AU2009201919A1 - Rock anchors - Google Patents

Description

P00/o1 Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Invention Title: ROCK ANCHORS The following statement is a full description of this invention, including the best method of performing it known to me: 2 Rock anchors The invention relates to a rock anchor assembly for anchoring in solid ground in marine and fresh water conditions and to a method of installation. The invention is directed particularly but not solely towards a screw anchor for the marine environment. 5 Background of Invention Anchors have been used for years to secure any movable object in the marine and freshwater environments. In general uses for anchors have been either for mooring boats or aquaculture 10 farming which must be able to withstand extreme weather conditions and tidal movement. For most situations the user merely has to drop their anchor and adequate gripping is achieved. However this is reliant on the founding being gained by a wedging effect into soft-like conditions like sand, mud or overlying sediment/overburden/rubble/debris. 15 Screw anchors have been developed for this sort of soft overburden layer whereby founding is achieved by manual or power driving comprising a shaft with a spiral blade at the end opposite to the driving end. However for solid founding one has to either drill into place by diving or by simply not drilling and dropping a big enough weight-like a concrete block 20 In this specification unless the contrary is expressly stated, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge; or known to be 25 relevant to an attempt to solve any problem with which this specification is concerned. Object of the Invention It is an object of the invention to provide an improved rock anchor assembly and method of 30 installation that ameliorates some of the disadvantages and limitations of the known art or at least provide the public with a useful choice.

3 Summary of Invention In a first aspect the invention resides in a rock anchor assembly for drilling a hole and forming a mooring in overburden over solid rock underwater in saltwater or freshwater comprising an inner tubing having an outer thread, an outer sleeve which surrounds the inner 5 tubing, swivel eye assembly and cementitious matter, the inner tubing has a driving end and a drilling end, drilling means is provided at the drilling end and the outer sleeve is located and joined at the driving end of the inner tubing, the swivel eye assembly is attached to the outer sleeve at the driving end and provide attachment for a warp for mooring to keep the mooring above the seabed or lakebed and the cementitious material surrounds the inner 10 tubing of the drilled hole. Preferably, the cementitious material is grout. Preferably, the outer sleeve is attached to the inner tubing to allow drilling flushing fluid therebetween. 15 Preferably the drilling means is a sacrificial drill bit. Preferably the flushing fluid can be water. Preferably, the swivel eye assembly is bolted to the outer sleeve. Preferably, the minimum length of the outer sleeve into the rock is 300mm. Preferably, the outer sleeve has a length commensurate with the depth of overburden. 20 Preferably, the inner tubing has an outer thread and a minimum length protruding above the outer sleeve to allow a drilling machine to rotate it. Preferably the outer sleeve can have a minimum length of 200mm above the overburden. Preferably, the outer sleeve has a minimum length of 500mm for no overburden. Preferably, the inner tubing has length determined by strength calculations in relation to 25 holding power, rock strength, depth of hole and hole circumference. Preferably a domed nut is threaded on to the top of inner tubing to abut the top of the outer sleeve. Preferably, the outer sleeve is sch 80 65nb pipe and inner tubing can be R5 1. Preferably, the swivel assembly includes a swivel eye with an outer groove and warp, 30 wherein the outer groove is attachably fixed to the outer tubing and the swivel eye is slidably attached to the groove and the warp is attached to the apertures in the swivel eye.

4 In a second aspect the invention resides in a method of installing a rock anchor assembly as disclosed above by including the following steps of: - cutting inner tubing and outer sleeve to suit geology and tack welding the tubing and outer sleeve in place: 5 -attaching a self drilling end to drilling end of inner tubing; -drilling hole using percussion drill attached to top end of the inner tubing 10, firstly through the overburden : -continue with drilling through the rock to correct total depth giving minimum length of outer sleeve 15 above overburden 8 and at least so much within the solid portion-rock 9; 10 -replace flushing water with grout and pump down grout until drilled hole and inner tubing 10 are filled; -unscrew drill and disconnect from the inner tubing 10 of the rock anchor; -swivel support 21 a is then attached which is bolted to the outer sleeve 15; -large domed capping nut is then threaded on inner tubing 10 and tightened down on the 15 outer sleeve 15; -anchor assembly is then left to allow the grout to set before -attaching a warp or chain 23 to the swivel eye. Brief Description 20 The invention will now be described, by way of example only, by reference to the accompanying drawings: Figure 1 is a schematic cross sectional side view of the rock anchor assembly in accordance with a first preferred embodiment of the invention. 25 Figure 2 is a close up schematic view of the rock anchor assembly at the surface Description of Drawings The following description will describe the invention in relation to preferred embodiments of 30 the invention, namely a rock anchor assembly and method of installation. The invention is in no way limited to these preferred embodiments as they are purely to exemplify the invention only and that possible variations and modifications would be readily apparent without departing from the scope of the invention.

5 Figure 1 shows the rock anchor assembly 1 in use in a solid rock formation. Rock anchor assembly 2 includes an upper end 3 and lower end 4 whereby the lower end being distal to the user is the founding end and proximal end to the user is the driving end. The anchor is 5 constructed and adapted to be installed at a depth below the ocean floor/seabed/lake bed/river bed surface 5 at a depth 6 below that surface 6 whereby a set distance 7 of the anchor assembly is allowed to be left exposed or protrudes above the seafloor surface 6. Typically the ground will comprise a softer layer like for example overburden 8 lying over a solid layer 9 like rock for example though the assembly is also adapted to provide founding 10 when there is no softer overburden. The set distance 7 can be for example 3m which includes the depth within the overburden 8 and rock 9 and an exposed portion above the overburden 8. Rock anchor assembly 1 comprises a seamless steel inner sleeve or tube 10 which can be 15 cold rolled to form an outer/exterior threaded surface 11. Inner tubing 10 can be R5 1 for example which is available from a number of sources. The length of inner tubing 10 is determined by the type of rock being founded within. Please note that various terms are used to describe the inner and outer tubing which can also 20 be described as sleeves, pipes or tubing. The inner tubing can be cold formed. A sacrificial drilling means 12 comprising a drilling bit end is located and operatively joined to the lower end 4 such that any overburden 8 and solid formation like rock 9 can be drilled to a set depth as required to form a drilled hole 13 having a diameter larger than the diameter 25 of the outer tubing 15 - there being a space 14 between the inner tubing and the hole. Outer tubing 15 needs have least 200mm exposed and at least 300mmm is embedded in the solid substrate. The cold formed inner tubing 10 is of a length to give the required holding power given the hole sized with grout strength and rock strength characteristics - pulling strength and friction. As shown for example in figures 1-2, inner tubing 10 can be exposed by 30 300mm labelled "E". At the upper end 3 of the inner tubing 10, a outer sleeve 15 surrounds the inner tubing 10 according to the depth of overburden whereby the inner tubing 10 is affixed by fixing means 6 16 (see figure 2) to the outer sleeve 15 when the inner tubing 10 has been properly installed. The outer sleeve 15 functions to strengthen the anchor against bending moment and provide a suitable attachment point for the swivel eye assembly. 5 There is an annular space 17 between the inner tubing 10 and outer sleeve 15 so that there is minimally enough gap to allow an annular flow of flushing fluid for drilling and subsequent grouting. Fixing means 16 can be by tack welding or bolting for example but is such that the annual space 17 between the inner tube 10 and outer sleeve 15 is not closed. Outer sleeve 15 can be for example as shown in the figures 'sch 80 65nb pipe'- or any other heavy walled 10 steel pipe of similar specifications. Swivel eye assembly 20 is constructed and adapted to keep the mooring above the seabed/lakebed and comprises a swivel eye plate 21 and swivel support 21 a. The swivel eye plate 21 includes at least one aperture to slidably interfit with the swivel support 21 a. This 15 allows the swivel plate 21 to horizontally rotate as required in use. The support 21 a comprises a tubular section with an outer groove 22 and means 21b to allowing fixing to the outer sleeve tubing 15. The support 21a can include other shapes other than a tube but should have the groove 22 and allowance for attaching to the outer tubing 15. Swivel plate 21 has a one aperture 21c sized to fit and allow some sliding movement in the groove 22. 20 Swivel plate 21 also has means 21 d to allow a rope/wrap to be removably attached such as for example another aperture, slot or hole or may even be clamped to swivel plate 21. Also shown is inner tube fixing means 25 which is in the form of a large domed nut such as for example R51 having a threaded inner portion 26 which is adapted to intermesh with the 25 outer thread of inner tubing 10 and a stepped out surface 27. In use nut 25 is threaded downwardly onto the protruding portion of the inner tubing 10 to abut on a protruding end surface of the outer sleeve 15 to effectively transfer the holding power of the inner tubing 10 to the outer sleeve 15. The domed nut 25 functions to transfer the load from the inner tubing and outer sleeve 15 and vice versa as the join between the inner tubing and outer sleeve is 30 normally only able to be done in a temporary fashion ie by tack welding. This tack welding can be carried out anywhere including on site or in a factory etc and can be made more permanent if required whereby in one option, the domed nut 25 might not be needed.

7 Minimally there needs to be a gap there between the outer sleeve 15 and inner tubing 10 to allow for the flushing out of drilled debris. The pipes 10 and 15 are initially cut to length according to the geology requirements and 5 strength calculations though no problem is pipes in sleeves and/or tubing are too long. In the factory or on site both pipes are joined by tack welding or by any other suitable means. After the hole 13 has been drilled and before removing the drill machine, replacing the flushing water or air (used during drilling) with cementitious material 29 which can be grout for example and/or have reinforcing if necessary, pumped into the space 17 between the 10 hole and inner sleeve or tubing 10 until it is filled or overflows at the top. The drilling machine or driving means is then removed to allow the swivel eye assembly is then attached and secured in position not the outer sleeve 15. Finally the domed nut 25 is threadingly attached to the top of the protruding portion of inner sleeve 10. The whole assembly must then be left to allow the cementitious material to set before then attaching the warp or chain 15 23 that forms the mooring. Key: Outer sleeve 15 - for example can be sch 80 65nb pipe or similar special heavy walled tubing. 20 Inner tubing 10-for example can be R51 The length of inner tubing 10 is determined from the geology or rock properties and strength calculations such as the required holding power being equal to the depth of hole times the circumference times the rock strength. The weaker the rock the deeper one has to drill the 25 hole and so the longer the inner tubing 10. Any minimums are determined by how much holding power you require and so can be varied. The bigger the inner tubing 10 that is used, the larger the hole that is drilled so the larger the drilling machine required. In practice size of the drilling machine in practice limits the hole size and length of hole. 30 The length of outer sleeve 15 and/or tubing 10 is determined by the depth of overburden but if the sleeve or tubing is also too long this is not a problem. The outer sleeve 15- (sch 80 65nb) is cut to suit so that there is say 200mm above the overburden(sand) 8 and a minimum 8 of 300mm into the rock plus the depth of overburden of 500mm which gives a total minimum length of outer sleeve 15 of approximately meter labelled as "EM". With no overburden we can have a minimum 500mm for outer sleeve 15 (sch 80) but must 5 allow enough inner tubing 10 (R51 pipe) above the outer sleeve 15 (sch 80) so that the drill can operate. The drilling means is provided by a rotary percussion drill which attaches to the protruding inner tubing 10 at the top as in use. A method of installing the anchor assembly 1 includes the following steps of: 10 - analyse founding geology to determine approximate total anchor length required and type of drill bit; - cut inner tubing 10 and outer sleeve 15 to length to suit geology and tack weld them together in the factory; -provide inner tubing 10 of certain depth having a self drilling end attached; 15 -drill hole with flushing water or air using percussion drill attached to one end of inner tubing 10, firstly through the overburden 8; -continue with drilling through the rock 9 with flushing water or air to correct total depth giving a minimum outer sleeve length of 200mm above overburden and at least 300mm within the solid portion-rock 9; 20 -replace flushing water with grout and pump down until drilled hole and inner tubing10 are filled; - unscrew the drilling machine and disconnect from the top of the inner tubing 10 - alternatively detach drill by unclamping 10 and reversing drill rotation; -swivel eye plate 21a is then attached which is bolted to the outer sleeve 15; 25 -large domed nut 25 is then threaded on inner tubing 10 until it tightens on the top of outer sleeve 15; -anchor assembly is the left to allow the grout to set; -attaching warp or chain 23 to swivel eye 21. 30 This invention may also broadly be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of the parts, elements or features, and where specific 9 integers are mentioned herein which have known equivalents such equivalents are deemed to be incorporated herein as if individually set forth. Advantages a) Simple installation 5 b) longevity and able to withstand both extreme weather events c) Modest cost to manufacture d) Able to provide founding in solid ground conditions even with overburden e) Little or no diving is required to install such an anchor 10 Variations Throughout the description of this specification, the word "comprise" and variations of that word such as "comprising" and "comprises", are not intended to exclude other additives, components, integers or steps. Though terms like rock or overburden are used it is envisaged 15 that other forms of geology will also be included that functions and physically are similar. Drilling bit 12 can also be fitted either removably or permanently to the end of the inner tubing 10 and the inner tubing 10 can be seamless and coated for added long life in the marine environment. 20 It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is hereinbefore described. 25 To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and application of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be 30 limiting.

Claims (13)

1. A rock anchor assembly for drilling a hole and forming a mooring in a seabed or lakebed which includes overburden over solid rock underwater in saltwater of freshwater, the assembly comprising an inner tubing having an outer thread, an outer sleeve which surrounds 5 the inner tubing, swivel assembly and cementitious matter, the inner tubing has a driving end and a drilling end, drilling means is provided at the drilling end and the outer sleeve is located and joined at the driving end of the inner tubing, the swivel eye assembly is attached to the outer sleeve at the driving end and provides attachment for a warp for mooring to keep the mooring off the seabed or lakebed and the cementitious material surrounds the inner 10 tubing of the drilled hole.

2. A rock anchor assembly as claimed in claim 1 wherein the outer sleeve is attached to the inner tubing to allow drilling flushing fluid therebetween. 15

3. A rock anchor assembly as claimed in claim 2 wherein the minimum length of the outer sleeve into the rock is 300mm.

4. A rock anchor assembly as claimed in claim 3 wherein, the outer sleeve has a length commensurate with the depth of overburden. 20

5. A rock anchor assembly as claimed in claim 4 wherein the inner tubing has an outer thread and a minimum length protruding above the outer sleeve to allow a drilling machine to rotate it. 25

6. A rock anchor assembly as claimed in claim 5 wherein the outer sleeve can have a minimum length of 200mm above the overburden.

7. A rock anchor assembly as claimed in claim 6 wherein, the outer sleeve has a minimum length of 500mm for no overburden. 30 11

8. A rock anchor assembly as claimed in claim 7 wherein, the inner tubing has length determined by strength calculations in relation to holding power, rock strength, depth of hole and hole circumference. 5

9. A rock anchor assembly as claimed in claim 8 wherein a domed nut is threaded on to the top of inner tubing to abut the top of the outer sleeve.

10. A rock anchor assembly as claimed in claim 9 wherein, the swivel eye assembly includes a swivel eye plate and swivel eye support with an outer groove and warp, wherein 10 the outer groove is attachably fixed to the outer tubing and the swivel eye is slidably attached to the groove and the warp is attached to the aperture in the swivel eye.

11. A method of installing a rock anchor assembly as disclosed above by including the following steps of: 15 - cutting inner tubing and outer sleeve to suit geology and tack welding the tubing and outer sleeve in place: -attaching a self drilling end to drilling end of inner tubing; -drilling hole using percussion drill attached to top end of the inner tubing, firstly through the overburden : 20 -continue with drilling through the rock to correct total depth giving minimum length of outer sleeve above overburden and at least so much within the solid portion-rock; -replace flushing water with grout and pump down grout until drilled hole and tubing are filled; -unscrew drill and disconnect from the inner tubing of the rock anchor; 25 -swivel eye assembly is then attached which is bolted to the outer sleeve; -large domed capping nut is then threaded on inner tubing 10 and tightened down on the outer sleeve; -anchor assembly is then left to allow the grout to set before; and -attaching a warp or chain to the swivel eye. 30

12. A rock anchor assembly substantially as herein defined with reference to the accompanying drawings. 12

13. A method of installing a rock anchor assembly substantially as herein defined with reference to the accompanying drawings. 5 Attorneys for the Applicant 1) FIELDER, Graham Clyde 2) ROGERSON, Rebecca