Hydraulic Down-the-Hole Hammers and Subsea Piling

Abstract

The present invention relates to a hydraulic down-the-hole hammer. The hammer comprises an elongated shaft and a piston having a central bore therethrough. The piston is slidably mounted for reciprocating movement on the shaft and arranged to impact with a percussion bit. Forward and rear drive chambers for the piston are provided between the piston and the shaft, and the forward chamber is separated from the rear chamber by an annular shoulder formed inside the piston bore. The hammer also comprises a control valve for controlling the reciprocating movement of the piston. The control valve is disposed within the central bore of the piston. The hammer may be a disposable hydraulic hammer in which the piston is the outermost part of the hammer. The present invention also relates to methods and systems for installing load-bearing members on a seabed, and methods and systems for installing subsea anchors on a seabed, installing subsea piles and installing subsea anchors.

Description

[Technical field]

[0001] The present invention relates to a fluid operated hydraulic down-the-hole hammer, and more particularly to a disposable or single use hydraulic down-the-hole hammer. The present invention also relates to a method and system for installing submarine piles, and load bearing members and submarine anchors on the seabed. [Background technology]

[0002] Hydraulically powered down-the-hole hammers generally comprise three main components: an impacting piston at the front end of the hammer which applies percussion energy to the drill bit or device; a shuttle or control valve which controls hydraulic fluid flow within the hammer to apply pressure to the face of the impacting piston, thereby generating a cyclic force which causes the piston to reciprocate; and one or more accumulators which receive, store and supply hydraulic fluid with counter pressure to accommodate the changing instantaneous flow requirements generated by the reciprocating piston.

[0003] A prior art hydraulic down-the-hole hammer 100 is shown in FIG. 1. In such conventional hammers, a piston 101 is typically solid and reciprocates within an outer cylinder to impact a bit 109 with the front end of the hammer. Piston drive chambers 102, 103 are located between the piston and the outer cylinder 104, and a control valve 105 and accumulator 106 are provided at the rear end 107 of the piston. Working fluid is supplied to the hammer via pressure line P and returned via return line T. A separate flow of flushing fluid 108 is provided to flush cuttings from the hole. Due to the position of the control valve, the distance d between the control valve and the drive chamber is valve Since the accumulator 106 is typically located upstream of the valve, the distance d between the accumulator and the actuation chamber is relatively long. accuThe length of the flow channel between the piston, valve and accumulator is much longer. The long flow channel between the piston, valve and accumulator can generate pressure waves that can be harmful to the hammer member. The long flow channel also causes pressure losses. The distance between the piston and the accumulator causes a significant delay in the exchange between the piston and the accumulator, so the accumulator does not operate efficiently.

[0004] In a typical water-driven hydraulic hammer, the setup is similar to the hammer shown in FIG. 1 and outlined above. However, in the water-driven hammer 200 shown in FIG. 2, there is no return line T. Instead, the driving fluid is used for the flushing flow 208. Furthermore, the piston 201 is fully submerged in water, and only a small portion of the piston's cross-sectional area is used to drive the piston. The remaining cross-sectional area is exposed to the water at atmospheric pressure and does nothing. This means that the non-driving area of ​​the piston needs to displace a large amount of water during the operation of the hammer. This is achieved by having a central hole 210 through the piston such that the front end 211 and the rear end 207 of the piston are in fluid communication with each other. The hole must be large enough to avoid significant pressure losses that would adversely affect the hammer. Pressure losses can also be reduced by minimizing the non-driving area of ​​the piston. By increasing the size of the central hole and decreasing the non-driving area of ​​the piston, the cross-sectional area of ​​the piston becomes very small. This tends to be too light for effective drilling. This is solved by increasing the length of the piston to provide sufficient weight, but this causes problems that are exacerbated by the position of the valve relative to the rear of the piston at such a length that the hammer becomes impractical. Existing water hammers are also expensive to manufacture due to their complex design.

[0005] It would be desirable to provide a hydraulic down-the-hole hammer which overcomes some of the disadvantages associated with existing devices.

[0006] Subsea piles may be used to anchor structures used to tie offshore structures, such as wind turbines, to the seabed. The upper layers of the seabed are usually composed of soil or silt and may be weak or unstable. Piles are load-bearing members that extend through these upper layers to lower, more stable layers of denser soil and rock, thereby transferring loads from the anchored structure to these lower layers of the seabed.

[0007] Current onshore piling involves drilling a hole with a hammer, during which the hole is drilled and the casing is pulled into the hole by the hammer. Once the hole reaches the target depth, the hammer is removed from the hole, thereby leaving the casing in place. Rebar is dropped into the center of the casing and the hole is then filled with grout. The casing can be removed before the grout has hardened, which bonds the rebar to the surrounding land material.

[0008] However, there are a number of difficulties with subsea piling, which means that such land construction methods are not suitable. One common method of fixing subsea anchors to the seabed is to use driven piles which are driven into the seabed by large subsea hydraulic hammers. Alternatively, suction piling can be used, where a hollow pile is sunk to the seabed and a seal is formed between the bottom of the pile and the seabed. Water is then pumped out of the hollow centre of the pile, creating a suction effect which drives the pile further into the seabed.

[0009] The subsea piles described above can be used to secure a subsea anchor to the seabed. Such a subsea anchor can comprise a frame or template that is secured to the seabed by means of one or more piles. A wind turbine or other offshore structure can be tethered or secured to the subsea anchor.

[0010] A method for installing such a subsea pile cap anchor is disclosed in US Pat. No. 5,399,633. The method includes providing a frame on the seabed, positioning a subsea drill on the frame, and using the drill to drive the pile cap anchor into the seabed. Grout is then pumped around the pile cap anchor to bond the pile to the ground. This process may be repeated multiple times to secure the frame to the seabed. Mooring connections to the frame may be used to connect offshore structures to the anchor.

[0011] There are a number of disadvantages to these approaches. Both driven and suction piles are relatively slow to install. For driven piles, the subsea hammers are large, complex, expensive and require large support vessels. The suction method is only suitable where the seabed is stiff and sandy and cannot be used where rocks or obstructions are present. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] US Patent Application Publication No. 2015 / 0233079 Summary of the Invention [Problem to be solved by the invention]

[0013] It would be desirable to provide a method and system for installing piles or load bearing members on the seabed for mooring structures, such as wind turbines, that overcomes the disadvantages associated with existing methods. [Means for solving the problem]

[0014] According to one aspect of the present invention, there is provided a hydraulic down-the-hole hammer, the hydraulic down-the-hole hammer comprising: An elongated shaft; a piston having a central bore therethrough, slidably mounted for reciprocal movement on said shaft and positioned for impact with a percussion bit; a control valve disposed within the central bore of the piston to control reciprocating motion of the piston, forward and rear drive chambers for the piston being provided between the piston and the shaft, and the front chamber being separated from the rear chamber by an annular shoulder formed inside the piston bore.

[0015] The term "forward" is used herein to refer to the end of the hammer that faces the percussion bit - i.e., the drilling end of the hammer. The term "rearward" is used herein to refer to the end of the hammer that faces away from the percussion bit - i.e., the end of the hammer that is outermost during drilling.

[0016] There are several advantages to this arrangement. Because the valve is located inside the piston, the distance the fluid must travel between the valve and the actuation chamber is minimised, eliminating harmful pressure waves. Pressure losses are also very low. Because the actuation chamber is inside the piston rather than between the piston and an outer sleeve, the sealing diameter is reduced compared to conventional hammers. This reduces leakage, which is particularly important for hydraulically actuated hammers where the working fluid has a low viscosity. The hammer is also less expensive to manufacture due to its simple design.

[0017] Preferably the control valve is located within the shaft.

[0018] In a preferred embodiment, the piston is of monolithic or unitary construction, i.e. the piston is formed as a single piece, and an annular shoulder on the piston separating the front and rear chambers is provided within the bore of the piston so that it is possible to manufacture the piston and assemble it into the hammer as a single piece.

[0019] Ideally, the piston is positioned to impact with an annular shoulder at the rear end of the percussion or drill bit, which may be provided on the skirt of the drill bit. The advantage of this arrangement is that the impact force is transferred directly to the gauge of the drill bit at the point where the greatest impact energy is required to break the hole.

[0020] In certain embodiments, the hammer may include at least one accumulator located at the rear end of the piston. Because the valve is located inside the piston, the accumulator(s) may be located closer to the piston than in conventional devices, thereby reducing the accu is reduced, resulting in improved efficiency.

[0021] In one embodiment of the hammer, the working fluid is water. In this embodiment, the rear chamber is connected to a pressure fluid channel and the control valve may be arranged to connect the front chamber with the rear chamber during backward movement of the piston and to connect the front chamber to a flushing fluid channel via the shaft and the percussion bit when the piston moves forward. Because the rear chamber is connected to a pressure fluid channel through the cycle of the piston, the pressure in the rear chamber is constant and the pressure in the front chamber varies.

[0022] In some embodiments, the hammer may further comprise an outer wear sleeve within which the piston is housed. In conventional hammers, the outer wear sleeve protects the piston from wear during drilling. The percussion bit may be located at the front end of the wear sleeve. In some embodiments of the present application, the hammer is a closed loop hammer and a flushing fluid channel may be provided through the percussion bit between the piston and the wear sleeve. This means that the entire outer surface of the piston is exposed to the flushing fluid, which cools the piston very efficiently.

[0023] In another embodiment, the working fluid of the hammer is water, and a flow annulus is provided between the piston and the outer wear sleeve to provide fluid communication between the front and rear ends of the piston. A flushing fluid channel is provided through the shaft and the percussion bit. Since the drive chamber of the hammer is provided within the bore of the piston, the flow path between the front and rear ends of the piston can be provided by a flow annulus on the outside of the piston, rather than through the bore of the piston as in conventional underwater hammers. Such a flow annulus has an inherently large flow area even with a small radial clearance between the piston and the wear sleeve. This means that the cross-sectional area of ​​the piston can be increased compared to conventional underwater hammers, allowing a sufficient piston weight with a shorter piston. By providing the bubble inside the piston, the length of the hammer is further reduced.

[0024] According to one aspect of the invention, the piston is the outermost part of the hammer. That is, the hammer does not have an outer wear sleeve that houses the piston. By eliminating the traditional outer wear sleeve from the hammer, the cost of the hammer is reduced, which allows the hammer to be used as a single-use hammer, a sacrificial hammer, or a disposable hammer. Because the piston is the outermost part of the hammer, it is exposed to wear from cuttings. However, because the hammer is disposable, the piston only needs to last long enough to drill one hole. For example, the hammer may be left in the hole when the hole is drilled.

[0025] A flushing port may be provided at the front end of the piston within the shaft extending from the central bore to an outer surface, allowing a portion of the flushing water to flow between the impact surface of the piston and the impact surface of the bit to flush cuttings away from the impact surface to prevent damage to the impact surface.

[0026] In various embodiments of the hammer according to the invention, the shaft may comprise a coupling member at its front end, which couples the percussion bit to the hammer and transmits the rotational drive.

[0027] An engagement means may be formed on the coupling member, the engagement means being engageable with a complementary engagement means formed inside the bit, whereby rotational drive from the shaft may be transmitted to the bit. In one embodiment, the coupling member is formed with a central bore and the flushing port is provided in the coupling member and extends from the central bore to an outer surface of the coupling member at the forward end of the piston. The engagement means may comprise a plurality of axially extending splines formed on the exterior of the coupling member, and the complementary engagement means may comprise a plurality of corresponding axially extending splines formed inside the bit. In another embodiment, the engagement means may comprise a portion of the coupling member having a hexagonal or square cross section, and the complementary engagement means may comprise an inner portion of the bit formed with a correspondingly shaped inner wall.

[0028] The hammer may further comprise bit retaining means on the coupling member configured to retain the bit in the hammer by engaging complementary retaining means on the bit. The bit retaining means may comprise a first thread formed on the exterior of the coupling member at a forward end, and the complementary engagement means may comprise a second thread formed on the interior of the bit. A bit for the hammer may be mated by threading the bit on the coupling means such that the first thread is forward of the second thread. This arrangement allows for retaining the bit in the hammer and limiting longitudinal movement of the bit.

[0029] In another embodiment, the bit retaining means comprises a bit retaining ring including a plurality of sub-annular sectors and the complementary engagement means comprises a shoulder formed on the interior of the bit. In this embodiment, the coupling member may comprise a chuck.

[0030] According to one aspect of the present invention, there is provided a method of installing a load-bearing member, such as a subsea pile, on a seabed, the method comprising: drilling a hole of a desired depth into the seabed using a hydraulic down-the-hole hammer operated by supplying a working fluid; stopping the supply of working fluid to the hammer while the hammer is placed or positioned within the hole; supplying grout to the hammer to at least partially fill the hammer and the hole in which the hammer is located with grout; and allowing the hammer and the grout to harden so that they form a load-bearing member on the seabed.

[0031] Filling the hammer and / or the hole includes partially filling the hammer and / or the hole with grout such that the hammer is bonded to the seabed material in which the hole is formed. In certain embodiments, the hammer and / or the hole may be completely filled with grout. Grout may be supplied to the hammer until the grout is substantially flush with the surface of the seabed.

[0032] The method has a number of advantages over existing methods for installing subsea piles. In particular, the method disclosed herein allows for faster installation. Furthermore, the down-the-hole hammer allows the piles to be installed in a variety of seabed types, even in areas with little sand or soil and with rocks or boulders. However, since the hammer itself constitutes the load-bearing member, it is intended to be one-time use and therefore less expensive than typical hammers used to drive piles into the seabed.

[0033] The hammer may be according to any of the embodiments described above. The hammer used to carry out the method may be a disposable, single use, or sacrificial hammer, such as those described above, in which the working fluid is water. In one embodiment, the disposable or sacrificial hammer does not include an outer wear sleeve. Rather, the piston is the outermost member of the hammer.

[0034] In some embodiments, a drilling rig is connected to the hammer and the hammer and drilling rig are lowered to the seabed before drilling the hole. The drilling rig may be operated to rotate and provide force to the hammer while drilling the hole. After the hole is filled with grout, the drilling rig is detached from the hammer and brought to the sea surface. In some embodiments, a drill pipe is provided between the drilling rig and the hammer and the drill pipe is used to fill the drilled hole with grout by the hammer. Together the hammer, drill pipe and grout then form a load bearing member or subsea pile.

[0035] According to another aspect of the present invention, there is provided a system for installing a load-bearing member on a seabed, the system comprising: Hydraulic down-the-hole hammer and a working fluid supply to which the hammer can be connected for drilling a hole of a desired depth in the seabed; A grout supply is provided which the hammer is connectable to while mounted or positioned within the hole such that the hammer and the hole can be filled with grout.

[0036] The system may include a drilling rig configured to rotate and provide a force to the hammer during drilling of the hole, the drilling rig being connected to the hammer and lowered to the seabed by the hammer prior to drilling of the hole.

[0037] The system may further comprise at least one drill rod or pipe connected between the drilling rig and the hammer. The drill pipe may be a sacrificial pipe and the hole may be grouted by the hammer, such that the hammer, drill pipe and grout together form a load bearing member or subsea pile.

[0038] The working fluid supply and the grout supply are provided at a surface level above the seabed, and the system may further comprise an umbilical. The hammer is connectable to the working fluid supply and the grout supply via the umbilical. In an embodiment, a working fluid pump is configured to provide the working fluid supply to the hammer, and a grout pump is configured to provide the grout supply to the hammer. The pumps may be provided on a vessel or device located at or near the sea surface. The umbilical may include one or more cables or hoses configured to connect the hammer and / or the drilling rig to surface equipment, such as the working fluid pump and the grout pump. The umbilical may comprise a single channel selectively connectable to the working fluid supply and the grout supply. Alternatively, the umbilical may include a first channel connectable to the working fluid supply to supply working fluid to the hammer, and a second channel connectable to the grout supply to supply grout to the hammer.

[0039] The hammer may have a central hole through which grout is delivered to the hammer and to the hole. The drill pipe may also have a central hole through which the working fluid and grout are delivered to the hammer. The working fluid of the hammer may be water. The hammer piston may be the outermost member of the hammer. The hammer may be any of the embodiments described above. Suitably the hammer may be a disposable or sacrificial underwater hammer as described above.

[0040] In one embodiment, the percussion bit has a larger diameter than the piston such that the diameter of the drilled hole is larger than the diameter of the piston and an annular cavity exists between the piston and the wall of the drilled hole.

[0041] In one embodiment, the diameter of the percussion bit may be 300 mm or less. The resulting load-bearing members may be referred to as micropiles. The micropiles may be preferable to larger piles because they are small, light, inexpensive, easy to install, and produce less noise and vibration.

[0042] According to one aspect of the present invention there is provided a submarine pile comprising: a hydraulic down-the-hole system located in or on the seabed; and hardened grout disposed within the hammer and between the hammer and the wall of the hole such that the hammer is bonded to the seabed material by the grout.

[0043] The hammer may be a hammer according to any of the embodiments described above. For example, the subsea pile hammer may be a disposable, single use, or sacrificial hammer in which the working fluid is water. In one embodiment, the disposable or sacrificial hammer does not include an outer wear sleeve. Rather, the piston may be the outermost member of the hammer.

[0044] The submarine pile may further comprise at least one drill rod or pipe connected to the hammer and disposed within the hole in the seabed, the hardened grout being further disposed within the drill rod or pipe and between the drill rod or pipe and the wall of the hole, whereby the drill rod or pipe is also bonded to the material of the seabed by the grout.

[0045] In one embodiment, the submarine piles may be submarine micropiles having a diameter of 300mm or less.

[0046] The subsea pile may be equipped with a hydraulic down-the-hole hammer and optionally a grouted pillar into which a drill pipe is embedded.

[0047] According to one aspect of the present invention, there is provided a method of installing a submarine anchor on a seabed, the method comprising the steps of: connecting one or more down-the-hole hydraulic hammers and a drilling device configured to rotate and provide a force to each of the one or more hammers to the anchor frame; lowering the anchor frame to the seabed; supplying a working fluid to the or each of the hammers such that the or each of the hammers drills a hole of a desired depth into the seabed; ceasing the supply of working fluid to the or each of the hammers while the or each of the hammers is located in its respective hole; and supplying grout to the or each of the hammers to at least partially fill the or each of the hammers and the hole in which the hammer is located with grout. allowing the grout to harden such that the or each hammer is bonded to the seabed material by the grout; Decoupling the drilling rig from the anchor frame.

[0048] The or each of the hammers may be a hammer according to any of the embodiments described above. For example, the or each of the hammers used to perform the method may be a disposable, single use, or sacrificial hammer in which the working fluid is water. In one embodiment, the or each of the disposable or sacrificial hammer does not include an outer wear sleeve. Rather, the piston may be the outermost member of the hammer.

[0049] The method has a number of advantages over existing methods of installing subsea anchors. In particular, the piles that secure the anchors to the seabed are formed using a disposable or sacrificial down-the-hole hammer in which the holes are grouted, so no separate hydraulic hammers are required to perform the drilling. These single-use hammers can be cheaper than typical hammers used to drive piles into the seabed.

[0050] Suitably the drilling device provides additional rotation and force to the or each hammer, thereby enabling holes in the seabed to be drilled simultaneously.

[0051] Stabling lines may be coupled to the anchor frame to suspend an offshore structure, such as a wind turbine, to the seabed.

[0052] According to one aspect of the present invention, there is provided a system for installing a submarine anchor on a seabed, the system comprising: An anchor frame; one or more down-the-hole hydraulic hammers connectable to the anchor frame, and a drilling rig configured to rotate and provide a force to each of the one or more hammers; a working fluid supply to which the hammer can be connected for drilling a hole of a desired depth in the seabed; A grout supply is provided that is connectable to the hammer while positioned within the corresponding hole such that the hole can be at least partially filled with grout.

[0053] Preferably the drilling rig comprises an independent feed and rotation system for each of the one or more hammers.

[0054] The working fluid supply and the grout supply are provided at a surface above the seabed and the system may further comprise an umbilical, the or each hammer being connectable to the working fluid supply and the grout supply via the umbilical.

[0055] The or each of the hammers may be a hammer according to any of the embodiments described above. The or each of the hammers may have a working fluid of water. The or each of the hammers may be a disposable or sacrificial hammer as described above. The or each of the hammers may have a piston that may be the outermost member of the hammer. The or each of the hammers may have a larger diameter than the piston. The or each of the hammers may have a larger diameter than the piston, such that an annular cavity exists between the or each of the hammers and the wall of the respective drilled hole.

[0056] The anchor frame may be provided with connection means for connection to the one or more hammers. In one embodiment the connection means may include one or more connectors for connection to the or each of the hammers. Each connector may have a mounting sleeve or boss.

[0057] The system may further comprise at least one drill rod or pipe connected between the drilling rig and the or each of the hammers. The drill pipe may also be a sacrificial pipe, and the or each of the holes may be grouted by a corresponding hammer, whereby each hammer, drill pipe and grout together may constitute a load bearing member or subsea pile connected to the anchor frame to anchor the anchor frame to the seabed.

[0058] According to one aspect of the present invention there is provided a submarine pile comprising: An anchor frame provided on the seabed; one or more hydraulic down-the-hole hammers mounted in respective corresponding holes in the seabed and connected to the anchor frame; and hardened grout disposed within the, or each, hammer and between the hammer and the wall of each corresponding hole, the or each, hammer being held together by the grout.

[0059] The or each of the hammers may be a hammer according to any of the embodiments described above. The or each of the hammers of the subsea anchor may be a disposable, single use or sacrificial hammer in which the working fluid is water. In one embodiment, the or each of the disposable or sacrificial hammer does not include an outer wear sleeve. Rather, the piston may be the outermost member of the hammer.

[0060] The submarine pile may further comprise at least one drill rod or pipe connected to the or each hammer and disposed within the hole in the seabed, the hardened grout being further disposed within the drill rod or pipe and between the drill rod or pipe and the wall of the hole, whereby the drill rod or pipe is also bonded to the material of the seabed by the grout. [Brief description of the drawings]

[0061] [Figure 1] FIG. 1 is a schematic diagram of a conventional hydraulic down-the-hole hammer. [Diagram 2] FIG. 1 is a schematic diagram of a conventional down-the-hole hydraulic hammer. [Diagram 3] 1 is a schematic diagram of a hydraulic down-the-hole hammer according to an embodiment of the present invention; [Figure 4] 1 is a schematic diagram of a hydraulic hammer according to an embodiment of the present invention; [Diagram 5] 1 is a schematic diagram of a disposable hydraulic hammer according to an embodiment of the present invention; [Figure 6a] FIG. 2 is a perspective view of a coupling member and a bit of a hammer according to the invention; [Figure 6b]Figure 6b is a cross-sectional view of the coupling member and bit of Figure 6a, in which the coupling member is assembled to the piston and shaft of the hammer; [Figure 6c] Fig. 6c is a cross-sectional view of the assembly of Fig. 6b, in which the bit is coupled to the coupling member; [Figure 7a] FIG. 1 is a cross-sectional view of a disposable hydraulic hammer according to an embodiment of the present invention. [Figure 7b] FIG. 7b is a detailed view of a portion of the hammer of FIG. 7a. [Figure 8a] 7a and 7b show different stages of the hammer cycle of the hammer. [Figure 8b] 7a and 7b show different stages of the hammer cycle of the hammer. [Figure 8c] 7a and 7b show different stages of the hammer cycle of the hammer. [Figure 8d] 7a and 7b show different stages of the hammer cycle of the hammer. [Figure 9] FIG. 1 is a cross-sectional view of an assembly including a drilling rig and a disposable hydraulic hammer connected to a drill pipe, suitable for use in a system for installing subsea piles. [Figure 10] FIG. 10 is a cross-sectional view of a system for installing subsea piles including the assembly of FIG. 9 during drilling of a hole in the seabed. [Figure 11] FIG. 11 is a cross-sectional view of the system of FIG. 10 after drilling a hole into the seabed. [Figure 12] FIG. 10 is a cross-sectional view of the submarine pile with the hammer and drill pipe of FIG. [Figure 13] FIG. 1 is a perspective view of an assembly for use in a system for installing submarine anchors on the seabed in accordance with an aspect of the present invention. [Figure 14] FIG. 14 is a perspective view of the assembly of FIG. 13 after deployment of the hammer. [Figure 15] FIG. 15 is a side view of the assembly shown in FIG. [Figure 16] FIG. 1 is a perspective view of a submarine anchor installed on the seabed. [Figure 17] FIG. 17 is a side view of the marine anchor of FIG. [Figure 18a] FIG. 1 is a cross-sectional view of a disposable hydraulic hammer according to an embodiment of the present invention. [Figure 18b] FIG. 18b is a detailed view of a portion of the hammer of FIG. 18a. [Figure 19a] 18a and 18b show different stages of the hammer cycle of the hammer. [Figure 19b] 18a and 18b show different stages of the hammer cycle of the hammer. [Figure 19c] 18a and 18b show different stages of the hammer cycle of the hammer. [Figure 19d] 18a and 18b show different stages of the hammer cycle of the hammer. [Figure 20a] FIG. 2 is a perspective view of the coupling member, chuck and bit of the hammer according to the invention; [Figure 20b] Figure 20b is a cross-sectional view of the coupling member, chuck and bit of Figure 20a, in which the chuck is assembled to the coupling member of the hammer. [Figure 20c] Fig. 20c is a cross-sectional view of the assembly of Fig. 20b, in which the bit is coupled to the chuck. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] A hydraulic down-the-hole hammer 300 according to an embodiment of the invention is illustrated in Figure 3. The hammer includes an elongated shaft 312 having a central bore 314 formed therein. A piston 301 also has a central bore 310 therethrough. The shaft is received within the piston bore such that the piston is slidably mounted for reciprocal movement on the shaft 312 and positioned to abut an annular shoulder 315 at a rear end 316 of a percussion bit 309. The piston 301 is housed within an outer wear sleeve 317, with the percussion bit 309 disposed at a forward end 318 of the wear sleeve.

[0063] The front and rear drive chambers 302, 303 for the piston are located between the piston 301 and the shaft 312. An annular shoulder 313 on the piston formed inside the piston bore 310 separates the front chamber 302 from the rear chamber 303. The inside diameter of the piston 301 rearward of the shoulder 313 is larger than the inside diameter of the piston forward of the shoulder, such that the rear chamber has a larger drive area than the front chamber. The hammer also includes a control valve 305 located in the central bore 314 of the shaft to control the reciprocating motion of the piston. In other embodiments, the valve 305 may be located in the central bore 310 of the piston, between the piston and the shaft.

[0064] Hammer 300 is a closed loop hammer in which hydraulic fluid is supplied to the hammer via pressure line P and returned via return line T. A flushing fluid passage 308 is provided between the piston 301 and wear sleeve 317 and through the percussion bit 309 such that flushing fluid exits the passage at the bit face 319.

[0065] The hammer 300 further comprises a pressure and return fluid accumulator 306 disposed at the rear end 307 of the piston. The accumulator is disposed a distance d from the rear drive chamber 303 of the piston. accu are placed apart.

[0066] A hydraulic down-the-hole hammer 400 according to another embodiment of the invention is shown in Figure 4. As with the embodiment of Figure 3, the hammer comprises an elongated shaft 412 having a central bore 414 formed therein. A piston 401 also has a central bore 410 therethrough. The shaft is received within the piston bore, with the piston slidably mounted for reciprocal movement on the shaft 412 and positioned to abut an annular shoulder 415 at the rear end 416 of a percussion bit 409. The piston 401 is housed within an outer wear sleeve 417, with the percussion bit 409 disposed at a forward end 418 of the wear sleeve.

[0067] A front drive chamber 402 and a rear drive chamber 403 for the piston are disposed between the piston 401 and the shaft 412. An annular shoulder 413 on the piston formed inside the piston bore 410 separates the front chamber 402 from the rear chamber 403. The inside diameter of the piston 401 rearward of the shoulder 413 is larger than the inside diameter of the piston forward of the shoulder, such that the rear chamber has a larger drive area than the front chamber. The hammer also includes a control valve 405 disposed in a central bore 414 of the shaft to control the reciprocating motion of the piston.

[0068] The hammer 400 shown in FIG. 4 is an open loop hammer in which a working fluid, such as water, is supplied to the hammer via a pressure line P. However, unlike the hammer of FIG. 3, the hammer 400 does not have a return line. Instead, the driving fluid is used for flushing flow 408 through a central hole 414 in the shaft and through a percussion bit 409 to exit at the bit face 419. Unlike prior art hammers, the outer surface of the piston is not a sealing surface, so a flow annulus 420 that allows fluid communication between the front and rear ends of the piston is provided between the piston and the wear sleeve, rather than through the piston hole as in the conventional hydraulic hammer shown in FIG. 2. This allows the cross-sectional area of ​​the piston to be increased compared to such conventional hydraulic hammers, thereby allowing a sufficient piston weight to be achieved with a short piston. Also, by locating the valve 405 in the piston, the distance d accu can be shortened, and the length of the hammer can be shortened.

[0069] A low-cost disposable or single-use hydraulic down-the-hole hammer 500 according to an embodiment of the invention is shown in FIG. 5. As with the embodiment of FIG. 4, the hammer includes an elongated shaft 512 having a central bore 514 formed therein. A piston 501 also has a central bore 510 therethrough. The shaft is received within the piston bore such that the piston is slidably mounted for reciprocating movement on the shaft 512 and positioned to strike an annular shoulder 515 at the rear end 516 of the percussion bit 509. A forward drive chamber 502 and a rear drive chamber 503 for the piston are disposed between the piston 501 and the shaft 512. An annular shoulder 513 on the piston formed within the piston bore 510 separates the forward chamber 502 from the rear chamber 503. In this embodiment, the internal diameter of the piston 501 rearward of the shoulder 513 is smaller than the internal diameter of the piston forward of the shoulder such that the forward chamber has a larger drive area than the rear chamber. The hammer also includes a control valve 505 disposed within a central bore 514 of the shaft for controlling the reciprocating motion of the piston.

[0070] Like the hammer of Figure 4, the hammer 500 shown in Figure 5 is an open loop hammer in which a working fluid, such as water, is supplied to the hammer via pressure line P. However, unlike the hammer of Figure 4, the hammer 500 does not include an outer sleeve, such that the piston 501 is the outermost member of the hammer. This reduces the cost of the hammer so that it can be used as a disposable or sacrificial hammer used to drill only a single hole.

[0071] In this embodiment, the rear chamber 503 is connected to a pressure fluid channel P such that a constant pressure exists in the rear chamber. A control valve 505 is arranged to connect the front chamber 502 to the rear chamber 503 while the piston is moving in the rearward direction, and to connect the front chamber 502 to a flushing fluid channel 508 through the shaft and a central bore of the percussion bit when the piston is moving in the forward direction, causing alternating pressure changes in the front chamber 502.

[0072] Because the hammer 500 does not include an outer wear sleeve or cylinder, the piston itself is subject to wear from the drilling cuttings. However, because the hammer is disposable, the piston only needs to last long enough to drill one hole. Additionally, a radial flushing port 521 extends from the central bore 514 of the shaft to the outer surface of the shaft, allowing a portion of the exhaust fluid to exit between the forward end 522 of the piston 501 and the impact face 515 of the bit. This directs the drilling cuttings away from the impact face of the bit and piston, preventing premature damage to the impact face.

[0073] Figures 6a, 6b and 6c show a coupling device for coupling a percussion bit to a hammer according to the invention. The hammer 600 shown in Figures 6a, 6b and 6c is similar in some respects to the disposable hammer 500 shown in Figure 5, but the coupling device shown can also be applied to the hammers 300, 400 shown in Figures 3 and 4, as well as other hammers according to the invention.

[0074] The shaft 612 of the hammer 600 is provided with a coupling member 622 at its front end 623. As shown in Figures 6b and 6c, the outer diameter of the coupling member is greater than the outer diameter of the body 638 of the shaft, so that the front chamber is sealed by the coupling member and the piston. A portion 624 of the coupling member is formed with a square cross section and a corresponding internal portion 625 of the bit 609 is formed with a square shaped inner wall, so that when the bit is assembled to the coupling member of the shaft, the portion 624 of the coupling member is received within the portion 625 of the bit, such that the rotational drive is transmitted from the shaft to the bit. In other embodiments, the portion 624 of the coupling member may be formed with a hexagonal or octagonal cross section and the internal portion of the bit may be of a corresponding shape. In further embodiments, axially extending splines may be provided on the exterior of the coupling member to be engageable with corresponding splines provided on the interior of the bit for the transmission of the rotational drive.

[0075] Coupling member 622 further comprises bit retaining means engageable with complementary bit retaining means on bit 609 to longitudinally couple the bit to the hammer. In the embodiment shown in Figures 6a, 6b and 6c, the bit retaining means comprises a first thread 626 formed on the exterior of coupling member 622 at its front end 627. The complementary engagement means comprises a second thread 628 formed on the interior of the bit.

[0076] The bit is coupled to the hammer by threading the bit over the first thread 626 with the second thread 628 in front of the second thread. This may longitudinally couple the bit to the coupling member and hold the bit to the hammer while allowing longitudinal movement of the bit to be limited. The bit is then rotated to align a portion 625 of the bit with the square shaped portion 624 of the coupling member such that the portion 624 of the coupling member is received within the portion 625 of the bit and engages the rotational coupling. The coupling member 622 is coupled to the body 638 of the shaft by a threaded connection.

[0077] A control valve 705 suitable for use in a hammer 700 according to the invention is shown in Figures 7a and 7b. This valve is particularly suitable for a disposable hammer according to the invention, such as that shown in Figure 5. The valve 705 comprises a top or rear inlet port 728 and a top or rear outlet port 729. The valve further comprises a bottom or front inlet port 730 and a bottom or front outlet port 731. Also shown in Figure 7a are a valve chamber 732, a pilot chamber 733, a pilot port 734, a front control end 735, a rear control end 736 and a control valve cap 737.

[0078] An example of a hammer cycle for a disposable hammer including the valves of Figs. 7a and 7b is shown in Figs. 8a-8b. 8d. In FIG. 8a, the piston 801 is moving in an upward or rearward direction (to the left as shown in the drawing). The rear chamber 803 is connected to the pressure fluid via a hammer cycle. The front chamber 802 is connected to the high pressure fluid via the valve chamber 832 and the rear chamber 803, as indicated by the arrows. Due to the larger inner diameter of the piston 801, the front chamber has a larger pressure area than the rear chamber and the piston moves in the rearward direction. The valve pilot chamber 833 is pressurized via the front control end 835, which connects the pilot chamber to the rear chamber 803. The pilot chamber has a larger pressure area than the valve chamber. The flow connection between the front chamber 802 and the shaft bore 814 is closed and the flow connection between the front chamber and the valve chamber 832 is open. The valve chamber is in continuous communication with the rear chamber 803 via the rear outlet port 829.

[0079] In Figure 8b, the piston 801 reaches a point where the flow connection from the pilot chamber 833 to ambient pressure is opened via the rear control end 836. The pressure in the pilot chamber drops, creating a net hydraulic force that switches the valve 805.

[0080] In FIG. 8c, valve 805 switches. The valve closes front inlet port 830 and opens front outlet port 831, allowing wastewater to flow into shaft bore 814, as shown by the arrows. Hydraulic force reverses the direction of piston 801, driving it toward drill bit 809. Most of the wastewater flows through the shaft bore and bit, as shown by the arrows, and out the bit face 819, washing cuttings away from the bit face. A small portion of the wastewater flows out through radial holes or ports 821 located near the bit impact face 815, as shown by the arrows, washing cuttings away from the bit-piston impact face.

[0081] In Figure 8d, the piston 801 is moving towards the bit 809 (to the right as shown in the drawing). Just before impact, the piston 801 connects the pilot chamber 833 to the rear chamber 803 via the front control end 835. This causes the valve to switch just after the piston impacts the drill bit. The cycle begins again as shown in Figure 8a.

[0082] A hydraulic down-the-hole hammer 1800 according to another embodiment of the present invention is shown in Figures 18a and 18b. The hammer shown is a low-cost disposable or single-use hammer. However, various aspects of this embodiment may also be applied to a multiple-use hammer. As with the above embodiment, the hammer includes an elongated shaft 1812 having a central bore 1814. A piston 1801 also has a central bore 1810 therethrough. The shaft is received within the piston bore. The piston is slidably mounted for reciprocating movement on the shaft 1812 and positioned to strike an annular shoulder 1815 at the rear end 1816 of the percussion bit 1809. A forward drive chamber 1802 and a rear drive chamber 1803 for the piston are disposed between the piston 1801 and the shaft 1812. An annular shoulder 1813 on the piston formed within the piston bore 1810 separates the forward chamber 1802 from the rear chamber 1803. In this embodiment the inside diameter of the piston 1801 rearward of the shoulder 1813 is smaller than the inside diameter of the piston forward of the shoulder such that the front chamber has a larger driving area than the rear chamber. The hammer also includes a control valve 1805 located in a central bore 1814 of the shaft to control the reciprocating motion of the piston.

[0083] The control valve 1805 is shown in more detail in Figure 18b. The valve 1805 comprises a top or rear inlet port 1828 and a top or rear outlet port 1829. The valve further comprises a bottom or front inlet port 1830 and a bottom or front outlet port 1831. Also shown in Figure 18B are the valve undercut 1832, pilot chamber 1833, pilot port 1834, valve shoulder 1839 and valve high pressure chamber 1840.

[0084] An example of a hammer cycle for a disposable hammer including the valves of Fig. 18a and 18b is shown in Fig. 19a-19d. In Fig. 19a, the piston 1901 is moving in an upward or rearward direction (to the left as shown in the drawing). The rear chamber 1903 is connected to the pressure fluid throughout the hammer cycle. The front chamber 1902 is connected to the high pressure fluid through the rear outlet port 1929, the pilot chamber 1933, the valve undercut 1932 and the front inlet port 1930 as shown by the arrows. The front chamber has a larger pressure area than the rear chamber due to the larger inner diameter of the piston 1901, which moves in the rearward direction. The valve pilot chamber 1933 is pressurized through the pilot port 1934 and / or the rear outlet port 1929. The pilot chamber 1933 has a larger pressure area than the valve high pressure chamber 1940 and is continuously connected to the high pressure fluid. The flow path connection between the front chamber 1902 and the shaft bore 1914 is closed.

[0085] In Figure 19b, the piston 1901 has reached the point where it disconnects the rear exit port 1929 from the rear chamber 1903. The front chamber 1902 receives no pressurized fluid from the rear chamber and the piston continues to move upwards due to its inertia. The pressure in the front and pilot chambers 1933 suddenly drops, creating a net hydraulic force that switches the valve 1905.

[0086] In FIG. 19c, the valve 1905 has been switched. The valve 1905 closes the flow connection between the rear chamber 1903 and the front chamber 1902 and opens the front exit port 1931, allowing the effluent water to flow into the shaft bore 1914, as shown by the arrow. The hydraulic force reverses the direction of the piston 1901, driving it towards the drill bit 1909. The effluent water flows through the shaft bore and the bit, as shown by the arrow, and out the bit face 1919, flushing cuttings from the bit face. Although not shown, radial flushing ports can also extend from the central bore of the shaft to the outer surface of the shaft, allowing some of the effluent fluid to exit between the front end of the piston and the impact face of the bit, as described above.

[0087] In Figure 19d, the piston 1901 is moving towards the bit 1909 (to the right as shown in the drawing). Just before impact, the piston 1901 connects the pilot chamber 1933 to the rear chamber 1903 via the pilot port 1934. This causes the valve to switch just after the piston impacts the drill bit. The cycle begins again as shown in Figure 19a.

[0088] Figures 20a, 20b and 20c show a coupling device for coupling a percussion bit to a hammer according to the invention. The hammer 2000 shown in Figures 20a, 20b and 20c is similar in some respects to the disposable hammer 1800 shown in Figures 18a and 18b, although the illustrated coupling device may also be applied to other hammers according to the invention.

[0089] The shaft 2012 of the hammer 2000 is provided with a coupling assembly 2050 at its front end 2023. The coupling assembly comprises a sealing flange 2022 and a coupling member in the form of a chuck 2041. As shown in Figures 20b and 20c, the outer diameter of the sealing flange is greater than the outer diameter of the body 2038 of the shaft, such that a front chamber is sealed by the sealing flange and the piston 2001. The sealing flange 2022 is provided with connection means at its front end, consisting of an internal thread 2043. The rear part of the chuck is provided with complementary connection means, consisting of an external thread 2044. Engagement means in the form of an axially extending spline 2045 on the exterior of the chuck are engageable with complementary engagement means in the form of a corresponding spline 2046 on the interior of the bit 2009, so that rotational drive from the shaft can be transmitted to the bit. In other embodiments, the chuck may be formed with a square, hexagonal or octagonal cross-section, as described above, and the interior portion of the bit may be of a corresponding shape.

[0090] The hammer 2000 further comprises bit retaining means on the chuck engageable with complementary retaining means on the bit 2009 to longitudinally couple the bit to the hammer. In the embodiment shown in Figures 20a, 20b and 20c, the bit retaining means comprises a bit retaining ring 2042 including a plurality of partial annular sectors, the complementary bit retaining means comprising a shoulder 2049 formed on the interior of the bit at a rear end thereof.

[0091] The bit is coupled to the hammer by threading the threads 2044 on the chuck into the threads 2043 on the sealing flange 2022. The sealing flange is also connected to the body 2038 of the shaft 2012 by a threaded connection. Between the forward end 2047 of the sealing flange and the annular shoulder 2048 on the chuck, sufficient space is left to insert a sector of the bit retaining ring 2042 therebetween. The drill bit is pressed onto the chuck so that the splines 2045 on the chuck engage with the complementary splines 2046 on the drill bit. The threaded connection between the chuck and the sealing flange is then tightened by rotating the drill bit 2009. When the connection is tightened, the annular shoulder 2048 on the chuck is pressed towards the forward end 2047 of the sealing flange, thereby forcing the sector of the bit retaining ring 2042 outwards, as shown in FIG. 20c. The drill bit is held in the hammer by the engagement between the shoulder 2049 and the bit retaining ring 2042.

[0092] An assembly 950 for use in a system for installing load bearing members, such as subsea piles, on the seabed is illustrated in Figure 9. The assembly comprises a disposable or sacrificial hydraulic down-the-hole hammer 900. The hammer 900 is a hydraulic hammer similar to the hammer 700 shown in Figures 7a and 7b and comprises a piston 901 arranged to impact a bit 909. The piston 901 is the outermost member of the hammer and the percussion bit 909 has a diameter D greater than the diameter D of the piston. The assembly further comprises a drill pipe 951 connected between the drilling rig 958 and the hammer, the drill pipe having a central bore 955 passing therethrough.

[0093] The drilling rig 958 is configured to provide rotation and feed forces to the hammer during drilling of the hole. The drilling rig is coupled to the drill pipe 951 and the hammer 900 and is lowered together with the hammer to the seabed 954 prior to drilling.

[0094] As shown in Figure 10, the system also includes an umbilical 952, where the hammer is connectable via a drill pipe to a pressurized water supply and a grout supply via the umbilical. The water supply and grout supply are provided at sea level 953. Water and grout pumps on board the vessel 959 provide the water and grout supplies, respectively.

[0095] In use, the drilling rig is connected to the hammer via drill pipe 951 and the assembly is lowered to the seabed 954. The hammer 900 is operated by supplying water via the umbilical 952 to drill a hole 956 in the seabed, as shown in Figures 10 and 11. Rotation and feeding forces are provided by the drilling rig. Operation of the hammer is as described above with reference to Figure 8. When the hole reaches the desired depth, as shown in Figure 11, the rotation and feeding forces are stopped and the supply of water to the hammer is stopped, for example by disconnecting the umbilical from the water pump. As shown in Figure 11, the diameter of the drilled hole 956 is larger than the diameter of the piston 901 such that there is an annular cavity 957 between the piston and the wall of the drilled hole.

[0096] Grout 960 is then fed through the umbilical to the hammer, for example, by connecting the umbilical to a grout pump. The grout flows through the drill pipe and central hole 955 of the hammer 900, through the bit 909 and into the hole 956. The grout is pumped into the hole until the hole is at least partially filled, as shown in FIG. 12. The drilling rig is disconnected from the hammer and returned to the surface. Once the grout has hardened, the hammer, drill pipe and drill pipe are bonded to the seabed material such that the hammer, drill pipe and grout form a subsea pile, as shown in FIG. 12.

[0097] An assembly 1300 for use in a system for installing subsea anchors on the seabed is shown in Figures 13 to 15. The assembly comprises an anchor frame or template 1301. In the embodiment shown, the anchor frame is generally triangular in shape and is provided with a number of ribs 1308 to enhance its structural integrity. In other embodiments, the anchor may be rectangular or of any other suitable shape. Mooring connections 1310 are also provided on the anchor frame to allow mooring lines to be connected thereto for mooring an offshore structure such as a wind turbine.

[0098] The assembly further comprises a drilling rig 1302, three sacrificial down-the-hole hydraulic hammers 1303 and corresponding drill rods or pipes 1304, each connected to the anchor frame 1301 via a connector 1307 in the form of a mounting sleeve or boss at the outer end of the frame 1301. Each hammer 1303 is a hydraulic hammer similar to the hammer 700 shown in Figures 7a and 7b. The drilling rig 1302 comprises three identical feed and rotation systems 1305, whereby the drilling rig is configured to provide rotation and feed forces to each of the hammers 1303. In other embodiments, the system can comprise more or fewer hammers and the drilling rig can comprise a corresponding number of feed and rotation systems. As shown in Figure 13, the drilling rig 1302 is configured such that each hammer and drill pipe pair is positioned at an acute angle with respect to the seabed 1306.

[0099] Each hammer 1303 and corresponding drill pipe 1304 can be connected to a working fluid supply for drilling holes 1311 of a desired depth in the seabed 1306, as shown in FIG. 15. In the illustrated embodiment, the holes are drilled at an angle to the vertical to minimize bending or shear forces on the anchors. However, in other embodiments, the holes may be drilled vertically downwards to the seabed or at an angle between 20 degrees and 90 degrees to the seabed. The working fluid can be supplied from a rig or vessel at sea level, as shown in FIG. 10. The drilling rig 1302 includes three independent power supply and rotation systems 1305, so that the holes 1311 may be drilled simultaneously. Alternatively, the holes may be drilled sequentially. As the hammers 1303 are operated, each hammer 1303 and drill pipe 1304 passes through a corresponding connector 1307. As the holes are drilled, the top of each drill pipe 1304 is held in a corresponding connector 1307 to connect the anchor to the drill pipe, as shown in Figures 14 and 15. Once the holes are drilled, each hammer is connected to a grout supply while positioned in its respective hole to allow the hammer and hole to be at least partially filled with grout. The grout may be delivered via an umbilical, as shown in Figure 10.

[0100] Once the holes 1311 are filled with grout, the drilling rig 1302 is disconnected from the hammer 1303 and returned to the sea surface leaving the subsea anchor on the seabed as shown in Figures 16 and 17. Once the grout has hardened, the subsea anchor including the anchor frame 1301 is secured to the seabed by the hammer 1303 and corresponding drill pipes 1304 connected to the anchor frame via connectors 1307. Nuts or other fasteners may be connected to the upper ends 1309 of each of the drill pipes to secure the anchor frame to the subsea pile formed by the hammer and drill pipe pair. Each of the hammer and drill pipe pairs is secured in place in a respective hole in the seabed by the grout such that the anchor is secured in place by bonding each hammer and drill pipe to the seabed material 1306.

[0101] As used herein in relation to the present invention, the words "comprising" and "having" are used to specify the presence of stated features, integers, steps or components, but do not exclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0102] It will be appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Claims

1. 1. A hydraulic down-the-hole hammer, comprising: An elongated shaft; a piston having a central bore therethrough, slidably mounted for reciprocal movement on said shaft and positioned for impact with a percussion bit; a control valve disposed within the central bore of the piston to control reciprocating motion of the piston; a front drive chamber and a rear drive chamber for the piston are provided between the piston and the shaft, and the front chamber is separated from the rear chamber by an annular shoulder formed inside the piston bore; Hydraulic down-the-hole hammer.

2. 2. The hydraulic down-the-hole hammer of claim 1, wherein the shaft has a central bore and the control valve is disposed within the shaft.

3. 3. A hydraulic down-the-hole hammer as claimed in claim 1 or 2, wherein the piston has a monolithic structure.

4. 4. The hydraulic down-the-hole hammer of claim 3, wherein the piston is positioned to impact an annular shoulder at a rear end of the percussion bit.

5. 5. The hydraulic down-the-hole hammer of claim 4, further comprising at least one accumulator disposed at a rear end of the piston.

6. 6. A hydraulic down-the-hole hammer according to claim 5, The working fluid of the hammer is water. the rear chamber is connected to a pressure fluid channel; the control valve is arranged to connect the front chamber with the rear chamber during the piston's movement in a rearward direction and to connect the front chamber to a flushing fluid channel via the shaft and the percussion bit when the piston moves in a forward direction. Hydraulic down-the-hole hammer.

7. 7. The hydraulic down-the-hole hammer of claim 6, further comprising an outer wear sleeve within which the piston is housed, the percussion bit being disposed at a forward end of the wear sleeve.

8. 8. The hydraulic down-the-hole hammer of claim 7, wherein the hammer is a closed loop hammer and a flushing fluid channel is provided through the percussion bit between the piston and the wear sleeve.

9. 8. A hydraulic down-the-hole hammer as claimed in claim 7, wherein the working fluid of the hammer is water, a flow annulus is provided between the piston and the outer wear sleeve, and a flushing fluid channel is provided through the shaft and the percussion bit.

10. 7. A hydraulic down-the-hole hammer as claimed in claim 6, wherein the piston is the outermost part of the hammer.

11. 11. The hydraulic down-the-hole hammer of claim 10, further comprising a flushing port in the shaft at a forward end of the piston extending from the central bore of the shaft to an outer surface of the shaft.

12. 12. The hydraulic down-the-hole hammer of claim 11, wherein the shaft includes a coupling member at a forward end thereof, the coupling member coupling the percussion bit to the hammer and imparting rotational drive thereto.

13. 13. The hydraulic down-the-hole hammer of claim 12, further comprising engagement means formed on the coupling member, the engagement means engageable with complementary engagement means formed within the bit, whereby rotational drive from the shaft is transmitted to the bit.

14. 14. The hydraulic down-the-hole hammer of claim 13, further comprising bit retaining means on the coupling member configured to engage complementary retaining means on the bit to retain the bit within the hammer.

15. 15. The hydraulic down-the-hole hammer of claim 14, wherein the bit retaining means comprises a first thread formed on the exterior of the coupling member at a forward end, and the complementary engaging means comprises a second thread formed on the interior of the bit.

16. 1. A method of installing a load-bearing member on a seabed, comprising the steps of: drilling a hole of a desired depth into the seabed using a hydraulic down-the-hole hammer operated by supplying a working fluid; stopping the supply of working fluid to the hammer while the hammer is located within the bore; supplying grout to the hammer to at least partially fill the hammer and the hole in which the hammer is located with grout; allowing the grout to harden so that the hammer and the grout form a load bearing member on the seabed; The method according to claim 1,

17. 17. The method of claim 16, connecting a drilling rig to the hammer and lowering the hammer and drilling rig to the seabed prior to drilling the hole; manipulating the drilling device to rotate and apply force to the hammer while drilling the hole; The method further comprising:

18. 18. The method of claim 17, further comprising the step of removing the drilling equipment from the hammer after the hole is at least partially filled with grout.

19. 1. A system for installing a load-bearing member on the seabed, comprising: Hydraulic down-the-hole hammer and a working fluid supply to which the hammer can be connected for drilling a hole of a desired depth in the seabed; a grout supply to which the hammer is connectable while disposed or positioned within the hole such that the hammer and the hole can be filled with grout; A system comprising:

20. 20. The system of claim 19, wherein the working fluid supply and the grout supply are provided at an ocean surface above the ocean floor; The system further comprises an umbilical; the hammer is connectable to the working fluid supply and the grout supply via the umbilical; system.

21. 21. The system of claim 20, wherein the working fluid is water.

22. A system according to any one of claims 19 to 21, a working fluid pump configured to provide the working fluid supply to the hammer; a grout pump configured to provide the grout supply to the hammer; A system comprising:

23. 23. The system of claim 22, a drilling device configured to rotate and provide a force to the hammer during drilling of the hole; the drilling device is connected to the hammer and lowered to the seabed by the hammer prior to drilling the hole; system.

24. A system as claimed in claim 23, wherein the hammer is a hammer as claimed in any one of claims 1 to 15.

25. 25. The system of claim 24, The hammer is a hammer according to any one of claims 1 to 15, the percussion bit has a larger diameter than the piston such that the diameter of the drilled hole is greater than the diameter of the piston and an annular cavity exists between the piston and the wall of the drilled hole; system.

26. a hydraulic down-the-hole hammer located or positioned in a hole on the seabed; a hardened grout disposed within the hammer and between the hammer and the wall of the hole, whereby the hammer is bonded to the seabed material by the grout; Underwater piles.

27. 1. A method for installing a submarine pile on a seabed, comprising the steps of: connecting one or more hydraulic down-the-hole hammers and a drilling device configured to rotate and provide force for each of the one or more hammers to the anchor frame; lowering the anchor frame to the seabed; supplying a working fluid to the or each of the hammers such that the or each of the hammers drills a hole of a desired depth into the seabed; ceasing the supply of working fluid to the or each of the hammers while the or each of the hammers is located in its respective hole; and supplying grout to the or each of the hammers to at least partially fill the or each of the hammers and the hole in which the hammer is located with grout. allowing the grout to harden such that the or each hammer is bonded to the seabed material by the grout; decoupling the drilling rig from the anchor frame; The method according to claim 1,

28. 28. A method according to claim 27, wherein the drilling device provides additional rotation and force to the or each hammer.

29. 29. The method of claim 28, wherein each hammer drill simultaneously drills a respective hole in the seabed.

30. 30. The method of claim 29, further comprising coupling a stanchion line to the anchor frame.

31. 1. A system for installing a submarine anchor on a seabed, comprising: An anchor frame; one or more down-the-hole hydraulic hammers connectable to the anchor frame and a drilling rig configured to rotate and provide a force to each of the one or more hammers; a working fluid supply to which the hammer can be connected for drilling a hole of a desired depth in the seabed; a grout supply connectable to said hammer while positioned within said hole such that said hammer and said hole can be at least partially filled with grout; A system comprising:

32. 32. The system of claim 31 , wherein the drilling rig comprises an independent feed and rotation system for each of the one or more hammers.

33. 33. The system of claim 32, wherein the working fluid supply and the grout supply are provided at an ocean surface above the ocean floor; The system further comprises an umbilical; the hammer is connectable to the working fluid supply and the grout supply via the umbilical; system.

34. 31. A method according to claim 30, wherein the or each hammer is a hammer according to claim 1.

35. 35. The system of claim 34, The or each hammer is a hammer according to any one of claims 1 to 15, the hammer or the percussion bit of the hammer has a larger diameter than the piston, such that the diameter of the drilled hole is greater than the diameter of the piston, and an annular cavity exists between the or each piston and the wall of the drilled hole; system.

36. An anchor frame provided on the seabed; one or more hydraulic down-the-hole hammers mounted in each corresponding hole in the seabed and connected to the anchor frame; hardened grout disposed within the or each of the hammers and between the hammer and a wall of each corresponding hole; the or each of the hammers is bonded by the grout; Undersea anchor.

37. 13. A hydraulic down-the-hole hammer substantially as hereinbefore described with reference to and / or as shown in any one of Figures 1 to 8 of the accompanying drawings.

38. 13. A system for installing a load bearing member as hereinbefore described with reference to and / or substantially as shown in any of Figures 9 to 12 of the accompanying drawings.

39. 13. A subsea pile substantially as hereinbefore described with reference to and / or as shown in any of Figures 12 of the accompanying drawings.

40. 13. A system for installing a submarine anchor as hereinbefore described with reference to and / or substantially as shown in any of Figures 13 to 17 of the accompanying drawings.

41. 15. A submarine anchor substantially as hereinbefore described with reference to and / or as shown in Figure 16 or 17 of the accompanying drawings.

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