Construction Method of Multi-section Drilled and Expanded Cast-in-situ Pile

Abstract

The invention discloses a construction method for multi-section drilled and expanded cast-in-situ piles, which comprises the following operation steps: ① sequentially leveling the construction site, setting out the pile position and burying the casing; ② centering and leveling the drilling rig; ③ drilling, Multi-section reaming until the designed hole bottom depth; ④ Implement the first hole cleaning; ⑤ Lift the drilling and expansion device and the slurry discharge pipe out of the drill hole; ⑥ Lower the reinforcement cage; ⑦ Lower the pouring conduit; Secondary hole cleaning; ⑨ underwater concrete pouring; ⑩ multi-section drilled and expanded cast-in-situ piles into piles and maintenance. It realizes the construction of multi-section drilled and expanded cast-in-situ piles by one machine and completes them in one go. It rewrites the history of the existing technology that multiple machines are alternately constructed, the construction efficiency is low, and the construction quality is difficult to guarantee. It pushes the construction technology of variable-diameter cast-in-place piles forward. to a whole new level. The above-mentioned construction method can not only ensure the quality of the pile, but also greatly improve the construction efficiency, and lay a solid foundation for the promotion and application of multi-section drilled and expanded cast-in-place piles.

Description

technical field [0001] The invention relates to a variable-diameter cast-in-situ pile construction technology, in particular to a construction method for multi-section drilled and expanded cast-in-situ piles. Background technique [0002] Bored cast-in-place piles with mud retaining walls first appeared abroad and have a history of more than 100 years. They are also one of the earliest and most widely used pile types in my country. On the basis of mud retaining bored piles, variable-diameter cast-in-place piles are produced, such as bored bottom-expanded cast-in-place piles, rotary expansion piles, and squeezed-expanded cast-in-place piles. The multi-section drilled and expanded cast-in-place pile disclosed by the present invention also belongs to the category of variable-diameter cast-in-place piles. This type of pile utilizes the principle that the end resistance of the same area is far greater than the side friction resistance, and several enlarged heads (expanded heads) ...

AI Technical Summary

Problems solved by technology

[0010]a. The hole-forming process of extruded and expanded piles is complex, requiring a variety of mechanical equipment to be constructed alternately. The extruded and expanded equipment occupies a large construction site, and low construction efficiency has become a prominent problem

b. The construction process of pile formation is complicated, the drilling wall encounters a variety of mechanical lifting and scraping, and the hole drying time is long, so it is difficult to control the quality of the hole formation

c. The bearing plate is not formed by extrusion and expansion at one time. The extrusion arm is greatly affected by the characteristics of the formation and manual operation factors, and the direction of expansion is easily shifted. The wedge-shaped cavity formed by each extrusion of the working arm may not be mutually They are overlapped to form a complete set-up cavity, but the outer edge of the cavity and the vertical misalignment of the cavity are unavoidable, and the molding size of the cavity cannot be guaranteed

d. In view of the operating characteristics of the extrusion equipment and the characteristics of the soil layer, during the extrusion process, the apertures at the upper and lower ends of the disk are reduced, the diameter of the disk is reduced, and the height of the outer edge of the disk is reduced, which seriously affects the bearing capacity of the single pile.

e. The extrusion and expansion construction technology itself has little adaptability to the stratum. In the sandy soil layer, the extrusion and expansion support plate is easy to collapse the hole, and it cannot be squeezed in the hard stratum, so the plate position design has to be changed.

f. In the process of extrusion and expansion, a large amount of sediment will fall into the pan cavity or the bottom of the hole. There is no way to clean up the sediment in the pan cavity, and we can only let it go, which greatly reduces the bearing capacity of the pan; The sediment needs to be mobilized to drill back and forth for the first hole cleaning, which is labor-intensive and time-consuming

[0011] In summary, it can be seen that the construction of variable-diameter cast-in-situ piles in the prior art requires a variety of construction machinery and equipment to be constructed alternately, namely three processes of drilling, reaming and cleaning Different construction equipment needs to be replaced to complete; the alternate operation of various construction machines makes the already compact construction process complicated, equipment scheduling and quality monitoring are difficult, and the construction progress is severely restricted; the forming effect of the bearing plate (enlarging head) is difficult To achieve the expected goal, the sediment at the bottom of the plate is difficult to remove, and the quality of hole formation and pile formation is not stable enough; the defects of construction equipment and construction technology make the technical and economic advantages of the above pile types not outstanding, which restricts its application scope

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