Construction of pipe joint anchor rod in mine shaft support engineering(3)

5. Application of Pipe Joint Bolt(Split Set Bolt) in roadway support

5.1 Main technical requirements for pipe joint anchors

The surface of the Pipe Joint Anchor rod should be flat without bending, and the pipe joint anchor rod itself shall not be deformed, and the surface shall be smooth. There are no cracks or air bubbles in the joints of the pipe joint anchors. The tray should be able to move freely. The best slit opening should be between 1700 and 1900.

5.2 Construction procedures

Support is divided into primary support and secondary support. A supporting and blasting operation is carried out at the same time. Install the leech plug immediately after blasting the hole. After the secondary support is completed, the support methods mainly include roadway slagging, surrounding rock deformation and stability.

5.3 Pipe joint anchor construction

Anchoring force (also called pull-out force) is the basic condition of bolt support. The anchoring force mainly depends on the lithology of the surrounding rock, anchoring method and construction quality. In order to effectively limit the deformation of the surrounding rock, the installation of the slot bolt hole must be straight, otherwise it will not be able to enter, and the pallet must be in close contact with the surrounding rock surface. The higher the pre-tightening force and the swinging force, the better the effect. Due to the difference between the anchoring length, anchoring diameter, and anchoring diameter, and the hole diameter is proportional to the anchoring force, the anchoring force can be adjusted by adjusting the length and hole of the leeches to effectively control the deformation of the surrounding rock. Reasonable anchorage can make the surrounding rock an important condition for the stability of the surrounding rock structure. To ensure the integrity of the surrounding rock or better, use 2.5-meter bolts with a diameter difference of 2 to 3 mm. A 3.0-meter long anchor rod with a diameter of 1.5 mm can be used at the location where the rock cracks occur. This not only facilitates installation and ensures adequate anchoring, but also uses anchor rods to better strengthen the surrounding rock and play the role of anchor rods. Compared with other types of bolt support, pipe joint type bolt support can achieve the anchoring force of bolts within a time limit, reduce roadway maintenance, and have the advantages of permanent support. According to the nature of the surrounding rock of the roadway, pipe joint anchor rods are used, generally in a rectangular arrangement, with a row spacing of 800 mmxSOOm M seedling rods. Obviously, the anchor rod should be perpendicular to the surrounding anchor rod.

5.4 Test and Evaluation of Anchor Rod Pulling Force

The pulling force of the bolt is a criterion for bolt support. However, in the construction process, the bolt pull-out force gauge is used to check the time-consuming cost of the bolt, which affects the progress of the project. In order to enable quality inspectors to quickly grasp the pulling force of the anchor rod, the relationship between the torque and the pulling force can be tested (using ACID1500 type acousto-optic torque wrench to measure torque, ZY-20 bolt type digital drawing tension meter) to measure the tension.