The influence of the anchoring depth of the spike on its pull-out resistance
- What is the reasonable anchoring depth range of spikes?
The reasonable anchoring depth of spikes in concrete sleepers is usually 100 - 120mm, and the pull - out resistance can reach 60 - 80kN, which can meet the needs of ordinary railways. The anchoring depth of spikes in wooden sleepers is slightly shallower, generally 80 - 100mm. Due to the low strength of wood, too deep anchoring is easy to cause sleeper cracking, and the pull - out resistance is usually 40 - 60kN.
- What problems will be caused by too shallow anchoring depth?
The pull - out resistance is significantly reduced. For example, when the depth is reduced from 100mm to 80mm, the pull - out resistance may decrease by 30% - 40%. The spike is easy to be pulled out, leading to rail loosening and difficulty in maintaining the gauge. When the train passes, the spike is unstable, which will aggravate the collision and wear with the sleeper, expand the nail hole, form a vicious circle, and eventually require sleeper replacement.
- What impact does too deep anchoring depth have on the use of spikes?
Too deep anchoring in concrete sleepers (more than 140mm) may penetrate the bottom of the sleeper, reduce the structural strength of the sleeper, and even cause sleeper cracking, affecting the overall bearing capacity. The installation difficulty increases. Too deep anchoring requires greater installation force, which may cause the spike to bend or damage, and also increase material consumption and construction time.
- What are the differences in depth requirements for spikes with different anchoring methods?
Sulfur anchoring has strict requirements on depth, and the deviation must be controlled within ±5mm. Too deep or too shallow will significantly affect the anchoring strength, because the strength distribution of sulfur mortar is sensitive to depth. The depth tolerance of resin anchoring is slightly larger, and when the deviation is ±10mm, the change of pull - out resistance is within 5%. The bonding performance of resin is more uniform and less sensitive to depth.
- How to ensure that the spike anchoring depth meets the design requirements?
Check the depth of sleeper nail holes before construction, measure with special measuring tools, and repair or replace sleepers with unqualified nail holes. Use tools with depth limit during installation, such as marking depth lines on the spike, to ensure accurate insertion depth and avoid human operation deviation. Sampling inspection after installation, measure the actual anchoring depth with a depth gauge, check at least 5 points per kilometer, and the qualified rate must reach 100%.