Core filling tubular pile cement composite foundation pile and construction method

Abstract

The invention discloses a core filling tubular pile cement composite foundation pile, which comprises a core pile and a cement pile wrappring around the core pile, and is characterized in that the diameter ratio of the core pile to the outer-layer pile is 0.375-0.50, the length ratio thereof is 0.50-0.76; the cement pile is a cement pile of a repeated spraying section in a range of 2-6m on the upper part and below the core pile bottom end; expansive concrete with C30-C80 of strength grade is filled into hollows on the upper part of the core pile; the length of the core filling concrete is 6-10 times of the diameter of the core pile. The construction method of the core filling tubular pile cement composite foundation pile is characterized by comprising the following steps: the outer-layer cement pile is constructed by a high-pressure spraying, blending and stirring method; the upper end and the lower end of the core pipe are sealed; the central concentric static force is pressed into the core pile to the designed elevation before the outer-layer cement is initially solidified, the upper part of the core pile in the range of 6-10 times of pile diameter is filled with micro-expansive concrete with C30-C80 of strength grade and is provided with 4-8 anchorage steel bars. The invention solves the limitation that high-strength prestress tubular piles are applied in high-rise buildings and high-intensity areas.

Description

technical field [0001] The invention relates to a high-bearing-capacity foundation pile used in soft soil areas, that is, a foundation pile compounded by inserting a core-filled high-strength prestressed pipe pile into a large-diameter cement-soil pile. Background technique [0002] The currently disclosed and used composite piles whose outer layer is cement soil and whose inner core is a pipe pile can be divided into two types according to the pile size, one is a medium-diameter pile type, and the other is a large-diameter pile type. [0003] The medium-diameter pile type is formed by the outer layer of cement-soil piles formed by deep-layer mixing method or high-pressure rotary spraying method, and the middle and small-diameter pipe piles are inserted in the center. The medium-diameter pile type is limited by the pile-forming method and pile equipment. The pile diameter is concentrated between 500 and 700mm, and the pile length is relatively short. The bearing capacity pro...

AI Technical Summary

Problems solved by technology

However, there are such defects in the large-diameter composite piles disclosed at present: (1) the economic matching relationship between the geometric size and strength of the core pile and the outer layer pile is not provided, resulting in the strength of the core pile material and the pile side provided by the outer layer of cement soil by the soil around the pile. The frictional resistance cannot be brought into full play at the same time, thereby increasing the cost per unit bearing capacity; (2) The bearing capacity of a single pile is determined by the structural bearing capacity of the prestressed concrete tubular pile as the core pile, and there is a limit to the improvement of the bearing capacity of a single pile, which often increases As a result, the bearing capacity of the core pile has reached the limit and the side friction of the outer cement-soil pile has not been fully exerted, that is, the core pile and the outer cement-soil pile have not reached an economic matching relationship, and there is a waste of side friction of the outer cement-soil pile; Even if the strength of the core pile material and the pile side frictional resistance provided by the soil around the pile reach the limit at the same time, since the bearing capacity of a single pile is determined by the structural bearing capacity of the core pile, the maximum diameter of the outer cement-soil pile is limited to 1500mm; (3) The connection problem with the cap has not been solved, and it cannot be used directly as a foundation pile. When used as a composite foundation reinforcement, the outer layer of cement and soil is prone to failure first, which leads to the phenomenon of pipe pile pressure explosion failure; (4) The construction method is simple, without providing detailed technical parameters and guarantee measures to meet the design requirements, it is difficult to guide the specific implementation

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