PROBLEM TO BE SOLVED: To provide a bottom-expanded steel pipe pile capable of forming a large bottom-expanded portion with a simple structure, realizing a large bearing capacity, and exerting a large propulsive force at the time of rotational press-fitting. SOLUTION: The shaft steel pipe 2 is composed of a bottom-expanded side steel pipe 3 having a diameter larger than that of the shaft steel pipe joined to the lower end of the shaft steel pipe, and a tip member 4 joined to the lower end thereof and exerting excavation propulsion force. The tip member comprises an end face plate 10 fixed to the lower end surface of the bottom-expanded steel pipe and having inclined surface portions inclined upside down, and a plate-shaped excavation blade 31 fixed vertically to the lower surface thereof. The excavation blade has a notch 31a that opens facing the center hole 32 formed in the center of the end face plate. In the joint structure between the shaft steel pipe and the bottom-expanded steel pipe, a circular flat plate 21 is welded and fixed to the upper end of the bottom-expanded steel pipe, and a short pipe 5 having the same diameter as or slightly larger than the shaft steel pipe diameter and thicker than the shaft steel pipe is formed on the upper surface thereof. It is a joint structure in which the upper end of the short pipe and the lower end of the shaft steel pipe are welded and fixed by welding. [Selection diagram] Fig. 1
展开▼
