Abstract: This depression-provided steel pipe has plural depressions on an outer peripheral surface, the depressions being formed so as to form a line along an axial direction of the steel pipe, in which each of the depressed portions has, inside thereof, a columnar groove portion extending along the axial direction of the steel pipe and depressed deeper than a bottom surface of these depressed portions; 0.95?HA/HB?1.05 is satisfied, where HA is an average Vickers hardness in each of the depressed portions, and HB is a Vickers hardness at a portion between the depressed portions adjacent to each other in the axial direction of the steel pipe; and the outer peripheral surface is covered with a mill scale.

Abstract: This depression-provided steel pipe has plural depressions on an outer peripheral surface, the depressions being formed so as to form a line along an axial direction of the steel pipe, in which each of the depressed portions has, inside thereof, a columnar groove portion extending along the axial direction of the steel pipe and depressed deeper than a bottom surface of these depressed portions; 0.95?HA/HB?1.05 is satisfied, where HA is an average Vickers hardness in each of the depressed portions, and HB is a Vickers hardness at a portion between the depressed portions adjacent to each other in the axial direction of the steel pipe; and the outer peripheral surface is covered with a mill scale.

Abstract: A steel pipe ground reinforcement of the present invention is driven into a ground and injects a grouting material into the ground. The steel pipe ground reinforcement includes: a recess portion and a smooth portion that are arranged on an outer peripheral surface thereof; and a plurality of through-holes that are arranged in the recess portion or the smooth portion that communicates between the inside and outside of the steel pipe ground reinforcement.