Standard for Control of Compression Permanent Deformation of Rail Pads
What is the compression permanent deformation of rail pads, and what is its significance?
Compression permanent deformation refers to the amount of plastic deformation that a rail pad undergoes after unloading from a long-term load, preventing it from returning to its original thickness. It reflects the pad's elasticity retention and anti-aging performance. The smaller the deformation, the more stably the pad can provide elastic support over a long period, ensuring the track's geometric dimensions and vibration reduction effect.
What are the hazards of excessive compression permanent deformation of rail pads?
Excessive deformation leads to uneven rail surface, increasing wheel-rail impact; disrupts track stiffness matching, reducing vibration damping and buffering effects; causes uneven stress on fasteners, leading to bolt loosening and elastic clip breakage; accelerates damage to sleepers, track slabs, and ballast, significantly increasing track maintenance costs.
What are the key factors affecting the compression permanent deformation of rail pads?
Material formulation (elasticity, cross-linking degree, and anti-aging agents of rubber, polyurethane, and rubber-plastic composites), structural design (thickness, hardness, pattern, and layered structure), operating environment (temperature, UV radiation, water immersion, and corrosion), and load conditions (axle load, traffic density, and impact magnitude) all significantly affect the amount of deformation.
What are the standard requirements for compression set of track pads in China?
According to industry standards, the compression set of ordinary track pads should be ≤15%; high-performance track pads for high-speed, heavy-load, and ballastless tracks should be ≤10%; and vibration-damping track pads should be ≤12%. Standards are even stricter for special high-temperature and low-temperature environments to ensure long-term stability.
How to reduce compression set and extend the service life of track pads?
Select highly elastic, creep-resistant, and aging-resistant materials; optimize structural and hardness design; strictly control production processes and cross-linking density; rationally match thickness and structure according to track grade; avoid uneven pressure and obstruction during installation; conduct regular inspections and replace pads exceeding the standards promptly.