Anchoring Methods and Selection of Railroad Spikes
- What are the common anchoring methods of spikes, and which sleepers are they suitable for?
Common anchoring methods include sulfur anchoring, resin anchoring, and mechanical anchoring. Sulfur anchoring is to mix sulfur, cement, and sand in proportion, heat them, and pour them into the sleeper nail holes. It is suitable for wooden sleepers and ordinary concrete sleepers, with high anchoring strength and low cost, but heating is required during construction, which has certain safety hazards. Resin anchoring uses resin anchoring agents to achieve anchoring through chemical reaction curing. It is suitable for prestressed concrete sleepers, with convenient construction, environmental protection, fast curing speed, and stable anchoring force, and is widely used in high-speed railways and heavy-haul railways. Mechanical anchoring is fixed through the threaded connection between the spike and the sleeper pre-embedded sleeve. It is suitable for lines with high maintainability requirements, facilitating the disassembly and replacement of spikes, and is often used in special track sections such as turnouts.
- How to determine the length of the spike according to the sleeper thickness and anchoring method?
The length of the spike needs to meet the requirements of anchoring depth and exposed length. For sulfur anchoring, the anchoring depth of the spike is generally not less than 120mm, and the length exposed on the sleeper surface is determined according to the sleeper thickness. When the thickness of the ordinary concrete sleeper is 200mm, the length of the spike is about 220 - 240mm. The anchoring depth of resin anchoring is usually 100 - 120mm. When the thickness of the sleeper is 220mm, the length of the spike is 220 - 250mm. In mechanical anchoring, the threaded part of the spike must be completely screwed into the pre-embedded sleeve. The anchoring depth is determined by the length of the sleeve. Generally, the length of the sleeve is 150mm, and the length of the spike needs to be 50 - 70mm longer than the length of the sleeve to ensure sufficient connection strength and exposed length.
- What are the differences in performance and application between spikes of different materials (such as carbon steel, alloy steel)?
Carbon steel spikes (such as Q235 material) have moderate strength, good toughness, and low cost. They are suitable for lines with small loads such as ordinary railways and branch railways, and can meet basic anchoring needs, but their wear resistance and corrosion resistance are relatively poor. Alloy steel spikes (such as 45# steel, 35CrMoA steel) have significantly improved strength, hardness, wear resistance, and corrosion resistance by adding alloy elements. They are suitable for lines with large loads and harsh use environments such as high-speed railways and heavy-haul railways, can withstand greater impact and vibration, and have a longer service life, but the cost is relatively high.
- After the spike is installed, how to detect whether the anchoring quality is qualified?
The anchoring quality can be detected through pull-out force test and appearance inspection. Use a spike pull-out tester to apply tension to the spike. The pull-out force of spikes for ordinary railways should not be less than 60kN, and the pull-out force of spikes for high-speed railways should reach more than 70kN. If the pull-out force is insufficient, it indicates that the anchoring is not firm. Visually inspect whether the spike is perpendicular to the sleeper surface, and the inclination deviation should not be greater than 3°; check whether the anchoring agent around the spike is full and whether there are holes or cracks. If these problems exist, the anchoring strength will be affected, and re-anchoring is required.
- How to select spikes and anchoring methods in special environments (such as alpine, corrosive areas)?
In alpine areas with low temperatures, the spike material needs to have good low-temperature toughness to avoid brittle fracture at low temperatures, and alloy steel spikes can be selected; resin anchoring is preferred as the anchoring method, because the resin anchoring agent can still cure normally at low temperatures and has stable anchoring force. Sulfur anchoring is easy to be brittle at low temperatures, which affects the anchoring effect. In corrosive areas (such as coastal areas, chemical areas), corrosion-resistant spikes should be selected, such as galvanized spikes and stainless steel spikes; resin anchoring or mechanical anchoring can be used as the anchoring method to avoid the reaction between sulfur in sulfur anchoring and corrosive media, which reduces the anchoring strength. At the same time, strengthen the anti-corrosion treatment of spikes and anchoring parts to extend the service life.