than the side away from the abutment.When the rate of subgrade swelling with road-bridge transition section is 0.08%,the amount of heave on the rail reaches the adjustable threshold value of 4mm on the arch of the ballastless track.The peak value of the axial stress of the rail near the side of the abutment is much greater than that of the side away from the abutment.