Views: 0 Author: WU Publish Time: 2024-10-11 Origin: Site
Rotary digging is the most widely used construction method of bored pile. Rotary drilling rig uses telescopic drill pipe to drive rotary short auger bit, drill bucket or other operating devices to make holes, just like chefs to use different knives to deal with different ingredients, rotary digging construction also needs to choose different forms of drill bucket and drill bit according to different formation conditions.
At present, the rotary digging drill bucket and drill bit used can be roughly divided into: screw drill, rotary digging drill bucket, cylindrical ring bit and expanding bottom bit four categories. Below we briefly introduce the characteristics of different rotary drilling tools and applicable strata.
01
-------------------------Auger bit-------------------------
peculiarity
The screw bit structure has straight screw and conical screw, there are single head single screw, double head single screw, double head double screw three kinds. The cutting tool of rock auger bit is a cutter, and the cutting tool of soil auger bit is a shovel shaped wear-resistant alloy bucket tooth or bucket tooth plus cutter. The direct screw has better conductivity and stronger slag carrying ability than the cone screw, but the turning resistance moment is larger. The single screw bit has the advantages of fast drilling speed, easy slag removal and small turning resistance. The twin-screw bit has good guiding performance, strong slag carrying ability, but big turning resistance. There are two kinds of rock screw bits: cone screw and straight screw, and soil screw bits are straight screw.
Single head single conical spiral rock drill Double head double straight screw soil drill
Applicable formation
Rock auger drill is suitable for weathering bedrock, well cemented gravel formations and hard permafrost. The soil screw bit is suitable for the soil layer above the water table, the sand layer, the dense sand layer with a small amount of clay and the gravel layer with small particle size, and the single screw bit is suitable for drilling the gravel layer and the soil layer with good consolidation. The twin-screw bit is suitable for drilling into loose formations and soft and hard interbedded formations.
02
-------------------------Rotary digging drill bucket-------------------------
peculiarity
The drill bucket is both a drilling tool and a drilling slag loading tool. The bottom of the drill bucket has a single bottom plate and a double bottom plate. The structure of the single bottom plate is simple, and the two layers of the double bottom plate can be relatively rotated, and the opening is closed to prevent the drilling slag from slipping when lifting the drill. The soil inlet has two kinds of single opening and double opening, and the single opening has a larger opening area. The bucket teeth or pick teeth are arranged at the bottom of the drill bucket according to different strata. In order to facilitate slag discharge, the bottom plate opening and closing locking mechanism can be installed. In order to achieve silent slag discharge, the dredging plate and other soil discharge devices can be added in the drill bucket. There is also a half-closed drill bucket that can be split into two pieces.
Double bottom plate and double cut teeth rotary digging drill bucket Half drill bucket
Applicable formation
The rotary drill bucket can be used for sand, silt, clay, silty subclay, sand gravel, pebble and weathered soft bedrock formations below the water table. Single-floor drilling bucket is suitable for drilling slag should not slide off the viscous and cementation formation, and double-floor drilling bucket is suitable for drilling sand layer and poor cementation of gravel layer. Because of the large opening, the single opening drill bucket is suitable for drilling large particle size gravel layer, large pebble layer and drifter layer.
03
-------------------------Cylindrical ring drill bit-------------------------
peculiarity
Cylinder-type annular bit can be divided into coring annular bit and non-coring annular bit according to whether the core is taken. According to the different strata drilled, it can be divided into truncated ring drill bit for weathering bedrock and permafrost and cone ring drill bit for hard bedrock drilling.
Cylindrical cutter drill Cylindrical Trident cutter drill
Applicable formation
For the hard bedrock formation, large drifter layer and hard permafrost layer, it is difficult to drill with rotary drill bucket or spiral drill bit, and it is necessary to drill with the combination of cylinder ring drill bit and spiral drill bit and dredge drill bucket.
04
-------------------------Bottom expanding bit-------------------------
peculiarity
The bottom expanding bit can be divided into push-down bottom expanding bit and up-pressing bottom expanding bit. The open bottom expansion hole has large bottom expansion Angle and small rotary torque. Open bottom expanding bit, expanding bottom Angle is small, rotary torque is large. The bottom expanding bit itself does not have a slag loading mechanism.
Applicable formation
The bottom expanding bit can be used for bottom expanding drilling in common soil, various rock formations and hard frozen soil. The open bottom expanding bit is suitable for stable formation, and the open bottom expanding bit is suitable for more complex formation.
With different buckets and bits, rotary digging method can be used for pile foundation drilling in most strata. In addition, if combined with a long screw drill, the rotary drilling rig becomes a long screw drill. In loess and other special strata, the need to squeeze soil drilling construction, rotary drilling rig can also be equipped with squeezing drill bits.
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