The Impact Of Unballasted Track Construction Sequence On Multiline Cable-Stayed Bridge Track Regularity

On the Multiline and long-span bridges, due to unballasted track’s site construction, track weight imposed to beam surface gradually. When track weight is large and bridge span is longer, the beam surface will appear gradually larger changed flexural deformation. Because of unballasted track’s construction features, before the start of construction, track-plates must be fixed and leveling. But after the completion of construction, the fundamental part of track can not be adjusted. Therefore, when one segment is constructing, the flexural deformation produced by track’s weight will impact on the track geometry of completed segment. The resulting track irregularity, which is equivalent to initial irregularity (increasing maintenance difficulty and costs in day-to-day operations), is almost inevitable, and after the construction is completed, it is difficult to have better measures to solve. In summary, for the unballasted track’s construction on the Multiline and long-span bridges, analysis on the impact of track’s loads and construction’s sequencing is necessary. Taking into consideration of all the possible construction plans and evaluating the pros and cons, in order to formulate a more reasonable construction plan.This article select a Multiline, long-span, double-layer, steel-truss and cable-stayed bridge as an example. First, according to the bridge’s actual situation, set up several possible construction plan, using the finite element analysis software to establish a analysis model, and computational analyzing the impact of various unballasted track forms under different construction programs on track linear; Second, combined vehicle-track coupling dynamics to establish analysis model, computational analyzing the impact of various unballasted track forms under different construction programs on vehicle-track’s dynamic characteristics, at the same time, from the view of the railway engineering affairs, borrowed track quality status evaluation method to comparative analyze the track irregularity generated by construction, and evaluated different construction programs from two aspects(dynamics and railway engineering affairs); Finally, summarized research works of this paper, and draw some valuable conclusions and recommendations.