METHOD FOR EXCAVATING BASE ROCK OF ON THE SEA

摘要

The present invention relates to a method for excavating sea bedrock in a semiground state using a composite cofferdam method and, more particularly, to a method for excavating sea bedrock to excavate large bedrock positioned on the surface of the sea and having one or more concave areas (A) in a predetermined area in terms of a planar structure or bedrock in which only a partial area is exposed above the surface of the sea and the other partial area is positioned below the surface of the sea to form an area (A′) below the sea surface, on land. The method comprises: a step (S10) of forming a plurality of explosive loading holes needed on land to remove large bedrock exposed to the surface of the sea; a step (S20) of loading an explosive in the explosive loading holes and subsequently sequentially blasting the large bedrock to excavate the bedrock to have a predetermined height above the surface of the sea; a step (S30) of installing a facility cofferdam (100) on the outer side of the concave area (A) or the area (A′) below the sea surface; a step (S40) of discharging internal seawater of the facility cofferdam (100); and a step (S50) of sequentially excavating the bedrock, which has been excavated to have a predetermined height above the surface of the sea, from the central portion of the excavation area toward an edge thereof on land to excavate the bedrock below the surface of the sea (S50). Since introduction of seawater to the excavation area through a natural ground cofferdam is effectively blocked, a sea bedrock excavation operation can be stably performed on land.