Hybrid anchor

Abstract

A hybrid anchor (10) comprises a caisson comprising a lid (35) and a rigid skirt (37) wherein the skirt defines an open end of the caisson and the lid comprises a valve, the skirt of the caisson being configured to engage with a substrate upon which it is placed, thus defining a sealed interior space and, in use, the skirt (37) is induced to sink into the substrate by evacuating the contents of the interior space through the valve. A drilling template is fixed to the lid (35) of the caisson, the drilling template being configured to receive at least one pile (40) at a respective location relative to the caisson lid (35) such that the at least one pile (40) may be driven though the caisson lid and into the substrate at an angle from 90 degrees to the plane of the lid up to an angle avoiding intersection between the at least one pile and the skirt to fix the position of the hybrid anchor within the substrate.

1 . A hybrid anchor comprising:
 a caisson comprising a lid and a rigid skirt wherein the skirt defines an open end of the caisson and the lid comprises a valve, the skirt of the caisson being configured to engage with a substrate upon which it is placed, thus defining a sealed interior space and, in use, the skirt is induced to sink into the substrate by evacuating the contents of the interior space through the valve; and   a drilling template fixed to the lid of the caisson, the drilling template being configured to receive at least one pile at a respective location relative to the caisson lid such that the at least one pile may be driven though the caisson lid and into the substrate at an angle ranging from approximately perpendicular to the lid through to an angle avoiding intersection between the at least one pile and the skirt to fix the position of the hybrid anchor within the substrate,   wherein the at least one pile comprises a micropile comprising at least one hollow cylindrical shell defining an axial channel and one or more apertures in said shell allowing grout injected through said channel to pass through said apertures and to bond said micropile in place within said substrate.   
     
     
         2 . (canceled) 
     
     
         3 . The hybrid anchor of  claim 1  comprising a plurality of piles. 
     
     
         4 . A subsea foundation system comprising a plurality of hybrid anchors in accordance with  claim 1 . 
     
     
         5 . A method of installing the hybrid anchor of  claim 1  comprising:
 positioning the drilling template in fixed relationship to the lid of the caisson; 
 deploying the caisson to the substrate; 
 evacuating the interior space of the caisson such that the caisson sinks into the substrate; 
 locating at least one pile in the drilling template; and 
 drilling the at least one pile through the caisson lid into the substrate. 
 
     
     
         6 . The method of  claim 5  further comprising:
 injecting grout through the at least one pile to bond said pile in place within said substrate. 
 
     
     
         7 . The method of  claim 5  further comprising:
 positioning another pile at a location within said drilling template spaced apart from a location of a previous pile; 
 drilling the another pile into the substrate; and 
 repeating the previous two steps until the desired number of piles have been located in said substrate.