Railroad ejection

The throwing of the way is a serious threat to the railway transport. Passengers may suffer. And in the event of such an occurrence, movement on the section of the canvas is closed. So what is it and what is it connected with?

Official statistics

According to official data of the Department of the ways and structures of the Ministry of Railways of the Russian Federation, from 1998 to 2001, nine train wrecks in the Volga, East Siberian, North Caucasian, Moscow and South-Eastern roads occurred due to the ejection of the canvas section under the trains. All the wreckage occurred in the period from noon to 16 hours from April to September.

Deformations occurred with the standard designs of the weldless path, R65 rails. Under the canvas lay ferro-concrete sleepers, crushed stone ballast. Accidents occurred on straight sections of the road, and there were only two cases on circular curves with a radius of 400 to 650 m.

For a full analysis of the causes of the crash, you need information about the technical condition of the track and the units of the rolling stock that have come off the rails. In the materials of the Ministry of Railways of the Russian Federation there is no such data. However, what is important is that the ejection of the road took place at the end of the train, and not before it, and all the wagon congestions occurred precisely for this reason.

The above examples show that the wreck of the railroad train because of this can happen in the future. It is necessary to take measures to prevent emissions of tracks under the trains.

The throwing out of the path - what is it?

There are several types of railway track malfunction: ejection, skew, splash, hijacking.

The ejection of the path is the result of an increase in the voltage in the rails and its spontaneous discharge. Temperature stress is one of the types of mechanical stress that occurs when the temperature distribution is uneven. In a solid, such stress arises because of the limitation of the possibility of expansion or contraction from other bodies. In particular, the lengthening or shortening of the rail is hampered by the joint flaps and the resistance in the supports.

When heated, the length would increase by a certain amount in accordance with the coefficient of thermal expansion of the steel. Accordingly, it would decrease with decreasing. For such changes, design gaps between the rails are provided. If the deformations are greater, the latter are stretched or closed. Thus, in winter it is possible to cut off the butt bolts, in the summer - a violation of the stability of the rail-grinding lattice.

The temperature ejection of the path is sharp, during a time of about 0.2 seconds, the curvature of rails by several waves from 30 to 50 cm, which occurs in the horizontal plane at a distance of up to 40 m. Simultaneously, rubble is scattered, a part of the sleepers is split. The rails become unsuitable for further operation, as they acquire residual deformation.

How to avoid?

To prevent the ejection of a continuous welded path, it is necessary to observe the temperature regime when laying the tracks. Thus, the size of the butt gap should be set in strict accordance with the heating of the web. In the unshielded way, the middle part of the rail whip is stationary. Only the ends can shorten or lengthen. The voltage that occurs in the fixed part of the rail does not depend on the length or type of the rail.

Its change causes temperature. For this reason, the rails need to be fixed to the temperature interval. The latter is calculated depending on the stability of the track and the strength of the rail. Allowable compression and tension stress correspond to temperature differences. There are special formulas for determining the minimum and maximum temperatures. Work should be done at the rail temperature, which corresponds to the upper third of the calculated interval. If the conditions differ from the optimal ones, the length of the rail is changed by a forced hydraulic tensioner. Thus, the rail is inserted into the desired temperature regime.

Unfavourable conditions

If the calculated temperature range is less than 10 ° C or negative, the subsequent use of the railroad cloth is possible only with periodic discharges of voltage.

For this, it is necessary to fix equalizing whips. In such designs, the rails can be periodically replaced with longer or shorter ones. Equalizing devices can also be used.

Research

In the world, one saw the ejection of the path. People are already confronted with its consequences. In Russia, at one of the departments of the Samara State Unitary Enterprise, a test stand has been built and tested, in which students can simulate in practice a pathway that is very important for studying this destructive phenomenon. The training ground of the university includes a 70 m long railway track with a curve of 400 m. With the help of hydraulic cylinders, it is possible to create a load of up to 300 tons, to set various deviations in the content of the railway track and to record under what loads and conditions the release occurs. In this case, the process takes place on a real design.