Rotary-drilling and bottom-expanding construction process for cast-in-place pile

Abstract

The invention discloses a rotary-drilling and bottom-expanding construction process for a cast-in-place pile. A rotary drilling rig is adopted to conduct rotary drilling to form a hole, helix pieces in the middle of a drill bit of the rotary drilling rig are equal in diameter, and the diameters of helix pieces on the upper portion and the lower portion of the drill bit are gradually reduced. The construction process includes the steps of setting-out positioning, in-place arrangement of the rotary drilling rig, primary drilling, burying of a steel casting, rotary drilling and hole forming, bottom expanding, hole clearing, hoisting and arranging of a reinforcement cage, installation of a guiding pipe, concrete pouring and the like. According to the rotary-drilling and bottom-expanding construction process for the cast-in-place pile, construction is convenient, the dimension is accurate, and the quality is good.

Description

technical field [0001] The invention relates to the field of building construction, in particular to a construction technology of rotary excavation and bottom expansion grouting piles. Background technique [0002] Foundation and foundation engineering is one of the leading projects of building construction, and it is also a sub-project with relatively complex construction technology, greater difficulty, longer construction period, and more investment. In recent years, with the rapid development of my country's economic construction, urban construction has increased day by day, and the importance of foundation and foundation construction has attracted increasing attention and attention from all parties. [0003] Recently, most large and medium-sized buildings in my country use pile foundations, and engineering piles generally use two methods. One is to use manual excavation. Although the quality of the holes is good, the degree of mechanization is low and it takes a long tim...

AI Technical Summary

Problems solved by technology

[0003] Recently, most large and medium-sized buildings in my country use pile foundations, and engineering piles generally use two methods. One is to use manual excavation. Although the quality of the holes is good, the degree of mechanization is low and the time is long.

Another method is to use a rotary excavator to form a hole. Although the hole forming speed is fast, due to the poor effect of mechanical bottom expansion, the bottom of the hole is not cleaned cleanly, and the quality of the hole is not ideal.

[0004] When mud wall protection is used, changes in the relative density, viscosity, sand content, colloid rate, water loss rate, mud skin thickness, static shear force, pH and other properties of the mud directly affect the drilling speed, hole wall stability, There are a series of pore-forming process issues such as in-hole purification and prevention of in-hole accidents. However, the mud in the existing construction is usually directly composed of water, clay and expansive soil, and its performance cannot be guaranteed.

[0005] At present, a large-mass force hammer is usually used to make bottom-expanded cast-in-situ piles. The disadvantage of this method is that the force hammer repeatedly beats the concrete layer, providing downward pressure, which causes the diameter of the pile hole to expand. However, the shape of the bottom expansion is irregular, and the expansion cannot be calculated. The specific specifications of the bottom pile are not conducive to the calculation of bearing capacity, and the beating effect is random, so the specific specifications of the cast-in-place pile body cannot be selected

[0006] After the pile foundation of the bored pile is in place under the steel cage, if the pile foundation concrete is not poured immediately, the slag in the mud in the pile hole will settle again, causing the pile bottom sediment to be too thick

[0007] Due to the above defects, the quality of bored piles cannot be guaranteed at present. In order to ensure safety, only the safety factor is increased, which wastes a lot of material and financial resources.

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