Process of anchoring a floating platform on a rocky seabed

Abstract

A process of anchoring a floating platform on a rocky seabed, comprising the following steps:providing at least one trench portion in the seabed, the trench portion extending along a line,installing an anchor structure in the trench portion, the anchor structure comprising a core extending along the line, steel plates welded to the core and extending from the core radially with respect to the line, and at least a first grout line,injecting grout in said first grout line in order to fill the trench portion with grout, the plates being at least partly surrounded by the injected grout, andafter curing of the injected grout, connecting a connecting point of the core (to the platform using a mooring chain.

1 . A process of anchoring a floating platform on a rocky seabed, comprising the following steps:
 providing at least one trench portion in the seabed, the trench portion extending along a line,   installing an anchor structure in the trench portion, the anchor structure comprising a core extending along the line, steel plates welded to the core and extending from the core radially with respect to the line, and at least a first grout line extending along the line,   injecting grout in said first grout line in order to fill the trench portion with grout, the plates being at least partly surrounded by the injected grout, and   after curing of the injected grout, connecting a connecting point of the core to the platform using a mooring chain.   
     
     
         2 . The process according to  claim 1 , wherein providing the trench portion includes digging the seabed along the line using a subsea trencher. 
     
     
         3 . The process according to  claim 1 , wherein the line is straight. 
     
     
         4 . The process according to  claim 1 , wherein the plates are perpendicular to the core. 
     
     
         5 . The process according to  claim 1 , wherein the trench portion has a length along the line comprised between 5.0 m and 40 m. 
     
     
         6 . The process according to  claim 1 , wherein the trench portion has an average horizontal width perpendicularly to the line, said width being comprised between 0.3 m and 2.5 m. 
     
     
         7 . The process according  claim 1 , wherein the trench portion has an average depth comprised between 1.0 m and 5.0 m. 
     
     
         8 . The process according to  claim 1 , wherein the trench portion has a U-shaped or V-shaped section perpendicularly to the line. 
     
     
         9 . The process according to  claim 1 , wherein the mooring chain has a portion lying on the seabed and exerting efforts on the anchor structure, said portion of the mooring chain and the line defining an angle at the connecting point, the angle being smaller than 30°. 
     
     
         10 . The process according to  claim 1 , wherein the core comprises a steel H-beam, a plurality of steel H-beams mechanically connected to each other along the line, or a grid of reinforcing steel bars at least partly surrounded by the injected grout. 
     
     
         11 . The process according to  claim 1 , wherein the core comprises a steel H-beam defining a first open housing and a second open housing transversely opposed to each other, a first group of said plates being received in the first open housing, and a second group of said plates being received in the second open housing. 
     
     
         12 . The process according to  claim 11 , wherein said first grout line extends along the first open housing and successively crosses holes respectively defined by the first group of plates, the anchor structure further comprising a second grout line extending along the second open housing and crossing holes respectively defined by the second group of plates. 
     
     
         13 . The process according to  claim 1 , further comprising a step of cleaning the trench portion before injecting grout, said cleaning using water jets directed at walls of the trench portion. 
     
     
         14 . The process according to  claim 1 , further comprising:
 providing a second trench portion in the seabed, the second trench portion extending along a second line, the second line and the line converging towards the connecting point,   installing a second anchor structure in the second trench portion, the second anchor structure comprising a second core extending along the second line, steel plates welded to the second core and extending from the second core radially with respect to the second line, and at least a grout line extending along the second line, the second core being mechanically connected to the connecting point, and   injecting grout in said grout line in order to fill the second trench portion with grout, said plates being at least partly surrounded by the injected grout.   
     
     
         15 . An anchoring system adapted for anchoring a floating platform on a rocky seabed, the anchoring system comprising:
 at least one trench portion located in the seabed and extending along a line,   an anchor structure at least partly located in the trench portion, the anchor structure comprising a core extending along the line, steel plates welded to the core and extending from the core radially with respect to the line, and at least a first grout line extending along the line,   grout located in the trench portion, the plates being at least partly surrounded by the grout, and   a mooring steel chain connected to a connecting point of the core the mooring chain being intended to be connected to the platform.