Release of the way - this is a serious threat to railway transport.Can cause injury to passengers.And in case of such an event on the movement web site is closed.So what is it and what is due?
Official statistics
According to official data of the Department of Rails and Structures of the Ministry of Railways from 1998 to 2001, nine derailments of trains on the Volga, East Siberian, North Caucasus, Moscow and South-East roads were caused by the release web site under the train.All the crash occurred in the period from noon to 16 hours from April to September.
strain comes from the types of constructions welded rails, rails P65.Under the cloth lay concrete sleepers, crushed stone ballast.The accident occurred on straight stretches of road, and there were only two cases in circular curves with a radius of 400 to 650 m.
For a full analysis of the reasons for the collapse of the necessary information about the technical condition of the track and rolling stock units, derailed.The materials of the Ministry of Railways of the data is not present.However, it is important that the release of the path occurs at the end of the train, but not in front of him, and all gatherings of cars is precisely for this reason.
These examples indicate that the crash of trains because of this can happen in the future.Measures should be taken to prevent the emission path of a train.
Emission way - what is it?
There are several kinds of faults of railway track: output, distortion, splash, theft.
Release of the way - is the result of increasing the voltage rails and spontaneous discharge.Thermal stress - is a type of stress that occurs in uneven temperature distribution.In a solid, such stress occurs because of the limited capacity expansion or compression of other bodies.In particular, the lengthening or shortening of the rail joint lining and prevent resistance in the bearings.
When heated, the length would be increased by a certain amount in accordance with the coefficient of thermal expansion of steel.Accordingly, it would decrease with decreasing.For these structural changes are provided gaps between the rails.If the deformation of the more recent stretch or closed.Thus, the winter can cut butt bolts, summer - a violation of the stability of rail grid.
temperature emission path - a sharp, for a time of about 0.2 seconds, the curvature of the rails in several waves of 30 to 50 cm, which takes place in a horizontal plane at a distance of 40 m. At the same time scattered rubble of the split sleeper.The rails are unsuitable for further use as acquire permanent deformation.
How to avoid?
To prevent ejection jointless track temperature conditions must be observed when laying railway tracks.Thus, the size of the gap to be butt-mounted in strict dependence on the heating of the web.In the middle part of the continuous welded rail track whip stationary.Only the ends can be shortened or lengthened.Voltage which occurs in the stationary part of the rail is independent of the length or type of rail.
It causes changes in temperature.For this reason, it is necessary to fix the rail lashes given temperature range.The latter depends on the stability and strength of the rail path.The allowable stresses of compression and tension correspond to changes in temperature.There are special formulas, which can determine the minimum and maximum temperature.Work must be carried out at a rail which corresponds to the upper third of the calculated interval.If the conditions differ from the optimal length of a rail lash changes forced hydraulic tensioner.Thus rail is injected into the desired temperature.
Conditions to
If the calculated temperature range is less than 10 ° C or negative, the subsequent use of the railway line is only possible with periodic detente.
To do this, you must attach equalizing whip.In such designs, the rails may be periodically replaced by longer or shorter.You can also use the equalizing devices.
Research
The world saw the release of the path of unity.People already facing its consequences.In Russia, one of the departments of the Samara Pgups built and passed the test stand on which students can practice to simulate the release of the path, which is very important for the study of this devastating phenomenon.University training ground includes a rail track length of 70 m radius curve of 400 m. With the help of hydraulic cylinders you can create a load of up to 300 tons, set various deviations in the content of the railway track and fix, under any load conditions and emission occurs.When this process takes place on the actual design.
