Vacuum-assisted post-grouting device and method for cast-in-situ bored pile

Abstract

The invention discloses a vacuum-assisted post-grouting device and method for a cast-in-situ bored pile. The vacuum-assisted post-grouting device comprises grouting pumps, outer grouting pipes, innergrouting pipes, a grouting device, a vacuum pump, a vacuum bin, an outer vacuum pipe, an inner vacuum pipe, and a negative pressure device. Grouting holes are distributed in the grouting device and located in a gravel layer; negative pressure holes are distributed in the negative pressure device and located in a sand cushion layer; sand prevention cloth covers the negative pressure holes in the negative pressure device; the sand cushion layer is laid at the pile bottom, and the gravel layer is laid on the sand cushion layer; the lower ends of the inner grouting pipes are communicates with thegrouting device; the upper ends of the inner grouting pipes extend out of a pile hole and are detachably connected with the outer grouting pipes; the lower end of the inner vacuum pipe is communicatedwith the negative pressure device, and the upper end of the inner vacuum pipe extends out of the pile hole and then is detachably connected with the outer vacuum pipe; the upper ends of the inner grouting pipes and the upper ends of the inner vacuum pipes can be sealed through pipe caps; the inner grouting pipes, the grouting device, and the inner vacuum pipe are connected to a reinforcement cage, and the bottom end of the reinforcement cage is located inside the gravel layer; valves are arranged on the outer grouting pipes and the outer vacuum pipe; and a valve and a vacuum degree detectionpart are arranged between the vacuum pump and the vacuum bin. According to the vacuum-assisted post-grouting device and method for the cast-in-situ bored pile, the post-grouting quality is high.

Description

technical field [0001] The invention belongs to the field of pile foundation construction, and in particular relates to a vacuum-assisted post-grouting device and method for bored cast-in-place piles. Background technique [0002] The bearing layer of bored piles requires a relatively complete rock layer. When the bearing layer is a non-rock layer, the post-grouting method is generally used to strengthen the foundation at the pile end. Pile end grouting technology refers to: bury the grouted steel pipe along the outer wall of the pile reinforcement cage, and after the pile concrete strength meets the requirements, press the cement slurry through the steel pipe into the pores of the gravel layer at the pile end by pressure, so that the original bad holding force Layer, cemented into a high-strength combination, the cement slurry diffuses from the pile end in the pores of the gravel layer to the surrounding under pressure. The downward diffusion is equivalent to increasing th...

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Problems solved by technology

[0003] At present, there are the following problems when grouting after bored piles: 1) The water-cement ratio should not be too large or too small. If it is too large, it will cause difficulty in grouting, and if it is too small, the cement slurry will form segregation under pressure; 2) The grouting often occurs along the side of the pile or in other parts, the grouting effect is difficult to judge and difficult to control, and the single pile grouting period is long; 3) The pressure control of the grouting process is cumbersome. The pre-set amount of grouting, but when it reaches a certain pressure, the grouting should be stopped. If the pressure of grouting is too high, it will cause the grout to segregate, block the pipeline, disturb the gravel layer, and even make the pile body float.

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