Method for alternately constructing underground vertical members using top-down construction method

A construction period shortening method through a method for alternately constructing underground vertical members, comprising:

• (a) a step of constructing a temporary earth retaining wall in a ground by a conventional method;
• (b) a step of vertically installing an above-ground level core part and pillar, from above ground, which is constructed upward in parallel with construction of a underground structure downward when the underground structure and the above-ground structure are constructed;
• (c) a step of excavating the first above-ground level, constructing a floor part thereof, excavating the first underground level, and then constructing a floor part thereof;
• (d) a step of excavating each of the remaining underground levels in order in a downward direction and constructing the floor part, and simultaneously constructing core parts of one underground level or a plurality of underground levels first to support the above-ground level core part which is preferentially constructed upward;
• (e) a step of preferentially constructing the above-ground level core part in an upward direction on an upper part of the underground level core part which is constructed first, and installing the underground level frame in the downward direction in parallel therewith;
• (f) a step of alternately installing the core parts after the core part of one underground level is installed first in the step of installing the underground level frame in the downward direction;
• (g) a step of forming the foundation after the underground level frame is completed to the foundation, and installing the core parts of the remaining levels to be alternately constructed downward in the upward direction from the lowest level to the underground level core part which is constructed first, during the same time period or sequentially;
• and
• (h) a step of constructing the construction completion through the remaining frame construction of the above-ground level and the final construction that is finishing work,
• wherein the underground core parts are constructed first or during the same time period within a certain possible range to exclude them from a main process line critical path to shorten an overall construction period.