Selection of spike rod diameter and anchoring
- What are the common shank diameters of railway spikes?
Ordinary spike diameters are 16mm and 18mm; 16mm for wooden sleepers and light concrete sleepers, 18mm for heavy concrete sleepers. Screw spike diameters are 22mm and 24mm; 22mm for ordinary sleepers, 24mm for turnout areas and heavy-haul railway sleepers. Diameter deviation must be ≤0.5mm; oversize may crack sleepers, undersize results in insufficient anchoring force.
- What is the relationship between diameter selection and sleeper material?
Wooden sleepers, with soft material, use 16mm thin-diameter spikes to reduce splitting risk, relying on wood's elastic gripping force for anchoring. Concrete sleepers, with high hardness, require 18mm and larger diameter spikes, transferring loads through mechanical interlock between anchoring agent and shank. Composite sleepers (e.g., fiberglass) with intermediate strength commonly use 18mm diameter, with ribbed shanks to enhance anchoring.
- What is the influence law of shank diameter on anchoring force?
For every 2mm increase in diameter, anchoring force increases by 15%-20%. 16mm spikes have anchoring force of 50-60kN, 18mm reach 65-75kN, 22mm screw spikes up to 80-100kN. However, larger diameter is not always better; exceeding the sleeper hole design diameter by over 3mm will make local sleeper stress exceed the allowable value, causing cracks.
- What are the differences in installation tools and processes for different diameter spikes?
16-18mm ordinary spikes are manually installed with spike hammers, requiring controlled striking force to avoid shank bending. 22-24mm screw spikes need electric wrenches with sockets for tightening, torque controlled at 150-200N·m. Before installing 18mm+ spikes, concrete sleepers require pre-drilling (hole diameter 1-2mm smaller than shank), wooden sleepers can be directly driven but need pre-drilling for guidance.
- How to determine the spike diameter for specific sleepers?
Select ≥22mm diameter for sleepers with design bearing capacity ≥100kN. Refer to sleeper manufacturer recommendations: C50 concrete sleepers recommend 20mm, C60 recommend 22mm. Verify through on-site tests, testing anchoring force of different diameter spikes on the same type of sleeper, selecting the diameter that meets requirements without damaging the sleeper.