Extrusion pile-forming method of belled prefabricated pile body with high bearing ability

Abstract

The invention relates to a construction method for building pile foundation engineering, in particular to an extrusion pile forming method of a high-bearing-capacity enlarged-base precast pile body. The pile forming method of the invention comprises the following process steps: a. an immersed tube with a metal pile head is sunk to a hard soil layer for designing elevation; b. the metal pile head is drawn out; c. extrusion equipment is used for enlarging the base and forming a lower base space, and the immersed tube is drawn upward to a preset height H, and an upper base space is formed by the extrusion equipment, and fine earth is thoroughly sucked by an earth sucking device; d. concrete is cast into the lower base from the opening of the immersed tube; e. a lower precast solid pile body with dowels at the lower end is connected with an upper precast hollow pile by steel bars and inserted into the immersed tube to the right position, and an upper base is cast; and f. the immersed tube is pulled out, and slurry is poured into the gap. The construction method has the advantages and effects of high utilization rate of the material strength, and the strength reduction can reach 0.9 to 1.0.

Description

technical field [0001] The invention relates to a construction method of building pile foundation engineering, in particular to a pile forming method of prefabricated pile body with enlarged bottom. Background technique [0002] According to the national standard, the whole body is cast-in-place (that is, the pile body is cast-in-place concrete, and the base is also cast-in-place concrete). The maximum diameter ratio of the base of the expanded bottom pile is limited to 3-3.5, while the immersed tube prefabricated steel concrete expanded bottom pile, this kind of pile It is prefabricated concrete for the pile body and cast-in-place concrete for the base. Obviously, the ratio of 3-3.5 is broken, and generally can reach 3.5-5. Although the bearing capacity is greater, it still cannot meet the needs of the project, especially when the diameter of the expanded bottom is greater than 1.5 meters. , the end bearing capacity should be discounted by 0.9. For this reason, immersed tu...

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Problems solved by technology

These two points are quite unfavorable to multi-bearing plate (multi-level bottom expansion) piles. In other words, it brings two problems. 1) The national building code stipulates that the end bearing of the base of the pile expansion bottom using the positive and negative circulation method The force has to be multiplied by a factor of 0.45, because there is mud and the sediment at the bottom of the pile cannot be cleaned up. (The standard in Zhejiang Province is 0.24 discount). However, the construction conditions cannot be protected. In addition, the positive and negative circulation method works underwater, so the bottom expansion construction cannot be seen, and it is difficult to measure and record. It also often happens that a piece of upper soil falls off when the bottom is expanded underwater. Occurrence, also because the multi-stage piles of the prior art all use cast-in-place concrete for the whole body, and the strength of cast-in-place concrete is not high, and the quality is difficult to guarantee, and the quality is difficult to control when pouring concrete in water, plus multiple bases The bearing capacity of the piles is relatively large, the diameter of the pile body must be made larger due to the above factors, and this kind of multiple bases is most afraid of a large diameter of the pile body. Research and tests have shown that as the diameter of the pile body increases, its bearing capacity will be greatly attenuated.

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