Hollow structure, and preparation method thereof

A hollow-core structure comprising:

• a plurality of individual inner mold segments that have a hollow cylindrical shell shape;
• a plurality of individual outer mold segments that have a hollow cylindrical shell shape to correspond to the plurality of individual inner mold segments, and in which the inner mold segments are disposed to be separated;
• and
• a filling member that is filled in a separation space between the inner mold and the outer mold, wherein
• the filling member being layered and a plurality of individual filling members being coupled to each other, the filling member further includes a plurality of non-shrink high-strength mortar layers that are filled between individual filling members, in which stresses on contact surfaces between the individual filling members are evenly distributed, and wherein
• the filling member further includes shear keys that are interposed at ends of the individual filling members to reinforce a coupling between the individual filling members.