The railway sleeper is one of the important foundations of the railway track. It is used to carry the weight of the train and pass it to the rail bed. This paper classifies the railway sleepers according to the materials, describes their performance characteristics, and focuses on the research and analysis of the use of several composite sleepers that have appeared in recent years.
The wooden sleeper is the first type of railway sleeper used in the railway, especially the pine sleeper, which is used more often, and later concrete sleepers appeared. However, on the railway steel bridge, due to the poor elasticity of the concrete sleeper, it cannot be used, and only the wooden sleeper can be used. Although the wooden sleeper has good elasticity, it has a short service life and frequent replacement. Therefore, it is necessary to study a new type of sleeper - composite sleeper for the steel bridge. In recent years, several composite sleepers have been researched and produced using new technologies and processes at home and abroad. These composite sleepers include FFU synthetic sleepers, polyurethane composite elastic sleepers, integral coated recycled rubber composite sleepers, composite rubber elastic sleepers and so on. This paper compares the performance of wooden sleepers, concrete sleepers and several composite sleepers.
The performance advantages of wooden sleepers include light weight, good elasticity, good insulation performance, simple production, convenient transportation and maintenance, etc. But there are disadvantages of short life, frequent replacement, large consumption of wood, and A large number of human and financial resources and material resources consumption per replacement. Orbital geometry is also not easy to maintain and other shortcomings.
The performance advantages of concrete sleepers include the less affect by climate or decay, warranted size, uniform elasticity, good stability, long service life, less maintenance and repair times, low cost. In addition, higher track bed resistance of concrete sleeper is very beneficial to improve the lateral stability of the seamless line; however, its disadvantages include heavy weight, poor elasticity and insulation performance. A buffer insulation layer is required at the bottom part of the rail, and the rail joint parts are complicated. It is more difficult to replace.
FFU synthetic sleeper, referred to as long glass fiber reinforced foam polyurethane. A long glass fiber and a hard polyurethane resin are used as a main component, and a molded plate compress and bond to frm the synthetic sleepers. Compared with other materials, this material has high corrosion resistance, fatigue resistance, electrical insulation resistance, long service life, up to 50 years, low replacement frequency, and can reduce cycle cost. And the FFU synthetic sleeper is light in weight, its weight is only 1/3 of the concrete sleeper, and its waste can be recycled after being crushed and pressurized to make a new recycling product.
Polyurethane composite elastic sleeper, the structure is divided into inner core and peripheral layer. The inner core is made of strong - concrete core such as full-grain FRP, and the FRP steel bar made of high-performance fiber such as glass fiber, it has the advantages of light weight, high strength, fatigue resistance, corrosion resistance, etc. The pre-stressed concrete core is characterized by high strength, high ductility, good corrosion resistance, good insulation and long service life. The peripheral layer is made of a material such as a glass long fiber reinforced polyurethane resin foam, and the long glass fibers are uniformly distributed in a monofilament shape, and the foam maintains completely independent bubbles. The peripheral layer has the characteristics of high strength, good elasticity, insulation and corrosion resistance. The composite sleeper has good shock absorption and noise reduction performance, corrosion resistance, good insulation and service life of more than 50 years.
The coated reclaimed rubber composite sleeper, the structure is also composed of the inner core and the outer layer, and then integrally molded by special equipment.
The inner core structure of composite sleeper is divided into a w-groove inner core structure and a wooden core type structure. The w-groove inner core structure is composed of a w-shaped groove, a fixed nail block, and concrete. The inner core of the w-shaped groove is pressed from the steel plate to take the leading load. The fixing block is made of composite material, it is installed on the bearing part to facilitate the installation of the fastener system and increase the elasticity of the sleeper. Fill the concrete material in the spare part of the groove to enhance the load bearing capacity and increase the stability.
The wooden core structure is divided into old wooden sleeper repair type, new wooden sleeper type, and wood powder composite type.
Recycled rubber-plastic composite material has the high elasticity of rubber and the high strength of plastic, so that its outer layer has the advantages of good elasticity and high compressive strength, so as to cope with the dynamic effect of train wheel and rail in railway transportation; at the same time, it can absorb noise. reduce vibration and make the track structure more stable.
How are composite rubber railway elastic sleepers made? combines waste plastics, waste paint and recycled rubber powder made of waste tires to plasticize and blend, and then extrude a new material-recycled rubber-plastic composite material. The property of material is close to wood, but the strength, elasticity, corrosion resistance and processing performance are more than wood. Compared with the existing wooden sleeper and concrete sleeper, the composite sleeper has good insulation, shock absorption and noise reduction performance, low installation and maintenance cost, long service life and high comprehensive cost performance.
The sleeper is an important part of the railway. In China, the railway sleeper is mainly made up of concrete sleepers, and the wooden sleepers are used on the steel bridge. Due to the lack of wood resources and the short service life of the wooden sleepers, it is necessary to study the composite sleepers on the steel bridges, compared with the wooden sleepers. Concrete sleepers and composite sleepers meet the requirements of railway construction development in terms of performance and recyclability. They will bring both huge economic profits and far-reaching environmental benefits.
With the development of science and technology, adopt new materials, new processes and new technology, the research and application of composite sleepers will become more and more extensive, and will certainly become the development direction of railway special section sleepers.