Anchoring Technology and Installation Stability Guarantee for Rail Spikes
What are the core steps of the spike sulfur anchoring process?
The core steps of the spike sulfur anchoring process include four links: drilling and hole cleaning, boiling anchoring agent, pouring anchoring agent and inserting spikes. First, it is necessary to drill holes on the sleeper. The hole diameter and depth must match the spike size. After drilling, high-pressure air is used to remove dust and debris in the hole to avoid affecting the combination of the anchoring agent and the hole wall. The second step is to boil the sulfur anchoring agent. The anchoring agent is mixed with sulfur, cement, sand and paraffin in proportion. The boiling temperature is controlled at 140-160℃, and it is stirred evenly until it is fluid. Then the molten anchoring agent is quickly poured into the hole, and the pouring height should be slightly higher than the hole mouth to prevent gaps after the anchoring agent cools and shrinks. Finally, insert the spike in time, adjust the verticality of the spike, and after the anchoring agent cools and solidifies, the spike can be firmly anchored on the sleeper.
What are the advantages of chemical anchoring compared with sulfur anchoring?
The first advantage of chemical anchoring compared with sulfur anchoring is higher anchoring strength. The chemical anchoring agent is a polymer resin material. After curing, the bonding strength with the spike and concrete hole wall can reach more than 30MPa, which is much higher than that of sulfur anchoring agent. The second advantage is strong adaptability to the construction environment. The chemical anchoring agent can be constructed in the temperature range of -10℃ to 40℃, while the sulfur anchoring agent cures slowly in low-temperature environments and is easy to soften in high-temperature environments. The third advantage is higher construction convenience. The chemical anchoring agent is a pre-packaged material, which does not need on-site boiling, and can be injected into the hole after mixing in proportion, greatly shortening the construction time. In addition, the chemical anchoring agent has better corrosion resistance, stable performance in humid and corrosive environments, and no moisture regain or cracking of the sulfur anchoring agent.
Which sleeper type is the pre-embedded anchoring process suitable for?
The pre-embedded anchoring process is mainly suitable for precast concrete sleepers. The pre-embedding of spikes is completed synchronously during the production of sleepers, which is a factory-based anchoring method. This process requires precise positioning of the spike position in the sleeper mold to ensure that the verticality and spacing of the spikes meet the design requirements, and then concrete is poured to firmly combine the spikes with the sleepers. The advantage of the pre-embedded anchoring process is high positioning accuracy. The verticality deviation of the spike can be controlled within ±1°, which is far superior to the on-site anchoring process. This process is suitable for track types with high installation accuracy requirements, such as high-speed railway ballastless tracks and urban subway tracks. For cast-in-place concrete sleepers or old sleeper renovation projects, the pre-embedded anchoring process is not applicable, and sulfur anchoring or chemical anchoring processes should be selected.
What is the requirement for the verticality deviation of spike installation?
The verticality deviation of spike installation must be strictly controlled within ±2°. This requirement is to ensure uniform stress on the spike and avoid local stress concentration due to inclination. When the verticality deviation exceeds 2°, the force transmission direction of the spike will shift when it bears the train load, and the bonding surface between the spike and the anchoring agent is prone to stress concentration. Under long-term load, the anchoring agent will crack and the spike will loosen. During construction, a level or special positioning tool should be used to assist installation. After inserting the spike, the verticality should be detected in time, and the deviation should be adjusted immediately if found. For pre-embedded anchored spikes, it is necessary to strictly control the mold positioning accuracy during sleeper production to ensure the verticality of the spikes from the source. The precise control of spike verticality is the key to ensuring its long-term stable service.
How to improve the pull-out resistance of spikes after installation?
The first measure to improve the pull-out resistance of spike installation is to optimize the anchoring process parameters. Sulfur anchoring must strictly control the boiling temperature and ratio of the anchoring agent to ensure that the anchoring agent is closely combined with the hole wall; chemical anchoring should select high-quality anchoring agent and ensure that the anchoring agent fills the hole without bubbles and gaps. The second measure is to increase the embedding depth of the spike. The deeper the embedding depth, the larger the contact area between the anchoring agent and the spike, and the stronger the pull-out resistance. Generally, the embedding depth of the spike is not less than 100mm. The third measure is to select ribbed spikes. The ribs on the surface of the spike can enhance the mechanical interlocking force with the anchoring agent. Compared with smooth spikes, the pull-out resistance can be increased by more than 20%. In addition, hooks or expanded heads can be set at the bottom of the spike to further enhance the mechanical anchoring effect. Through comprehensive measures, the pull-out resistance of the spike can be increased by 30%-50% to meet the load requirements of different lines.