Research on longitudinal service condition monitoring of small resistance fasteners on long-span connecting bridge continuously welded rail based on machine vision
The Fuxia High speed Railway Yuxi Extra Large Bridge was taken as an example,and a monitoring scheme based on machine vision for the longitudinal service condition of small resistance fasteners was proposed to obtain the time-varying characteristics of longitudinal deformation of continuous welded rail and leakage of composite pad on long-span connecting bridge;Meanwhile,based on the experimental results of beam rail temperature and beam end displacement,the correlation between beam body temperature,rail temperature,cumulative beam end displacement,beam-rail relative displacement,and the leakage of composite pad was analyzed.The results show that according to the image recognition results,the rail will undergo different directions of expansion and contraction with temperature changes during the monitoring period,and the displacement of the rail is slightly greater than the displacement of the composite pad.The temperature difference between day and night of the rail is significantly greater than the bridge deck temperature,the air temperature in the continuous beam,the top plate temperature,and the web temperature,and the temperature change amplitude of the beam body is significantly smaller than that of the rail,the reason is that the specific heat capacity of the rail is smaller,and the temperature change amplitude is large when the same heat input and output occurs.The longitudinal displacement of the beam end varies slightly with temperature,with a maximum daily displacement of 0.15 mm.During the monitoring period,the cumulative displacement at the end of the beam shows a fluctuating decreasing trend,indicating a slow contraction of the beam body.The reason is that the temperature gradually decreased from summer to autumn,and the maximum average displacement change rate is 0.09 mm/d.The correlation coefficients between the temperature of the beam body,the temperature of the rail,the accumulated displacement of the beam end,the accumulated beam-rail relative displacement,and the leakage of composite pad are all greater than 0.8,indicating a significant correlation and a great positive correlation.By using a machine vision based method for monitoring the condition of small resistance fasteners,it can be seen that the small resistance fasteners have good longitudinal service status in the section of the Fuxia High Speed Railway Yuxi Extra Large Bridge,and the railway line status is normal during the monitoring period,verifying the applicability of this type of scheme in on-site monitoring of small resistance fasteners.
long-span connecting bridgecontinuously welded railmachine visionsmall resistance fastenerlongitudinal service
万方数据
维普
