Research On Anti-creeping Technology Of CWR Track On Open Deck Of Large Span Steel Truss Bridge

Steel truss bridge is an important equipment across river gorge on existing railway line in our country.Due to the early construction age,it is difficult to upgrade to track structure with strong anti-creeping ability such as ballasted track and slab ballastless track.In the operation of steel truss bridge open bridge deck,especially in the large span steel truss bridge open bridge deck,the phenomenon of steel rail creeping still often occurs.The research on anti-creeping technology of CWR track of open deck of large span steel truss bridge can reduce the investment of human labor and machine in regulating rail creeping,ensure the quality of line equipment on bridge,guide equipment management unit maintenance and maintenance of open deck track,and ensure the normal operation of trains,which has important practical significance.This paper analyzes the main defects of open deck of long span steel truss bridge in Shanghai Bureau and the status quo of rail creeping.Based on the indoor test and finite element calculation results of the longitudinal resistance of fastener,the causes of creeping of the the CWR track on the open deck of Wuhu Yangtze River Bridge of Huainan Line in the bureau are analyzed.Through theoretical analysis and field test laying,the anti-creeping technology of CWR track on open deck of long span steel truss bridge is studied.The main research conclusions are as follows:(1)Due to the increase of axle weight and running density of trains,the difficulty of replacing wooden pillows and fastener on open bridge deck,and the long service time,four major diseases such as wooden pillows injury,fastener disease,hanging plate disease and rail expansion regulator disease appear on open bridge deck CWR track of long-span steel truss bridge.The CWR track of open bridge surface of Wuhu Yangtze River Bridge has serious creeping,and the creeping section is in the downhill braking section with adjustable gauge K type fastener.(2)The lack of longitudinal resistance of adjustable gauge K type fastener is the main reason for the creeping of CWR track on open bridge deck.The test results show that when the nut torque is 80 ～ 140 N·m,without nylon shoulder pad,the measured longitudinal resistance value of adjustable gauge K type fastener is 50% ～ 78% of that of non-adjustable gauge K type fastener.When the nut torque is 80 ～ 120 N·m,without nylon shoulder pad,the measured average longitudinal resistance of adjustable gauge K type fastener and non-adjustable gauge K type fastener are 5.23 k N and 7.75 k N respectively.(3)The finite element calculation results of the adjustable gauge K type fastener show that when the nut torque is 80 ～ 140 N·m,the stress state of the gauge block and the rail of the adjustable gauge K type fastener is normal and meets the strength requirements;When the torque of the nut is 140 N·m,there is stress concentration at the contact point between the rail clamp and the double spring washer,and the stress there is greater than the yield strength,which does not meet the strength requirements.The torque of adjustable gauge type K type fastener nuts is recommended to be no more than140 N·m.(4)The long rails EJ1 ～ EJ3 and EJ3 ～ EJ5 of the rail expansion adjusters of the open deck of Wuhu Yangtze River Bridge crawl abnormally,which is mainly caused by the low longitudinal resistance of the adjustable gauge K type fastener.The following measures can effectively prevent rail crawling on the open deck of Wuhu Yangtze River Bridge:(1)The longitudinal resistance of the line reaches 15.4k N/(m· rail)when the adjustable gauge K-type fasteners are arranged in full tightness,which is equivalent to the longitudinal resistance of the line when the non-adjustable gauge K-type fasteners are arranged in 1(tight)-1(loose)-1(tight),which can effectively prevent rail crawling.(2)Under the condition that the site tightness configuration is not changed,the heavy spring washer is used to replace the standard double spring washer for the adjustable gauge K-fastener,and the 8.8S class high-strength T-bolt pair is used to replace the existing ordinary T-bolt pair.When the nut torque is screwed to 150 ～ 200 N·m,the longitudinal resistance of the adjustable gauge K-fastener is 93% of that of the non-adjustable gauge K-fastener.Can effectively prevent rail creep.(3)The design requirements should be strictly implemented when the CWR track of the open deck of the large-span steel truss bridge is laid.After laying,the maintenance quality should be ensured from the aspects of fasteners,rail expansion regulator,anti-climbing equipment,rail protection,inspection and monitoring,so as to provide a strong guarantee for effectively improving the anti-climbing ability of the line.