First of all, from the structural theory, the effective pile length of manual digging pile includes the enlarged head, and it must be included, because the enlarged head plays an important structural role.
Manual dig-hole pile, engineering terminology, manual dig-hole, reinforced concrete pile poured on site. Manual digging piles are generally thicker in diameter, and the thinnest is over 800 mm, which can bear the structural main body with fewer floors and greater pressure, and are widely used at present. Pile caps are set on the piles, and then tied and connected by pile cap beams, so that the stress of each pile is evenly distributed and the whole building is supported. Manual digging cast-in-place pile refers to the pile formed by manual excavation, then placing steel cages and pouring concrete.
The pile caps of both manual and mechanical bored piles are single pile caps (one column and one pile). The original intention of setting the pile cap is a transition piece of a component, which is beneficial to the mechanical and geometric connection between the pile, longitudinal and transverse beams and columns, so it is only necessary to square the circle within a certain height range. Quite a few designers didn't understand the specification thoroughly, so they drew the pile cap bigger. During construction, the excavation should be widened according to the size, and the slope may be widened, which is normal.
Manual digging pile foundation in high-rise building does not need pile caps.
Pile cap refers to a pile cap with one column and one pile. The requirements for pile cap structure in JGJ94-2008 Technical Specification for Building Pile Foundation are as follows:
1. The connection structure between pile and cap shall meet the following requirements:
For large-diameter cast-in-place piles, when one column and one pile are used, the pile caps or piles can be directly connected with the columns.
2. The connection structure between column and column cap shall meet the following requirements:
For a pile foundation with one column, when the column is directly connected with the pile, the length of the longitudinal main reinforcement of the column anchored into the pile body should not be less than 35 times the diameter of the longitudinal main reinforcement.
3. The connection structure between caps shall meet the following requirements:
When one column and one pile are used, coupling beams should be arranged at the top of the pile along the two main axes. When the ratio of section diameter of pile to column is greater than 2, coupling beam is not required.
(low pile area+pile top area+low pile area under root number * pile top area) /3* height = number of piles.
This is a general formula for computing platforms.
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