Wave-shaped grouting bulb of micropile and method for forming same

Patent metadata

Field	Value
Publication number	US-10501905-B2
Application number	US-201716097929-A
Country	US
Kind code	B2
Filing date	Aug 10, 2017
Priority date	Aug 10, 2016
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

The present invention provides a wave-shaped grouting bulb (100) for securing an underground bearing capacity of a steel bar (10), the bulb comprising a plurality of protrusions (120), which have a predetermined maximum diameter (D1) and are formed along the longitudinal direction of a cylindrical pillar part (110) extending downward, wherein the neighboring protrusions (120) are formed to be spaced from each other by a predetermined formation distance (s). The present invention has an advantageous effect of improving a skin friction force and resistance to compression and pullout in the grouting bulb integrated with the steel bar and thus enhancing structural stability in the micropile body.

First claim

The invention claimed is:

1. A method for forming a wave-shaped grouting bulb for securing an underground bearing capacity of a steel bar, wherein a micropile is constructed using jet-grouting, the method comprising:
a first step of forming a drilled hole by using a jet-grouting device which comprises a drilling machine that drills a ground to form the drilled hole, a grout material spray hole that sprays a grout material, and a grout material feeding pipe that supplies the grout material to the grout material spray hole, and forming the grouting bulb by spraying, at high pressure, the grout material from the grout material spray hole into the drilled hole;
the wave-shaped grouting bulb comprising:
a plurality of protrusions, which have a uniform maximum diameter and are formed along the longitudinal direction of a cylindrical pillar part extending downward, wherein
the neighboring protrusions are formed to be spaced from each other by a predetermined formation distance,
the wave-shaped grouting bulb, wherein a longitudinal cross-section of the wave-shaped grouting bulb forms a waveform,
the wave-shaped grouting bulb, wherein the steel bar is inserted into the pillar part,
the wave-shaped grouting bulb, wherein a length of the protrusions is twice the maximum diameter,
the wave-shaped grouting bulb, wherein the formation distance is the maximum diameter or twice the maximum diameter.

2. The method of forming the wave-shaped grouting bulb of claim 1 , further comprising:
a second step of withdrawing the jet-grouting device out of the drilled hole, and forming the pillar part inside the drilled hole by spraying the grout material from the grout material spray hole into the drilled hole; and
a third step of inserting the steel bar into the pillar part.

Assignees

• Korea Inst Civil Eng & Building Tech

Inventors

• Han Jin Tae
• Jang Young Eun

Classifications

• E02D5/665

  for making piles · CPC title

• E02D5/80

  Ground anchors {(for galleries, tunnels or shafts E21D21/00)} · CPC title

• E02D5/56

  Screw piles {(placing piles by screwing down E02D7/22)} · CPC title

• E02D5/54

  Piles with prefabricated supports or anchoring parts; Anchoring piles {(E02D5/44 takes precedence; ground anchors E02D5/80; anchored foundations E02D27/50)} · CPC title

• E02D2200/1685

  cylindrical · CPC title