无砟轨道涵洞过渡段路基膨胀引起的轨道上拱响应

Response of Track Arching Caused by Subgrade Expansion in Culvert Transition Section of Ballastless Track

以我国西北地区某客运专线3处典型路涵过渡段轨面高程异常工点为研究对象,基于现场监测及数值模拟,进行无砟轨道涵洞过渡段路基膨胀引起轨道上拱响应研究。结果表明:引起无砟轨道涵洞过渡段轨面异常上拱的主要原因是过渡段路基表面地表水渗入填料导致的路基膨胀;涵洞等过水构筑物对于钢轨上拱位移的传递具有一定的抑制作用,具有直立墙身的盖板涵和预制箱涵抑制效果最为明显;路基膨胀引起的上拱段钢轨轴向应力沿线路走向分布是压应力区过渡到拉应力区,再过渡到压应力区,同时涵洞对于钢轨上拱位移传递的抑制作用会引起上拱回落区域产生轴向应力的突变和放大效应。

Taking 3 typical rail surface elevation abnormal work sites in the roadbed-culvert transition section of a certain passenger dedicated line in Northwest China as the research object, based on field monitoring and numerical simulation, the response of track arching caused by subgrade expansion in the culvert transition section of ballastless track was studied. Results show that the main cause for the abnormal arching on the rail surface in the culvert transition section of ballastless track is the subgrade expansion caused by surface water permeating into the filler on the embankment surface. Overwater structures, such as culverts, have a certain inhibitory effect on the transfer of rail arching displacement, and the slab culvert and prefabricated box culvert with vertical wall body have the most obvious inhibitory effect. The distribution of the rail axial stress in the arching section caused by the subgrade expansion along the line is the transition from compressive stress zone to tensile stress zone and then to compressive stress zone. At the same time, the inhibitory effect of the culvert on the transfer of rail arching displacement will cause abrupt change and amplification effect of the axial stress in the fallback area of rail arching.