Steel pipe

Abstract

This article is a steel pipe used for reinforcing the ground by connecting four steel pipes with different diameters. As shown in the reference figure 1, this article is an extended steel pipe (10) in which four steel pipes (10A to 10D) with different diameters are nested and can be extended in the axial direction, and is a stopper-equipped extended steel pipe with a stopper (20) for temporarily fixing the steel pipes so that they do not slide relative to each other when the steel pipes are nested. The stopper (20) consists of a cylindrical pipe part with a diameter larger than that of the largest-diameter steel pipe and a donut-shaped disk part fixed to one end face thereof. A protector (40) that provides a gap between the stopper (20) is fixed to the outer periphery of the stopper-side end of the smallest-diameter steel pipe 10D. A hole with a nut-shaped inner surface that engages with a bolt (30) is formed in the pipe part of the stopper (20). With the disk part of the stopper (20) in contact with the end of the protector (40), the bolt (30) is screwed into the hole formed in the pipe part of the stopper (20), and the bolt end is pressed against the outer periphery of the largest-diameter steel pipe (10A), thereby fixing the stopper (20) to the extended steel pipe (10). Each of the three steel pipes (10B to 10D) excluding the largest-diameter steel pipe (10A) has a first tubular member (50) with a tapered end fixed to the outer periphery of the first end (the end opposite to the stopper), and a second tubular member (60) with an inner diameter smaller than the inner diameter of each steel pipe and a flange formed at one end is fixed to the second end (the stopper-side end) of the three steel pipes (10A to 10C) excluding the smallest-diameter steel pipe (10D). In the state where the steel pipes are nested and contracted before driving into the ground (reference figure 1), the flanges of the second tubular members (60) of adjacent steel pipes come into contact with each other, locking the sliding of the steel pipes in the direction opposite to the extension direction. Also, in the state where the steel pipes are extended (reference figure 2), the stopper-side end face of one first tubular member (50) and the stopper-opposite end face of the other second tubular member (60) of adjacent steel pipes come into contact with each other, locking the sliding of the steel pipes so that the steel pipes do not fall out in the extension direction. When the extended steel pipe of this design is in use, the screwing of the bolt is loosened and the stopper is removed. As a result, the steel pipes can slide axially relative to each other, that is, they can be extended. When extending during driving, as shown in reference figure 3, it becomes a long steel pipe.

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