Low-disturbance hole forming device for soft mudstone anchor rod/cable hole and hole forming method

Abstract

The invention relates to a low-disturbance hole forming device for a soft mudstone anchor rod / cable hole and a hole forming method. The device comprises a plurality of sections of hollow outer drill rods, inner drill rods and a breaking drill bit. The outer drill rods can be connected with one another, and a hole-forming drill bit is installed at one ends of the outer drill rods. The inner drill rods are installed in the outer drill rods, the inner drill rods can rotate along the axis line of the outer drill rods, a water flow channel is formed in the inner drill rods in the length direction of the inner drill rods, and spiral fins are arranged on the inner drill rods. The breaking drill bit is installed at the ends, relatively close to the hole forming drill bit, of the inner drill rods,a water outlet hole is formed in the breaking drill bit, and the water outlet hole is communicated with the water flow channel. Drill bit cooling is achieved in the manner that water enters the innerdrill rods and water flows out of the inner walls of the inner drill rods and the inner walls of the outer drill rods, and the cooling manner can prevent the problem that surrounding rock in the holewall is greatly soaked and accordingly strength is reduced and even softening and collapsing are caused.

Description

technical field [0001] The invention relates to the field of tunnel engineering bolt / cable installation hole-making engineering, in particular to a low-disturbance pore-forming device and method for weak mudstone bolt / cable holes. Background technique [0002] During tunnel construction, pneumatic rock drills are often used to cool down and discharge slag during the bolt-cable drilling process. [0003] Tunnel construction often encounters weak mudstone. In this case, it is not suitable to directly add water to flush the slag. This is mainly because the water flows into the bottom of the hole through the drill pipe and then passes through the drill pipe during the process of adding water to the traditional pneumatic rock drill. The gap between the hole wall and the hole wall will flow out, which will cause a large amount of water immersion in the surrounding rock, and at the same time make the mudstone soften and even expand rapidly when it meets water, which not only increa...

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Problems solved by technology

[0003] Tunnel construction often encounters weak mudstone. In this case, it is not suitable to directly add water to flush the slag. This is mainly because the water flows into the bottom of the hole through the drill pipe and then passes through the drill pipe during the process of adding water to the traditional pneumatic rock drill. The gap with the hole wall will flow out, and this will cause a large amount of water immersion in the surrounding rock, and at the same time make the mudstone soften and even expand rapidly when it meets water, which not only increases the difficulty of slag extraction, but also is very unfavorable to the stability control of the surrounding rock in the later stage

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