Abstract: Taking the three-hole 32.0 m standard span prestressed simply supported box girder of a ballastless track-bridge on Shanghai-Kunming high-speed railway as the research object, a multi-section and multi-structure monitoring system was established to carry out the dynamic response test of the ballastless track-bridge structure, and to study the dynamic response law and the track structure-bridge coordinate deformation characteristics of the ballastless track-bridge structural layers at different driving speeds. The results show that: the vertical vibration acceleration of the beam of the prestressed simply supported box girder increases with the increase of train speed when the traveling speed is 290~350 km/h and reaches the peak at 320~340 km/h. The vertical and lateral accelerations of each stratum structure in the beam show a progressively decreasing trend from top to bottom, and the vibration attenuation is significant. There is no obvious correlation between vertical dynamic displacement of the measured points in the mid-span and 1/4-span of the beam body and the driving speed, and vibration deformation meets the requirements of specifications. The relative dynamic displacement between the track plate and the base plate is much greater than that between the base plate and the deck plate, and the vertical relative dynamic displacement is both greater than the lateral relative dynamic displacement. Under the condition of long-term dynamic cyclic loading and unloading, this kind of relative dynamic displacement may cause large plastic cumulative deformation, which should be paid attention to.

Key words: bridge engineering, ballastless track-bridge structure, monitoring test, dynamic response, coordinated deformation

摘要： 以沪昆高铁某无砟轨道-桥梁的三孔32.0 m标准跨径预应力简支箱梁为研究对象，建立多断面多结构监测系统开展无砟轨道-桥梁结构动力响应测试，研究该无砟轨道-桥梁各结构层在不同行车速度下的动力响应规律及轨道结构-桥面协调变形特性。研究结果表明：在行车速度为290~350 km/h情况下，该预应力简支箱梁的梁体跨中竖向振动加速度随着列车行车速度的增大而增大，在行车速度320~340 km/h之间达到峰值；梁体跨中各结构层的竖向、横向加速度从上至下呈现明显的逐级减小趋势，振动衰减明显；梁体跨中及1/4跨测点竖向动位移与行车速度没有明显相关关系，振动变形满足规范要求；轨道板-底座板间相对动位移远大于底座板-桥面板间相对动位移，竖向相对动位移均大于横向相对动位移，在长期动力循环加卸载条件下，此种相对动位移可能引起较大的塑性累积变形，应予以重视。

关键词: 桥梁工程, 无砟轨道-桥梁结构, 监测试验, 动力响应, 协调变形