Track Creeping Knowledge Popular Science

Track creeping is also called line creeping. The creeping phenomenon of rails along the line. With the increase of railway transportation tasks, the impact of wheels on rails during train operation has accelerated the creeping of tracks.

Introduction Track creeping is also called line creeping. The creeping phenomenon of rails along the line. With the increase of railway transportation tasks, the impact of wheels on rails during train operation has accelerated the creeping of tracks. Track creeping can cause many line diseases. In order to prevent the occurrence of track creeping diseases, the real cause of the disease must be found out to effectively eliminate the disease.

There are two different forms of track creeping: the movement of rails along the soft pillow surface caused by insufficient fastener pressure; the longitudinal movement of the track caused by insufficient roadbed resistance. The reason for the occurrence is that the longitudinal force of the rails is generated by wheel rolling and longitudinal slippage, train braking, rail temperature changes, and the flexural deformation of the rails under the action of wheel loads, etc., causing creeping. This causes continuous blind seams or large rail seams on the line, pulls the inclined sleepers to form joint diseases and poor gauge and direction, etc., until the track loses stability and expands the track. Comprehensive prevention and control can be carried out by installing sufficient anti-climbing equipment on the line, using anti-climbing rail fasteners, and effective ballast bed tamping measures.

Causes of track creepin.g When the train is running, the wheels act on the track, which not only generates vertical and lateral forces, but also causes the rails to bend in a wave shape under the action of dynamic loads due to the rolling and longitudinal sliding of the wheels. A longitudinal horizontal thrust is generated. This longitudinal horizontal thrust can cause the longitudinal displacement of the rails, and sometimes also drives the sleepers to move together. This movement is called track creeping.

In short, there are many reasons for creeping, mainly: the deflection of the rails under dynamic loads; the longitudinal force of the train running; the temperature change of the rails; the wheels hitting the rails at the joints; the train braking, etc. When there is insufficient anti-climbing equipment on the line, the buckling pressure of the fasteners and the longitudinal force resistance of the ballast bed are insufficient, and the line creeping will be aggravated. It is generally believed that rail deflection is the main cause of track creep, while other factors contribute to and aggravate track creep.

Measures to prevent track creep The main measure to prevent track creep is to increase the longitudinal resistance of the track.

(1) Strengthen the anti-climbing resistance between the sleeper and the ballast bed

The method is to maintain the standard section of the ballast bed, ensure that the thickness of the ballast under the sleeper is sufficient, the ballast in the sleeper box is full, the ballast shoulders at both ends of the sleeper are wide enough, and strengthen tamping; make the long flat and keep the line smooth: compact the ballast bed. It is very important to do a good job of compaction. According to measurements, the resistance of each wooden sleeper along the line direction of an uncompacted gravel ballast bed is about 500kg. And the compacted one is about 800-1000kg. In addition, the severely dirty ballast bed must be cleaned and screened to prevent the longitudinal resistance of the line from being reduced due to mud overflow and track bottom creep.

(2) Strengthen anti-climbing equipment The function of anti-climbing equipment

is to prevent track creep, increase the longitudinal movement resistance of the track, and strengthen the buckling pressure of the intermediate fastener and the clamping force of the joint clamp. Anti-climbing equipment includes anti-climbing devices and anti-climbing supports. Anti-climbing devices include spring anti-climbing devices and pin-type anti-climbing devices. Pin-type anti-climbing devices are widely used in my country's railways. Each of these anti-climbing devices can withstand a creeping force of 3,000 kg and consists of a rail clamp with a baffle and a pin. The rail clamp tightly clamps the bottom of the rail on one side, and the gap between the rail clamp and the bottom of the rail on the other side is wedged with a wedge-shaped pin to firmly clamp it on the bottom of the rail. To fully utilize the anti-climbing ability of the pin-type anti-climbing device, a pair of anti-climbing devices and 3 to 4 sleepers must be connected with anti-climbing supports to form a group of anti-climbing devices to jointly resist the track creeping force transmitted by the anti-climbing device. The anti-climbing support can be made of wood, stone, or reinforced concrete. Install the anti-climbing device and anti-climbing support according to the specifications, and add anti-climbing equipment if necessary. Failed anti-climbing equipment should be replaced and repaired promptly.

(3) Maintain the proper clamping pressure of fasteners

To increase the resistance between the rail and the splint, between the rail and the pad, and between the pad and the sleeper, the bolts should be tightened in time, the floating spikes should be tightened, and the fasteners should be tightened. Failed spikes and fasteners should be replaced and repaired in time.

(4) Timely repair of joint defects

Defective joints will increase the impact of the train on the rails and increase rail creep. Therefore, saddle-type wear joints, low joints, and damaged rail heads should be repaired in time. Continuous large rail gaps and sections with uneven rail gaps should be adjusted.

Line creep is the source of all diseases. It will cause the sleeper position to be skewed, the spacing to be incorrect, and the rail gap to be uneven. When the rail creeps, it often drives a part of the sleepers and the joint sleepers to move together. In this case, the splint will drive the spikes to tear the sleepers, or cause the sleepers to leave the original solid bed surface, causing various diseases in the rail joints, which must be repaired in time.

When the train is running, there will be a longitudinal force (mainly friction) between it and the rail, which will cause the rail to move longitudinally, and sometimes even drive the rail to move together. This phenomenon is called track creep.

Track creep often causes line diseases such as uneven rail joints and crooked sleepers, which are extremely destructive to the track and even endanger driving safety in severe cases. Therefore, measures must be taken. The main measure is to install anti-climbing facilities on the track. Commonly used anti-climbing facilities are pin anti-climbing devices and anti-climbing supports.