Research On The Causes And Repair Of Track Damage During Hump Area On A Marshalling Yard

Due to the increasing of railway freight in China,the carrying capacity of the marshaling station gradually exceeds its design capacity.As a result,track damage in hump occurs frequently.In this paper,we classified varied damages after practical investigation,and analyzed how the vehicle load affected the track and why those damages occurred.Besides,we explored the best measure for track repair.The main research contents and conclusions are as follows:(1)Practical investigation shows that rail ditch crushing,sleeper cracking,sleeper looseness,concrete shoulder cracking and slab cracking are main damages on hump track.(2)In this paper,we establish a finite-element track model to analyze how the vehicle load affect the track.The results show that unfixed rails in decelerating line warp upwards more than 3mm when a train enter or exit the line.Due to the vehicle load,rails move downwards 1.6mm,and sleepers under wheels take up more than 80%load.Due to worn rubber pads,the increase of the vertical stiffness will cause higher pressure for rail ditches.As a result,the interfaces between sleepers and slabs crack,so the vertical stiffness is not allowed more than 92 k N/mm when the wheel-force doubles.The affordable force of a single concrete shoulder is 9.1k N in the decelerating line.Large lateral wheel-rail force and worn rubber pads lead to shoulders cracking.Because of worn rubber pads,the decelerating line’s lateral supportability decreases 12～15%.(3)Based on the finite element method,we establish a track model to analyze how vehicle load and temperature affect the repair material.The results show that the appropriate thickness of the repair material is more than 40 mm,and the appropriate elastic module is less than 1GPa.It is much better to repair the track when the temperature is 15 degrees.(4)In order to find the best way to repair the concrete shoulder during the decelerating line,a shoulder model is established.The analytical results show that the best way is using three 4cm long rebars with a radius of 2.5mm and putting them at the point which is 40 mm away from the rail ditch.Supportability of reinforced concrete shoulder increases 30% after repair.