synonymtrack(Terminology of railway science and technology) Generally refers to railway track (cooperation with switch on the railway enables the train to walk without turning)
Railway tracks are made of steel, which can bear more weight than other materials.Sleepers, also known as sleepers, grey sleepers, or road sleepers, are used to distribute the weight of rails and the pressure on rails separately, maintain a fixed gauge, and maintain theGauge。From the originalWooden pillow, change toConcrete sleeper。
The track is subject to various vertical, horizontal and longitudinaldead loadandLive load, load fromrailadoptsleeperandBallastPass tosubgrade。Through mechanical theory, the stress and strain of each component of the track under various load conditions are analyzed and studied to determine its bearing capacity and stability.
Track mechanicsAnalyze the stress and deformation of track structure under the action of locomotives and vehicles, and the impact of track structure diseases on track damage and train operation, so as to design track structure and formulatetrackProvide basis for management standards.
Composition
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The track is composed ofBallast、sleeper, rail, connecting parts, anti climbing equipment and turnout.firstrailCast forrail, and then developed into I-shaped rails. In the 1980s, most of the worldRailwayStandards adoptedGauge(SeeRailway track geometry）1435 mm (4 feet 8 ½ inches).Narrow scaleNarrow gaugeRailway, wider than this is called wide gauge railway (seerailway engineering）。
The track bed is directly paved on the subgrade surface,BallastGravel, pebble, slag and other materials shall be used.RailsleeperBallast bed is composed of materials with different mechanical properties in different ways.Generally speaking, the bottom of the track is the track bed, which provides flexibility and drainage functions for the track.Rails can also be laid on concrete bases (quite common on bridges), or even embedded in concrete.
Sleepers are buried in the track bed, generally laid horizontally, with woodreinforced concreteOr steel.
Ballast is laid on the subgrade,sleeperThe object used to hide the sleeper.According to the laying position, it can be divided into two layers, the upper layer is the top ballast, and the lower layer is the bottom ballast.
The functions of ballast are as follows:
1. Bear the pressure transmitted by the sleeper and evenly distribute the pressuresubgradeOn.
2. Fix the sleeper position and maintain the correct line type and gradient of the track.
3. Drain the rainwater around and below the sleepers to prevent the subgrade soil from deformation due to wet and soft.
4. Increase the elasticity of the track, so thatrailQuickly return to the original correct position.
5. Prevent weeds from growing on the track.
modernTrack worksIn order to ensure the safe operation of high-speed railway, improve the strength of subgrade, reduce the cleaning and maintenance of ballast, replace ballast, sleepers and subgrade with concrete foundation, which is called "slag free track".It can reduce maintenance time, maintain good quality and driving safety.
rail
railIt is a railway structure for rolling train wheels. Its main functions are as follows:
Regardless of the weight of the rail, the section mass ratio should be approximately 42% at the head, 21% at the waist, and 37% at the bottom, and the height of the rail should be equal to the width of the bottom.When the rail head is worn to 0.64 cm, the rail shall be replaced immediately.
The purpose of railway spike is torailSnap onsleeperAnd maintain the fixation between the two railsGaugeThe most commonly used railway spikes are ordinary spikes, hook spikes and spiral spikes.
Rail connection parts
The rail connecting parts are used to maintain the strength and stiffness of the joints, so that the rail has uniform elasticity.Generally, two fishtail plates are attached to the waist on both sides of the rail, andSpring washerTighten the bolts of.There are two types of fishtail: 60cm and 90cm. The 60cm version requires 4 bolts, and the 90cm version requires 6 bolts.
In order to completely improve the defects of track connecting parts, modern track adopts continuous welding toContinuous weldingThe rail replaces the rail joint to reduce the maintenance work of the rail and increase the service life, which is called long welded rail.
To supportrailThe outer waist is used to resist the lateral force on the head of the rail and prevent the loose spike caused by the inclination of the rail.
fastener
embedsleeperFasten the metal clip or handle on the bottom of the rail, which can not only resist the vertical rolling and lateral thrust of the wheel, but also prevent the rail from longitudinal crawling.
Anti creep equipment
It is installed under the rail and is supported by one sidesleeper(and backing plate), in addition to preventing the longitudinal creep of the rail caused by wheel rolling, it can also control the extension of the rail caused by temperature rise.[2]
technical standard
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All high-speed railways adoptStandard gauge(1435mm).(The only exception is the 1520 mm used in Russia and FinlandBroad gaugeHigh speed railway).General railway generally divides the gauge into three typesBroad gauge、Standard rail、Narrow gauge。Most of the early Chinese railways were built by British and Belgian engineers plus the pro Western policy at that time, so their gauge followed the British standard, which was standard gauge, so most of China used standard gauge (1435mm). In Yunnan Guizhou region, Henan Province and Northeast Forest Farm, there were narrow gauge railways built before liberation and early liberation, also known as meter gauge, because the gauge was one meter,Some local railways and factory and mine self operated railways also use meter gauge, which has been gradually transformed in recent years.
