Effect Of CPâ…¢ Position Variation On Track Geometry Measurement Of Bridge Section

The safe operation of the high-speed railway requires high-quality track regularity, so track geometry measurement is a basic work for the maintenance of high-speed railway. In the usual case, the free-station with total station use CPⅢ control points, which were set up along with the rail, and then the track geometry can be measured and documented by the track measurement trolley in concert with total station. For the seasonal temperature variation could be 60, the location of CPⅢ on the beam will change with the transverse displacement and longitudinal displacement of beam deformation. The variation of CPⅢ will have impacts on station of free-station, and then on track geometry measurement. Presently, there were some studies on the change of CPⅢ coordinates after the beam deformation of the concrete continuous beam and the steel truss girders. To this issue, different scholars came up with various solutions. The change of the beam width lead to the change of the relative position of a couple of CPⅢ. There is no study on the effect of the change of the same couple CPⅢ. This pervasive question not only exists in the concrete continuous beam and the steel truss girder section but in the simple beam section. The Widespread use of strategy having bridge instead of subgrade, makes the bridge account for a large proportion of the china high-speed railway. In this case this question has a significant impact on the maintenance of track alignment. It is very necessary to explore and analyze the influence of this question.In this study, the CPⅢ network and high-speed rail was simulated at first. Then the observation data of free station and the track geometry measurements were simulated under the changed position of CPⅢ that across different magnitude deformation. Through the analysis of the station coordinates, the track position and track regularity, this study discusses the effect of CPⅢ position variation on track geometry measurement of bridge section. In order to fully consider the actual situation of high-speed railway, this study takes into account the straight line bridge section, curve bridge section and roadbed-bridge transition section. It also analyzes the effect of observing with total stations in different precision.In the straight line bridge section and curve bridge section, the X coordinate (transverse displacement) of station will be under the influence of relative position changes of every couple CPⅢ in CPⅢ network, while the relative position change have no influence on the Y coordinate (longitudinal displacement) of station. And the transverse displacement have a variation of approximate proportion with the relative position change. The relative position change have a similar effect on the track. In roadbed-bridge transition section, the relative position change have impacts on longitudinal displacement of the station and track. Observing with total stations in different precision have no impact on the track geometry measurement.In roadbed-bridge transition section, with the number of the CPⅢ on the bridge which is involved in free station increasing, the influence of the relative position change on the X coordinate (transverse displacement) of station get larger. With two pairs of CPⅢ on the bridge and two pairs of CPⅢ on the roadbed, the Y coordinate (longitudinal displacement) of the station are influenced greatly. The relative position change of CPⅢ have a similar effect on the track.In the straight line bridge section, the relative position change of CPⅢ don’t affect track alignment irregularity derived by 30m and 300m baseline length; the affect mainly exist in the overlapping part between two neighboring station.