CN114737597A

CN114737597A - Construction method for fixing foundation of offshore platform on seabed

Info

Publication number: CN114737597A
Application number: CN202210448840.9A
Authority: CN
Inventors: 孙震; 薛冬梅; 顾时雨; 王星浩
Original assignee: China India Hengsheng Beijing Trading Co ltd
Current assignee: China India Hengsheng Beijing Trading Co ltd
Priority date: 2022-04-27
Filing date: 2022-04-27
Publication date: 2022-07-12

Abstract

The present invention provides a construction method for securing the foundation of an offshore platform to the seabed, the platform comprising at least one buoy having a bottom plate of a downwardly directed bottom cone-shaped object. In the method, a concrete bed is poured in the seabed and at least one float is pressed into the concrete bed to form an inverted cone impression of a conical object in the concrete bed. The bottom cone of at least one float is aligned with the inverted cone indentation, and then the platform couples the bottom cone and inverted cone indentation together to secure the float to the seabed.

Description

Construction method for fixing foundation of offshore platform on seabed

Technical Field

The present invention relates to a construction method for securing the foundation of an offshore platform to the seabed, and in particular to a construction method for securing an offshore platform adapted to support wind turbines, bridges and offshore structures to the seabed in a marine environment.

Background

Supporting the development of marine resources, including offshore wind, ocean current and tidal energy, marine fish farms, even the construction of marine cities, and the like, requires a platform support. The base may be fixed to the seabed or may be arranged to float in the water. One disadvantage of floating foundations is that it is difficult to moor the foundation for anchoring at water depths less than 50 m. If the mooring lines break, the foundation can drift around unintentionally, which can be a great hazard to users and to sea traffic.

Disclosure of Invention

The invention discloses a construction method for fixing the foundation of an offshore platform to the seabed, the platform comprising at least one buoy having a bottom plate of a downwards directed bottom cone. In the method, a concrete bed is poured in the seabed and at least one float is pressed into the concrete bed to form a mirror image inverted conical impression of a conical object in the concrete bed. The base cone of the at least one float is aligned with the reverse tapered indentation and the platform then couples the base cone and the reverse tapered indentation together to secure it to the seabed.

Drawings

FIG. 1 is an aerial view of a floating platform

FIG. 2 is a left side elevation view of the platform of FIG. 1, with the right side elevation view being a mirror image of the left side elevation view

Fig. 3 is a top view of a multi-vessel.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A 50m x 50m platform is supported by 4 x 9.8m diameter buoys, the platform has a self weight of 9000 tons and the total weight of all dead and live loads supporting the building thereon is 14000 tons, and in general, the innovative technique exemplified by the exemplary embodiments may further comprise replacing the typically solid vertical piers or columns used in conventional offshore platforms with hollow, cylindrical, vertically arranged buoyancy tubes (buoys) that provide buoyancy, so that a single buoy or a plurality of interconnected buoys forming an offshore platform may float in a body of water. The buoyancy provided by the float reduces the bearing pressure on the underlying formation in either the temporary or permanent state. By using a unique cone matching technique as part of the installation and construction method described below, the bottom of the float can be easily secured to the concrete bed on the seabed. I.e. by installing a small diameter pile through the inner bore of the raft and sinking into the bedrock and forming a pile cap therein, i.e. fixing the upper end of the pile in the floating body.

The float is a hollow cylindrical member, and its upper and lower ends are covered with plates. The lower end may be conical with the apex of the cone pointing downwards towards the seabed/seafloor. The buoyancy of the float enables the float to float on its own and compensate for some or all of the self weight of the platform as it sinks into the body of water. In one example, the ocean platform includes only one vertically aligned hollow cylindrical float, including a bottom plate configured to have a conical shape (or multiple conical shapes) with its apex pointing downward. A conical or tapered floor of the float is desirable so that the base layer or the bearing pressure on the base layer can be minimized to a smaller value; this is ideal for gravity floats. Such conical floats can accommodate batter piles (piles installed at an angle).

Claims

1. A construction method for securing the foundation of an offshore platform to the seabed, characterized in that: comprising a supporting foundation platform for a wind turbine, at least one float having a bottom plate with a downwardly directed bottom cone, pressing the at least one float into the concrete bed to form an inverted cone-shaped impression in the concrete bed, aligning the bottom cone of the at least one float with the inverted cone-shaped impression.

2. A construction method for securing the foundation of an offshore platform to the seabed as claimed in claim 1, wherein at least one float is replaced with a steel mould having an external profile similar to the profile of the bottom cone to form an inverted conical impression of the conical object in the concrete bed.

3. A construction method for anchoring the foundation of an offshore platform to the seabed, as claimed in claim 1, wherein it is necessary to adjust the level and alignment of at least one float or steel form and form a concrete cushion before the initial setting of the concrete; lowering at least one float or steel form completely immersed in the concrete pad; maintaining the level and alignment of the at least one float or steel form until the concrete sets; and lifting at least one float or steel form to form an inverted conical impression in the concrete bed.

4. A construction method for securing a foundation of an offshore platform to a seabed as claimed in claim 3, wherein lowering the platform to couple the base cone to the reverse tapered indentation further comprises: lowering the platform so that at least one float is naturally seated in the inverted cone-shaped pit in the concrete bed to couple the two cones; grout is injected in at least one float using a plurality of pre-installed pressure pipes to fill the gap between the opposing faces of the cone.

5. A construction method for securing the foundation of an offshore platform to the seabed as claimed in claim 4, wherein the construction process further comprises driving a steel pipe having a diameter greater than the diameter of the at least one float into the seabed to a given depth; and welding the multilayer steel support on the steel pipe, removing soft materials in the soft soil layer in the steel pipe around the horizontal plane of the top surface of the concrete bed, and cutting the selected steel support extending to the position above the concrete base to be poured.

6. A construction method for anchoring the foundation of an offshore platform to the seabed as claimed in claim 5, wherein installing a plurality of piles as a pile foundation further comprises: drilling through the floor of the at least one float to install a plurality of vertical piles; pouring a layer of concrete to form a concrete plug in the bottom plate to prevent water from entering; cutting the residual pile length extending above the floater, fixing pile cap reinforcing steel bars, and pouring pile cap concrete; a plurality of raking piles are installed from a deck layer of the platform, and then pile caps are poured on the deck layer.

7. A construction method for securing the foundation of an offshore platform to the seabed, i.e. a foundation for installing one or more piles, i.e. a pile foundation, according to claim 6, comprising: a steel casing is pre-installed for each pile between the bottom cone and the platform deck elevation, with intermediate support from at least one float wall.

8. A construction method for anchoring the foundation of an offshore platform to the seabed, as claimed in claim 4, wherein the penetration length of the steel pipe is adapted to mobilize the surface friction between the steel pipe surface and the soft earth layer, allowing a frictional resistance greater than all load combinations from the construction stage to the in-use condition; the steel structure consisting of the steel rings and the steel brackets has a strength suitable for carrying all load combinations from the construction stage to the use state.