Impact of Shrinkage and Cracking of Track Spike Anchoring Agent on the Reliability of Anchoring Systems
Q1: Why does the anchoring agent shrink after curing?
A1: The volume of the anchoring agent will slightly shrink during the chemical reaction curing process, forming a small gap between the rail and the spike. Environmental drying and temperature changes will further aggravate the shrinkage and weaken the interface bonding force.
Q2: What changes will occur in the pull-out resistance of spikes after shrinkage and cracking?
A2: Shrinkage reduces the contact surface between the anchoring agent and the spike. After the crack is formed, the gripping force further decreases. When subjected to tension or shear, interface peeling is easy to occur, the pull-out resistance is significantly reduced, and even the spike is pulled out as a whole.
Q3: How does vibration load accelerate the cracking failure of anchoring agent?
A3: Train vibration causes repeated fretting of spikes, cracks continuously expand and penetrate under vibration, and the anchoring agent gradually pulverizes and loosens. Finally, the anchorage system loses integrity, spikes loosen and incline, and cannot restrain rail displacement.
Q4: Why does the anchoring agent fail faster in a humid environment?
A4: After water invades the crack, it will destroy the structure of the anchoring agent and reduce the bonding strength; freeze-thaw cycle will further expand the crack sharply. At the same time, it corrodes the spike, forms volume expansion, and further squeezes and crushes the anchoring agent.
Q5: How to select and construct anchoring agent to reduce shrinkage and cracking?
A5: Select low-shrinkage, high-toughness, anti-aging anchoring agent; strictly mix according to the ratio to ensure full curing; ensure that the hole is clean and dry during construction; adopt thermal insulation measures in winter to avoid low temperature affecting curing quality.