Construction method for increasing one-time qualification rate of pile foundation in karst or broken zone area

Abstract

The invention relates to a construction method for increasing one-time qualification rate of a pile foundation in a karst or broken zone area. The construction method comprises the following steps of(1) measuring and laying lines at the position of a pile foundation hole, embedding a steel protective cylinder, and controlling the verticality; (2) utilizing a rotary excavating drill to drill intothe bottom of a clay layer, replacing the rotary excavating drill with a percussion drill after the rotary excavating drill reaches a hard soil layer, reducing the drilling frequency when drilling isconducted at the portion 1-1.5 m deep in a top base rock, and repeatedly conducting drilling up and down until the soil layer is penetrated through; (3) putting out a drilling machine, filling a pilehole with crushed stones and clay, simultaneously putting a guide pipe into the pile hole to spray mixed slurry, and carrying out pre-pressing and compacting; (4) using the percussion drill for continuing drilling a crushed stone layer which is compacted by prepressing, and penetrating through a karst cave or a bottom plate of the crushing zone area until the drill reaches the bottom elevation ofa pile; (5) cleaning the holes, removing the drilling machine, lowering a reinforcement cage, and pouring concrete. The method can eliminate the influences of grouting leakage, hole collapse, pile hole inclination, diameter reduction and the like, reduce the construction cost, simplify the flow and improve the hole formation quality of the pile foundation.

Description

technical field [0001] The invention belongs to the field of geotechnical engineering design and pile foundation construction, and in particular relates to a construction method for improving the first pass rate of pile foundations in karst or broken zone areas. Background technique [0002] At present, bored piles in construction engineering have been used as a relatively mature foundation form, and have been widely used in bridges, station buildings, tunnels and other projects, and have gained certain construction experience. Due to the complex geological conditions in karst and broken zone areas, the large number of karst caves, and the lack of force-transmitting layers, it is easy to have cracks and slurry leakage, collapsed holes, skewed pile holes, concrete overfilling and shrinkage during drilling. The diameter and other problems will affect the quality of the pile body. Therefore, improving the pass rate of pile holes has an important impact on improving the quality...

AI Technical Summary

Problems solved by technology

[0002] At present, bored piles in construction engineering have been used as a relatively mature foundation form, and have been widely used in bridges, station buildings, tunnels and other projects, and have gained certain construction experience. Due to the complex geological conditions in karst and broken zone areas, the large number of karst caves, and the lack of force-transmitting layers, it is easy to have cracks and slurry leakage, collapsed holes, skewed pile holes, concrete overfilling and shrinkage during drilling. diameter and other issues, affecting the quality of the pile body

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