Dismantling method of tower-type wind power generation system

A dismantling method of a tower type tower wind power generation system including a hollow tower body and a wind power generator provided in an upper end part of the hollow tower body, an upward-tapering part provided in the upper end part of the hollow tower body, the method comprising:

• an inner column building step of building an inner column extending to an upper side of a lower end part of the upward-tapering part inside an internal cavity of the hollow tower body;
• a tower body-upper part supporting step of applying an upward supporting force equal to or larger than a load of an entire system above the upward-tapering part to the upward-tapering part by a jack provided in an upper part of the inner column via an abutting support member that abuts on a predetermined position on an inner wall of the upward-tapering part of the hollow tower body;
• a work bench setting step of suspending a work bench on which a worker can climb and perform work from an upper part of the hollow tower body in a liftable manner;
• a tapering part-lower part removal step of cutting and removing, over an entire periphery of the hollow tower body, a predetermined region lower than an abutting position of the abutting support member of the upward-tapering part in a supported state by an operation on the work bench;
• a tapering part lowering and placing step of, after the tapering part-lower part removal step, lowering and placing, by the jack, a remaining upward-tapering part on a placement protrusion on which an entire system above the upward-tapering part is placeable provided in a protruding manner on an inner wall of the hollow tower body remaining on a lower side;
• an uppermost part of lower part removal step of using the work bench to cut and remove a predetermined range of an uppermost part of the hollow tower body remaining on a lower side over an entire periphery of the hollow tower body after the tapering part-lower part removal step;
• an inner column shortening step of removing a lower end part of the inner column in a state where the inner column is suspended from a remaining upward-tapering part and lowering the inner column from which the lower end part is removed on a ground in the internal cavity;
• and
• a lowering and removal repeating step of repeating the tapering part lowering and placing step, the uppermost part of lower part removal step, and the inner column shortening step.