Types of Railroad Spikes and Anchoring Techniques
- What are the common types of railway spikes?
There are ordinary spikes, also known as dog-headed spikes, with square or round heads and round steel shanks, mainly used in wooden sleeper tracks to fix rails and sleepers together. Screw spikes, with threaded shanks and square or round nuts on the top, are often used in concrete sleepers, connected to the anchoring agent in the sleepers through threads, with more reliable fixing effect. There are also elastic spikes, made of elastic materials, with certain buffering performance, suitable for lines with high requirements for vibration and noise control, such as urban rail transit.
- What are the anchoring methods for screw spikes?
There is mainly the sulfur anchoring method. Sulfur, cement, sand and paraffin are heated and melted in a certain proportion, injected into the nail holes of the sleeper, and screw spikes are inserted at the same time. After the anchoring agent solidifies, the spikes are fixed. This method has high anchoring strength, but attention should be paid to safety during construction to avoid sulfur gas poisoning. There is also the resin anchoring method, which uses materials such as epoxy resin as the anchoring agent, injects it into the nail hole and then inserts the spike, and realizes anchoring after curing, which has the advantages of convenient construction, environmental protection and high strength, suitable for electrified railways and seamless lines.
- What is the impact of different sleeper types on the selection of spikes?
Ordinary spikes are usually selected for wooden sleeper tracks, because their shanks can be better embedded in wood, providing sufficient grip, and are convenient to install and replace. Concrete sleepers are hard, and ordinary spikes are difficult to fix. Screw spikes must be selected, which can achieve a stable connection through the combination of threads and anchoring agents. For steel sleeper tracks, specially designed spikes are generally used, such as welded spikes, which are directly welded to the steel sleepers to ensure connection strength.
- What are the testing indicators for spike anchoring quality?
Including pull-out resistance, that is, the force required when the spike is pulled out. The pull-out resistance of ordinary spikes is not less than 60kN, and that of screw spikes is not less than 80kN. Insufficient pull-out resistance will cause the spike to loosen. The bonding performance between the anchoring agent and the spike and the nail hole requires that the anchoring agent is closely combined with both, without empty drum phenomenon. It can be judged by tapping the spike to listen to the sound. A clear sound is qualified, and a dull sound may indicate empty drum. The perpendicularity of the spike. After installation, the spike should be perpendicular to the sleeper surface, with a deviation not greater than 1°, otherwise the stress will be affected.
- How to ensure the anchoring effect of spikes under special geological conditions?
In soft foundations or areas with large settlement, lengthened spikes can be used to increase the anchoring length between the spike and the sleeper and improve the pull-out resistance. In corrosive soil environments, galvanized spikes or stainless steel spikes are selected to enhance their corrosion resistance, and anti-corrosion anchoring agents such as resin anchoring agents are used to reduce the impact of soil corrosion on the anchoring effect. In alpine regions, the sulfur anchoring method (which is easy to be brittle at low temperatures) should be avoided. The resin anchoring method can be used, and cold-resistant resin materials should be selected to ensure good anchoring performance at low temperatures.