High-speed railway spiral spike vertical pull-out test

High-speed railway is different from ordinary railway. Due to the high speed, the load on the track is large, which has higher requirements for ballastless track and fasteners. An important component of the high-speed railway track system is the fastener system. The fasteners tightly connect the rails to the bottom sleepers. In order to ensure that the train runs at a high altitude on the rails, it is required to provide sufficient longitudinal, transverse and vertical resistance. The construction of spiral spikes is relatively convenient, and the combination with spring clip fasteners forms a restraining effect on the rails.

Spiral spikes on high-speed railways are mostly used in conjunction with corresponding spring clip fasteners. When the train passes at a high speed, it will produce complex forces on the rails. At this time, the change in the force of the rails will be reflected in the change in the force of the spring clip fasteners, which will then produce a large vertical pull-out force on the spiral spikes. Only when the pull-out resistance of the spiral spikes has a sufficient safety factor can the safe operation of high-speed trains be ensured.

Part 5 of the standard QCR352-2016 "Anchoring of spiral spikes in concrete sleepers" requires that the test method for the pull-out force of spiral spikes be carried out in accordance with the provisions of TB/T 3396.7. The test should be carried out 10 minutes after the anchoring of sulfur anchors and 6 hours after the anchoring of other anchors.

1. Principle:

Apply a vertical load to the embedded fasteners pre-buried in the concrete, and determine the pull-out force of the embedded parts by the load retention capacity during the test and the state of the joint between the embedded parts and the concrete after the test.

2. Test equipment:

1) Loading equipment: Equipment that can apply a vertical load of 150kN at a loading rate of 40kN/min~60kN/min static loading.

2) Load sensor: An instrument for measuring the load applied to the embedded parts, with an accuracy level of 1.

3. Test steps:
For embedded parts that are embedded sleeves for bolts to be screwed into, the load should be applied to the sleeves through the bolts of the fastener system, and the bolt screwing depth is the designed screwing depth of the fastener system. For other embedded fastener parts, the load should be applied at the position where the embedded parts are subjected to pull-out force.

The pull-out test of spiral spikes is carried out on the anchored sleepers. Before the pull-out test of spiral spikes, the embedded sleeves of the sleepers need to be cleaned, and the spiral spikes are screwed into the sleeves through the through-hole jacks. The spiral spikes are vertically loaded by the jacks according to the force specified in the standard. After each level of load is loaded, it is necessary to check the integrity of the concrete around the sleeve.