Underwater concrete structure for preventing subsidence at seabed soft ground, and construction method therefor

Abstract

An underwater concrete structure for preventing subsidence at seabed soft ground, includes: a main concrete structure installed on an upper part of seabed soft ground on a top of seabed rock, wherein the main concrete structure is spaced apart upward from the seabed rock and has a plurality of vertical penetration holes extending vertically; and a plurality of concrete columns formed continuously along the vertical penetration holes and the seabed soft ground and the seabed rock located under the vertical penetration holes.

1 . A construction method for an underwater concrete structure for preventing subsidence at seabed soft ground, the construction method comprising:
 installing a main concrete structure having a plurality of vertical penetration holes extending vertically on an upper part of seabed soft ground which is on a top of seabed rock;   forming a ground perforated part in the seabed soft ground and the seabed rock by perforating the seabed soft ground and the seabed rock located under each of the vertical penetration holes through the vertical penetration hole after the installing of the main concrete structure; and   forming a concrete column along the vertical penetration hole and the ground perforated part by inserting a concrete column formation part, which comprises a concrete reinforcing member extending vertically, a waterproof membrane covering lower and side portions of the concrete reinforcing member, and fresh concrete injected into the waterproof membrane, into the vertical penetration hole and the ground perforated part after the forming of the ground perforated part, wherein the concrete column is divided into a penetration hole concrete column part located in the vertical penetration hole, a soft ground concrete column part located in the seabed soft ground, and a rock concrete column part located in the seabed rock, wherein the soft ground concrete column part is formed to support a lower end of the main concrete structure by having a diameter larger than a diameter of the penetration hole concrete column part.   
     
     
         2 . The construction method of  claim 1 , wherein a waterproof membrane protective cover with a shape of a tube or a basket is provided on an outer side of the waterproof membrane, with an upper end of the waterproof membrane protective cover positioned on a vertical middle of the waterproof membrane. 
     
     
         3 . The construction method of  claim 2 , wherein the waterproof membrane protective cover is formed as a mesh and is coupled to the outer side of the waterproof membrane via a skirt member. 
     
     
         4 . The construction method of  claim 1 , wherein in the forming of the ground perforated part, a protection pipe extending vertically is inserted through the vertical penetration hole, and the inserted protection pipe is positioned across the vertical penetration hole and the ground perforated part; and
 in the forming of the concrete column, the waterproof membrane is inserted into the vertical penetration hole and the ground perforated part along an interior of the protection pipe, and the protection pipe is removed after the waterproof membrane is inserted.   
     
     
         5 . An underwater concrete structure for preventing subsidence at seabed soft ground, the underwater concrete structure comprising:
 a main concrete structure installed on an upper part of seabed soft ground on a top of seabed rock, wherein the main concrete structure is spaced apart upward from the seabed rock and has a plurality of vertical penetration holes extending vertically; and   a plurality of concrete columns formed continuously along the vertical penetration holes and the seabed soft ground and the seabed rock located under the vertical penetration holes,   wherein each of the concrete columns is divided into a penetration hole concrete column part located in each of the vertical penetration holes, a soft ground concrete column part located in the seabed soft ground, and a rock concrete column part located in the seabed rock, and   the soft ground concrete column part supports a lower end of the main concrete structure by having a diameter larger than a diameter of the penetration hole concrete column part to prevent subsidence of the main concrete structure.   
     
     
         6 . The underwater concrete structure of  claim 5 , wherein the concrete column comprises a concrete reinforcing member formed vertically and arranged across the vertical penetration hole, the seabed soft ground and the seabed rock, a waterproof membrane covering lower and side portions of the concrete reinforcing member, concrete poured and cured inside the waterproof membrane, and a waterproof membrane protective cover with a shape of a tube or a basket located on an outer side of the waterproof membrane and having an upper end positioned on a vertical middle of the waterproof membrane to protect the waterproof membrane located in the seabed soft ground. 
     
     
         7 . The underwater concrete structure of  claim 6 , wherein the waterproof membrane protective cover is formed as a mesh and is coupled to the outer side of the waterproof membrane via a skirt member.