Subsea anchor and anchoring

Abstract

Method of providing a fixation support at a subsea seafloor surface location comprises drilling a bore into the subsea seafloor surface at a desired location, locating an elongate hollow and rigid bod

Description

The present invention relates to a method and apparatus for providing a fixation support and a subsea anchor. In particular, but not exclusively, the present invention relates to expanding a wall of a multi-layered pile that is partially driven into a drilled bore in a seabed and thereby held in a friction fit. Each pile provides a fixation support and an anchor body that includes a connection element for a mooring line can be mounted on and secured to free ends of the piles. Certain fixation supports are used in a range of industries to help support the forces and / or moments exerted by structures located on land - including building foundations, bridges and other infrastructure - and offshore, for example to help secure floating production facilities, storage facilities, wind turbines, floating structures and the like. In offshore applications, fixation supports often provide a point to which other elements can be fixed to help hold those structures in place. For example, a fixation support may be secured to a seabed, thereby transferring forces that are applied to the support via an anchor body to the surrounding seabed. Conventionally, floating structures have been secured to the seabed using a variety of anchors that have different fixation techniques such as suction piles; gravity structures, which rely on self-weight to resist upwards force; buried “hooking” devices; and helical piles. Many of these fixation techniques are not suitable for installation on rocky ground conditions because they are intended to penetrate soft seabed such as soil and do not have the capacity to penetrate rock. Whilst gravity anchors can be installed in different ground conditions, the mass associated with these anchors create challenges for the transportation and installation process which have significant cost implications. Meanwhile there is a growing demand for fixation solutions suitable for supporting floating platforms in areas with a seafloor predominantly composed of rock. Various types of rock anchor have been developed, however each of these proposed solutions have deficiencies. Self-drilling grouted anchors have been proposed and these usually include a hollow central rod which is drilled into position and then grouted. Such anchors are sometimes used to provide anchoring for rock seafloors with a shallow sediment layer that prevents utilisation of suction-based solutions and is designed to accommodate the mooring forces axially. In a selfdrilling grouted anchor, the hollow central rod usually carries a drill head and provides a capability for transporting grout which is pumped out of the drill head to help secure the anchor to surrounding rock. However, the anchor provides little or no support in shear force loading due to the sectional property of its hollow central rod. To accommodate lateral shear loads, rod elements of such anchors are positioned at an angle to the perpendicular axis defined by the seafloor (i.e., nearing horizontal) to transfer lateral loads to the seabed in tension rather than shear. Therefore, self-drilling grouted anchors use a drilling template - a specially designed structure with high manufacturing tolerances, levelling and jacking systems and the like - as an anchor body structure to accommodate the required alignment and high tolerance and which is designed to be permanent. The use of a drilling template as a final anchor body structure significantly increases the manufacturing costs, as each template cannot be reused, is bespoke, and has very high manufacturing tolerances. Many of the same limitations apply to grouted anchors with suction piles. An alternative self-drilling anchor that has been proposed contains drilling equipment at a distal flared end of the anchor body that is expandable using a central tensile stem thereby helping to secure the anchor against drilled rock surface at the distal flared end. A conical sleeve is sometimes used, near the opposing end of the anchor body structure, to engage against the drilled surface of the cavity when the anchor is under tension. However, whilst such anchors may support some axial tensional and / or compressive forces, they are weak to lateral shear loads because the sleeve body of the anchor is free of the rock surface thus providing no lateral shear support. Also, combining the drilling head and anchor body structure may necessitate abandonment of the whole anchor if the drilling or flaring of the end cannot be completed successfully. Another weakness of this anchor is that the flared end is effectively plastically deformed by the system to expand. Thus, any over stressing of the flared section may result in breakage of the flared section and loss of anchorage. It is an aim of the present invention to at least partly mitigate one or more of the above-mentioned problems. It is an aim of certain embodiments of the present invention to move away from depending on grout for axial and lateral capacity of a fixation support. It is an aim of certain embodiments of the present invention to increase the lateral shear capacity of a fixation support relative to conventional techniques without using angled piles. It is an aim of certain embodiments of the present invention to provide apparatus for increased surface contact area with the seafloor relative to conventional techniques. It is an aim of certain embodiments of the present invention to provide apparatus for increased coefficient of friction with the seafloor relative to conventional techniques. It is an aim of certain embodiments of the present invention to provide a fixation support in the form of a friction pile with or without the use of grout at the pile soil interface. It is an aim of certain embodiments of the present invention to provide apparatus and a methodology for anchoring one or more floating (submerged or otherwise surface floating) bodies at a desired relative position with respect to a subsea surface that might be a sea bed or sea floor. It is an aim of certain embodiments of the present invention to provide a methodology for securing an anchor body to one or more pile like elements that are partially driven into a sea bed / floor in a subsea location so that the anchor body is firmly kept in place. It is an aim of certain embodiments of the present invention to provide strong anchoring capability at a variety of different possible terrain sites such where the underlying terrain may be rocky or sandy or the like. It is an aim of certain embodiments of the present invention to provide a subsea anchor as apparatus for securing a floating platform at a desired relative position with respect to a subsea surface that is usable with a wide variety of floating platforms such as floating platforms for a wind turbine or a sailing vessel or a riser or the like. It is an aim of certain embodiments of the present invention to provide a method for reusing a drilling template when providing a fixation support at seafloor rock. According to a first aspect of the present invention there is provided a method of providing at least one fixation support at a respective desired location at a subsea seafloor surface location, comprising the steps of: via a drill member, drilling into a subsea seafloor surface at a desired location thereby providing a drilled bore via a drilling step at the desired location; locating an elongate body that is hollow and rigid at least partially in the drilled bore; and subsequently radially expanding at least a region of at least an inner layer of an elongate body wall of the elongate body thereby urging a corresponding region of at least one drilled surface-engaging element, disposed at a radially outer surface of the inner layer of the elongate body wall, against a drilled surface associated with the drilled bore thereby providing a friction fit between the drilled surface and at least a region of an outer surface of a covered portion of the elongate body that is in the drilled bore. Aptly, the method further comprises: guiding the drill member, as it drills into the subsea seafloor surface, via a drilling guide element of a drilling template; and removing the drilling template subsequent to providing one or more respective drilled bores and locating at least a portion of a respective elongate body in each drilled bore. Aptly, the method further comprises: radially expanding said a region of at least the inner layer of the elongate body wall by urging an expansion member along a void space of a chamber region surrounded by the elongate body wall; and via the expansion member, driving at least one abutment element radially outwardly against an inner surface of the inner layer at selective locations that optionally radially expand substantially a whole surface area of the inner layer of the covered portion. Aptly, the method further comprises: radially expanding said a region by repeatedly urging the expansion member along the void space or by repeatedly urging an abutment element outwardly. Aptly, the method further comprises: as the abutment element is driven radially outwardly, deforming the inner layer radially outwardly thereby urging an outer surface of said a corresponding region of said at least one drilled surface-engaging element at the drilled surface. Aptly, the method further comprises: providing at least one fixation support comprises providing a plurality of fixation supports, each provided by a top free end region of a respective elongate body wall of a respective elongate body, in a predetermined pattern. Aptly, the method further comprises: subsequent to radially expanding said a region of the at least an inner layer, at least partially filling a chamber region surrounded by the elongate body wall with a contraction resistant material that optionally is a settable material or sand or grout. Aptly, the method further comprises: levelling the drilling guide template by varying a length of at least one leg member associated with the drilling guide template. Aptly, the method further comprises: the at least one drilled surface-engaging element comprises an outer layer that is coaxial with and circumferentially extends around the inner layer, and urging the corresponding region comprises urging the outer layer against the drilled surface. Aptly, the method further comprises: each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart arcuate protrusions that extend radially outwards from the inner layer, and urging the corresponding region comprises urging an outer surface of each arcuate protrusion against the drilled surface. Aptly, the method further comprises: each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart cylindrical elements adjacent to, and supported by, the inner layer, and urging the corresponding region comprises urging an outer surface of each cylindrical element against the drilled surface. According to a second aspect of the present invention there is provided apparatus for securing a floating platform at a desired relative position with respect to a subsea seafloor surface, comprising: a plurality of fixation supports provided via protruding free end regions of a respective plurality of friction pile members driven into a subsea seafloor surface in a predetermined pattern; and an anchor body member comprising a base, a plurality of sheath elements each disposed to receive a free end region of a respective fixation support and at least one connection element each for connecting to at least one mooring line. Aptly, each friction pile member comprises: an elongate friction pile member wall comprising an inner layer and at least one drilled surface-engaging element disposed at a radially outer surface of the inner layer. Aptly, the inner layer is manufactured from a first material and the at least one drilled surfaceengaging element is manufactured from a further material that is different to the first material. Aptly, each sheath element comprises: at least one pile engaging element disposed to engage with at least a region of an upper end region of a free end region of a respective friction pile member. Aptly, each pile engaging element is a recess or protruding element that cooperates with a mating protuberance or recessed region at a free end region of a friction pile member. Aptly, an end region of at least one sheath element is slit, further comprising: at least one securing strap that is securable around the slit region of a respective sheath element to thereby crimp and force radially inwards spaced apart fingers of the sheath element in the slit region. Aptly, the base of the anchor body member further comprises: a plurality of perforations spaced apart and disposed in a pattern around an edge region of the base. Aptly, the anchor body member comprises: either an integrally formed anchor body unit or a plurality of anchor body modules that are interconnected. Aptly, each anchor body module further comprises: at least one interconnection element for interconnecting a first anchor body module with at least one further anchor body module. Aptly, wherein the apparatus comprises a subsea anchor. Aptly, said at least one drilled surface-engaging element comprises: an outer layer that is coaxial with and circumferentially extends around the inner layer. Aptly, each drilled surface-engaging element comprises: a one of a plurality of circumferentially spaced apart arcuate protrusions that extend radially outwards from the inner layer. Aptly, each drilled surface-engaging element comprises: a one of a plurality of circumferentially spaced apart cylindrical elements adjacent to, and supported by, the inner layer. According to a third aspect of the present invention there is provided a method of providing a subsea anchor for securing a floating platform at a desired relative position with respect to a subsea seafloor surface, comprising the steps of: providing an anchor body member, comprising a base and at least one connection element for a mooring line and a plurality of sheath elements, at a subsea location; lowering the anchor body member towards a subsea seafloor surface thereby locating a respective one protruding free end region of a friction pile member, of a plurality of friction pile members disposed in a predetermined pattern at the subsea seafloor surface, in a respective sheath element; and for each sheath element and respective friction pile member, securing the sheath element to the friction pile member, thereby securing the anchor body member at a desired relative position with respect to the subsea seafloor surface. Aptly, the method further comprises: securing each sheath element to said respective friction pile member by engaging at least one pile engaging element with at least a region of an upper end region of a free end region of said respective friction pile member, whereby each pile engaging element is a recess or protruding element that cooperates with a mating protuberance or recessed region at a free end region of said respective friction pile member. Aptly, the method further comprises: tightening at least one securing strap around a slit region of an end region of at least one sheath element and thereby crimping and forcing radially inwards spaced apart fingers of the sheath element in the slit region. Aptly, the method further comprises: subsequent to locating said respective free end region in a respective sheath element, radially expanding at least a region of at least an inner layer of an elongate body wall of said respective friction pile member thereby urging a corresponding region of at least one drilled surface-engaging element at a radially outer surface of the inner layer of the elongate body wall against a drilled surface associated with a drilled bore at the subsea seafloor surface, thereby providing a friction fit between the drilled surface and at least a region of an outer surface of a covered portion of said respective friction pile member that is in the drilled bore. Aptly, the method further comprises: prior to lowering the anchor body member, radially expanding at least a region of at least an inner layer of an elongate body wall of said respective friction pile member thereby urging a corresponding region of at least one drilled surface-engaging element at a radially outer surface of the inner layer of the elongate body wall against a drilled surface associated with a drilled bore at the subsea seafloor surface, thereby providing a friction fit between the drilled surface and at least a region of an outer surface of a covered portion of said respective friction pile member that is in the drilled bore. Aptly, the method further comprises: the at least one drilled surface-engaging element comprises an outer layer that is coaxial with and circumferentially extends around the inner layer, and urging the corresponding region comprises urging the outer layer against the drilled surface. Aptly, the method further comprises: each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart arcuate protrusions that extend radially outwards from the inner layer, and urging the corresponding region comprises urging an outer surface of each arcuate protrusion against the drilled surface. Aptly, the method further comprises: each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart cylindrical elements adjacent to, and supported by, the inner layer, and urging the corresponding region comprises urging an outer surface of each cylindrical element against the drilled surface. Aptly, the method further comprises: radially expanding said at least a region of at least the inner layer further comprises urging a corresponding region of drilled surface-engaging elements placed intermittently along a longitudinal axis of said respective friction pile member against the drilled surface. According to fourth aspect of the present invention there is provided apparatus for providing a fixation support at a desired location, comprising: an elongate body, that is hollow and rigid, comprising an elongate body wall that surrounds a chamber region that is elongate, said elongate body wall comprising an inner layer of a first material and at least one drilled surface-engaging element at a radially outer surface of the inner layer of a further material. Aptly, the inner layer is radially expandable outwards away from an imaginary central axis that extends along a length of the elongate body. Aptly, the further material has a higher coefficient of friction than the first material. Aptly, the inner layer is a metal or metal alloy. Aptly, the at least one drilled surface-engaging element is a metallic material that is softer on a Mohs scale than steel alloy. Aptly, the at least one drilled surface-engaging element is a rubber or rubber like material. Aptly, the at least one drilled surface-engaging element is a ceramic material. Aptly, the elongate body has a whole length of 3 meters or more. Aptly, the apparatus further comprises: a portion of an outer surface of the elongate body wall, provided by the at least one drilled surface-engaging element, is a cylindrical surface. Aptly the apparatus further comprises: at a first end region of the elongate body wall that extends from an extreme end of the elongate body wall, the body wall comprises a plurality of outwardly protruding and / or radially inwardly recessed rings. Aptly, the at least one drilled surface-engaging element is an outer layer comprising a generally coaxial circumferentially extending layer. Aptly the outer layer has a uniform thickness. Aptly the outer layer has a variable thickness. Aptly, the at least one drilled surface-engaging element may be intermittently on the outer surface of inner material forming longitudinal strips along the length of the elongated body. Aptly, the at least one-ground engaging element may have a tubular section. According to a fifth aspect of the present invention there is provided apparatus for guiding a plurality of drilling steps at a subsea location, comprising: a plurality of drilling guide elements each supported on a respective base member; and a plurality of beam elements that interconnect the drilling guide elements and support the drilling guide elements in a predetermined spaced apart pattern. Aptly, each drilling guide element comprises a cylindrical sheath that extends orthogonally to a respective base member and that has a bore that is associated with a longitudinal bore axis that guides a drilling path during a drilling step. Aptly, each drilling guide element is manufactured from a hard material that has a Mohs hardness scale of 8 or more and provides a smooth cylindrical surface that has a surface roughness of around 0.8 pm Ra or smaller along which a drill head can advance. Aptly, each base member comprises a rigid plate secured at a base end of a respective drill guide element and the rigid plate comprises a primary through aperture that a predetermined drill head can pass through in a drilling step. Aptly, each rigid plate comprises a plurality of secondary through holes. Aptly, the apparatus is a drilling template. According to a sixth aspect of the present invention there is provided a fixation device assembly for anchoring floating structures to the seafloor formed of rock, comprising: a subsea structure accommodating at least one rock anchor formed of a hollow section characterised by having an external surface adapted to achieve high friction against the elongated cavity formed in the rock. Aptly, the said hollow section is deformed internally along its length, providing an expanded hollow section, so to engage the said external surface and adapted surface against the log cavity formed by the drilling operation in rock. Aptly, the said expanded hollow section forming the rock anchor may be filled with grout internally to prevent bounce back of the deformed surface. Aptly, the said hollow section forming the anchor forms a composite section with the exterior surface encased with a coating applied to its surface. Aptly, the said coating may be of metallic material that is softer than steel so as to allow easier engagement against the rough drilled surface of the rock formed by the drilling operation. Aptly, the said rock anchor is installed in a predetermined location to suit the permanent subsea structure by means of a template guide that is removed once the installation of the said piles is completed. Aptly, the final subsea structure accommodating the mooring connection is then lowered and installed onto the said piles protruding on the seafloor. Aptly, the said protruding rock anchor piles are locked onto the said seafloor structure by mean of cooperating sheaths wherein the cooperating surfaces are provided by undulating surfaces that engage one another, where in the top portion of the sheaths and or piles are provided with longitudinal cuts along the cooperating length so as to allow the sections to diametrically change allowing the said undulations to move past as the said seafloor structure is lowered onto the piles. Aptly, the said undulations are locked against one another by means of an external compression ring that effectively compresses the said undulations on the cooperating surfaces together to completely lock the two surfaces against one another. Aptly, the bounce back may be resisted by installation of compacted earth or sand that is compacted into the hollow section forming the pile. Aptly, the said subsea structure is provided with 3 locations for accommodating moorings lines, one centrally and one at each end. Aptly, the said subsea structure can be made to be connected to one another so as to form a modular structure the features provided to accommodate mooring line connections at either end. According to a seventh aspect of the present invention there is provided a fixation device assembly for anchoring floating structures to the seafloor formed of rock, comprising: a subsea structure accommodating at least one rock anchor formed of a hollow section characterised by having an external surface adapted to achieve high friction against the elongated cavity formed in the rock. Aptly, the said hollow section is expanded radially by means of a tool internally along its length so to engage the said external surface against the long cavity formed by the drilling operation in rock. Aptly, the hollow section forming the anchor is comprised of a composite section with the inner layer comprising of metallic alloy and the exterior layer encasing the inner layer adapted to achieve high friction against the drilled rock socket surface. Aptly, the said outer layer may be of metallic material that is softer than steel alloy. Aptly, the said outer layer may be of rubber material. Aptly, the said outer layer may be of ceramic material. Aptly, the said rock anchors are installed on a predetermined arrangement using a removable drilling template. Aptly, the said protruding rock anchor piles from the seafloor are locked onto the said seafloor structure by mean of cooperating sheaths. Aptly, the cooperating surfaces of the anchor and sheath are provided by undulating surfaces that engage one another. Aptly, the top portion of the sheath on the subsea structure are provided with longitudinal cuts along the cooperating length so as to allow the sheath to diametrically change allowing the said undulations to engage one another as the said seafloor structure is lowered onto the piles. Aptly, the said undulations are locked against one another by means of an external compression ring. Aptly, the said expanded circular hollow section forming the rock anchor may be filled. Aptly, the said infill is a cementitious grout. Aptly, the said infill is compacted soil. Aptly, the said subsea structure is provided with 3 locations for accommodating moorings lines, one centrally and one at each end. Aptly, the said subsea structure is connected to another of the same to form a modular structure by means of the features provided to accommodate mooring line connections at either end. According to an eighth aspect of the present invention there is provided a fixation device as substantially as hereinbefore described with reference to accompanying drawings. Certain embodiments of the present invention provide apparatus for securing a floating platform at a desired relative position with respect to a subsea surface. The terrain of the surface may be rocky or sandy or the like. Certain embodiments of the present invention provide a subsea anchor and a methodology that provides a subsea anchor where desired. Certain embodiments of the present invention provide a subsea fixation support. The fixation support may be a friction pile that engages with surrounding terrain where it is driven in via a high friction contact. The friction effect can be assisted by utilisation of a material on the outside surface of the pile that offers up a high coefficient of friction. Certain embodiments of the present invention provide for a methodology of providing a subsea anchor that separates the drilling and piling process from a step of providing an anchor body. That helps enable equipment and tools used during drilling and piling to be reused at other sites. Certain embodiments of the present invention utilise a drilling template that helps guide drill bits or other such members as they drill into a seafloor / seabed. This helps enable a good deal of accuracy to be achieved. Certain embodiments of the present invention utilise a pile member whereby an upper free end of the pile member, when suitably located and engaged in a respective drilled bore, provides a fixation support to which a wide variety of different structures, such as but not limited to a subsea anchor body, can be affixed. One, two or more pile members can be used for each subsea structure. Certain embodiments of the present invention utilise multiple fixation supports set out in a predetermined pattern to help restrain twisting or sliding forces. The pattern of fixation supports cooperates with and mates / connects with respective elements on a discrete and separate structure body (such as but not limited to a subsea anchor body). Certain embodiments of the present invention do not result in fissures in rock strata, undermining a shear capacity at the interface between a pile and surrounding rock particularly when subjected to fatigue loading. Certain embodiments of the present invention engage the outer wall layer with the surface of rock strata and do not under rim the surface of rock strata. Certain embodiments of the present invention provide enhanced shear capacity without resorting to angled piles by use of tubular steel section substantially in contact with rock. Certain embodiments of the present invention provide apparatus that decouples the drilling template from the subsea structural template. This helps allow the drilling template to accommodate the required levelling mechanism and tolerances to ensure accurate position of the piles. Furthermore, it allows the permanent subsea structure used for anchoring the mooring to be optimised without due concerns to the drilling template requirements. Certain embodiments of the present invention provide a controlled means for expansion of a tubular section so as to ensure adequate contact stress with rock without undermining the rock interface as well as preventing over plasticisation of the tubular section. Certain embodiments of the present invention help remove the problem of abandonment in the event of inadequate pile capacity associated with both grouted and non-grouted anchors. Certain embodiments of the present invention provide apparatus with improved frictional resistance between the steel tube and the rock surface by means of provision of surface treatment and / or an outer layer of softer material designed for achieving high friction with the rock surface. Certain embodiments of the present invention provide large contact surface with drilled rock surface rather than only a distal flared section, which helps to reduce the risk associated with variation in the rock properties and fissures. Certain embodiments of the present invention provide a method that helps to increase the lateral shear capacity of the fixation support relative to conventional techniques. Certain embodiments of the present invention provide a method that facilitates drill reuse in providing an anchor. Certain embodiments of the present invention provide a method that facilitates expansion tool reuse in providing an anchor. Certain embodiments of the present invention provide apparatus for anchoring in subsea ground comprising soil ranging from soft to heavy clays or rock foundations. Certain embodiments of the present invention provide apparatus for selecting ungrouted sheath thickness to accommodate the desired shear load. Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which: Figure 1A illustrates an offshore environment; Figure 1B illustrates a drilling template; Figure 2 illustrates a seafloor including piles in position prior to installation of an anchor body; Figure 3 illustrates an anchor body; Figure 4 illustrates a detail “A” indicated in Figure 3; Figure 5 illustrates a section view along B-B indicated in Figure 4; Figure 6 illustrates a section view of a pile installed into a seafloor; Figure 7 illustrates an axial section view along C-C of a pile illustrated in Figure 6; Figure 8 illustrates a section view of an expanded pile installed into a seafloor; Figure 9 illustrates an offshore environment including a floating platform; Figure 10 illustrates a method of providing at least one fixation support; Figure 11 illustrates an end region of an alternative pile; Figure 12 illustrates a section view of an alternative pile illustrated in Figure 11; Figure 13 illustrates an end region of an alternative sheath; Figure 14 illustrates a section view of an alternative sheath illustrated in Figure 13; Figure 15 illustrates an alternative pile and an alternative sheath; Figure 16 illustrates a section view of an alternative pile and an alternative sheath; Figure 17 illustrates an axial section view of an alternative pile; Figure 18 illustrates an axial section view of a further alternative pile; and Figure 19 illustrates a plurality of anchor body modules. In the drawings like reference numerals refer to like parts. Figure 1A illustrates an offshore location 100. It will be appreciated that the offshore environment 100 may alternatively be a sea, lake, river, pond environment or the like. At the offshore location illustrated in Figure 1A, a floating vessel 101 (e.g., a ship, platform, or the like) is located around the surface of the water. The floating vessel 101 includes at least one mooring line 102. It will be appreciated that alternatively the mooring line 102 may be a cable, chain, or the like for lowering a mass. The mooring line is a long windable strong element that may support mass as it is lowered or raised through a body of water. Aptly, the floating vessel 101 floats on the water. The floating vessel 101 may be located above a seafloor 105. Aptly, the floating vessel 101 may be located above a bed of a lake, river, pond, water environment or the like. Aptly, the floating vessel 101 may be located above a desired location 106 near which an anchor should be installed. In some embodiments, a Remotely Operated Vehicle (ROV) 108 may be at the offshore location 100. Aptly, the ROV may be connected to the floating vessel 101 by one or more cables 109. The cables 109 may transfer power, data, or the like between the floating vessel 101 and the ROV 108. One end of the mooring line 102 is secured to the floating vessel 101. The other end of the mooring line 102 is secured to a drilling template 110. It will be appreciated that alternatively the drilling template 110 may be replaced by an anchor body, a pile, an underwater pile hammer, or the like. Thereby, the drilling template 110 or other desired object can be lowered into position at the desired location 106. Aptly, the ROV 108 may help lower or assist in installation of the drilling template 110, anchor body, anchor, pile, or the like. Figure 1B illustrates an isometric view of a drilling template 110 used for installation of a subsea anchor (not shown). The subsea anchor is a structure that is secured to a sea bed / sea floor and remains in place whilst other floating structures may be connected to it via a mooring line or the like. The subsea anchor thus can be used to secure a floating platform at a desired respective position with respect to a subsea surface. The drilling template 110 is temporary and is not included in the ultimate anchor itself. It will be appreciated that in some embodiments, the drilling template 110 may alternatively form part of the anchor. The drilling template 110 illustrated in Figure 1 has a generally rectangular footprint and is constructed primarily from metal alloys although it will be appreciated that alternatively, metals, metal alloys, composite materials, polymers or the like or any combination of materials may be used. Likewise, the shape of a drilling template may be non-rectangular. The drilling template 110 is located above the seafloor 105. It will be appreciated that prior to drilling and piling some landscaping of the subsea terrain may take place to level and / or recess an area of the original subsea surface where the subsea anchor is to be located. It will likewise be appreciated that alternatively the seafloor 105 may be a bottom of a body of water including a lake, river, or the like. The drilling template 110 shown includes six legs 120. The legs 120 are hollow cylindrical sheath legs / sleeve legs. Aptly, the drilling template 110 includes one or more three-dimensional truss structures 125 that help to hold the legs 120 to each other in a rigid spaced apart configuration. It will be appreciated that the drilling template 110 may alternatively be constructed without truss structures and / or with a different footprint, shape, or the like. Aptly, the drilling template 110 includes one, two, three, four, five, six (1,2, 3, 4, 5, 6) or more legs. Each leg 120 includes a respective foot 130. Alternatively, a foot may extend across multiple legs and thus be “shared”. The feet illustrated in Figure 1 are mudmats 130. Aptly the mudmat 130 is constructed of a metal, a metal alloy or the like. The mudmat 130 is for contacting the seafloor 105 and provides a higher contact area than the leg 120 for load distribution. It will be appreciated that the drilling template may be capable of any combination of the following: self-levelling, levelling, tilt adjustment. Aptly, a length of the leg 120 may be varied to help provide any of the previously mentioned features. Aptly, the leg 120 may include hydraulic actuators to vary a length of the leg 120. The drilling template 110 may be used for guiding a drill member 140 through the hollow leg 120. It will be appreciated that the hollow leg 120 may alternatively be referred to as a drilling guide element 120. The leg is thus an element that to at least some extent helps guide a path of a drilling bit or other such drilling member during a process of drilling a bore into the subsea surface. The drill member 140 provides a hole in the seafloor 105 with a diameter greater than a pile 150. The hole can be a bore into the terrain of the seabed / seafloor location. Aptly, the drill member 140 may alternatively be a hammer or other hole providing device. Aptly, the d ri 11 i ng template is used for guiding a pile 150 through the drilling guide element 120. In guiding the drill member 140 and / or the pile 150 through the drilling guide element 120, the drilling template 110 helps to provide accurate positions of the pile 150 in the seafloor 105. It will be appreciated that whilst Figure 1B shows one pile 150, a total of six piles 150 are installed using the drilling template 110 shown. After all the required piles 150 are positioned in their respective desired locations in the seafloor 105 using the drilling template 110, the piles 150 are then expanded using an expansion tool 180. The expansion tool 180 will be described in more detail with respect to Figure 8. It will be appreciated that alternatively, the expansion tool 180 may be used to expand the piles 150 at a different stage, for example after removal of the drilling template 110, after installation of an anchor body, or the like. In Figure 1B, following expansion of the piles 150, the template 110 is removed. Aptly, only the length of the pile 150 at or under the seabed 105 is expanded. That is to say, a portion of the pile 150 located in a hole in the seabed 105 is expanded using the expansion tool 180. Aptly the entirety of the pile 150 is expanded by the expansion tool 180. Aptly multiple sections of the pile 150 are expanded by the expansion tool 180, wherein the sections are optionally spaced apart at predetermined intervals. Aptly multiple regions distributed intermittently (that is to say at different spaced apart relationships) along the length of the pile 150 may be expanded by the expansion tool 180. Other numbers of piles and cooperating legs and different patterns (not necessarily laid out in columns and rows) could of course be utilised. Figure 2 illustrates the seafloor 105 including six piles 150 in position prior to installation of a subsea anchor structure. It will be appreciated that the piles 150 may be referred to as micropiles. The piles 150 are at least partially located in / embedded in drilled bores 210 provided by the drill 140 and then expanded by deploying the expansion tool 180 also illustrated in Figures 1B and 3 in the seafloor 105. The drilled bore 210 is thus provided via a drilling step of the drill 140 (a drill member). The drilled bore 210 provides a drilled surface. Thus, the piles 150 are partially embedded in the drilled bores 210 in the seafloor 105. A free end 220 of each pile 150 protrudes out of the seabed 105. An upper region 230 of the free end 220 of each pile 150 is located at a distal end of the pile 150. The piles 150 illustrated in Figure 2 are in two evenly spaced columns of three although it will be appreciated that any number of piles and / or any arrangement of piles may be provided instead. Aptly the piles 150 are perpendicular to a surface defined by the seafloor 105. Aptly the piles 150 are alternatively at an angle a0 to the surface of the seafloor 105. That is to say a primary axis associated with the elongate body that forms a pile is oriented at or close to ninety degrees to an effective surface offered by the terrain in the local environment. Aptly, a micropile is a long, slender generally tubular structure for providing support to an associated structure. Aptly a whole length of each micropile is between 2 and 100 metres or between 4 and 60 metres or between 6 and 30 metres. Aptly, micropiles are piles with a relatively small diameter of around 50 to 500mm, 100mm to 250mm, or the like. Aptly, micropiles are provided by high strength steel, or the like. Aptly a micropile may refer to a minipile, pin pile, needle pile, root pile, lightweight pile, or the like. Each pile 150 may have a hollow, rigid and / or cylindrical construction. Aptly the pile 150 may be an elongate body. Aptly the pile 150 has an outer diameter of 0.1 to 10m. Aptly the pile 150 has a body that is formed by extruding a face in an axial dimension. Aptly the pile 150 has a regular (continuous) cross section along its length. It will be appreciated that in some embodiments the pile 150 may have protruding elements on its outer surface. The pile 150 includes an inner layer and at least one drilled surface-engaging element (not shown). The drilled surface-engaging element / s are at a radially outer surface of the inner layer. The drilled surface-engaging element / s are designed to interface with ground, eg seabed 105 or the like. Aptly the inner layer and the drilled surface-engaging element / s of the pile 150 are provided by different materials. Further details regarding the piles 150 are provided in respect of Figures 4-8 Each pile is an example of an element that can provide a fixation support. Each friction pile can be provided by an elongate body that has an elongate body wall. Although in the present embodiment the piles 150 have been expanded during the step illustrated in Figure 1B before the drilling template 110 is removed, it will be appreciated that alternatively, the expansion tool 180 may be used to expand the piles 150 after the drilling template 110 has been removed. Aptly a region of the pile 150 may be expanded by the expansion tool 180. Aptly the region may correspond to a length of the pile 150 located in the drilled bore 210. Aptly the whole pile 150 may be expanded. Aptly the region may include multiple sections distributed along the length of the pile 150 that may be expanded by the expansion tool 180. Aptly multiple regions distributed intermittently (that is to say at different spaced apart relationships) along the length of the pile 150 may be expanded by the expansion tool 180. Figure 3 illustrates a subsea anchor 300. The anchor 300 includes an anchor body 305 mounted on and secured to six piles 150. It will be appreciated that the anchor 300 may alternatively include one, two, three, four, five, six (1,2, 3, 4, 5, 6) or more piles 150. Aptly the anchor body 305 is constructed from steel. Aptly the anchor body 305 is alternatively constructed from any metal, alloy, composite, reinforced concrete, or combination thereof or the like. The anchor body 305 illustrated in Figure 3 has a rectangular footprint defined by a base provided as a mudmat 310 which is usually in contact with the seafloor 105 when the anchor is in use. Aptly the mudmat 310 is a base. Aptly the mudmat 310 has a square, circular, or the like footprint. The mudmat 310 optionally includes a plurality of perforations 312. The perforations 312 may be circular through-holes, square through-holes, or the like. The perforations 312 may help to increase a speed of descent of the anchor body 305 when lowered through a body of water. They thus help the base offer less drag as it is lowered through or raised through a body of water. The mudmat 310 may optionally be provided with a skirt 350 as illustrated in Figure 3. Aptly, the skirt 350 is a structure that protrudes roughly perpendicular to the mudmat along the edges of the mudmat, thus providing a partially-enclosed region defined by walls of the skirt 350. The anchor body 305 illustrated in Figure 3 also includes an anchor plate 320. The anchor plate 320 is generally perpendicular to the mudmat 310 and may be located along a central axis of the length of a face of the mudmat 310. Aptly the anchor plate 320 is oriented at any angle to the mudmat 310. The anchor plate 320 may provide one or more attachment points 322. These are examples of connection elements. The three attachment eyes 322 illustrated in Figure 3 and which provide three respective connection elements are provided by through-holes disposed towards a periphery of the anchor plate 320 for connecting to mooring lines as required and / or for interconnecting an anchor body module to a neighbouring anchor body module. Aptly the attachment eyes 322 may be provided by threaded through-holes, bolts, locking mechanisms, nuts, or the like. It will be appreciated that alternatively the attachment eyes 322 may be for engaging with cables, beams, or the like. Aptly, the attachment eyes 322 illustrated in Figure 3 may additionally or alternatively provide respective interconnection points. In other words, a first anchor body 305 may be connected to a second anchor body 305 using the attachment eyes 322. An example of such an arrangement is illustrated in Figure 19. The anchor body 305 also includes six sheaths / sleeves 330. Aptly the anchor body 305 includes one, two, three, four, five or six (1, 2, 3, 4, 5, 6) or more sheaths 330. Each sheath 330 may include a hollow cylindrical region for locating the pile 150. The sheaths 330 may be joined in part by a cut-out plate 332. The cut-out plate has a face which is parallel to a face of the mudmat 310 and from which the sheaths 330 illustrated in Figure 3 protrude. The mechanical interaction between the pile 150 and surrounding sheath 330 may constrain and thereby restrain motion of the anchor body 305. The anchor body 305 includes a plurality of optional mudmat stiffeners 342 and / or anchor plate stiffeners 344 and / or sheath stiffeners 346. Aptly the anchor body 305 may include a plurality of beam stiffeners 342, 344, 346. The beam stiffeners 342, 344, 346 may help to hold the sheaths in a rigid spaced apart relationship. The anchor body 305 illustrated in Figure 3 may be installed by being lowered onto the six piles 150 in position on the seafloor 105, for example, at least as illustrated in Figures 1A and 2, thereby providing the anchor 300. That is to say, the arrangement of the piles 150 as defined by the drilling template 110 may correspond to the arrangement of the sheaths 330 of the anchor body 305. Once the piles 150 are correctly located in the sheaths 330, the piles 150 may be secured in place by grouting, mechanical devices, or the like. The revealed / exposed free ends of the friction piles are thus set out in a predetermined pattern that mate with and match the pattern / layout of sheaths 330 on the anchor body. Although in the present embodiment the piles 150 have been expanded during the step illustrated in Figure 1B before the drilling template 110 is removed, it will be appreciated that alternatively, the expansion tool 180 may be used to expand the piles 150 after the anchor body 305 has been installed on the piles 150. Aptly a region of the pile 150 may be expanded by the expansion tool 180. Aptly the region may correspond to a length of the pile 150 located in the drilled bore 210. Aptly the whole pile 150 may be expanded. Aptly the region may include multiple sections distributed along the length of the pile 150 that may be expanded by the expansion tool 180. Aptly multiple regions distributed intermittently (that is to say at different spaced apart relationships) along the length of the pile 150 may be expanded by the expansion tool 180. Figure 4 illustrates a detail “A” of the anchor 300 indicated in Figure 3. Figure 4 shows that the pile 150 may be located inside the sheath 330. Aptly the pile 150 is coaxial to the sheath 330. It will be appreciated therefore that an outer diameter of the pile 150 may broadly correspond to an inner diameter of the sheath 330. It will be appreciated that the feature illustrated in Figure 4 is a simplification and that the methodology and elements for securing the pile 150 to the sheath 330 are not shown. Figures 4 and 5 help to illustrate how the sheath of the anchor body is provided as a generally cylindrical wall having an associated sheath wall thickness. Each pile is an elongate body with an elongate body wall that is a multi-region wall. The multiregion wall of each pile 150 has two regions in the embodiment shown in Figure 4 (illustrated in more detail in Figure 6). It will be appreciated that more than two regions might be used for a pile body wall. Alternatively, an inner layer and at least one drilled surface-engaging element at a radially outer surface of the inner might be used for a pile body wall. Figures 4-10 refer to piles 150 with an inner layer and an outer layer. Figures 17 and 18 illustrate some alternatives. Each layer of the pile wall has a respective one or more thicknesses that might be the same or one layer may have a thickness greater than the other layer. For example, the outer layer of the elongate body wall (the pile wall) may be a high friction coating and as such would be considerably thinner than the other layer that offers up the structural integrity of the pile itself. Figure 5 illustrates a cross-section of the detail illustrated in Figure 4 along a plane “B-B”. That is to say Figure 5 illustrates a cross-section of the sheath 330 and corresponding pile 150. Figure 5 also shows that the pile 150 includes a hollow chamber / cavity 510. A separation distance di is illustrated between the outer surface of the pile 150 and the inner surface of the sheath 330. Aptly, the separation distance di is around 1 mm to around 100 mm, or around 10 mm to around 50 mm or the like. It will be appreciated that in some embodiments there may be no separation distance di. The pile 150 shown in Figure 5 also includes a wall 520. Further details regarding the wall 520 are provided in respect of at least Figure 6. In Figure 5 the elongate body wall is shown as a single layer structure for ease of understanding as to the relationship with the sheath. Figure 6 illustrates a cross-section of a covered region of the pile 150 installed in the seafloor 105. The seafloor 105 illustrated in Figure 6 is at least partially composed of drilled rock strata 610. The drilled rock strata 610 may be simply referred to as ground. Aptly, an upper layer of the seafloor 105 is composed of softer material relative to a lower layer of seafloor which is composed of rock. Other terrain material could of course be drilled into depending upon the location and local geology where the anchor is to be located and fixed in place. Drilled rock strata 610 may be provided by drilling effects of the drill member 140 or the like. Aptly, drilled rock strata 610 is a blind hole in rock of the seafloor 105. The drilled hole may be a bore. The bore has a generally cylindrical shape. Aptly, drilled rock strata 610 has a surface roughness Rs measured in micrometres (pm). It will be appreciated that a lower section of the piles 150 shown in Figure 2 are arranged in the seafloor 105 as illustrated in the present Figure. Figure 6 shows the pile 150 is horizontally separated from a surface of drilled rock strata 615 by a gap d2. It will be appreciated that the surface may be referred to as a drilled surface 615. Features of the pile 150 may engage with the drilled surface 615. Aptly, the gap ds is around 1 mm to around 100 mm, or around 5 mm to around 50 mm, or the like. Some lower sections of each pile are thus covered in the sense that they are located in a drilled hole / bore. Remaining ends of each pile are uncovered in the sense that they extend out of the bore away from the seafloor surface. The pile 150 includes a hollow chamber region 510 and a wall 520. Aptly, the wall 520 of the pile 150 is expandable at least when a force or pressure is applied to an internal surface of the wall 520. Aptly, a width of the pile 150 may be increased from a starting diameter when the force or pressure is applied to the internal surface of the wall 520. The wall 520 includes an inner wall layer 620 and at least one drilled surface-engaging element 630 at a radially outer surface of the inner wall layer 620. In particular, on the pile 150 illustrated in Figure 6, the at least one drilled surface-engaging element 630 is an outer wall layer. It will be appreciated that alternatively the drilled surface-engaging element / s 630 may be arcuate protrusions, cylindrical elements, tubular elements, teeth, or the like. It will be appreciated that in some embodiments the pile 150 may include more than two wall layers. Aptly the wall 520 is a composite body of the pile 150. The inner wall layer 620 may form a structural member of the wall 520. The outer wall layer may be formed of a different material relative to the inner wall layer 620. It will be appreciated that ground will be understood to refer to rock, soil, bedrock, subterrain, earth, or the like, whereby the ground may be located at or under a body of water, surface of land, or the like. Aptly ground refers to the region surrounding a foundation element that has been installed. Aptly rock strata 610 may instead refer to rock, soil, bedrock, subterrain, earth, or the like. Figure 7 illustrates an axial section view along C-C of the pile 150 illustrated in Figure 6. The pile 150 includes the inner wall layer 620 and the drilled surface-engaging element 630. The ground engaging element 630 of the pile 150 illustrated in Figure 7 is provided by an outer wall layer 710. The pile is surrounded by rock strata 610. The outer wall layer 710 of the pile 150 illustrated in Figure 7 is distributed evenly around the inner wall layer 620 in an annular formation. That is to say, the outer wall layer 710 has a uniform thickness along the axial dimension of the pile 150. Alternatively the inner wall layer 620 and / or the outer wall layer 710 may not have a uniform thickness, or they may have the same or different wall thicknesses. Aptly, the outer layer 710 has a generally coaxial circumferentially extending layer. Aptly the outer layer 710 broadly has a singular value of thickness. Aptly the outer layer 710 has a variable thickness. Aptly, the outer layer 710 is built upon an outer surface of the inner wall layer 620. In some embodiments the outer layer 710 may itself be made up of two, three, four or more sub-layers. Aptly, the sub-layers of the outer layer 710 may have different material properties, mechanical properties, and / or thicknesses. Aptly, the drilled surface-engaging element / s 630 (provided by the outer layer 710 in the embodiment illustrated in Figure 7) are formed of a softer material relative to the inner wall layer 620. The softer drilled surface-engaging elements 630 may deform easier so as to engage the surface roughness of drilled rock strata 610 to achieve high friction with a surface of drilled rock strata 610 without creating fissures and breakage in rock strata 610 which undermine the shear capacity of the interface between the drilled surface-engaging elements 630 and rock strata 610. It will be appreciated that high friction may refer to a relative higher friction coefficient compared to a friction coefficient between a harder material and rock strata 610. Aptly, softness in respect of the drilled surface-engaging elements 630 and the inner wall layer 620 may refer to Ei >E2, where Ei is a Young’s Modulus of the inner wall layer 620 and E2 is a Young’s Modulus of the drilled surface-engaging elements 630 and / or to 01 » o2, where 01 is a Yield Stress of the inner wall layer 620 and o2 is a Yield Stress of the drilled surfaceengaging elements 630. Aptly, the drilled surface-engaging elements 630 have a higher friction coefficient with rock strata 610 than the inner wall layer 620. Aptly the angle of static friction ¢) degrees with rock strata 610 is such that ¢2 >¢1, where ¢1 is an angle of friction of the inner wall 620 and ¢2 is an angle of friction of the drilled surface-engaging elements 630. Aptly R2 >Ri, where R- is an average surface roughness of the inner wall 620 and R2 is an average surface roughness of the drilled surface-engaging elements 630. Aptly, the inner wall layer 620 of the pile 150 is formed of Stainless Steel. Aptly, the inner wall layer 620 of the pile 150 is formed of a steel alloy, metal alloy, or the like. Aptly, the drilled surface-engaging elements 630 of the pile 150 are formed of a material that is particularly chosen to achieve high friction with rock strata 610. Aptly, the drilled surface-engaging elements 630 of the pile 150 are formed of rubber. Aptly, the drilled surface-engaging elements 630 of the pile 150 are formed of ceramic, ceramic type composites, metallic materials, alloys, or the like. Aptly the drilled surface-engaging elements 630 are formed using a deposition process such as vulcanisation in the case of rubber; thermal spray for metals and ceramics on to the inner wall layer 620; or the like. Aptly surface roughness (e.g., using average profile parameter: Ra, unit: pm) may be measured by a roughness meter whereby a probe is traced across a surface of the target to measure the vertical deflection along a horizontal axis. It will be appreciated that an alternative method for measuring surface roughness may be used. Figure 8 illustrates a cross-section of an expanded pile 810 installed into the seafloor 105. It will be appreciated that the expanded pile 810 may be the pile 150, except that at least a region of an inner surface of the inner wall layer 620 has been expanded. Aptly, the inner wall layer 620 of the pile 150 has been radially expanded. Aptly, an average diameter of the expanded pile 810 is greater than a corresponding average diameter of the pile 150. The expanded pile 810 may be provided, from the pile 150, by a mechanism that applies force and / or pressure to at least the inner wall layer 620 of the pile. It will be appreciated that alternatively other methods may be used to expand the pile 150. Figure 8 thus helps illustrate how after an elongate body that is hollow and rigid has been located in a drilled bore, at least one region of an inner layer of the elongate body can be radially expanded. The region that is expanded might extend along a whole length of a covered section of the elongate body. Alternatively, one or more sections of the covered length might be expanded. For example, only a lower section of a covered part of a pile or an upper section of a covered part of a pile might be expanded. Aptly, only a selected one or more region within any section of a pile might be expanded outwards in a radial direction away from a central primary axis associated with the elongate pile. This might be the case where the local geology makes a friction fit unstable in certain areas. The regions that are expanded help urge the outer surface of the elongate body against the drilled surface of the bore in areas that corresponded to the expanded areas. The expanded pile 810 includes the wall 520 including the inner wall layer 620 and the outer wall layer 710. Aptly, the wall layers 620, 710 illustrated in Figure 8 have been compressed relative to the corresponding wall layers 620,710 of the pile 150. The wall 520 of the expanded pile 810 is now at least partially in contact with a surface of rock strata 610. In Figure 8 a contact surface 820 is illustrated between the expanded pile 810 and rock strata 610. A contact pressure force Pa is thereby provided at the contact surface 820 between the outer wall layer 710 and the seafloor 105. Aptly, the contact pressure force Pa may be approximated to around 30 MPa. Aptly, the contact pressure force Pa is 0.01 Mpa, 10 Mpa, 1000 Mpa, or the like. Aptly, the contact pressure is sufficient to plastically deform the expanded pile 810 outwardly and provide sufficient pressure to generate the desired frictional force required at pile rock strata interface. Aptly, contact pressure force may be calculated using a force meter to measure force applied to the expansion tool 180 and an applied surface area over which the force is applied. Aptly, the expanded pile 810 includes a filler material 830. The filler material 830 illustrated in Figure 8 is grout. Aptly as an alternative, the filler material 830 is, sand, concrete, particles of a material, any appropriate infill material, or the like. The grout 830 helps to prevent the expanded pile 830 from being compressed inwards due to inwards pressure applied by rock strata 610 and / or the surrounding seafloor 105. Aptly, the grout 830 helps to prevent so-called bounce back after the pile 150 has been expanded. Aptly, the grout 830 helps to prevent a reduction in the average diameter of the expanded pile 810. The piles (150) may be expanded by employing the expansion tool 180 either after installation of piles (150) on to seabed as presented in Figure 2 or post installation of the subsea anchor 300 on to the said piles 150 as depicted in Figure 3, or the like. Expansion of the pile 150 to provide the expanded pile 810 may be carried out as follows. The expansion tool 180 is inserted into the hollow chamber 510 of the pile 150. Aptly, the tool 180 is an expansion member. Aptly, the expansion member includes one or more abutment elements for expanding a diameter of an inner surface of the pile 150. Aptly, expansion of the pile 150 is carried out during any stage of the anchoring process including at least the stages referenced in Figures 1B, 2 and 3. Aptly, expansion of the pile 150 is repeated more than once. Aptly, alternative mechanisms may be used to expand the pile 150. The pile 150 is expanded such that the wall 520 may engage with a surface of the seafloor 105. Aptly, expansion is varied such that the contact pressure force Pa between the outer wall layer 710 and drilled rock strata 610 is set to a determined value of pressure. Aptly, the expansion tool 180 may include at least one expansion member 840 (one provided in Figure 8) and / or at least one abutment member 845 (four provided in Figure 8) and / or at least one pivotable joint. Aptly during operation, the expansion member 840 may be moved towards the top of Figure 8, thereby driving the abutment members 845 radially outwards (left and right in Figure 8) through rotation of the joints. It will be appreciated that the expansion tool 180 may alternatively be provided by a different mechanical assembly; by pumping fluid into the chamber 510; by driving an expansion rod along the chamber 510; or the like. Aptly, expanding may involve urging the expansion member 840 along the void space of the chamber region 510. Aptly, expanding may involve driving said abutment element / s 845 radially outwardly (once) against at least a region of an inner surface of the inner wall layer 620 at chosen locations. Aptly, expanding may involve repeatedly driving the abutment element 845 radially outwardly against at least a region of the inner surface of the inner wall layer 620 at chosen locations. Aptly, repeatedly may refer to at least twice. Aptly, expanding may involve radially expanding the region / s by urging the expansion tool 180 against the inner surface of the inner wall layer 620. Figure 9 illustrates the offshore environment 100 where the anchor 300 may be used. That is to say the anchors 300i,2 (two are illustrated in Figure 9 in elevation) illustrated in Figure 9 may provide anchor supports at a respective desired location. It will be appreciated that alternatively at least one anchor support may be provided at a lake, river, pond, or the like. That is to say, the offshore environment 100 may alternatively be a lake, river, pond environment or the like. Also, one, two, three or more anchors may be located in a nearby relationship depending upon how much anchoring force is needed and how the local terrain will secure any given anchor. The respective anchor body members 305 of one, two, three or more anchors 300 may be referred to as anchor body modules 305, and the collective respective anchor body modules 305 and corresponding piles 150 as one anchor. An example of such an arrangement is illustrated in Figure 19. The offshore environment 100 includes the seafloor 105 and a floating platform / structure 910. Aptly, the seafloor 105 may be located at a depth greater than around 30 meters. Aptly, the floating platform 910 is a wind turbine assembly. Aptly, the floating structure 910 is an extraction facility, a floating production storage and offloading (FPSO) unit, an electricity generation facility, or the like. The floating platform 910 shown is located at / on a surface 920 of the sea. The two anchors 300i,2 shown in Figure 9 each include respective anchor bodies 305i,2 and respective piles 150. The piles 150 (not shown) are engaged with the seafloor 105. Aptly the anchors 300i,2 are secured to the seafloor 105. Aptly the anchors 300i,2 are capable of supporting a tensile force and / or a shear force provided by corresponding cables 930i,2. The cables 930i,2 shown in Figure 9 are mooring lines. Aptly, the cables 930i,2 may alternatively be beams, chains, ropes or the like. The cable 930i is secured to the anchor 300i by the connection elements 322i. Similarly, the cable 9302 is secured to the anchor 3002 by the connection 3222. It will be appreciated that the cables 9301,2 may be secured by any of various methods of attachment / connection to the floating platform 910. The anchors 300i>2 thereby secure the floating platform 910 at a desired relative position with respect to the surface 920. Figure 10 illustrates a method 1000 of providing at least one fixation support 150 at a respective desired location at a subsea surface location. It will be appreciated that the anchor body 305 may be secured to the pile 150 or to more than one pile set out in a predetermined pattern thereby providing the subsea anchor 300 for ultimately securing the floating platform 910 when needed. A start stage S1005 involves determining a desired location. Determining the desired location may involve determining a desired relative position of the floating platform 910 for securing to at least one fixation support 150 via the anchor body 305. It will be appreciated that the desired location may be at a ground of a sea, lake, river, pond, or the like. In the present example the desired location is at the ground of the sea: the seafloor 105. Next, an installing step S1010 involves placing, on the seafloor 105 at the desired location, the drilling template 110. The drilling template 110 may be lowered at the desired location from the floating vessel 101 for example as illustrated in Figure 1 A. Aptly, the drilling template 110 may be placed at the desired location by a Remotely Operated Vehicle (ROV) 108 or another mechanism. The mudmats 130 of the drilling template 110 may contact the seafloor 105 that may or may not have been in some way pre-prepared. Next, a levelling step S1015 involves levelling the drilling template 110. Levelling may involve any combination of self-levelling, levelling, tilt adjustment, or the like. Aptly, the length of one or more drilling guide elements 120 may be varied to help provide levelling. Aptly, the drilling guide elements 120 may include hydraulic actuators to vary the length of the drilling guide elements 120. Aptly levelling may involve adjusting an angle between an axis of the drilling template 110 and a direction in which gravity acts. The base of the drilling template is associated with a principal plane and that plane might be tipped and / or twisted during the levelling step to associate the drilling guides at a desired angle with respect to the local seafloor terrain. Next, a drilling step S1020 involves drilling a hole in the seafloor 105 thereby exposing drilled rock strata 610. The drilling step may further involve installing the drill member 140 on the pile 150 and passing the drill member and pile through the drilling guide element 120 of the drilling template 110 until the drill member 140 is in contact with the seafloor 105. It will be appreciated that alternative techniques may be used to provide the hole for partially inserting the pile 150. The drilling creates a respective bore that is a blind hole in the sea bed. Multiple bores may be drilled simultaneously or one by one. Next, a locating step S1025 involves locating the pile 150 in the hole of drilled rock strata 610 provided by the drill 140. It will be appreciated that the pile 150 may be positioned using the mooring line 102 and floating vessel 101. Aptly, the pile 150 may be positioned using the ROV 108. Optionally one or more divers may assist and guide each elongate body into a respective bore. Next, an expanding step S1030 involves expanding the pile 150 whilst in position in the seafloor 105 by installing the expansion tool 180 as outlined in Figures 1B, 2, 3 or 8. The pile 150 is expanded to provide the expanded pile 810. The pile 150 may be expanded at least as outlined in Figure 8. Once the pile 150 is expanded, a contact surface may be provided between the expanded pile 810 and the surrounding seafloor 105. The contact surface may provide contact pressure force. The contact pressure force may provide friction to resist movement of the expanded pile 810. Aptly, a shear force may be transferred from the expanded pile 810 to the seafloor 105. Aptly, a tensile force may be transferred from the expanded pile 810 to the seafloor 105. Aptly, the expanding step S1030 may involve urging the expansion member along the void space of the chamber region 510. Aptly, the expanding step S1030 may involve driving the abutment element radially outwardly against at least a region of the inner surface of the inner wall layer 620 at chosen locations. Aptly, the expanding step S1030 may involve repeatedly driving the abutment element radially outwardly against at least a region of the inner surface of the inner wall layer 620 at chosen locations. Aptly, the expanding step S1030 may involve radially expanding the region / s by urging the expansion member at an expansion pressure against the inner surface of the inner wall layer 620, wherein the desired expansion pressure to achieve required frictional resistance is achieved. Aptly the required frictional resistance may be at between 20 and 40 Mega Pascals (Mpa) of expansion pressure. Aptly the required frictional resistance may be at around 30 Mega Pascals (Mpa) or higher. Aptly, the expanding step S1030 may alternatively be carried out after removing the drilling template 110, after installing the anchor body 300, or the like. Next, a filling step S1035 involves filling the hollow chamber 510 of the expanded pile 810 with filler material 830. Aptly, the filler material 830 is grout. Aptly, the filler material 830 is, sand, concrete, particles of a material, any appropriate infill material, or the like. Aptly, the grout 830 helps to prevent the expanded pile 830 from being compressed inwards due to pressure applied by rock strata 610 and / or the surrounding seafloor 105. Aptly, the grout 830 helps to maintain the contact pressure force of the expanded pile 810 with the seafloor 105. Aptly, the filling step S1035 may alternatively be carried out after removing the drilling template 110, after installing the anchor body 300, or the like. Next, a removing step S1040 involves removing the drilling template 110. It will be appreciated that alternatively, the removing step S1040 may be executed before the expanding step S1030 and filling step S1035. That is to say, in some embodiments, the expanding and filling steps S1030, S1035 may be executed at a later stage such as after the drilling template 110 is removed, after the anchor body 305 is installed, or the like. The removing step S1040 is followed by an end step whereby the method 1000 ends. Figures 11 and 12 illustrate an alternative pile 1100. The alternative pile 1100 may be the pile 150 previously described with respect to earlier figures with the additional inclusion of a partially ribbed outer body. Figure 11 illustrates an isometric view of the pile 1100. Figure 12 illustrates a cross-section view of the pile 1100. The alternative pile 1100 includes the hollow chamber 510, the wall 520 and four spaced apart coaxial ribs 1110. It will be appreciated that alternatively there may be at least one thread 1110. Alternatively, there may be one, two, three, four or more ribs. The wall 520 may include the inner wall layer 620 and the drilled surface-engaging element / s 630. The ribs 1110 may be spaced-apart adjacent protrusions located on an outer surface of the wall 520. They may each extend fully in a circumferential direction around the pile wall or just for a part or parts of a respective circumference. Aptly, the ribs may be one or more threads 1110 which are helical protrusions located on an outer surface of the wall 520. The ribs 1110 may engage with features of the sheaths 330 of the anchor body 305, illustrated in at least Figures 13-16. Aptly, the ribs 1110 may provide a locking action with the sheath 330. Aptly the ribs 1110 may be located near an end region 1120 at a free end region 1125 of the pile 1100. Aptly the threads 1110 may be located between the end region 1120 and a proximal region 1130 of the pile 1100. Figures 13 and 14 illustrate an alternative sheath 1300 of the anchor body 305. The alternative sheath 1300 may be the sheath 330 with the additional inclusion of longitudinal slits 1310 (while twenty (20) are shown in Figure 13 the number of longitudinal slits may be varied to suit) spaced apart around a circumference of the sheath 1300 and / or four internal circumferential protrusions 1315. It will be appreciated that alternatively there may be at least one protrusion 1315. Figure 13 illustrates an isometric view of the sheath 1300. Figure 14 illustrates a cross-section view of the sheath 1300. The longitudinal slits 1310 are located from an end 1320 of the sheath 1300 along a wall of the sheath to a given depth 1330 of the sheath 1300. The slits thus extend through a slit region which is an end region of a sheath. It will be appreciated that alternatively there may be one, two, three, or more longitudinal slits 1310. Put another way each slit extends from an end of a sheath into the body of the sheath by a set distance, d. Each slit may be a cut of even length in the body of the sheath or slits may have different lengths. The slits help introduce an ability to be contracted and / or expanded into a top end region of the sheath. They thus allow for deformation in an otherwise rigid structure. The longitudinal slits 1310 may include internal protrusions 1315 or recesses that may help to engage with the ribs 1110 of the alternative pile 1100. Aptly the internal protrusions 1315 may provide a cooperating locking action with the pile 1100. It will be appreciated that the longitudinal slits 1310 may help enable passage of the pile 1100 through the sheath 1300 by allowing the sheath 1300 to expand radially thereby accommodating the protruding ribs 1110 of the pile 1100. Thus, the threads 1100 of the pile 1100 and internal protrusions 1315 of the sheath 1300 may pass each other and engage. Aptly, when engaged, the internal protrusions 1315 may limit relative axial movement of the protruding ribs 1110 as may be illustrated in at least Figures 15 and 16. This helps prevent the anchor body from separating from the pile / s that provide it with fixation support. Figures 12 to 16 refer to embodiments in which ribs 1110 of the pile 150 may cooperate with corresponding internal protrusions 1315 of the sheath 1300. Aptly, the pile 150 may have ribs 1110 whilst the sheath 1300 may have a smooth internal surface. Aptly, the pile 150 may have a smooth external surface whilst the sheath 1300 may have internal protrusions 1315. Figures 15 and 16 illustrate an assembly 1500 of the pile 1100, the sheath 1300 and a securing mechanism 1510. A securing strap is illustrated. Figure 15 illustrates an isometric view of the assembly 1500. Figure 16 illustrates a cross-section view of region D illustrated in Figure 15. In Figures 15 and 16, the ribs 1110 of the pile 1100 are engaged with the internal protrusions and recessed regions 1315 of the sheath 1300. Aptly the pile 1100 with ribs 1110 are fully engaged with the sheath 1300. To help prevent slippage between the threads 1110 and the internal protrusions 1315 (shown in particular in Figure 16), a securing strap in the format of a ring 1510 is provided. The ring 1510 has an inner cylindrical region. Aptly the ring 1510 is not a complete cylinder: two radial protrusions 1520 at respective ends of the ring are separated by a gap. Thereby, a diameter of the ring 1510 may be varied by increasing or reducing the gap between the radial protrusions 1520. Effectively pulling the strap more tightly together provides a compressive effect. It will be appreciated that the ring 1510 that provides a securing strap may alternatively be replaced with a tightening band, a hose clamp, or the like. The ring 1510 may also include a nut 1530 and bolt 1535 assembly. Aptly, a hole in the radial protrusions 1520 may provide means for inserting the bolt 1535 from a first axial direction of the hole through the radial protrusions such that the nut 1530 may be engaged with the bolt 1535 in a further axial direction of the hole. Aptly, the nut 1530 may be tightened on the bolt 1535 when installed in the radial protrusions 1520 to reduce the diameter of the ring 1510. Aptly, tightening of the nut 1530 may be provided subsea by the ROV 108. Aptly, when the diameter of the ring 1510 is reduced the ribs 1110 and internal protrusions 1315 may be fully engaged as illustrated in Figure 16. It will be appreciated that herein, fully engaged may refer to the internal protrusions 1315 preventing movement of the ribs 1110. Aptly, the ring 1510 may fully engage the internal protrusions 1315 and the ribs 1110 such that a grouted connection is not required. Figure 17 illustrates an axial section view of an alternative embodiment of the pile 150 embedded in rock strata 610. The pile 150 includes the inner wall layer 620 surrounded by the drilled surface-engaging elements 630. In Figure 17, the drilled surface-engaging elements 630 are provided by four arcuate protrusions 1710i-4. Aptly, two, three, or more arcuate protrusions 1710 may be provided. Aptly, the arcuate protrusions 1710 may have any arc angle. The arcuate protrusions 1710 run along the length of the pile 150. Optionally the arcuate protrusions 1710 may be intermittently arranged along the length of the pile 150. The pile 150 illustrated in Figure 17 has a constant axial section, therefore the drilled surface-engaging elements 630 are provided here as longitudinal strips along the length of the pile 150. It will be appreciated that the arcuate protrusions 1710 may be welded or otherwise attached to the outer surface of the inner wall layer 620. Aptly, Figure 17 illustrates a cross sectional view C-C as depicted in Figure 6 according to an alternative embodiment wherein the said elements 630 may be positioned intermittently onto the inner layer 620 so as to form longitudinal strips 1710 along the pile 150. Aptly during expansion of the pile 150, the arcuate protrusions 1710 may bite into the drilled surface 615 of the rock strata 610 surrounding the pile 150. The arcuate protrusions 1710 may thereby provide the pile 150 with increased surface area and / or improved transfer of force / moments from the pile 150 to the surrounding rock strata 610. Having circumferentially spaced apart protrusions helps rock to invade in spaces between the protrusions subsequent to expansion of the pile which helps create a fixed point and helps avoid rotation. Figure 18 illustrates an axial section view of an alternative embodiment of the pile 150. The pile 150 includes the inner wall layer 620 surrounded by the drilled surface-engaging elements 630. In Figure 18, the drilled surface-engaging elements 630 are provided by eight tubular elements 1810i-s. Aptly, two, three, or more tubular elements 1810 may be provided. Aptly, Figure 18 illustrates a cross-sectional view C-C as depicted in Figure 6 according to an alternative embodiment where in the protrusions 1710 themselves are made of hollow cylindrical sections 1810. The hollow sections 1810 may be welded to the outer surface of the inner wall layer 620. It will be appreciated that alternatively, any means of securing may be provided. Aptly the drilled surface-engaging element 630 includes a series of hollow tubes 1810. Aptly the tubes 1810 have an outside diameter of between 10 and 30 mm. Aptly the hollow tubes have a wall thickness of between 1 and 5 mm. Aptly the hollow tubes 1810 are welded to the inner wall layer 620. The outside of the tubes might be smooth or rough or include a high friction coating. Aptly during expansion of the pile 150, the tubular elements 1810 may bite into the drilled surface 615 of the rock strata 610 surrounding the pile 150. The tubular elements 1810 may thereby provide the pile 150 with increased surface area and / or improved transfer of force / moments from the pile 150 to the surrounding rock strata 610. Figure 19 illustrates a modular assembly 1900 according to an alternative embodiment. The modular assembly 1900 includes two anchors 3003,4. The anchors 3003,4 include respective anchor bodies 3053,4 and respective piles 150. It will be appreciated that alternatively, the modular assembly 1900 could include more than two anchors 300. Aptly, the modular assembly 1900 including anchors 300 may be collectively referred to as one anchor, wherein the anchor includes a plurality of anchor body modules 305 that are interconnected, and their respective piles 150. In the modular assembly 1900 illustrated in Figure 19, a first anchor body module 3053 and a second anchor body module 305s are secured together by a pair of locking beams 1910. It will be appreciated that alternatively, one, three, or more locking beams 1910 may be provided to secure the first anchor body module 305a to the second anchor body module 3054 via the attachment eyes 322. The attachment eyes 322 provide respective interconnection points. The locking beams 1910 are examples of interconnection elements. Aptly, the interconnection elements 1910 may be for interconnecting an anchor body module 305 to a neighbouring anchor body module 305. Aptly, three or more anchor body modules may be secured to their respective neighbouring anchor body modules by respective locking beams 1910. Aptly, the locking beams 1910 may transfer a force and or a moment from one anchor body module 3053,4 to another anchor body module 3053,4. Aptly, the provision of locking beams 1910 may help to accommodate increased horizontal and / or vertical loads that the modular assembly 1900 is subjected to. Aptly, the locking beam 1910 may provide a loading sharing bridge between the two anchors body modules 3053,4. Aptly, the modular assembly 1900 may be further extended by securing one or more still further anchor body modules 305 to the first and / or second anchor body modules 3053,4 in the same fashion as indicated in Figure 19. The modular assembly 1900 may include at least one locking pin 1920. Aptly the locking pin 1920 may engage the locking beam 1910 and the anchor 3003,4at the attachment eye 322. Aptly the locking pin 1920 may secure the locking beam 1910 to the anchor body module 3003,4. Aptly the locking pin 1920 may provide a transfer of a force and / or a moment between the anchor body module 305 and the locking beam 1910. It will be appreciated that alternatively, more than one locking pin 1920 may be provided. Aptly, the locking pin 1920 may alternatively be a bolt or any other mechanism for securing the locking beam 1910 to the anchor body module 305. Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to” and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of the features and / or steps are 5 mutually exclusive. The invention is not restricted to any details of any foregoing embodiments. The invention extends to any novel one, or novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 10 The reader’s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

4CLAIMS:

1. A method of providing at least one fixation support at a respective desired location at a subsea seafloor surface location, comprising the steps of:via a drill member, drilling into a subsea seafloor surface at a desired location thereby providing a drilled bore via a drilling step at the desired location;locating an elongate body that is hollow and rigid at least partially in the drilled bore; andsubsequently radially expanding at least a region of at least an inner layer of an elongate body wall of the elongate body thereby urging a corresponding region of at least one drilled surface-engaging element, disposed at a radially outer surface of the inner layer of the elongate body wall, against a drilled surface associated with the drilled bore thereby providing a friction fit between the drilled surface and at least a region of an outer surface of a covered portion of the elongate body that is in the drilled bore.

2. The method as claimed in claim 1, further comprising:guiding the drill member, as it drills into the subsea seafloor surface, via a drilling guide element of a drilling template; andremoving the drilling template subsequent to providing one or more respective drilled bores and locating at least a portion of a respective elongate body in each drilled bore.

3. The method as claimed in claim 1 or claim 2, further comprising:radially expanding said a region of at least the inner layer of the elongate body wall by urging an expansion member along a void space of a chamber region surrounded by the elongate body wall; andvia the expansion member, driving at least one abutment element radially outwardly against an inner surface of the inner layer at selective locations.

4. The method as claimed in claim 3, further comprising:the selective locations radially expand substantially a whole surface area of the inner layer of the covered portion.

5. The method as claimed in claim 3 further comprising:radially expanding said a region by repeatedly urging the expansion member along the void space or by repeatedly urging an abutment element outwardly.

6. The method as claimed in claim 3 or claim 5, further comprising:as the abutment element is driven radially outwardly, deforming the inner layer radially outwardly thereby urging an outer surface of said a corresponding region of said at least one drilled surface-engaging element at the drilled surface.

7. The method as claimed in any one of the claims 1 to 6, further comprising:providing at least one fixation support comprises providing a plurality of fixation supports, each provided by a top free end region of a respective elongate body wall of a respective elongate body, in a predetermined pattern.

8. The method as claimed in any one of claims 1 to 7, further comprising: subsequent to radially expanding said a region of the at least an inner layer, at least partially filling a chamber region surrounded by the elongate body wall with a contraction resistant material.

9. The method as claimed in claim 8, further comprising:the contraction resistant material is a settable material or sand or grout.

10. The method as claimed in claim 2 and any claim dependent thereon, further comprising:levelling the drilling guide template by varying a length of at least one leg member associated with the drilling guide template.

11. The method as claimed in any one of claims 1 to 10, whereby the at least one drilled surface-engaging element comprises an outer layer that is coaxial with and circumferentially extends around the inner layer, and urging the corresponding region comprises urging the outer layer against the drilled surface.

12. The method as claimed in any one of claims 1 to 10, whereby each drilled surfaceengaging element comprises a one of a plurality of circumferentially spaced apart arcuate protrusions that extend radially outwards from the inner layer, and urging the corresponding region comprises urging an outer surface of each arcuate protrusion against the drilled surface.

13. The method as claimed in any one of claims 1 to 10, whereby each drilled surfaceengaging element comprises a one of a plurality of circumferentially spaced apart cylindrical elements adjacent to, and supported by, the inner layer, and urging the corresponding region comprises urging an outer surface of each cylindrical element against the drilled surface.

14. Apparatus for securing a floating platform at a desired relative position with respect to a subsea seafloor surface, comprising:a plurality of fixation supports, each fixation support provided at a respective desired location at a subsea seafloor surface location according to the method of any one of claims 1 to 13, provided via protruding free end regions of a respective plurality of friction pile members driven into a subsea seafloor surface in a predetermined pattern, each friction pile member comprising an elongate friction pile member wall comprising an inner layer and at least one drilled surface-engaging element disposed at a radially outer surface of the inner layer; andan anchor body member comprising a base, a plurality of sheath elements each disposed to receive a free end region of a respective fixation support and at least one connection element each for connecting to at least one mooring line.

15. The apparatus as claimed in claim 14, further comprising:the inner layer is manufactured from a first material and the at least one drilled surface-engaging element is manufactured from a further material that is different to the first material.

16. The apparatus as claimed in claim 14, further comprising:each sheath element comprises at least one pile engaging element disposed to engage with at least a region of an upper end region of a free end region of a respective friction pile member.

17. The apparatus as claimed in claim 16, further comprising:each pile engaging element is a recess or protruding element that cooperates with a mating protuberance or recessed region at a free end region of a friction pile member.

18. The apparatus as claimed in claim 16 or claim 17, wherein an end region of at least one sheath element is slit, further comprising:at least one securing strap that is securable around the slit region of a respective sheath element to thereby crimp and force radially inwards spaced apart fingers of the sheath element in the slit region.

19. The apparatus as claimed in any one of claims 14 to 18, wherein the base of the anchor body member further comprises a plurality of perforations spaced apart and disposed in a pattern around an edge region of the base.

20. The apparatus as claimed in any one of claims 14 to 19, wherein the anchor body member comprises either an integrally formed anchor body unit or a plurality of anchor body modules that are interconnected.

21. The apparatus as claimed in claim 20, further comprising:each anchor body module further comprises at least one interconnection element for interconnecting a first anchor body module with at least one further anchor body module.

22. The apparatus as claimed in any one of claims 14 to 21, wherein the apparatus comprises a subsea anchor.

23. The apparatus as claimed in any one of claims 14 to 22, further comprising:said at least one drilled surface-engaging element comprises an outer layer that is coaxial with and circumferentially extends around the inner layer.

24. The apparatus as claimed in any one of claims 14 to 22, further comprising:each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart arcuate protrusions that extend radially outwards from the inner layer.

25. The apparatus as claimed in any one of claims 14 to 22, further comprising:each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart cylindrical elements adjacent to, and supported by, the inner layer.

26. A method of providing a subsea anchor for securing a floating platform at a desired relative position with respect to a subsea seafloor surface, comprising the steps of:15 11 24providing an anchor body member, comprising a base and at least one connection element for a mooring line and a plurality of sheath elements, at a subsea location;lowering the anchor body member towards a subsea seafloor surface thereby locating a respective one protruding free end region, provided as a fixation support according to the method of any one of claims 1 to 13, of a friction pile member, of a plurality of friction pile members disposed in a predetermined pattern at the subsea seafloor surface, in a respective sheath element, each friction pile member comprising an elongate friction pile member wall comprising an inner layer and at least one drilled surface-engaging element disposed at a radially outer surface of the inner layer; andfor each sheath element and respective friction pile member, securing the sheath element to the friction pile member, thereby securing the anchor body member at a desired relative position with respect to the subsea seafloor surface.

27. The method as claimed in claim 26, further comprising:securing each sheath element to said respective friction pile member by engaging at least one pile engaging element with at least a region of an upper end region of a free end region of said respective friction pile member, whereby each pile engaging element is a recess or protruding element that cooperates with a mating protuberance or recessed region at a free end region of said respective friction pile member.

28. The method as claimed in claim 27, further comprising:tightening at least one securing strap around a slit region of an end region of at least one sheath element and thereby crimping and forcing radially inwards spaced apart fingers of the sheath element in the slit region.

29. The method as claimed in claim 26, further comprising:subsequent to locating said respective free end region in a respective sheath element, radially expanding at least a region of at least an inner layer of an elongate body wall of said respective friction pile member thereby urging a corresponding region of at least one drilled surface-engaging element at a radially outer surface of the inner layer of the elongate body wall against a drilled surface associated with a drilled bore at the subsea seafloor surface, thereby providing a friction fit between the drilled surface and at least a region of an outer surface of a covered portion of said respective friction pile member that is in the drilled bore.

30. The method as claimed in claim 26, further comprising:prior to lowering the anchor body member, radially expanding at least a region of at least an inner layer of an elongate body wall of said respective friction pile member thereby urging a corresponding region of at least one drilled surface-engaging element at a radially outer surface of the inner layer of the elongate body wall against a drilled surface associated with a drilled bore at the subsea seafloor surface, thereby providing a friction fit between the drilled surface and at least a region of an outer surface of a covered portion of said respective friction pile member that is in the drilled bore.

31. The method as claimed in claim 29 or claim 30, whereby the at least one drilled surfaceengaging element comprises an outer layer that is coaxial with and circumferentially extends around the inner layer, and urging the corresponding region comprises urging the outer layer against the drilled surface.

32. The method as claimed in claim 30 or claim 31, whereby each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart arcuate protrusions that extend radially outwards from the inner layer, and urging the corresponding region comprises urging an outer surface of each arcuate protrusion against the drilled surface.

33. The method as claimed in claim 29 or claim 30, whereby each drilled surface-engaging element comprises a one of a plurality of circumferentially spaced apart cylindrical elements adjacent to, and supported by, the inner layer, and urging the corresponding region comprises urging an outer surface of each cylindrical element against the drilled surface.

34. The method as claimed in any one of claims 29 to 33, whereby radially expanding said at least a region of at least the inner layer further comprises urging a corresponding region of drilled surface-engaging elements placed intermittently along a longitudinal axis of said respective friction pile member against the drilled surface.

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