The Study On Derailment Mechanism And Countermeasures Of No.6 Symmetrical Turnout Under Hump Of Marshaling Station

Derailments in symmetrical turnouts occurred randomly in recent years.These derailment occurrences disturbed operation and increased maintenance quantities significantly.The derailment can not be avoided absolutely by track geometry maintenance and layout optimization.The common features were obtained by typical derailment cases analysis.The derailment mechanism in turnout was analyzed by quasi-static contact theory.The analysis results showed that the contact patch between flange and switch rail was close to flange top,and the contact angle was obviously smaller than normal when wheelset entries turnout in facing way.Derailment coefficient in the range from switch toe to section with 15 mm width is smaller than plain track,which lead to derailment risk.Adverse contact features are the root cause of derailment in number 6 systematic turnout.The dynamic coupling model of vehicle/turnout was put forward.Taking lifted wheelset height as analysis index,the influences of vehicle,turnout on derailment risk were analyzed.The analysis results showed that derailment risk can be reduced by decreasing switch rail machined depth,reducing entry angle,improving track elasticity,maintaining elastic axle box positioning,lubricating switch and installing tangent track of 3m can reduce derailment risk.Through theoretical simulation analysis and dynamic experiment,four main countermeasures for preventing derailment were presented,such as adding derailment prevention device in turnout zone,optimizing the matching relationship between the switch and stock rails,reducing the lateral stiffness of track structure,and controlling the friction coefficient of rail surface.To avoid the contact status of wheel flange touching the switch toe,the wheelset lateral shift should be constrainted by new anti-derailment device.The minimum flangeway of new anti-derailment device is50 mm,the new anti-derailment device should be adjusted when flangeway reaches54 mm.The parallel length of new anti-derailment device is 600 mm,which starts in front of switch rail toe,ends at at the location switch rail with 10 mm width.The flangeway in flare is 80 mm the maximum flangeway at the opening is 95 mm.The dynamic test and long-term inspection show that new anti-derailment device can protect the wheel flange from contacting switch rail with less than 20 mm width to avoidderailment occurrence.75figures,12 tables,47 references...