Post-grouting technology adopting manual hole digging and all-casing construction method, and adopting manner of installing rubber capsule (cavity) at bottom of cast-in-place pile

Abstract

The invention discloses a post-grouting technology adopting a manual hole digging and all-casing construction method, and adopting a manner of installing a rubber capsule (cavity) at the bottom of a cast-in-place pile. The post-grouting technology is applicable to the technical field of foundation and underground space engineering. The background technology is that with regard to a borehole usinga mud protection wall at present, if a steel plate capsule is installed at the bottom of a reinforcement cage, the collapse of the hole wall of the borehole is easily caused, so that the sediment of the bottom of the hole exceeds the standard, and silt collapsing from the hole wall is easily accumulated on a steel plate, so that the quality of the cast-in-situ bored pile is influenced. The post-grouting technology has the most prominent characteristic that the limit conditions and the application conditions of closed grouting adopting a manner of installing a grouting container at the bottom of a pile are found; and the main content is that a manual hole digging method or an all-casing construction method is utilized for hole formation for the cast-in-place pile, the mud protection wall isnot used in a hole formation process, a grouting pipe is bound on the reinforcement cage, the steel plate is installed at the bottom of the reinforcement cage, the rubber capsule is installed on thebottom surface of the steel plate, and the grouting pipe penetrates through the steel plate and communicates with the rubber capsule. After the hole is formed by virtue of the construction method, thereinforcement cage is descended to reach the bottom of the hole, then concrete starts to be poured, and after the strength of the body of the pipe meets requirements, pressure grouting is carried outon the rubber capsule at the bottom of the pile through the grouting pipe.

Description

Technical field: [0001] Ground and Foundation Underground Space Engineering Technology Background technique: [0002] At present, in the foundation field, the post-cast-in-situ grouting technology listed in the construction pile foundation specification is open grouting, because the implementation process of open grouting is relatively simple, especially before grouting. The process at the bottom of the hole has little disturbance to the hole wall, but the controllability of the grout injection area of ​​the open grouting is low, and the formation of the enlarged head of the pile tip, the compaction effect on the surrounding strata, and the increase in the bearing capacity of the pile tip It is not as good as closed grouting with a grouting bag (cavity). Although the closed grouting with grouting pocket (cavity) at the bottom of the pile is more superior in terms of orientation, localization and quantification according to the requirements of the "three fixes" of grouting, ...

AI Technical Summary

Problems solved by technology

If a steel plate capsule (cavity) is installed at the bottom of the steel cage as a post-grouting container, in the process of going down to the bottom of the hole with the steel cage, the steel cage with the protective steel plate is like a piston in the drilled hole, and it is easy to form a vortex in the mud water. The mud flow between the edge of the steel plate and the wall of the drilled hole scours and disturbs the wall of the drilled hole, and the steel plate at the bottom is also likely to scratch the wall of the drilled hole. These factors are likely to cause the wall of the drilled hole to collapse, resulting in The sediment at the bottom of the drilled hole exceeds the standard after the grouting container reaches the bottom. At the same time, the silt that collapsed from the wall of the drilled hole is easy to accumulate on the top of the steel plate, which affects the quality of the drilled cast-in-place pile. In severe cases, the pile will be broken. The diameter of the steel plate is relatively small, or due to other reasons such as overfilling of the collapsed hole, the grouting capsule (cavity) at the bottom of the pile will be tightly wrapped by concrete and cannot function. This is also the technical specification for building pile foundations (JGJ94_2008). The main reason why the closed grouting method with grouting pocket (cavity) at the bottom of the hole pile is excluded (see the article description)