Method of installation of an offshore wind turbine tower, with pile-based foundations, and equipment for implementing said method

Method of installation of an offshore wind turbine tower, with pile based foundations:

• a) said wind turbine tower comprising:
• a tower mast,
• at least three piles,
• anchoring means,
• a platform with first securing means, and
• buoyancy means with second securing means,
• wherein each of the piles includes an upper area designed to be on a level with the platform in an installed condition and a lower area designed to receive said anchoring means below said upper area and above a planned level of the seabed in the installed condition,
• wherein the interaction between said first securing means of said platform and said second securing means of said buoyancy means produce a mutual securing thereof;
• b) ashore, applying said piles to said platform so that said piles are essentially vertical and each one of the piles are axially displaced with respect to said platform;
• c) ashore, applying the tower mast to said platform in a relative position of use in the installed condition of the offshore wind turbine tower;
• d) ashore, a disposing actuation and/or braking means operationally between each one of the piles and the platform, so that the actuation of the actuation and/or braking means control the axial displacement of each pile with respect to said-the platform;
• e) ashore, disposing the platform and the piles in a relative position such that the platform is placed in an intermediate position between the lower area and the upper area of each one of the piles, using the actuation of said actuation and/or braking means;
• f) anchoring one end of each one of the anchoring means to the lower area of each of the piles, respectively, and anchoring the other end of each one of the anchoring means to said platform, so that each one of the anchoring means does not substantially support any tensile stress and, in the installed condition of the offshore wind turbine tower, each one of the anchoring means forms an angle with the vertical;
• g) launching the buoyancy means;
• h) launching a base assembly, wherein the base assembly comprises the platform, the tower mast, the piles and the anchoring means;
• i) securing said base assembly to said buoyancy means using the application to one another of said first and second securing means to form a transport assembly, and providing said buoyancy means with sufficient floatability to keep afloat the transport assembly;
• j) transferring said transport assembly to the location planned for the wind turbine tower;
• k) actuating said actuation and/or braking means so that said piles displace downwards with respect to said platform, until an end of each one of the piles touches the seabed;
• l) fastening the lower end of each one of said piles to the seabed;
• m) actuating said actuation and/or braking means until said platform is on a level with said upper area of each one of the piles;
• n) mounting a wind turbine means on the tower mast;
• o) detaching said first and second securing means from one another and removing said buoyancy means from said platform;
• and
• p) tensioning said anchoring means.