Expansion track--Cause & Treatment
Feb 23, 2023| 1. Cause
The basic causes of rail expansion are line creep and rail gap blinding; There are hard curved tracks on the track, which are poor in level and direction, and the resistance of track bed is greatly reduced. Overtemperature operation in various maintenance and repair operations, too long uncovering track bed, too high track lifting amount, incomplete operation and low locking track temperature of jointless track are all the causes of track expansion.
2. Judgment
When the temperature stress of the rail increases continuously, the line will slowly appear transverse deformation, which is the rail expansion stage. When the temperature stress of the rail continues to increase and exceeds the critical value, the rail will suddenly swell with a huge sound in an instant, that is, the so-called runway phenomenon occurs.
3. Emergency treatment of track expansion runway
In case of track expansion on the line, the station shall be notified immediately, the train shall be slowed down or stopped, the protection shall be set, and emergency measures such as watering to cool down and track shifting shall be taken quickly.
Operation procedure:
(1) Ballast is stacked on the track pillow.
(2) From 50~100 m at both ends of the expansion section, slowly pour cold water to the middle to reduce the rail temperature (it is better to cover the rail surface with straw bags or white cloth to facilitate water absorption and cooling); After the rail temperature drops, the bulged part shall be rejected to the original position, and the ballast shall be added, and the section of the roadbed shall be added.
(3) Set the curve to slow through the train, and set the curve with radius not less than 200m from both ends of the expansion rail to the center. If the reverse curve is set, the straight line between the two curves shall not be less than 10m. After setting, the ballast shall be backfilled and the tamping shall be strengthened.
(4) When releasing the first train, the speed should not be greater than 5Km/h, and someone should be assigned to guard it.
Under difficult conditions, acetylene can be used to cut the rail, loosen the fastener to release the stress, reinforce it with splints and first-aid equipment, operate at a speed limit of 5 Km/h, and assign a guard.
4. Technical standards to be met after treatment of expansion track
(1) The track gauge is set according to the standard track gauge. The straight section is 1435mm, and the curve section is widened as required. The allowable error of track gauge is+6, - 2 mm.
(2) The top surface of the two rails of the line shall be kept at the same level in the straight section, and the superelevation shall be set for the outer rail of the curve section according to the regulations. The allowable error of the level of the two rails of the line is ± 4mm for the main line and the arrival-departure track, and ± 5mm for other station tracks.
(3) The allowable error of line direction shall be in accordance with Article 5.1.2 and 5.1.3 of the Maintenance Regulation.
(4) The radius of the temporarily aligned curve shall not be less than 200m, and the intermediate straight line between the reverse curves shall not be less than 10m.
5. Measuring tools and tools required for handling expansion track
Measuring tools required: universal track ruler, steel ruler, wooden folding ruler, rail gap ruler
Tools required: hydraulic diverter, bucket, watering can, crowbar, adjustable wrench
6. Safety protection when handling expanded track runway
When the line worker or patrol worker finds that the failure of the track expansion runway endangers the running safety, in addition to immediately sending out the alarm signal and using the stop hand signal protection, he should also take emergency measures to try to repair it, and quickly notify the station and the foreman or the foreman with the interphone, and set the deceleration or stop signal protection when necessary to slow down or stop the train operation. When it is difficult to deal with it for a while, it is strictly forbidden to put the car at risk.