Eccentric drilling hole-forming method of down-the-hole drill

Abstract

Disclosed is a hole-forming method of an earth-rock structural body. A down-the-hole drill is used for providing power. An eccentric drilling bit is used for punching and drilling in a rotary mode. When drilling, the eccentric drilling bit punches and smashes rocks, and smashed rock powder is blown away by gas from bottom to top and along gaps; the eccentric drilling bit clockwise rotates, and therefore the effective rotary radius of a drilling hole and the diameter of a drilled hole are increased, and a bushing is cast; after casting of one bushing is finished, a drilling rod and a bushing are connected, continuously, the eccentric drilling bit punches and drills in a rotary mode, and so on, until the eccentric drilling bit penetrates through the rocks. After penetrating trough the rocks, the eccentric drilling bit anticlockwise rotates, and effective radius of the eccentric drilling bit is reduced and retracts in the bushing, the drilling rod and the drilling bit are pulled out, and continuous bushings form a smooth hole duct. The method is convenient to construct and easy to operate, ensures that hole-forming efficiency is substantially improved and hole-forming expense is obviously reduced.

Description

technical field [0001] The invention belongs to a method for forming holes in the technical field of geotechnical engineering, and in particular relates to a method for forming holes by eccentric drilling of a down-the-hole drilling machine. It is suitable for riprap cofferdam section inspection holes, cofferdam stability monitoring holes, slope anchor holes, curtain grouting holes, mountain blast holes, gas drainage holes in mining areas, etc., especially for loose earth and rock structures such as riprap cofferdams. Background technique [0002] Along with the rapid development of the national economy, land reclamation has flourished in our country, and various structural forms of cofferdams and breakwaters have emerged, such as large cylinder type, floating box type, riprap type, foundation treatment plus filling bag type, etc. Among them, the riprap structure has the advantages of simple process, short construction period, and low price, and is especially suitable for ar...

AI Technical Summary

Problems solved by technology

[0005] The conventional process method is to grind off the riprap with the diamond drill bit, the normal drilling rate is 0.5~1.0m / h, and each time before drilling with a small diameter core tube, the core sample in the previous stage core tube needs to be removed. Take out, because the particle size of the riprap cofferdam stones is different, the sampling process takes a long time

[0006] In the conventional method, the drill bit at the bottom of the core tube is used to grind away the riprap, and the drill is drilled with a large drilling pressure. The drilling pressure is high, the speed is high, and the torque is large. The drill bit is severely worn during the hole forming process. Generally, a drill bit It will be damaged after drilling 5m~8m, and the drill pipe is also easy to bend and break

In addition, because the diameter of the hole formed by the drill bit is almost the same as the outer diameter of the core tube, the core tube is also severely worn, and it is generally damaged after drilling more than 100 meters.

[0007] Due to the characteristics of the conventional hole forming method, the hole forming efficiency is low and the cost is high

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