Anchoring Device and Method

Abstract

An anchoring device and method of securing an anchoring device to strata are disclosed. The anchoring device (1) includes a drilling rod (2) and an anchoring sleeve (3) at least partially surrounding the drilling rod (2), the drilling rod (2) comprising a driving end (31) for coupling to a drilling apparatus and a drilling end (32) with a drilling head (26) for drilling a hole in strata, wherein the device is configured to be coupled with and driven by a drilling apparatus to cause the drilling head (26) to drill a hole into strata and to force, as the hole is drilled, the anchoring sleeve (3) into the hole to an inserted position in which the anchoring sleeve (3) engages the surrounding strata.

Claims

1. An anchoring device for securement to strata, the device comprising a drilling rod and an anchoring sleeve at least partially surrounding the drilling rod, the drilling rod comprising a driving end for coupling to a drilling apparatus and a drilling end with a drilling head for drilling a hole in strata, wherein the device is configured to be coupled with and driven by a drilling apparatus to cause the drilling head to drill a hole into strata and to force, as the hole is drilled, the anchoring sleeve into the hole to an inserted position in which the anchoring sleeve engages the surrounding strata.

2. Anchoring device according to claim 1 comprising a resilient biasing means configured to bias the anchoring sleeve into engagement with surrounding strata when it is in the inserted position.

3. Anchoring device according to claim 1, wherein the drilling head is configured to drill a hole that is smaller than the outer dimension of the anchoring sleeve such that the anchoring sleeve is in interference fit with the hole.

4. Anchoring device according to claim 3, wherein the anchoring sleeve is formed of a material that is elastically deformable so as to bias, in use, resiliently the anchoring sleeve against the surrounding strata.

5. Anchoring device according to claim 1, wherein the anchoring sleeve comprises gripping means on its outer surface for engaging the surrounding strata.

6. Anchoring device according to claim 5, wherein the gripping means comprises a plurality of barbs.

7. Anchoring device according to claim 1, wherein the anchoring sleeve comprises a longitudinal slot along at least a portion of its length.

8. Anchoring device according to claim 1, wherein the anchoring sleeve comprises one or more stress relief features for reducing, in use, the peak stress experienced by the anchoring sleeve.

9. Anchoring device according to claim 8, wherein the or each stress relief feature comprises a longitudinal groove extending along at least a portion of the length of the anchoring sleeve.

10. Anchoring device according to claim 1, wherein the anchoring sleeve comprises a driving surface against which a driving collar of the drilling apparatus engages, in use, to force the anchoring sleeve into the hole.

11. Anchoring device according to claim 1, wherein the anchoring sleeve comprises a flange adjacent the driving end of the drilling rod.

12. Anchoring device according to claim 11 further comprising a resilient element at least partially surrounding the anchoring sleeve and configured to be compressed, in use, between the flange and the strata when the anchoring sleeve is in the inserted position, thereby to urge the anchoring sleeve along a direction that is opposite to the drilling direction.

13. Anchoring device according to claim 12, wherein the resilient element comprises a resilient washer.

14. Anchoring device according to claim 1, wherein the drilling head is larger than the internal dimension of the sleeve.

15. Anchoring device according to claim 1, wherein the drilling rod comprises a helical flute extending between the drilling head and the driving end.

16. An anchoring system comprising a drilling apparatus and one or more anchoring devices according to claim 1, wherein the drilling apparatus comprises a chuck for coupling with the drilling end of the drilling rod and a driving collar for engaging a driving surface or flange of the anchoring sleeve to force, in use, the anchoring sleeve into the hole as the hole is drilled.

17. A kit of parts for assembly into an anchoring device, the kit comprising an anchoring sleeve and a drilling rod for insertion into the anchoring sleeve such that the anchoring sleeve at least partially surrounds the drilling rod, the drilling rod comprising a driving end for coupling to a drilling apparatus and a drilling end with a drilling head for drilling a hole in strata, wherein the device, when assembled, is configured to be coupled with and driven by a drilling apparatus to cause the drilling head to drill a hole into strata and to force, as the hole is drilled, the anchoring sleeve into the hole to an inserted position in which the anchoring sleeve engages the surrounding strata.

18. A method of securing an anchoring device to strata, the method comprising coupling a drilling apparatus to the drilling end of a drilling rod, driving the drilling end of the drilling rod to cause a drilling head thereof to drill a hole into strata and, as the hole is drilled, forcing an anchoring sleeve that at least partially surrounds the drilling rod into the hole to an inserted position in which the anchoring sleeve engages the surrounding strata.

19. Method according to claim 18, wherein the anchoring sleeve is urged into engagement with the surrounding strata by a resilient biasing means when the anchoring sleeve is in the inserted position.

20. Method according to claim 18, wherein the hole that is drilled is smaller than the outer dimension of the anchoring sleeve such that the anchoring sleeve is forced into an interference fit with the hole.

21. Method according to claim 20, wherein the anchoring sleeve is formed of a material that is elastically deformable so as to bias resiliently the anchoring sleeve against the surrounding strata.

22. Method according to claim 18, wherein the anchoring sleeve comprises gripping means on its the outer surface that is urged into engagement with the surrounding strata when the anchoring sleeve is in the inserted position.

23. Method according to claim 18, wherein the anchoring sleeve is forced into the hole by a collar of the drilling apparatus that engages a driving surface of the anchoring sleeve.

24. Method according to claim 23, wherein a flange of the anchoring sleeve that is adjacent the driving end of the drilling rod is engaged by the collar to force the anchoring sleeve into the hole.

25. Method according to claim 24, wherein a resilient element that at least partially surrounds the anchoring sleeve is compressed between the flange and the strata as the anchoring sleeve is forced into the inserted position.

26. Method according to claim 25 comprising retracting the collar of the drilling apparatus out of engagement with the flange after the anchoring sleeve is forced into the inserted position such that the resilient element urges the anchoring sleeve along a direction that is opposite to the drilling direction.

27. Method according to claim 18 comprising releasing the drilling rod after the hole is drilled such that the rod remains in the hole.

28. (canceled)

29. (canceled)

30. (canceled)

Description

BRIEF SUMMARY OF THE DRAWINGS

[0033] Embodiments will now be described by way of example only with reference to the accompanying drawings in which:

[0034] FIG. 1 is a sectional isometric section view of an anchoring device according to a first embodiment installed at a site of use;

[0035] FIG. 2 is a longitudinal section view of the anchoring device of FIG. 1;

[0036] FIG. 3 is a section view of the anchoring device of FIG. 1 taken through line A-A of FIG. 1;

[0037] FIG. 4 is an enlarged view of the anchoring device of FIG. 1 during installation at a site of use;

[0038] FIG. 5 is a schematic representation of part of an anchoring system including a drilling apparatus and an anchoring device; and

[0039] FIG. 6 is an isometric view of an axially toothed system.

DETAILED DESCRIPTION

[0040] Referring now to FIG. 1, there is shown an anchoring device or anchor 1 according to one embodiment engaging a bearing plate BP on a substrate S. The anchoring device 1 includes a drill rod 2, an anchor sleeve 3 and a washer (resilient element) 4. The anchoring device 1 is shown installed in a subsea seabed substrate S composed of stratified rock to provide a location for a tether (not shown) for restraining subsea pipelines. In some embodiments, the anchoring device 1 may find other alternative uses, for example to maintain the integrity of a rock wall.

[0041] Referring now to FIGS. 1 to 3, the drill rod 2 is an elongate member formed from steel, most preferably super duplex steel, and having a first, driving end 20 and a second, drilling end 21 connected by a shaft 22. The outer surface 23 of the shaft 22 includes a continuous helical groove 24, for the transport of spoil, and extends from the drilling end 21 to the driving end 20. The driving end 20 includes a connection pin 25 configured for releasable connection with a drilling apparatus (10 in FIG. 5). The drilling end 21 includes a drilling head 26 with cutting edges 27, where the drilling head 26 has an external dimension d.sub.1. The anchor sleeve 3 is also formed from steel, most preferably super duplex steel, and has a cylindrical hollow body 30 with a distal end 31 and a proximal end 32. The body 30 is split longitudinally in such a way that it has a segment shaped discontinuity or slot 33 in plan view. In this way the anchor sleeve 3 may be partially compressed diametrically by the application of an external force, but, upon release of that external force, will resiliently return to its original shape due to the inherent resilience of the super duplex steel.

[0042] An integral flange 34 projects outwardly from the distal end 31 of the body 30, the flange 34 having an upper, engaging face 35 and a lower, pressing face 36.

[0043] At the proximal end 32 the outer surface of the hollow body 30 includes a taper 37. The inner diameter d.sub.2 of the hollow body 30 is configured to be slightly less than the external dimension d.sub.1 of the drilling head 26.

[0044] A plurality of barbs 38 are included on the outer surface of the hollow body 30 and oriented towards the proximal end 32 thereof. Plural stress relieving channels 39 extend longitudinally into the outer surface of the hollow body 30, regularly spaced circumferentially. The stress relieving channels 39 allow a change in diameter of the anchor sleeve and therefore affects the radial loading it is subjected to.

[0045] A spring, preload or waved washer 4 is provided adjacent the flange 34 of the anchor sleeve 3. The washer 4 is of polyurethane in this example (but could be other suitable materials, or could be a Belville type sprung washer). The washer may extend further outwards radially than the flange 34. The washer 4 is provided at the lower face 36 (i.e. facing the body 30).

[0046] Referring now to FIGS. 4 and 5, there is shown an anchoring device 1 being installed in a substrate using an drilling apparatus 10 which includes a motor 11, a connector or chuck 12, an engagement collar 13 and an armature 14.

[0047] The motor 11, which is of a standard type suitable for subsea use, depends from a lower surface of the armature 14. The connection pin 25 of the anchoring device 1 is connected to the motor 11 via the connector 12. The engagement collar 13 includes an aperture 13a configured to encompass, in a non-contact fashion, the shaft 22 of the drill rod 2 which may therefore pass freely through the aperture 13a. The engagement collar 13 has a substantially flat lower surface 13b suitable for engagement with the engagement surface 35 of the flange 34 of the anchor sleeve 3. A bracket 15 rigidly fixes the engagement collar 13 to the armature 14.

[0048] In use, a substantially flat steel bearing plate BP, including a circular aperture (not shown) through its thickness, is affixed on a substrate S at an intended site of use. The diameter of the aperture is configured to allow free passage therethrough of the body 30 of the anchor sleeve 3 but to abut the outwardly projecting flange 34 thereof. A spring, preload or waved washer 4 is located around the aperture of the bearing plate BP, in this case a spring washer 4.

[0049] The drilling apparatus 10 is positioned at the intended site of use, such that the drill head 26 of the anchoring device 1 is aligned with the aperture of the bearing plate BP and the spring washer 4. The armature 14, of which only a portion is shown in FIG. 5, is driven downwards along the length of the anchoring device 1 in the direction of arrow B. The armature 14 may be driven by any suitable means, for example pneumatic or hydraulic actuation (neither of which is shown).

[0050] The motor 11 is then activated thereby causing the anchoring device 1 to rotate. The cutting surfaces 27 of the drill head 26 cut into the substrate S upon engagement therewith, thereby drilling a hole thereinto. As the anchoring device 1 is pushed into the thus formed hole, spoil from the drilled substrate S is transported from the hole along the helical groove 24 on the outside of the shaft 22.

[0051] Simultaneously, the lower surface 13b of the engagement collar 13 engages the engaging face 35 of the anchor sleeve 3, pushing it into the hole in the substrate S, in concert with the drill rod 2. The drilling head 26 drills a hole having a diameter which is less than the outer diameter of the anchor sleeve 3. The taper 37 at the distal end 32 of the anchor sleeve 3 engages the drilled hole first. The anchor sleeve 3 is compressed diametrically during its insertion into the drilled hole, as a consequence of the difference in diameter of the drilled hole and the outer surface of the anchor sleeve 3. Due to the diametric compression of the anchor sleeve 3 the outer surface thereof is radially biased against the inner wall of the drilled hole, providing a frictional gripping force thereagainst.

[0052] The drill rod 2 is drilled into the substrate S until the pressing face 36 of the flange 34 of the anchor sleeve 3 engages the spring washer 4, compressing it against the bearing plate BP. The downward force applied to the drilling apparatus 10 is subsequently removed and the motor 11 disconnected from the connection pin 25 of the drilling rod 2. Thus released from the drilling apparatus 10, the spring washer 4 resiliently urges the flange 34 of the anchor sleeve 3 away from the bearing plate BP. The anchor sleeve 3 is therefore urged back along the path of its previous travel, whereby the anchor sleeve 3 is secured in place.

[0053] The anchor sleeve 3 is secured in place either through friction between the outer surface of the anchoring sleeve and the inner wall of the drilled hole or through gripping means, e.g. barbs 38 on the outer surface of the anchor sleeve 3, which are forced into the inner wall of the drilled hole as the anchor sleeve 3 is urged back along the path of its previous travel. The drilling head 26 of the drill rod 2 has a greater external dimension d.sub.1 than the internal diameter d.sub.2 of the anchor sleeve 3, as described above, and therefore the drill rod 2 is retained by the anchor sleeve 3 within the drilled hole.

[0054] Aptly, to allow the drill rod to unlatch, the drill rod is not captive to the drill. The apparatus may include an axially toothed system so as to allow compressive loads to be transmitted to the drill rod during drilling, but not allowing tensile loads. For example, such system may be part of the connector or chuck 12. Alternatively the system may be a separate component between the drill rod and the connector. An example is shown in FIG. 6 in which two portions 40a and 40b are mateable by axial teeth. In this way the drill rod is detacheable from the drill apparatus. The diameter of the portions 40a and 40b may be larger than the internal diameter of the anchor sleeve to provide a means of retaining the drill rod if required, for example from falling through the anchor sleeve.

[0055] The resilience of the spring washer 4 (or other resilient element) in urging the anchor sleeve back along the path of its previous travel, pre-tensions the anchor sleeve. This allows the capacity of the anchoring device (for securement of the anchoring sleeve 3 within the strata) to be tested prior to removal of the drilling apparatus.

[0056] As with standard bolting practice, the length of the drill rod is dependent upon the load. The sleeve would not normally be taken beyond the yield point of the materials (e.g. for steels this would be about 2% strain).

[0057] Suitably configured attachments (not shown) may then be attached to the driving end 20 of the drill rod 2 in order to effect tethering of subsea pipelines and other subsea articles.

[0058] The drill rod 2 remains within the drilled hole as part of the anchoring device 1 and is not therefore useable in order to drill further holes in the or another substrate S. Therefore, a new drill bit 2 is required for the drilling of each anchoring device 1 according to the invention, resulting in an increase in the expense of drill materials. However, the method of installation of the invention, in contrast to known methods of subsea anchoring installation, may be achieved by a fully automatic remotely operated drilling apparatus 10. Advantageously, this automatic anchoring or installation system allows installation of anchoring devices 1 at subsea locations and depths at which divers may not operate, and therefore may not be installed via known methods of installation. Furthermore, the method of installation of the invention requires fewer stages than known methods of installation, leading to savings in installation time and consequent expenditure savings.

[0059] It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. For example, the anchoring device 1 may be installed at locations above the sea and/or in alternative substrates S for example in unstratified rock. Although the spring washer 4 is shown disposed between the flange 34 and the bearing plate BP it need not be and may be located at any position suitable for urging the anchor sleeve 3 outwardly from the drilled hole, for example between the drilling head 26 and the distal end 32 of the anchor sleeve 3. Additionally or alternatively, the spring washer 4 may be replaced by or supplemented with a spring or other resilient member. Although the anchoring device 1 is shown installed against a bearing plate BP on a substrate S it need not be and may instead be installed directly against the substrate S. Additionally or alternatively, although the engagement collar 13 is shown as being fixed to the armature 14 it need not be and may instead be fixed to the motor 11 or a further component of the drilling apparatus 10 by any suitable means.

[0060] It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.

[0061] With the above arrangement, the unit including the drilling rod and anchoring sleeve are drilled into and remain in the drilled hole. The unit remains as a unitary piece.

[0062] With this arrangement, an anchoring device is provided with a greater strength compared to known arrangements, e.g. allowing a flexible pipe to be tethered to the seabed.

[0063] 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.

[0064] Features, integers, characteristics, compounds, chemical moieties 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 such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any 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.

[0065] 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.