A method and device for applying pre-tightening force on anchor rods

Abstract

The invention provides a method and a device for exerting an anchor rod pretightening force and is suitable for general tunnel and roadway surrounding rock timbering engineering. During anchor rod pretightening force exerting, an anchor rod drilling hole is firstly constructed through a drilling machine, a resin medicine roll and an anchor rod are filled in the drilling hole sequentially, and a tray and a nut are sleeved on an external road section of the anchor rod. A pneumatic rock drill drives the anchor rod to rotate so as to break the medicine roll, and strength can be formed when the medicine roll is solidified; a hydraulic tensioner is installed; a hydraulic cylinder is started to exert a tension pretightening force on the anchor rod, and a suspended nut is screwed in by a wrench to be contacted with the tray; and the pressure of the hydraulic cylinder is reduced to be zero, and the hydraulic tensioner is removed. By means of the method and the device for exerting the anchor rod pretightening force, anchor rod pretightening force construction can meet the design requirements easily, the process that a traditional torque circumferential force is converted into an axial force in an anchor rod pretightening force construction method is changed, requirements on materials of the anchor is reduced, damage to the anchor rod is avoided, and the construction efficiency is improved.

Description

technical field [0001] The invention relates to a method and a device for applying bolt pretightening force, and is especially suitable for the commonly used bolt support technology in rock soil, shaft and tunnel engineering. Background technique [0002] In the fields of underground engineering and slope engineering, bolt support is the most widely used reinforcement technology. Due to the characteristics of the rock mass at different depths around the roadway and the different stress environments, it is easy to produce uncoordinated deformation, so the bolt needs to be pre-tightened with a nut to prevent the nut from loosening due to the deformation of the surrounding rock and cause support failure. The influence of anchor bolt prestress on roadway support effect mainly has the following three points: ① When installing anchor bolts, give enough positive pressure to the rock mass to prevent cracking, slippage and weakening of surrounding rock. ② Utilize prestress to restri...

AI Technical Summary

Problems solved by technology

The basic principle is to realize the conversion from circumferential force to axial force through the angle between the nut and the thread rolling section of the anchor rod. However, when the thread rolling section of the anchor rod is rough or the friction between the nut and the pallet is large, the torque applied to the nut cannot be effective. Converted into the axial tension of the anchor rod, the pre-tightening force of the anchor rod installation is greatly reduced, and the set pre-tightening force cannot be achieved; Pulse torque is used for tensioning, and the impact force will cause more damage to the bolt

At the same time, the pre-tightening force set by the anchor should not be too large. When the applied pre-tightening force exceeds the design parameters, it will not only cause waste but also damage the anchor.

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