Upper track structure: device and types

Any rail way is a complex complex of all sorts of engineering structures that form a road with a rail track rail. It consists of two main parts - the lower support and the upper one. The latter represents the road itself, along which the mobile staff goes.

Main purpose

верхнее строение пути воспринимает как вертикальные, так и горизонтальные нагрузки от его колес и передает их на земляное или искусственное основание. When the train moves, the upper structure of the track perceives both vertical and horizontal loads from its wheels and transfers them to an earthen or artificial base. Actually, the track determines the direction of movement of the train. The VSP is designed primarily taking into account the fact that in the future it should ensure the safe passage of trains with specified maximum speeds.

Design Features

верхнее строение пути железной дороги из двух основных частей: The upper structure of the railroad track consists of two main parts:

• The rail-and-pinion grating;

• Ballast prism.

The lattice design, in turn, includes the rails themselves, as well as sleepers made of different materials. The prism of the upper path can be one- or two-layer. Most often during the construction of the railway line, the latter option is used. The two-layer ballast prism consists of:

• A layer of sandy substrate;

• Crushed stone, made of hard rock.

For pouring a single-layer prism, materials such as sand and gravel mixture, crushed stone, asbestos waste, slag, shell rock can be used.

In addition to the lattice and the prism, the following elements of the upper structure of the path are distinguished:

• Bonding;

• Anti-theft;

• Intersections are deaf;

• Switches.

Design of the VSP

верхнее строение пути , инженеры должны решить следующие задачи: Drawing up drawings of such an important design as the top structure of the track , engineers must solve the following tasks:

• Determine the class, category and path group;

• Determine the design of the VSP itself;

• Determine the conditions for its laying;

• To calculate the increased and lowered temperature of the weaves taking into account their strength and stability;

• Calculate the intervals of fastening of the weaves;

• Determine the elevation of the rails and the width of the track in the curve.

The upper structure of the railway track: rails

This element of the VSP design is intended for the direction of movement of the composition. In some cases, the rails can also serve as a conductor of electric current (in areas with electric traction or self-locking). Р75 и Р43. This VSP element can be labeled as P50, P65, P75 and P43. Currently, in the construction of railways, the variant P65 is mainly used. Actually the rail itself consists of:

• Heads;

• Neck;

• Soles.

The standard length of the rails in the Russian Federation is 25 m. In some sections of the lines, shortened guide elements can also be laid - at 24.84 m and 24.92 m. In order to reduce the number of joints between the rails, they are often welded in 800 m and more.

Materials of the track structure: production of rails

Do this element of the VSP is usually at the enterprises of the metallurgical industry from open-hearth carbon steel. In this case, the rails are subjected to thorough heat treatment along the entire length by quenching in oil and tempering in the furnace. This procedure is carried out first of all in order to increase the wear resistance of the alloy. Served the hardened rails one and a half times longer than the untreated ones. At present, when assembling railway tracks, steel elements can be used:

• Low-temperature (P65);

• Tempered first group of boron-containing vanadium-niobium steel.

The last type of rails is usually used for laying roads in areas with severe climatic conditions - in the Far East, Siberia, etc.

VSP sleepers

The main purpose of the sub-rail supports in the track is to absorb the load from the rails and transfer them to the ballast prism. Also sleepers ensure the stability of the track width in the plan and profile. Nowadays, sleepers can be made of reinforced concrete or wood. Metal is not used for this purpose because of its susceptibility to corrosion. 80% of the sleepers laid in the country are made of wood. For the production of this VSP element, such species as fir, birch, larch, pine, etc. can be used.

Reinforced concrete sleepers are usually laid only on artificial structures - in tunnels and on bridges. Such supports may be small frames or slabs.

The length of sleepers depends on the features of the part of the track on which they are laid. железобетонных брусьев составляет 3-5.5 м, а мостовых — 3.25 м. Thus, wooden supports have a standard length of 2.75 cm. The permissible deviation from the norm is 2 cm. The length of the ferro-concrete bars is 3-5.5 m, and the bridge-bars - 3.25 m.

In cross-section, wooden sleepers can be:

• Edging;

• Half-finished;

• Unedged.

Reinforced concrete sleepers are manufactured with a variable cross-sectional length. For their production is used heavy concrete grade M500 or F200. The armature is then applied from the wire by 3 mm. Ties are laid on the way in the amount of 2000 pcs / km in complex areas. On direct they are distributed on 1440-1600 pieces per kilometer.

Classification of sleepers

Reinforced concrete pillars depending on the degree of crack resistance and the accuracy of geometric parameters are divided into products of the first and second grade. в разных случаях предполагает использование деревянных шпал следующих классов: The device of the upper structure of the track in different cases involves the use of wooden sleepers of the following classes:

• The first (I) is for the main paths.

• The second (II) - for stationary and access.

• The third (III) - for industrial paths that are not subjected to frequent loads.

Wooden sleepers serve without the need to replace 12-15 years, reinforced concrete - up to 50 years. The disadvantages of the latter, however, are their weight and high degree of conductivity.

Ballast VSP layer

слои такого основания, как земляное полотно (верхние) . The purpose of this VSP element is to transfer the load from the rails and sleepers directly to the layers of the foundation such as the earthen cloth (upper) . верхнего на мо с тах немного другое. The structure of the path of the upper one is different. обустраивается. The ballast prism in this case is not settling. е чаще всего изготавливают из щебня твердых пород. In the earthen areas, it is most often made of hard rock crushed stone. Sand-gravel ballasts, since they poorly divert water, settle only on insignificant lines. в большинстве случаев насыпается и трамбуется асбестовая подложка. On heavily clogged areas in most cases, asbestos substrate is poured and trampled . During the rain, it does not form a too thick crust. The latter serves as a good obstacle for the penetration into the ballast of various kinds of weeds.

Gear shifts

Elements of the upper structure of this type of road can serve to ensure the movement of trains from one track to another or to turn the crew 180 degrees. They are also used when crossing paths in one level. The main elements of the switch are:

• Actually an arrow with a transfer mechanism;

• Cross;

• Connecting paths;

• Uneven bars.

The main types of VSP

Currently, the following types of the upper track structure are used on the main roads of the Russian Federation:

• Heavy;

• Average;

• lungs.

The VSP class is determined depending on its gross weight. This is due primarily to the fact that, unlike most other engineering structures, all its components work with accumulating residual deformations.

верхнее строение пути предполагает применение в большинстве случаев рельсов класса Р75. The heavy upper structure of the track assumes the use in most cases of rails of class P75. As a basis, a prism made of crushed stone or asbestos waste is used. Such structures are designed for highways with a freight strength of 80 million tkm / km per year.

The average type involves the laying of rails P65. It is intended for lines with a freight intensity of 25-80 million tkm / km per year. и на участках с особо интенсивным движением. Also, such paths are laid for high-speed passenger trains and in areas with particularly intensive traffic.

The lightweight type of VSP, in turn, is divided into two main varieties:

• For lines with an intensity of 5 to 25 million tkm / km per year;

• Less than 5 million tkm / km per year.

In the first case, the rails P50 are used for laying. Also in such areas old steel guides P75 or P65 can be used. For the laying of tracks with an intensity of 5 million tkm / km per year, the used rails of P50 are usually used. Prism of light type VSP is usually arranged from a gravel-sand mixture.

Endless railway tracks

On sites with reliable soil it is recommended to equip this kind of VSP. In Russia, the length of the braiding of the welded-on track is on average 500-600 m. Their absolute advantages include:

• Facilitation of such a procedure as repair of the upper structure of the track;

• Extending the service life of the WWW;

• Increase the smoothness of train traffic.

The unbroken path is, in fact, a more advanced design in comparison with the conventional one. However, designing it - the procedure is somewhat more complicated. In this case, additional temperature stresses appear in the rails.