Pile-forming method for two-level expanding bottom mixed pile body

Abstract

The present invention relates to construction of building pile foundation engineering, and is especially piling process of two-stage under-reamed composite pile stem. The piling process includes the following steps: 1. immersing immersed tube with metal pile head into hardpan to design elevation; 2. taking out the metal pile head; 3. forming the lower base space, drawing upwards the immersed tube to designed distance, forming the upper base and taking out soil; 4. immersing the prefabricated hollow pile stem with welded long steel dowel assembly in the lower end into the immersed tube and to the hardpan; 5. pouring concrete into the prefabricated hollow pile stem to form the lower base, the upper base and the lower pile stem; and 6. withdrawing the immersed tube and injecting cement mortar to the gap. The present invention has the advantages of high location precision and concentricity, high material strength utilizing rate and deduction coefficient, and high bearing capacity.

Description

technical field [0001] The invention relates to a construction method of building pile foundation engineering, in particular to a method for forming piles of a combined pile body with secondary bottom expansion. Background technique [0002] It is well known that the quality of building foundation works plays a vital role in the influence of building quality, so each construction unit not only pays attention to the construction quality of above-ground buildings, but also pays more attention to the quality of foundation works. And invest in scientific research to tap the potential of the pile foundation project, so that it can improve the utilization rate of material strength on the premise of ensuring the quality of the project. As can be seen from the calculation, the bearing capacity of the pile tip designed by the solid pile only uses about 20% of the strength of the pile body. For the sake of safety, all countries have stipulated a safety factor, some countries have stip...

AI Technical Summary

Problems solved by technology

[0003] 1. Part of the soil body of the pile is dug out manually, the construction surface is too large, the workload of soil extraction is obviously increased, and the efficiency is low;

[0004] 2. Since there is no immersed tube as support for the bottom expansion equipment, the positioning is not accurate, the expansion angle of the base is too small, and the parameters in the bottom expansion process cannot be guaranteed, so that the quality of the pile is not easy to control, and it is difficult to meet the design requirements, resulting in the single pile The bearing capacity is greatly reduced;

[0005] 3. There are potential safety hazards for construction personnel, and construction personnel are prone to accidents if they do not pay attention;

[0006] 4. The scope of use is narrow, not only not suitable for bottom expansion of small-diameter piles, but also not suitable for bottom expansion and pile formation in prefabricated piles and high-complex geological conditions;

[0007] 5. The granular loose soil sediment in the cavity of the expanded bottom is not clean, which has a serious adverse effect on the bearing capacity of the pile. Based on the above situation, the reservoir must be improved to increase the bearing capacity of a single pile and reduce the cost of foundation engineering.

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