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The composition, development and advantages and disadvantages of the track are analyzed

SINCHOLD Port Engineering Co.,Ltd | Updated: Jan 03, 2018

Ballasts are the use of stone slag on the roadbed to use cement sleeper, which refers to pieces of rock, coal, etc., which are small stones used for roadbed on the railway.

The traditional railway track usually consists of two parallel rails, which are fixed on the sleeper, and are laid out as a ballast for small gravel. Both the road and the sleepers have increased the force surface, dispersed the pressure of the train, helped the track to carry weight, and prevented the tracks from sinking into the soil because of too much pressure. In addition, there are several effects on the small gravel: reduce noise, absorb heat, shock and increase water permeability.

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The composition of the track:

The traditional structure of the orbital structure is still the main structure of the current speed railway. Composed of rail, sleeper, connecting parts, Taoist and bifurcation.

1. Rail

The rail is one of the main structures of the track. In order to ensure the smooth running of the train, the base of the lower part of the line, the structure of the upper part of the track and all the rail parts should provide good conditions for the normal work of the rail.

And the steel rail itself, its inner quality, material properties, sectional tolerance, level and so on are very important characteristics. The steel rail should ensure sufficient strength, toughness, wear resistance, stability and stability in the technology, in order to guarantee reasonable overhaul period and reduce maintenance and maintenance work.

The type and intensity of rail rail is generally expressed in terms of the weight per meter. The greater the weight of the steel rail per meter, the higher the strength of the rail. The commonly used rail in Japan is 50kg/m and 60kg/m rail. At present, the Shinkansen adopts 60kg/m rail.

1) Rail weight

Rail type shall be determined according to the calculation of track vibration, rail impact, rail contact and rail longitudinal force. The transverse and vertical stiffness of the 60kg/m rail is required to meet the stress intensity of high-speed train. The rail of the Nippon Shinkansen, TGV and ICE high speed rail in Japan is 60kg/m rail. It can be seen that the choice of 60kg/m rail is suitable for the beijing-shanghai high-speed railway.

2) Allowable deviation and straightness of rail dimensions

High speed railway track structure different from normal line is the most important characteristics of strict control of track irregularity, reflect on the rail size is on the surface quality, straightness, surface roughness and distortion of strict requirements. The precision and shape of the rail is one of the basic guarantees of the smooth rail.

3) The chemical composition of the rail

The main form of quality problem of high-speed rail rail is the fatigue loss caused by internal inclusion and defect of rail. It is a powerful way to reduce the fatigue loss of rail, improve the reliability of rail and prolong its service life.

The chemical composition of the steel rail is the basic factor that influences its mechanical properties, welding performance and other performance, and is an important index of the purity of the steel rail.

2. Sleeper

Sleeper function: to support the rail to keep track and direction of the pressure of the rail to its effect.

Although the orbits in the development of high-speed rail without a frantic jumble proportion bigger and bigger, in many countries has become the first selection of track structure, but have a frantic jumble orbit is still one of the main form of high speed railway track structure, the quality and performance of concrete sleeper is still need to focus on.

As concrete sleeper long service life, less maintenance workload, a concrete products factory production of sleeper shape, size, performance, are standard, uniform, for the uniformity of rail support and track the dynamic comfort provides more reliable conditions, and high speed railway has a frantic jumble orbit around the world adopt concrete sleeper.

China's existing railway lines are mostly laid with concrete pillows, while high-speed railway requires concrete pillows.

High-speed railway concrete sleeper most of integral type, such as Germany, Italy, Spain and Japan and other countries of all kinds of sleeper, France is a frantic jumble track sleeper structure of traditional double block, still used in high speed railway double block type sleeper, but in a frantic jumble bridge due to the need of setting the guard rail, adopted integral sleeper.

Countries in the world of passenger dedicated line and high-speed railway has a frantic jumble track technology development show that integral and double block type concrete sleeper form can satisfy the high speed running in such aspects as bearing capacity, durability and stability the use requirement. China high-speed railway adopts monolithic concrete sleeper.

3. Fastener (connecting parts)

The fastener is an intermediate connecting part that connects the rail to the sleeper, which is used to fix the rail to the rails, keep the gauge and prevent the rail from moving in the direction of the sleeper.

In addition, the fastening of high-speed railway is required to have sufficient buckle pressure to ensure the longitudinal and lateral stability of the line. Besides, it also requires good elasticity to ensure good vibration reduction and noise reduction performance. Keep the pressure to maintain the ability to reduce the daily maintenance work; The insulation performance is good to improve the reliability of the track circuit, extend the length of the track circuit and reduce the investment of the track circuit.

Using elastic fasteners for many years history in our country, has successfully developed a play article Ⅰ fasteners, play a Ⅰ raised fasteners, article play Ⅱ type fastener and play Ⅲ fasteners etc, more than all fasteners have been through the ministerial appraisal and promote the use.

Article 1) spring Ⅰ type fastener

Composition: omega cartridge, screw spike, gauge baffle, baffle seat and elastic rubber gasket.

Type: type A: CHN50 rail B type: CHN60 steel rail.

(gauge baffle is used to adjust the gauge and transfer the horizontal thrust of the rail. There are long round holes in the middle of gauge baffle, its size is certain, but there are two kinds of hole center position, and there are two Numbers accordingly. Each of the 50, 60kg/m rails has two Numbers: 20, 14 and 10 and 6 respectively.

Article 2) play the Ⅱ type fastener

Article play Ⅱ type fastener besides play article adopts new material redesign, the rest of the parts and play the type I fasteners and general, is still the block shoulder, bolt fasteners.In the original article use spring type I fasteners, articles are available to play Ⅱ type fastener play to replace the original article type I fasteners to play.

Article 3) play Ⅲ type fastener

Composition: bullet, embedded iron base, insulation gauge block and rubber gasket.

Play a Ⅲ type fastener is developed for high-speed overloading and without bolt without shoulder fasteners. The unbolted and shouldered fastener is a trend of the development of the world sleeper fastener, which is especially suitable for heavy load, large volume and high density transportation conditions.

The system USES the hardcore embedded in the sleeper to keep track of the gauge, bearing the transverse force and fixing the bullet rod, and the steel rail is used as an insulating part and used for adjusting the gauge.

Advantage: the buckle pressure is great elasticity, strong keep track ability, use no bolt connection, reduce the maintenance and maintenance work of the fastener.

4. Ballast bed

The bed is an important part of the orbital structure. The particle bed should not only bear the various forces of the sleeper transmission, maintain the stability of the orbit structure, but also facilitate the maintenance. For high-speed railway, these effects of the granule bed are particularly important.

The function of the bed:

(1) Bear the pressure from the sleeper and transfer it evenly to the roadbed.

(2) Provide the horizontal and vertical resistance of the track to maintain the stability of the track.

(3) Provide the impact and vibration of orbital elasticity and absorption wheel rail.

(4) Provide good drainage performance to improve the load-carrying capacity of the roadbed and reduce the damage of the orbit.

(5) it is convenient to adjust the geometry of the track.

In order to adapt to the above functions, ballasters should have the following properties: they are tough, elastic, hard to crush and mash.Good drainage and water absorption.It is not easy to be weathered or swept away by wind or water.

Used as railway ballast materials are: gravel, grading natural pebble, screening of pebble and coarse sand, medium sand and furnace blast furnace in specific choose railway ballast material should be based on railway freight volume, locomotive axle load, driving speed, combined with cost and local materials such as condition to decide.

First class: heavy duty, heavy area first class.

Secondary railway ballast: primary railway ballast standard of our country is not from the Angle of technical and economic optimal's reserve but according to the national railway railway ballast supply and demand, and consider to improve the quality of railway ballast operation request.There is a big gap between the quality of the foreign Taoist.

5. Switch

A bifurcation is a line connecting device which transfers the locomotive vehicle from one channel to another, and is also one of the weak links of the track. It is usually laid in the station and marshalling yard.With bifurcation, the ability of the line can be fully utilized.Even a single line railway, laying a fork, and building a fork that is larger than the length of the train, can open the train.The bifurcation plays an important role on the railway line.

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Because the switch has number, complex structure, short service life, low limit the train speed, traffic safety, maintenance and repair in big wait for a characteristic, and curve, and joint and referred to as the three major weaknesses of the orbit.

There are three basic forms: the connection of the line, the intersection, the connection and the cross. There are various types of single-type bifurcation and multiple bifurcation in common connection. The cross has a vertical intersection and a diamond cross; The combination of connections and crosses are intersected and cross - crossing.

The development of the orbital track:

With the British industrial revolution, in order to transport large quantities of ore from the mines to the nearest docks, in 1605 there was the first track made of wood

In the middle of the 18th century, cast iron orbits.

In the 1840s, vertical wooden sleeper pillows were laid under the tracks to connect two rails.

In 1865, the rail was replaced by a narrow track. Built in orbit has the basic structure of modern track structure, in order to reduce the ground stress, and on the ground laid a layer of gravel roadbed under sleeper, ballast bed also increase the flexibility of orbit and drainage performance, to facilitate maintenance, orbit in the form of a medium material of traditional ballast track, also called normal orbit, namely we most often say a frantic jumble of orbit. With the high speed of the rail, the top speed is 250 kilometers per hour, and the track is designed to be more than 350 kilometers per hour.

Advantages and disadvantages of the track:

The advantages of the track are good elasticity, low price, convenient replacement and maintenance (small noise range), good noise absorption and short construction period.

Faults: with the improvement of driving speed, due to the uneven subsidence of frantic jumble orbit 120 hz frequency range of vibration severity, rail damage and deformation intensified, so that the maintenance workload increased significantly, significantly shorten the repair cycle.

According to the data of the high-speed railway in Germany, when the speed of the train is 250 ~ 300 km/h, the cost of the maintenance of the line will be about twice that of the speed of the driving speed of 160 ~ 200 km/h; The speed is 250 ~ 300km/h; A total weight of 300 million tons will require a full replacement.