Hydraulic variable-diameter reamer drill bit of long spiral drilling machine and cast-in-place pile construction method

Abstract

The invention discloses a hydraulic variable-diameter reamer drill bit of a long spiral drilling machine and a cast-in-place pile construction method. The hydraulic variable-diameter reamer drill bitincludes the long spiral drilling machine, a detachable upper power head is mounted on the long spiral drilling machine, a spiral drilling rod can be made to rotate, a hydraulic system is arranged inthe upper power head, a drill bit system is fixedly arranged at the lower end of the spiral drilling rod, the drill bit system is provided with a first cavity and a second cavity, an outwardly movablefirst drill bit with a piston is mounted in the first cavity, an outwardly extensible and movable second drill bit with an a piston is mounted in the second cavity, a pouring channel, a first hole channel and a second hole channel are formed in the spiral drilling rod, a rotatable lower power head is arranged on the lower part of the upper power head, a detachable rotating sleeve is arranged at the lower end of the lower power head, and the sleeve wraps the outer side of the drill bit system and enables the drill bit system to move vertically. While sleeve pulling out and diameter expanding can be realized, meanwhile, concrete can be poured, the construction efficiency is high, economic benefits is good, and bearing capacity of the pile end and lateral resistance of a pile body can be effectively improved.

Description

technical field [0001] The invention relates to a construction method of a reaming drill bit and a pile, in particular to a construction method of a hydraulic variable-diameter reaming drill bit of a long screw drilling rig and a construction method of a cast-in-situ pile, and belongs to the technical field of construction engineering. Background technique [0002] The existing buildings are gradually developing to high-rise buildings, and the loads borne by the buildings are increasing, which makes the pile-forming equipment and construction methods of cast-in-situ piles develop rapidly, and are widely used in foundation engineering. Constant cross-section or screw thread type, according to the practice, under the same conditions, the pile side resistance of the thread thread type pile body is about 2 times that of the equal cross section pile side resistance. In contrast, the thread thread type pile body has higher economic value and practical value. In soft soil areas, d...

AI Technical Summary

Problems solved by technology

Since the pile is still made of cylindrical steel casing, the non-rotating static drawing process cannot produce an upward torque to lift the casing, so vibratory hammer and crane vibration pulling are usually used, the construction process is cumbersome, the efficiency is low, and the formed Compared with ordinary cast-in-place piles with equal cross-section, the cylindrical cast-in-place pile with equal cross-section has lower lateral resistance, and the area of ​​the pile bottom is only equal to the bottom of the down-the-hole hammer, that is, the area of ​​the casing bottom. The bottom cannot be re-reamed to further Increase the vertical bearing capacity of piles

[0006] A construction method for full-casing vibratory extrusion and expansion grouting piles (Patent No. 201410814937.2), which uses a vibratory hammer to press the casing into the soil, and puts a special reamer in the pipe for vibratory reaming. When the soil layer is hard, it is difficult to press the casing into the soil layer only by the vibration force of the vibratory hammer machine

Use mechanical or manual soil extraction, and the immersed tube and soil removal are divided into two steps, the construction is cumbersome, the effect is low, and the time-consuming is too long

The bearing stratum at the bottom of the pile is a hard soil layer or rock layer. It is difficult to form a pile bottom expansion head by vibratory reaming, and it cannot effectively further improve the vertical bearing capacity of the pile.

[0007] Patent No. 201710486248.7 discloses an improved structure of a full-casing auger drilling rig and a construction method for a full-casing threaded cast-in-place pile. A helical member with a certain thickness and height is arranged on the outer wall of the casing, and a double power head is used to rotate the casing to drill or lift. The screw-type pile hole is formed at the same time, so as to bite the soil around the pile hole and form a threaded space with a certain thickness and depth (pile diameter 800mm-3000mm). The pile-diameter threaded casing has high resistance to the surrounding soil during drilling or lifting, and has high power requirements for the equipment, especially in hard soil layers, pebbles, gravel layers, or when it needs to enter rock layers, there will be large-diameter rocks The block is stuck in the thread pitch of the casing, making it difficult to drill or lift the casing

In addition, after the hole is formed, concrete is poured into the casing to a predetermined height, and the auger pipe is put into the casing again to rotate and lift the casing. Since the outer wall of the casing is subjected to the resistance of the surrounding soil, the inner wall is under the pressure of the concrete, further increasing the casing pullout. Difficulty, cumbersome construction and low efficacy

[0008] The existing full-sleeve rotary pile forming equipment and method overcome many technical problems in the construction process of cast-in-situ piles, and have high economic benefits. However, most of them adopt the construction method of casing piles. Because the screw teeth occlude the surrounding soil, it is difficult to rotate and pull out the pipe, which requires high power for the equipment. Effectively carry out secondary reaming in the rock stratum to increase the resistance of the pile end by increasing the area of ​​the pile bottom, so as to further improve the vertical bearing capacity of the pile

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