METHOD FOR BUILDING CONCRETE FOUNDATIONS FOR LATTICE-TYPE OFFSHORE STRUCTURES, AND FOUNDATIONS BUILT USING THIS METHOD

Abstract

The invention relates to a method for building concrete foundations for lattice-type offshore structures and to foundations built using this method, which has the main aim of replacing the piles used to anchor lattice structures to the seabed (7) with blocks of on-site reinforced concrete (1) which grant the necessary stability to the lattice structure (2), doing away with all pile-driving works but without performing any structural modification of said structure. Said elements (1) are positioned using templates (12). The advantages of this novel invention lie in the possibility of installation on any type of terrain, providing a perfect connection between the seabed and the foundations thanks to on-site concreting, as well as its ease of construction, reduction of noise emissions and of auxiliary means.

Claims

1. A method for building a concrete foundation for lattice-type offshore structures comprising, successively, the following steps: a) anchoring a recoverable template (12) defining, at the points where the connecting structure (4) of the lattice structure (2) is to be housed, cylindrical holes (13) that allow to house guiding cones (6); b) positioning of concrete guiding cones (6) introduced into the cylindrical holes (13) of the template (12), defining the exact position on the seabed (7) on which blocks (1) constituting the point supports of the lattice structure (2) are to be concreted; c) removing the template (12), leaving the cones (6) in the desired position of the seabed (7); d) positioning a formwork (14) on the seabed (7), in a position such that each of the guiding cones (6) is introduced into the inner hole (5) of each formwork (14); e) subsea concreting all the formwork (14) in the space between an outer wall (9) and an inner wall (8) thereof to form a concrete block (1) of the size and shape defined by the formwork (14), with a central cylindrical hole (5) in which the connecting structure (4) of the lattice structure (2) will be housed; f) placing the lattice structure (2), introducing each of its connecting parts (4) into the cylindrical holes (5) made in each of the concrete blocks (1); and g) sealing the connecting part (4) and the foundation hole (5) by injecting mortar into the space between the two elements.

2. The method according to claim 1, characterised in that, optionally, the first two steps of anchoring the template (12) and positioning the guiding cones (6) within each of the cylindrical holes (13) of said template (12) are carried out jointly.

3. The method according to any one of the preceding claims, characterised in that before placing the lattice structure (2) on the concrete blocks (1), introducing the corresponding connecting element (4) with the structure (2) in the holes (5), a layout of the coordinates of the set of all the holes (5) and, if necessary, the adjustments in any of the connecting parts (4) of the legs of the structure (2) are carried out.

4. Concrete foundation for lattice-type offshore structures comprising several independent blocks (1) of reinforced concrete built on-site on the seabed (7) in correspondence with the connections (4) existing at the support points of the lattice structure (2) to be supported, each of which comprising: a guiding cone (6) that is placed by means of a recoverable template (12) on the seabed (7) marking the precise location point of each of the connecting parts (4) of the lattice structure (2) to be supported; a lost formwork (14) having an outer wall (9) defining the configuration of the concrete block (1); an inner wall (8) forming the opening in which the connecting part (4) of the lattice structure is housed; and a structure (10) including several structural reinforcements between both walls (8) and (9) that hold them in a concentric position and that reinforce the concrete by being embedded therein; and a concrete filling taking the space between the walls (8) and (9) of the lost formwork (14), poured in this space once the guiding cone (6) and the formwork (14) have been positioned in their location on the seabed (7).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to complement the description that is being carried out and with the purpose of facilitating a better understanding of the characteristics of the invention, the present description is accompanied by a set of drawings as an integral part thereof, wherein, by way of a non-limiting example, the following has been represented:

[0037] FIG. 1 shows a perspective view of a foundation supporting a lattice structure (2).

[0038] FIG. 2 shows a front and plan view of the assembly once assembled.

[0039] FIG. 3 shows a vertical section and a plan view of one of the elements (1) of the invention.

[0040] FIG. 4 shows a perspective view of one of the concrete blocks (1) that together constitute the foundation object of the invention.

[0041] FIG. 5 shows a schematic image of the template (12).

[0042] FIGS. 6 and 7 show the process of positioning the template (12).

[0043] FIGS. 8, 9, 10 and 11 show the process of positioning the guiding cones (6).

[0044] FIGS. 12 and 13 show the process of removing the template (12).

[0045] FIG. 14 shows the final position of the guiding cones (6).

[0046] FIGS. 15 and 16 show the process of positioning the formworks (14).

[0047] FIGS. 17 and 18 show the process of concreting the formworks (14).

[0048] FIG. 19 shows the process of positioning the structure (2) on the concrete blocks (1) that make up the foundation.

[0049] FIG. 20 shows the process of sealing the connecting element of the structure (2) with the foundation.

PREFERRED EMBODIMENT OF THE INVENTION

[0050] The main object of the invention is the replacement of the piles with reinforced concrete blocks (1) concreted on-site that confer the necessary stability to the latticework structure (2), doing away with all pile-driving works but without having to perform any modifications to the structure (2). The building method is explained step-by-step below: [0051] A recoverable template (12), which anchors in the required position from a boat (B), is used that presents, at the points where the formwork (14) is to be fixed, cylindrical elements (13) that allow housing the guiding cones (6). See FIGS. 5, 6 and 7. [0052] Once the template (12) is anchored, the guiding cones (6) are positioned (FIGS. 8, 9, 10 and 11). The guiding cones (6) are concrete elements that are suspended (strapped) from a mooring (A) located at the apex of the cone thanks to which they anchor in a balanced way from the boat (B) until they are introduced into the cylindrical holes (13) of the template (12), thus fixing their exact position on the seabed (7). [0053] Once all the guiding cones (6) have been anchored and positioned, the template (12) is removed from the boat (B), the cones (6) remaining in the desired position of the seabed (7). See FIGS. 12, 13 and 14. [0054] Once the template (12) has been removed, the formwork (14) is positioned from the boat, so that each of the guiding cones (6) are inserted into the inner hole (5) of each of the formwork (14). See FIGS. 15 and 16.

[0055] The formwork is positioned as just indicated with the help of the guiding cones (6), which have been positioned before the formwork (14), on the seabed (7).

[0056] Each of the formwork (14) that allows the construction of a concrete block (1) that constitutes the support of one of the connections (4) of the latticework structure (2) has: [0057] An outer wall (9) defining the configuration of the concrete block (1). [0058] An inner wall (8) forming the hole (5) for subsequently housing the connecting part (4) of the lattice structure, which rests on the block (1) by means of a support plate (3) fixed on the connecting element (4) at the appropriate height. [0059] A structure (10) including several structural reinforcements between both walls (8) and (9) that hold them in a concentric position and that make up the concrete reinforcement when it is embedded in it in the concreting step. [0060] Once the formwork has been positioned, it is concreted, using the usual subsea concreting techniques, obtaining a concrete block (1) of the size and shape defined by the formwork (14), with a cylindrical central hole (5) where the connecting part (4) of the lattice structure (2) will be housed. This process is performed for all the concrete blocks (1) where each of the legs of the structure (2) will be supported. (FIG. 17) [0061] After checking the layout of the coordinates of the set of all the inner holes (5) for the connecting element (4) with the structure (2), which constitute all the elements of the foundation that will house all the legs of the same, and prior to its placement, any adjustment, if necessary, is made to any of the connecting parts (4) of the legs of said structure (2) and the placement of each of the legs of the lattice structure (2) is carried out by introducing it into the cylindrical inner holes (5) made in each of the concrete blocks (1), the support (3) of the structure (2) being above the concrete block (1) and the structure (2) in an upright position supported on the various blocks (1). See FIG. 19. [0062] Once the verticality of the entire lattice structure (2) has been checked, the connecting part (4) and the foundation hole (5) are definitively sealed, injecting mortar into the free space that may remain between the inner wall (8), the connection piece (4) and the cone (6).