Offshore wind power foundation with improved water-tightness and construction method thereof

Abstract

An offshore wind power foundation with improved water-tightness and a construction method thereof are provided. The offshore wind power foundation is configured such that a bonding material is injected into a space between a pile and a leg using a precast cap member to integrate the leg and the pile, and includes a precast cap member including a precasting housing, a bonding material rotation-injection port, and an elastic spring.

What is claimed is: 
     
       1. An offshore wind power foundation with improved water-tightness, configured such that a bonding material is injected into a space between a pile and a leg using a precast cap member to integrate the leg and the pile, wherein the precast cap member comprising:
 a precast housing, comprising flanges fixed to an upper surface of the leg by a first front expanding anchor and a housing body formed between the flanges; 
 a bonding material rotation injection port, being an inner pipe having a rotating blade inserted into an outer pipe and formed at an outer circumferential surface of the inner pipe, wherein the bonding material is rotation-injected into the space between the pile and the leg through the injection port formed in the housing body via the rotating blade; and 
 an elastic spring unit, configured to extend an elastic spring installed between the housing body of the precast housing and an upper surface of the pile upward, fix the elastic spring to an upper surface of the housing body via an upper fixing cap, and allow a downwardly applied pre-stress to be introduced to the first front expanding anchor using the injected bonding material as a support, 
 wherein the elastic spring unit includes the elastic spring set so that an upper end of the elastic spring unit is inserted into a through hole formed in the housing body of the precast housing and the upper fixing cap formed at the upper surface of the housing body, and the upper fixing cap includes a lower plate integrated with an upper surface of the elastic spring, an upper plate fixed to an upper surface of a center portion of the lower plate and having an upper plate fixing bolt extending upward and passing therethrough, and a fixing nut rotation-fastened to the upper plate fixing bolt and configured to maintain a state in which the upper plate is pressed onto the upper surface of the housing body of the precast housing. 
 
     
     
       2. The offshore wind power foundation of  claim 1 , wherein the precast housing further comprises a second front expanding anchor between the housing body and the upper surface of the pile to integrate the pile and the offshore wind power foundation via the downwardly applied pre-stress due to the elastic spring using the bonding material injected into the precast housing and the pile. 
     
     
       3. The offshore wind power foundation of  claim 1 , wherein the flanges of the precast housing are configured to secure water-tightness of an inner space of the precast cap member using an uneven part or a water stopping material on the leg in addition to the pre-stress introduced to the first front expanding anchor. 
     
     
       4. A method of constructing an offshore wind power foundation with improved water-tightness, the method comprising:
 (a) a step of providing an offshore wind power foundation having a lower end passing through a leg from an upper surface of the leg, wherein a first front expanding anchor is pre-installed at the upper surface of the leg so that an upper end of the offshore wind power foundation is exposed upward; 
 (b) a step of mounting the offshore wind power foundation on a seabed ground by inserting a hollow part of the leg into a head of a pile pre-constructed on a seabed surface and installing an elastic spring unit including an elastic spring having a lower end fixed to an upper surface of the finished pile; 
 (c) a step of setting a precast cap member on an upper surface of the leg by allowing the first front expanding anchor installed at the upper surface of the leg to pass through flanges of a precast housing of the precast cap member, allowing a second front expanding anchor to pass through a housing body of the precast housing, and allowing an upper end of the elastic spring unit to be set on a lower surface of a center portion of the housing body of the precast housing; 
 (d) a step of injecting a bonding material into a space formed between the precast cap member, the pile, and the leg through an injection port of the precast cap member using a bonding material rotation-injection port in a state in which a lower plate integrated with an upper end of the elastic spring extends upward; and 
 (e) a step of increasing a water stopping effect by introducing a pre-stress applied to the first front expanding anchor downward by re-fastening an upper plate of the elastic spring unit to an upper surface of the precast cap member using a fixing nut, the upper plate restraining an elastic spring using the bonding material with secured strength as a support, and compressing the offshore wind power foundation and the pile by allowing the pre-stress to also be introduced to the second front expanding anchor. 
 
     
     
       5. The method of  claim 4 , wherein the precast cap member in step (c) comprises:
 the precast housing, including the flanges fixed to the upper surface of the leg by the first front expanding anchor and the housing body formed between the flanges; 
 the bonding material rotation injection port, being an inner pipe having an outer circumferential surface at which a rotating blade inserted into an outer pipe is formed; and 
 the elastic spring unit, configured to extend the elastic spring installed between the housing body of the precast housing and an upper surface of the pile upward, fix the elastic spring to an upper surface of the housing body via an upper fixing cap, and allow the downwardly applied pre-stress to be introduced to the first front expanding anchor using the injected bonding material as a support. 
 
     
     
       6. The method of  claim 5 , wherein:
 in the step (c), the pre-stress of step (e) extends the lower plate integrated with the upper end of the elastic spring upward and extends the lower plate and the elastic spring by extending an upper plate fixing bolt, which is fixed to an upper surface of a center portion of the lower plate, upward by the fixing nut being unfastened; and 
 in the step (d), the pre-stress couples the upper plate of the elastic spring unit configured to restrain the elastic spring using the injected bonding material with secured strength as a support to the upper surface of the precast cap member by the fixing nut to introduce the downwardly applied pre-stress to the first front expanding anchor. 
 
     
     
       7. The method of  claim 6 , wherein:
 the elastic spring unit in the step (c) comprises the elastic spring having an upper end inserted into a through hole formed on the housing body of the precast housing, and an upper fixing cap formed at the upper surface of the housing body; and 
 the upper fixing cap comprises the lower plate integrated with an upper surface of the elastic spring, the upper plate fixed to the upper surface of the center portion of the lower plate and the upper plate fixing bolt extending upward and passing therethrough, and the fixing nut configured to be rotation-fastened to the upper plate fixing bolt and maintain a state in which the upper plate is pressed onto the upper surface of the housing body of the precast housing. 
 
     
     
       8. The method of  claim 4 , wherein the bonding material rotation-injection port in the step (d) is an inner pipe having an outer circumferential surface to which a rotating blade inserted into an outer pipe is formed, and allows the bonding material to be rotation-injected into a space between the pile and the leg through an injection port formed in the housing body by the rotating blade. 
     
     
       9. The method of  claim 4 , wherein:
 in the step (d), whether the bonding material is injected is measured through a discharge port formed in the precast cap member; and 
 in the precast housing of the precast cap member, the flanges secure water-tightness of an inner space of the precast cap member by using a water stopping material or an uneven part on the upper surface of the leg.