Hydraulic down-the-hole hammer and subsea pile

1 . A method for installing a load-bearing element in a seabed, comprising:

drilling a hole of a desired depth in the seabed using a hydraulic down-the-hole hammer, wherein the hammer is operated by supplying working fluid to the hammer;

while the hammer is located in the hole, ceasing supply of working fluid to the hammer;

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 grout to cure such that the hammer and the grout form a load-bearing element in the seabed.

2 . The method as claimed in claim 1 , further comprising:

prior to drilling the hole, connecting a drill rig to the hammer and lowering the hammer and drill rig to the seabed; and

operating the drill rig to provide rotation and feed force to the hammer during drilling of the hole.

3 . The method as claimed in claim 2 , further comprising:

after the hole has been at least partially filled with grout, disconnecting the drill rig from the hammer.

4 . A system for installing a load-bearing element in a seabed, comprising:

a hydraulic down-the-hole hammer;

a supply of working fluid, wherein the hammer is connectable to the supply of working fluid for drilling a hole of a desired depth in the seabed;

a supply of grout, wherein the hammer is connectable to the supply of grout while located in the hole to allow the hammer and the hole to be at least partially filled with grout the hammer being sacrificially grouted in the hole.

5 . The system as claimed in claim 4 , wherein the supply of working fluid and the supply of grout are provided at a sea surface level above the seabed, the system further comprising:

an umbilical, wherein the hammer is connectable to the supply of working fluid and the supply of grout through the umbilical.

6 . The system as claimed in claim 4 , wherein the working fluid is water.

7 . The system as claimed in claim 4 , comprising:

a working fluid pump configured to provide the supply of working fluid to the hammer; and

a grout pump configured to provide the supply of grout to the hammer.

8 . The system as claimed in claim 4 , further comprising:

a drill rig configured to provide rotation and feed force to the hammer during drilling of the hole, wherein the drill rig is connected to the hammer and lowered to the seabed with the hammer prior to drilling the hole.

9 . The system as claimed in claim 4 , wherein the hammer comprises:

an elongate shaft;

a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit, wherein forward and rear drive chambers for the piston are disposed between the piston and the shaft and wherein the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore; and

a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston.

10 . The system as claimed in claim 9 , wherein the piston is an outermost component of the hammer and wherein the percussion bit has a larger diameter than the piston, such that a diameter of the drilled hole is greater than a diameter of the piston and there exists an annular cavity between the piston and a wall of the drilled hole.

11 . A subsea pile, comprising:

a hydraulic down-the-hole hammer, located in a hole in the seabed; and

cured grout arranged within the hammer and between the hammer and a wall of the hole such that the hammer is bonded to the material of the seabed by the grout.

12 . A method for installing a subsea anchor on a seabed, comprising:

connecting a drill rig and one or more down-the-hole hydraulic hammers to an anchor frame, wherein the drill rig is configured to provide a rotation and feed force to each of the one or more hammers;

lowering the anchor frame to the seabed;

supplying working fluid to the or each hammer, such that the or each hammer drills a hole of a desired depth in the seabed;

while the or each hammer is located in its respective hole, ceasing supply of working fluid to the or each hammer and supplying grout to the or each hammer to at least partially fill the hammer and the hole in which the hammer is located with grout;

allowing the grout to cure such that the or each hammer is bonded to the material of the seabed by grout; and

disconnecting the drill rig from the anchor frame.

13 . The method as claimed in claim 12 , wherein the drill rig provides a separate rotation and feed force to the or each hammer.

14 . The method as claimed in claim 12 , comprising a plurality of hammers and wherein each hammer drills its respective hole in the seabed simultaneously.

15 . The method as claimed in claim 12 , further comprising coupling a mooring line to the anchor frame.

16 . A system for installing a subsea anchor on a seabed, comprising:

an anchor frame;

a drill rig and one or more down-the-hole hydraulic hammers connectable to the anchor frame, wherein the drill rig is configured to provide a rotation and feed force to each of the one or more hammers;

a supply of working fluid, wherein the or each hammer is connectable to the supply of working fluid for drilling a hole of a desired depth in the seabed;

a supply of grout, wherein the or each hammer is connectable to the supply of grout while located in its respective hole to allow the hammer and the hole to be at least partially filled with grout, the or each hammer being sacrificially grouted in the hole.

17 . The system as claimed in claim 16 , wherein the drill rig comprises a separate feed and rotation system for each of the one or more hammers.

18 . The system as claimed in claim 16 , wherein the supply of working fluid and the supply of grout are provided at a sea surface level above the seabed, the system further comprising:

an umbilical, wherein the or each hammer is connectable to the supply of working fluid and the supply of grout through the umbilical.

19 . The system as claimed in claim 16 , wherein the or each hammer comprises:

an elongate shaft;

a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit, wherein forward and rear drive chambers for the piston are disposed between the piston and the shaft and wherein the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore; and

a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston.

20 . The system as claimed in claim 19 , wherein the piston is an outermost component of the or each hammer and wherein the percussion bit of the or each hammer has a larger diameter than the piston, such that a diameter of the or each drilled hole is greater than a diameter of the respective piston and there exists an annular cavity between the or each piston and a wall of the respective drilled hole.

21 . A subsea anchor, comprising:

an anchor frame, disposed on the seabed; and

one or more hydraulic down-the-hole hammers connected to the anchor frame, the or each hammer located in a respective hole in the seabed; and

cured grout arranged within the or each hammer and between the hammer and a wall of the respective hole such that the or each hammer is bonded to the material of the seabed by the grout.