Drill bit for construction of cast-in-situ bored pile

Abstract

The invention discloses a drill bit for construction of a cast-in-situ bored pile. The drill bit comprises a hollow foundation rod, a connecting part positioned at the top end of the hollow foundationrod and used for being connected with a drill stem of a drilling machine, a retainer ring concentric with the hollow foundation rod, a plurality of connecting plates used for being connected with theretainer ring and a plurality of first scraper plates used for being connected with the retainer ring and provided with cutting teeth. A concentric guide drill sleeve is arranged outside the hollow foundation rod; the bottom end face of the guide drill sleeve is arranged to be a plane and the multiple cutting teeth are arranged on the bottom end face in the circumferential direction; the guide drill sleeve extends to the position below the bottom end face of the hollow foundation rod in the axial direction; a plurality of second scraper plates are arranged between the guide drill sleeve and the hollow foundation rod, wherein a plurality of cutting teeth are arranged at the bottom faces of at least two second scraper plates; all the connecting plates connected with the retainer ring and all the first scraper plates connected with the retainer ring at the same plumb line are arranged to be integrated type connecting plates and first scraper plates; and a plurality of cutting teeth are arranged on the bottom end face of the retainer ring. Drill holes, namely formed holes, of the drill bit in slop rock on the interface between soil and soft rock have good perpendicularity.

Description

technical field [0001] The invention relates to the technical field of pile foundation construction, in particular to a drill bit for constructing bored piles. Background technique [0002] Bored piles have the advantages of high bearing capacity, strong adaptability, pile length up to 100 meters, and can reduce the number of piles. The preferred foundation form for tanks and nuclear power plants. The main construction process of concrete bored piles includes: hole formation, slag removal, reinforcement cage lowering, concrete pouring, and testing. In the above-mentioned main construction process, hole formation is a key link, which directly affects the quality of pile formation. And the hole-forming drill bit of prior art generally adopts following structure: comprise hollow base bar, be located at the taper drill point of hollow base bar lower end, be located at outermost retaining ring, connecting retaining ring and hollow base bar middle and upper multiple A connectin...

AI Technical Summary

Problems solved by technology

There are following defects in the drill bit used for the above prior art construction bored piles: 1, because the distribution of the soil is layered, generally the lower the soil hardness is the higher, even need to drill into the soft rock layer, and the soil layer Boundary line or interface overwhelming majority situation is oblique, like this, in drilling process, when drilling from softer soil layer to harder soil layer or soft rock layer, because the drilling bit of prior art can only rely on the center's The drill tip is positioned, and the tapered drill tip of the drill bit first contacts hard soil or soft rock and is a point contact, and the straight-edge inclined structure of the scraper is not obvious for centering and positioning, and the retaining ring only acts as a passive mud retainer Therefore, when drilling from the inclined interface to the hard soil layer or soft rock layer, the phenomenon of drill bit deviation and drill bit slippage is easy to occur, which seriously affects the verticality of the hole formed by the bored pile. , this technical problem has puzzled those skilled in the art for many years and has not been properly solved so far

2. Mud circulation is required during drilling, especially during reverse circulation, relying on the hollow foundation rod to discharge slag from the bottom of the hole, while the drill tip of the prior art is located directly below the foundation rod, which hinders the mud and leads to poor slag discharge , the drilling slag is not discharged in time, resulting in slower drilling speed and shorter service life of the drill bit

3. The connecting plate and the scraper of the prior art drill bit do their own thing, either they are consumables, or they are slightly thin

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