Grout valve assembly for hydraulic down-the-hole hammer

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

[0001] GROUT VALVE ASSEMBLY FOR HYDRAULIC DOWN-THE-HOLE HAMMER

[0002] Field of the Invention

[0003] The present invention relates to a grout valve assembly or grout sub, such as may be suitable for use in grouting a bore hole. The grout valve assembly may be used with a hydraulic down-the-hole hammer to drill and grout a bore hole. The grout valve assembly of the invention allows for low pressure grouting in a bore hole.

[0004] Background to the Invention

[0005] International Patent Application Publication No. WO 2022 / 229363 discloses a hydraulic down-the-hole hammer, which may be used to install a load-bearing element or subsea pile in a seabed. This is achieved by operating the down-the-hole hammer, by supplying working fluid to the hammer, to drill a hole in the seabed. Once a desired depth has been reached, the supply of working fluid is ceased and grout is supplied to the hammer to at least partially fill the hammer and the drilled hole with grout. The grout is then allowed to cure so that the hammer and the grout together form a load-bearing element in the seabed.

[0006] In order to allow grout to flow through the drilling assembly and into the drilled hole, it is necessary that outlets or grout holes be provided in the drilling assembly. However, during drilling, working fluid must be prevented from leaking out through these grout holes. One possible solution to this problem is to provide a rupture disc or other valve arrangement that breaks or opens when subjected to a high pressure (of the order of 200 bar), that is higher than the operating pressure of the hammer, so that working fluid is prevented from leaking out through the grout holes during drilling operation. Grouting is then undertaken at a high pressure sufficient to rupture the disc or open the valve, thereby allowing grout to flow through the grout holes. However, there are a number of disadvantages associated with grouting at such high pressures. High pressure grouting may disrupt the seabed. Also, where a number of load-bearing elements are to be installed in the seabed, high pressure grouting may disturb the curing of nearby holes that have already been grouted. It is therefore desirable to provide an arrangement that allows drilling to be performed at high pressure without any risk that working fluid will leak out through grout holes in the drilling assembly and that allows grouting to be performed to be performed at low pressures, of the order of 1 to 2 bar.

[0007] In other arrangements, separate drilling and grouting devices may be used for drilling and grouting, respectively, of a bore hole to form a load-bearing element or subsea pile. It is also desirable to provide an arrangement that allows for low pressure grouting of such bore holes.

[0008] Summary of the Invention

[0009] The present invention relates to a grout valve assembly (or grout sub) comprising: a body having a central bore therethrough; a grout valve, comprising a moveable member (or valve disc) mounted in a valve chamber in the central bore, the moveable member comprising a central fluid passage therethrough; at least one grout outlet extending from the central bore to an outer surface of the grout valve assembly; wherein the moveable member is biased in a rearward direction to a closed position in which the at least one grout outlet is obstructed by the moveable member and wherein fluid supplied to the assembly flows through the central bore and the central fluid passage and acts on a forward pressure area of the moveable member to urge the moveable member in the rearward direction to the closed position; the grout valve assembly further comprising an opening member, insertable into the central bore to occlude the central fluid passage of the moveable member, thereby opening the valve.

[0010] When the opening member is inserted into the central bore of the grout valve assembly, fluid supplied to the assembly may urge the moveable member in a forward direction from the closed position to an open position in which the grout outlets are in fluid communication with the central bore. Preferably, the at least one grout outlet is provided at a rear end of the valve chamber, the at least one grout outlet extending from the central bore to an outer surface of the grout valve assembly. In other embodiments, the at least one grout outlet may be provided at an alternate location, for example, at a position intermediate a forward and a rear end of the valve chamber.

[0011] The terms “closed” and “open” used herein relate to the status of the at least one grout outlet. The term “closed position” used herein may refer to a position of the moveable member in which fluid is prevented from flowing from the central bore to the at least one grout outlet. In this position of the moveable member, fluid is permitted to flow through the grout valve assembly through the central fluid passage of the moveable member, for example, to a downstream element of an assembly into which the grout sub may be incorporated. The term “open position” used herein may refer to a position of the moveable member in which fluid is permitted to flow from the central bore to the at least one grout outlet. In this position of the moveable member, fluid may not be permitted to flow through the central fluid passage of the moveable member, due to the occlusion of the central fluid passage by the opening member.

[0012] The grout valve assembly may be suitable for use in an assembly for grouting a bore hole, for example, in the sea bed. In particular, the grout valve assembly may be suitable for use in a grouting assembly for grouting a bore hole, or in a drilling assembly for drilling and grouting a bore hole.

[0013] The central bore of the assembly may be arranged to supply fluid downstream of the valve assembly, for example, to a down-the-hole hammer or to one or more downstream elements of a grouting assembly. That is, when the moveable member is in the closed position, fluid supplied to the assembly flows through the central bore and the central fluid passage, to supply fluid downstream of the valve assembly, for example to a hammer or to one or more downstream elements of a grouting assembly.

[0014] The term “forward” is used herein to indicate an end of the assembly that is towards the front of the assembly, or lower when in use, for example, in a bore hole. Where the grout valve assembly is used with a down-the-hole hammer, “forward” indicates an end of the assembly towards a percussion bit of the hammer, that is, the drilling end of the hammer. The term “rear” is used herein to indicate an end of the assembly which is towards the back of the assembly, or higher when in use, for example, in a bore hole. Where the grout valve assembly is used with a down-the-hole hammer, “rear” indicates an end of the assembly away from the percussion bit, that is, an end of the assembly that is uppermost during drilling. The term “upstream” is used herein to indicate an element or an end of an assembly that is closer to a supply of fluid. The term “downstream” is used herein to indicate an end of the assembly that is further from the supply of fluid.

[0015] The moveable member is biased toward the closed position, so that the valve is initially closed, for example, prior to commencement of drilling. In the closed (or drilling) position of the moveable member, fluid supplied to the grout valve assembly flows through the central fluid passage of the moveable member, for example, to a downstream element of an assembly into which the grout sub may be incorporated. Where the grout valve assembly is incorporated into a drilling assembly, working fluid may be supplied to the drilling assembly, to flow through the grout valve assembly to operate the hammer. At least a portion of the fluid supplied to the assembly acts on the moveable member to urge it to the drilling position. Thus, once drilling begins, the moveable member is maintained in the closed position by the fluid acting on the moveable member. An advantage of this arrangement is that the valve is maintained in a closed position, in which the at least one grout outlet is obstructed by the moveable member of the valve, by fluid supplied to the assembly acting on the moveable member. Thus, when the grout valve assembly is being used in a drilling assembly, accidental opening of the valve is avoided, thereby preventing working fluid from leaking out of the drilling assembly via the grout outlet(s).

[0016] The forward pressure area of the moveable member may comprise a forward end face of the moveable member. The end face of the moveable member may be annular. The moveable member may be arranged in the valve chamber such that there exists a fluid path, at the forward end of the moveable member, that allows fluid is supplied to the assembly to act on the (annular) end face of the moveable member to urge the moveable member in the rearward direction to the drilling position. According to this arrangement, an area of the forward pressure area is greater than an area of a rear pressure area of the moveable member such that fluid flowing through the moveable member exerts a net rearward force on the moveable member.

[0017] Alternatively or additionally, a shoulder may be provided on an outer surface of the moveable member. The shoulder may be an outwardly directed shoulder with a forwardly-directed face. The forward pressure area of the moveable member may comprise the forwardly-directed face of the shoulder. The forwardly-directed face of the shoulder may be annular. The valve chamber and the shoulder may form a forward pressure chamber for the valve. Thus, fluid supplied to the assembly enters the forward pressure chamber and acts on the shoulder to urge the moveable member in the rearward direction to the drilling position.

[0018] The grout valve assembly may further comprise at least one port provided in the moveable member, the at least one port extending from the central fluid passage to the outer surface of the moveable member forward of the shoulder. The at least one port may provide a fluid path between the central fluid passage and a forward portion of the valve chamber.

[0019] The opening member is preferably shaped and / or dimensioned to fully occlude the central fluid passage of the moveable member when inserted into the central bore of the assembly. The opening member may be shaped and / or dimensioned to form a sealing engagement with the moveable member. Preferably, the opening member is spherical, for example, a steel ball. In other embodiments, the opening member may be bulletshaped, or otherwise. An outer diameter of the opening member may be greater than an inner diameter of the central fluid passage of the moveable member.

[0020] The central fluid passage of the moveable member may comprise a counterbore at a rear end thereof. The opening member may be received in the counterbore to form the sealing engagement with the moveable member. An outer diameter of the opening member may be substantially equal to an inner diameter of the counterbore.

[0021] An advantage of this arrangement is that, when the opening member is inserted into the grout sub, fluid (such as grout) subsequently supplied to the assembly is prevented from entering the central fluid passage of the grout valve and instead acts on the moveable member to urge it forward, thereby opening the grout outlet(s) to allow grout to flow into the hole. Unlike prior art arrangements, it is not necessary to supply the grout at high pressure in order to open the valve.

[0022] The grout valve assembly may further comprise a biasing element arranged in the valve chamber, wherein the biasing element is arranged to bias the moveable member in the rearward direction to the closed position in which fluid flows through the central fluid passage of the moveable member. When used in an assembly for grouting a bore hole, the closed position of the moveable member opposes gravity, and the biasing element ensures that the moveable member is initially biased toward the closed position. For example, where the grout valve assembly is used in a drilling assembly for drilling and grouting a bore hole, the moveable member is initially biased to the drilling or closed position, prior to commencement of drilling, thereby avoiding leakage of working fluid from the grout outlet(s) during drilling. Once drilling begins, the moveable member is maintained in the drilling (closed) position by the biasing element and the fluid acting on the moveable member, as described above. The biasing element may be a spring, for example, a helical spring. The spring may be arranged in the valve chamber around the moveable member. Where the moveable member comprises a shoulder on the outer surface thereof, the biasing element may be arranged to act against the shoulder to bias the moveable member in the rearward direction.

[0023] The biasing arrangement ensures that the grout outlet(s) are closed when the hammer is not in operation. In grout valves where a spring alone is used to maintain the valve in a closed or drilling position, the spring must be stiff enough that the pressure required to overcome the spring bias is relatively high, so that the grout valve can only be opened when grout is supplied at high pressure. However, with the present arrangement, both the working fluid and the bias provided by the spring or biasing element act together to keep the valve closed when high pressure working fluid is supplied to the hammer. This allows a lower stiffness of the spring or biasing element to be used, as compared with valves where the spring alone is required to keep the valve closed. The stiffness of the spring or biasing element may therefore be selected such that the bias can be overcome by grout supplied at a lower pressure, of the order of 1 to 2 bar, thereby facilitating low pressure grouting. This avoids disadvantages associated with high pressure grouting, such as disrupting the seabed and / or preventing curing of grout in nearby holes.

[0024] According to another aspect of the invention, there is provided a drilling assembly comprising a hydraulic down-the-hole hammer connectable to a supply of working fluid for drilling a bore hole of a desired depth and connectable to a supply of grout while located in the bore hole to allow the hole to be at least partially filled with grout, the drilling assembly further comprising a grout valve assembly according to any of the above-described embodiments, upstream of the hammer. A working fluid of the hammer may be water. The hammer may be a disposable, sacrificial or single-use hammer, in which case the hammer may also be at least partially filled with grout during the grouting process.

[0025] The drilling assembly may further comprise a backhead assembly, and the grout valve assembly may be integrally formed with the backhead assembly. In other embodiments, the grout valve assembly may be a separate element, connectable to the hammer. For example, the grout valve assembly may be provided upstream of the backhead assembly. The hammer may be connectable to the supply of working fluid and to the supply of grout via the grout valve assembly.

[0026] According to a further aspect of the invention, there is provided a method for operating a drilling assembly, comprising: drilling a hole of a desired depth using a drilling assembly, wherein the drilling assembly is a drilling assembly as described above and wherein the hammer of the drilling assembly is operated by supplying working fluid to the hammer via the grout valve assembly.

[0027] The method may further comprise: while the hammer is located in the hole, ceasing supply of working fluid to the hammer; inserting the opening member into the central bore of the grout valve assembly to occlude the central fluid passage of the moveable member and open the grout valve; supplying grout to the drilling assembly, wherein grout supplied to the drilling assembly urges the moveable member in a forward direction from the closed position to the open position, in which the at least one grout outlet is in fluid communication with the central bore to at least partially fill the hole in which the hammer is located with grout.

[0028] According to another aspect of the present invention, there is provided a grout valve assembly (or grout sub) for a hydraulic down-the-hole hammer, the grout valve assembly comprising: a body having a central bore therethrough, for supply of fluid to the hammer; a grout valve, comprising a moveable member (or valve disc) mounted in a valve chamber in the central bore; at least one grout outlet extending through the body from the central bore to an outer surface of the grout valve assembly; wherein the moveable member is biased in a rearward direction to a drilling (or closed) position in which the at least one grout outlet is obstructed by the moveable member; and wherein the moveable member comprises a central fluid passage therethrough for supply of fluid to the hammer and wherein a fluid path extends between the central fluid passage and a forward portion of the valve chamber such that, when (pressure) fluid is supplied to the assembly, for example, during drilling, a portion of the fluid supplied to the assembly flows from the central fluid passage into the forward portion of the valve chamber to urge the moveable member in the rearward direction to the drilling position.

[0029] According to an aspect of the present invention, there is provided a grouting assembly for grouting a bore hole, comprising: at least one elongate pipe section, having a central bore therethrough; and at least one grout valve assembly as described above, upstream of the at least one elongate pipe section, the central bore of the grout valve assembly coaxially arranged with the central bore of the elongate pipe section. The grouting assembly may be used for jet grouting of a bore hole. For example, flushing fluid may initially be supplied to the bore hole via the grout valve assembly and the elongate pipe section to flush debris from the hole. Grout may then be supplied to the bore hole via the grout valve assembly and the elongate pipe section to fill a lowermost portion of the bore hole with grout. The opening member may then be inserted into the grouting assembly to occlude the central fluid passage of the grout valve assembly, thereby causing the valve to open as described above. Grout subsequently supplied to the grouting assembly will flow out of the grout outlets of the grout valve assembly to fill an upper portion of the bore hole with grout.

[0030] In some embodiments, the grouting assembly may comprise a plurality of elongate pipe sections and a corresponding plurality of grout valve assemblies, each grout valve assembly arranged upstream of the corresponding pipe section and the central bore of each grout valve assembly coaxially arranged with the central bore of each elongate pipe section. The central fluid passage of each grout valve assembly may have a larger inner diameter than a grout valve assembly immediately downstream thereof. The opening member of each grout valve assembly may be dimensioned to occlude the central fluid passage of the moveable member of that grout valve assembly, but may be dimensioned to pass through the central fluid passage of the moveable member of each upstream grout valve assembly and the central bore of each upstream pipe section.

[0031] An advantage of this arrangement is that the bore hole may be filled with grout by initially supplying grout through the grouting assembly with all of the valves in the closed position to fill a lowermost portion of the bore hole with grout. Next, the opening member for the lowermost (furthest downstream) grout valve assembly may be inserted into the grouting assembly. This opening member is dimensioned to pass through the central fluid passage of the moveable member of each upstream grout valve assembly and the elongate pipe sections, but is dimensioned to occlude the central fluid passage of the moveable member of the lowermost (furthest downstream) grout valve assembly. Grout subsequently supplied to the grouting assembly will flow out of the grout outlets of the lowermost grout valve assembly to fill a second portion of the bore hole with grout. Sequentially larger opening members may each be inserted into the grouting assembly in turn so that the grout valve assemblies are opened to allow grout to flow out of the grout outlets of each of the grout valve assemblies in turn.

[0032] Brief Description of the Drawings

[0033] Figure l is a cross-sectional view of a grout valve assembly according to an aspect of the present invention, where the valve is in a closed position;

[0034] Figure 2 is a cross-sectional view of the grout valve assembly of Figure 1, where the valve is in an open or grouting position;

[0035] Figure 3 is a cross-sectional view of a drilling assembly according to an aspect of present invention;

[0036] Figure 4 is cross-sectional view of a grout valve assembly of the drilling assembly of Figure 3, where the valve is in a drilling or closed position;

[0037] Figure 5 is a cross-sectional view of the grout valve assembly of Figure 4, where the valve is in a grouting or open position; and

[0038] Figure 6 is a cross-sectional view of a grouting assembly, according to an aspect of the invention.

[0039] Detailed Description of the Drawings

[0040] A grout valve assembly or grout sub 100 suitable for use in an assembly for grouting a bore hole, in accordance with an aspect of the invention is shown in Figures 1 and 2. The grout valve assembly comprises a generally cylindrical body 101 having a central bore 102 therethrough, for supply of fluid downstream of the grout valve assembly. For example, the grout valve assembly may be provided in a drilling assembly, upstream of a down-the-hole hammer. Alternatively, the grout valve assembly may be provided in a grouting assembly and fluid may be supplied through the assembly to flush a bore hole prior to grouting, or to grout a lower portion of the bore hole.

[0041] The grout valve assembly also comprises a grout valve 103, comprising a moveable member or valve disc 104 mounted in a valve chamber 114 in the central bore. In the embodiment shown, a hollow spacer 117 is disposed in the central bore 102, upstream of the moveable member, to the rear of the valve chamber. The grout valve assembly further comprises a plurality of grout outlets 105 at a rear end 106 of the valve chamber. The grout outlets extend radially through the body 101 from the central bore 102 to an outer surface 107 of the grout valve assembly and are spaced apart around a circumference of the body. The moveable member 104 is slidably mounted in the valve chamber and is axially moveable between a rearward or closed position, shown in Figure 1, and a forward or open position, shown in Figure 2. Where the grout valve assembly is provided in a drilling assembly, the closed position may correspond to a drilling position, in which working fluid flows through the grout valve assembly to operate the hammer, and the open position may correspond to a grouting position, in which grout flows through the grout outlets to grout a hole drilled by the drilling assembly.

[0042] In the embodiment shown in Figure 1, a shoulder 111 is provided on an outer surface 112 of the moveable member. The shoulder 111 may be an outwardly directed annular shoulder. A portion of the moveable member forward of the shoulder 111 has a reduced outer diameter as compared with a rear portion of the moveable member, such that a spring chamber portion 110’ is provided around the forward portion of the moveable member. A spring 120 is arranged in the spring chamber portion 110’ of the valve chamber 114. The spring is arranged to act on the shoulder 111 to bias the moveable member in a rearward direction to the closed position in which the grout outlets 105 are obstructed by the moveable member, so that the grout valve is closed. In the embodiment shown, the spring is a helical spring arranged around a forward portion of the moveable member 104. In other embodiments, the bias may be provided by alternate means.

[0043] The moveable member comprises a central fluid passage 108 therethrough for supply of fluid downstream of the grout valve assembly. Fluid supplied to the assembly flows through the central fluid passage and into a forward portion of the valve chamber, which forms a forward pressure chamber 110 for the valve. That is, there exists a fluid path, at the forward end of the moveable member, between the central fluid passage and the forward pressure chamber, such that, when fluid is supplied to the assembly, it acts on a forward pressure face 113 of the moveable member to urge the moveable member in the rearward direction to the drilling position. In the embodiment shown, the forward pressure face 113 is an annular surface at a forward end of the moveable member.

[0044] In the embodiment shown in Figures 1 and 2, a plurality of ports 109 extend between the central fluid passage and the spring chamber 110’. The ports 109 extend radially through the moveable member from the central fluid passage 108 to the outer surface 112 of the moveable member. The ports 109 provide additional fluid paths between the central fluid passage and the spring chamber 110’, which also acts as an additional forward pressure chamber for the valve. A portion of the fluid supplied to the assembly flows from the central fluid passage into the additional forward pressure chamber 110’ via the ports 109 to act on a forwardly-directed pressure face 113’ of the shoulder 111 to urge the moveable member in the rearward direction to the drilling position. The ports 109 also allow fluid to flow from the spring chamber 110’ to the central fluid passage 108 when the valve moves from the closed to the open position. In other embodiments, the ports 109 may be omitted.

[0045] The central fluid passage 108 of the moveable member is formed with a counterbore 121 at a rear end thereof. The counterbore 121 has an increased internal diameter as compared with a forward portion of the central fluid passage. An inwardly directed shoulder is formed at a forward end of the counterbore 121, the shoulder having a rearwardly-directed pressure face 116’.

[0046] When the moveable member 104 is in the closed position as shown in Figure 1, a locking face 119 of the moveable member is seated on a valve seat 118 of spacer 117. Fluid supplied to the grout valve assembly flows downstream through the central fluid passage 108 of the moveable member. As described above, fluid supplied to the assembly acts on pressure faces 113 and 113’ of the moveable member to urge it to the drilling position. A combined area of the pressure faces 113 and 113’ is greater than a combined area of rear annular pressure faces 116 and 116’ of the moveable member such that fluid flowing through the moveable member exerts a net rearward force on the moveable member. In the embodiment shown, the closed position of the moveable member opposes gravity. That is, in order for the valve to be closed, the moveable member must be in its uppermost position in the valve chamber. The spring ensures that the moveable member is biased upwards to the closed position when the grout valve assembly is disposed in a bore hole, thereby avoiding leakage of fluid (such as flushing fluid, grout or working fluid for a hammer) from the grout outlets. When fluid is supplied to the grout valve assembly, the moveable member is maintained in the closed position by both the spring and the fluid acting on the moveable member. Thus, fluid supplied to the assembly and the bias provided by the spring act together to keep the valve closed when fluid is supplied to the assembly.

[0047] Referring now to Figure 2, the grout valve assembly further comprises an opening member 115. In the embodiment shown, the opening member is a steel ball, but other shapes and materials may be chosen to provide an opening member that is shaped and / or dimensioned to fully occlude the central fluid passage of the moveable member when inserted into the central bore of the assembly. A spherical opening member is particularly suitable, since regardless of how it is inserted, it will be correctly oriented to occlude the central fluid passage of the valve. In the embodiment shown, an outer diameter of the ball is larger than an inner diameter of the forward portion central fluid passage 108 of the moveable member. The outer diameter of the ball is substantially equal to the inner diameter of the counterbore 121, so that the ball is received in the counterbore. The diameter of the ball is also selected to be smaller than an inner diameter of upstream elements of an assembly in which the grout valve assembly is disposed.

[0048] When the grout valve is to be opened, the ball 115 is inserted into the central bore 102 to occlude the central fluid passage 108 of the moveable member. When inserted into the central bore 102, the ball 115 is received within the counterbore 121 and forms a sealing engagement with the moveable member, such that fluid, such as grout, supplied to the assembly is prevented from entering the central fluid passage 108 of the moveable member. The fluid (grout) pressure then acts on the ball and urges the moveable member in a forward direction. The moveable member moves forwards off the valve seat 118 of the spacer 117, to an open (or grouting) position in which the grout outlets 105 are in fluid communication with the central bore 102. Grout may be supplied to the drilling assembly at relatively low pressure, to flow out through the grout outlets 105 to at least partially fill a bore hole in which the assembly is disposed. Because the effective rear pressure face area is increased by insertion of the opening member into the assembly, unlike prior art arrangements, it is not necessary to supply the grout at high pressure in order to open the valve.

[0049] In the embodiment shown in Figures 1 and 2, the grout outlets are provided at a rear end of the valve chamber, extending from the central bore to an outer surface of the grout valve assembly. In alternate embodiments, the at least one grout outlet may be provided at an alternate location, for example, at a position intermediate a forward and a rear end of the valve chamber. The grout outlets may intersect the spring chamber forward of the shoulder on the moveable member. In such embodiments, the moveable member and the valve chamber may be configured such that there is a clearance between the valve chamber and an outer surface of a rear portion of the moveable member. Thus, when the moveable member moves to the forward or open position, fluid flows from the central bore around an outer surface of the moveable member into the valve chamber and through the grout outlets.

[0050] A drilling assembly 1 according to an aspect of the invention is illustrated in Figure 3. The drilling assembly comprises a hydraulic down-the-hole hammer 300 connectable to a supply of working fluid for drilling a hole of a desired depth and connectable to a supply of grout while located in the hole to allow the hole to be at least partially filled with grout. The drilling assembly further comprises a grout valve assembly 100, similar to that shown in Figures 1 and 2, which will be described in further detail below. In the embodiment shown, the working fluid of the down-the-hole hammer is water. The hammer shown in Figure l is a disposable, sacrificial or single-use hammer that is intended to remain in the drilled hole once grouting is complete. The hammer may be partially filled with grout during the grouting process. In other embodiments, the hammer may be removed from the hole after grouting. The drilling assembly may also comprise one or more drill rods 400. In the embodiment shown in Figure 1, the grout valve assembly 100 is integrally formed with a backhead assembly 200 for the hammer 300. In other embodiments, the grout valve assembly may be a separate element. For example, the grout valve assembly may be provided upstream of the backhead assembly. Working fluid and / or grout are supplied via the grout valve assembly 100.

[0051] The hammer 300 comprises an elongate shaft 312 formed with a central bore 314. 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 arranged to impact 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, and the percussion bit 309 is arranged at a forward end 318 of the wear sleeve. In other embodiments, the hammer 300 may not include an outer sleeve, so that the piston 301 is the outermost component of the hammer.

[0052] Forward 302 and rear 303 drive chambers for the piston are disposed between the piston 301 and the shaft 312. An annular shoulder 313 on the piston formed internally of the piston bore 310 separates the forward chamber 302 from the rear chamber 303. In this embodiment, an internal diameter of the piston 301 to the rear of the shoulder 313 is smaller than the internal diameter of the piston forward of the shoulder, such that the forward chamber has a larger driving area than the rear chamber.

[0053] The hammer also comprises a control valve 305 arranged within the central bore 314 of the shaft to control reciprocation of the piston. In other embodiments, the valve 305 may be arranged within the central bore 310 of the piston, between the piston and the shaft.

[0054] The hammer 300 is an open-loop hammer in which working fluid is provided to the hammer via a pressure line. The pressure fluid is supplied via backhead assembly 200 and grout valve assembly 100, as described in further detail below. The working fluid is also used for flushing flow through the central bore 314 of the shaft and the percussion bit 309 to exit via flushing channels 308 at the bit face 319. The rear chamber 303 is connected to the pressure fluid channel so that there is a constant pressure in the rear chamber. The control valve 305 is arranged to connect the forward chamber 302 to the rear chamber 303 while the piston is moving in a rearward direction and to connect the forward chamber 302 to a flushing fluid channel through the central bore of the shaft and the percussion bit when the piston is moving in a forward direction, so that there is an alternating pressure in the forward chamber 302.

[0055] The grout valve assembly or grout sub 100 is shown in further detail in Figures 4 and 5. The grout valve assembly comprises a generally cylindrical body 101 having a central bore 102 therethrough, for supply of fluid to the hammer. The grout valve assembly also comprises a grout valve 103, comprising a moveable member or valve disc 104 mounted in a valve chamber 114 in the central bore. In the embodiment shown, a hollow spacer 117 is disposed in the central bore 102.

[0056] The grout valve assembly further comprises a plurality of grout outlets 105 at a rear end 106 of the valve chamber. The grout outlets extend radially through the body 101 from the central bore 102 to an outer surface 107 of the grout valve assembly and are spaced apart around a circumference of the body. In the embodiment shown, grout outlets 320 are also provided in the outer wear sleeve 317. The moveable member 104 is slidably mounted in the valve chamber and is axially moveable between a rearward, closed or drilling position, shown in Figure 4, and a forward, open or grouting position, shown in Figure 5. The closed position corresponds to a drilling position, in which working fluid flows through the grout valve assembly to operate the hammer, and the open position corresponds to a grouting position, in which grout flows through the grout outlets to grout a hole drilled by the drilling assembly.

[0057] As described above with reference to the embodiment shown in Figures 1 and 2, a shoulder Il l is provided on an outer surface 112 of the moveable member. A spring 120 is arranged in the spring chamber portion 110’ of the valve chamber 114. The spring is arranged to bias the moveable member in a rearward direction to the drilling or closed position in which the grout outlets 105 are obstructed by the moveable member, so that prior to commencement of drilling, the grout valve is closed.

[0058] In the embodiment shown in Figures 3 to 5, the closed position of the moveable member opposes gravity. That is, in order for the valve to be closed, the moveable member must be in its uppermost position in the valve chamber. The spring ensures that the moveable member is biased upwards to the drilling position prior to commencement of drilling, thereby avoiding leakage of working fluid from the grout outlets during drilling. Once drilling begins, the moveable member is maintained in the closed position by both the spring and the fluid acting on the moveable member, as described in more detail below.

[0059] As also described above with reference to Figures 1 and 2, the moveable member comprises a central fluid passage 108 therethrough for supply of fluid to the hammer. Fluid supplied to the assembly flows through the central fluid passage and into a forward portion of the valve chamber, which forms a forward pressure chamber 110 for the valve. That is, there exists a fluid path, at the forward end of the moveable member, between the central fluid passage and the forward pressure chamber, such that, when fluid is supplied to the assembly, it acts on a forward pressure face 113 of the moveable member to urge the moveable member in the rearward direction to the drilling position. In the embodiment shown in Figures 3 to 5, the forward pressure face 113 is an annular surface at a forward end of the moveable member.

[0060] As described above with reference to Figures 1 and 2, ports 109 extend between the central fluid passage and the spring chamber 110’. The ports 109 provides additional fluid paths between the central fluid passage and the spring chamber 110’, which also acts as an additional forward pressure chamber for the valve, such that, when fluid is supplied to the assembly, for example, during drilling, a portion of the fluid supplied to the assembly flows from the central fluid passage into the additional forward pressure chamber 110’ to urge the moveable member in the rearward direction to the drilling position.

[0061] When the moveable member 104 is in the drilling (or closed) position as shown in Figure 4, a locking face 119 of the moveable member is seated on a valve seat 118 of spacer 117. Fluid supplied to the grout valve assembly flows through the central fluid passage 108 of the moveable member to the control valve 305 to operate the hammer. A portion of the fluid supplied to the assembly acts on the moveable member to urge it to the drilling position. Thus, once drilling begins, both the working fluid and the bias provided by the spring act together to keep the valve closed when high pressure working fluid is supplied to the hammer, so that the moveable member is maintained in the drilling (closed) position by the fluid acting on the moveable member.

[0062] Referring now to Figure 5, the grout valve assembly further comprises an opening member 115. In the embodiment shown, the opening member is a steel ball, but other shapes and materials may be chosen to provide an opening member that is shaped and / or dimensioned to fully occlude the central fluid passage of the moveable member when inserted into the central bore of the assembly. A spherical opening member is particularly suitable, since regardless of how it is inserted, it will be correctly oriented to occlude the central fluid passage of the valve. In the embodiment shown, an outer diameter of the ball is larger than an inner diameter of the central fluid passage 108 of the moveable member.

[0063] When the grout valve is to be opened, the ball 115 is inserted into the central bore 102 to occlude the central fluid passage 108 of the moveable member. When inserted into the central bore 102, the ball 115 forms a sealing engagement with the moveable member, so that such that fluid, such as grout, supplied to the assembly is prevented from entering the central fluid passage 108 of the moveable member. The grout pressure then acts on the ball and urges the moveable member in a forward direction. The moveable member moves forwards off the valve seat 118 of the spacer 117, to a grouting or open position in which the grout outlets 105 are in fluid communication with the central bore 102. Grout may be supplied to the drilling assembly at relatively low pressure, to flow out through the grout outlets 105 and 320 to at least partially fill a drilled hole. Unlike prior art arrangements, it is not necessary to supply the grout at high pressure in order to open the valve.

[0064] The drilling assembly 1 may be used to perform a method according to the present invention. First, the hammer 300 may be operated to drill a hole of a desired depth, by supplying water to the hammer via the backhead assembly 200. The grout valve is initially in the closed position due to the bias provided by the spring 120. During drilling, the grout valve remains closed due to the spring bias and the water acting on the moveable member to urge it in a rearward direction. Water therefore flows through the grout valve to the hammer, allowing drilling to take place in the usual manner. While the hammer is located in the hole, the supply of water to the hammer is ceased. The ball 115 is then inserted into the central bore 102 of the grout valve assembly 100 to occlude the central fluid passage 108 of the moveable member 104. Grout is then supplied to the drilling assembly, which urges the moveable member in a forward direction from the drilling position to a grouting position in which the grout outlets are in fluid communication with the central bore. The grout supplied to the assembly flows through the grout outlets 105 and 320 to at least partially fill the hole in which the hammer is located with grout. As the hammer is a disposable hammer, the hammer remains in the hole when grouting is completed, and may form a subsea pile or other load-bearing element with the grout, once cured.

[0065] A grouting assembly 600, according to an aspect of the invention, is illustrated in Figure 6. The grouting assembly 600 comprises a plurality of elongate pipe sections 601, 601’, 601”, 601”’. The grouting assembly also comprises a corresponding plurality of grout valve assemblies 100, 100’, 100”, 100’”. Each grout valve assembly may correspond to the grout valve assembly described above with reference to Figures 1 and 2. Each grout valve assembly 100 is arranged upstream of the corresponding pipe section 601. The central bore of each grout valve assembly is coaxially arranged with a central bore of each elongate pipe section.

[0066] The central fluid passage of each grout valve assembly 100’, 100”, 100’” has a larger inner diameter than the grout valve assembly immediately downstream thereof. Thus, in the embodiment shown, the uppermost grout valve assembly 100’” has a central fluid passage with the largest inner diameter, with the central fluid passages of each of grout valves assemblies 100”, 100’ and 100 being progressively smaller towards the bottom of the grouting assembly (to the right as shown in Figure 6). Thus, the lowermost grout valve assembly 100 has a central fluid passage with the smallest inner diameter.

[0067] The opening member of each grout valve assembly is dimensioned to occlude the central fluid passage of the moveable member of that grout valve assembly, but is dimensioned to pass through the central fluid passage of the moveable member of each upstream grout valve assembly and the central bore of each upstream pipe section. The grouting assembly 600 may be used for jet grouting of a bore hole. In one example, flushing fluid may initially be supplied to the bore hole via the grout valve assemblies 100, 100’, 100”, 100’” and the elongate pipe sections 601, 601’, 601”, 601’” to flush debris from the hole. Grout may then be supplied to the bore hole via the grouting assembly to fill a lowermost portion of the bore hole with grout. The opening member for grout valve assembly 100 may then be inserted into the grouting assembly. This opening member may pass through each of the grout valve assemblies 100’, 100” and 100’” and the elongate pipe sections to occlude the central fluid passage of grout valve assembly 100, thereby causing the valve of grout valve assembly 100 to open as described above. Grout subsequently supplied to the grouting assembly will flow out of the grout outlets of the grout valve assembly 100 to fill a next portion of the bore hole with grout.

[0068] Next, opening member for grout valve assembly 100’ may be inserted into the grouting assembly. This opening member may pass through each of the grout valve assemblies 100” and 100’” and the corresponding elongate pipe sections to occlude the central fluid passage of grout valve assembly 100’, thereby causing the valve of grout valve assembly 100’ to open as described above. Grout subsequently supplied to the grouting assembly will flow out of the grout outlets of the grout valve assembly 100’ to fill a next portion of the bore hole with grout. This process may be repeated for grout valve assemblies 100” and 100’”, until the entire bore hole has been filled with grout.

[0069] The words “comprises / comprising” and the words “having / including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0070] It is 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 sub-combination.

Claims

Claims1. A grout valve assembly comprising: a body having a central bore therethrough; a grout valve, comprising a moveable member mounted in a valve chamber in the central bore, the moveable member comprising a central fluid passage therethrough; at least one grout outlet extending from the central bore to an outer surface of the grout valve assembly; wherein the moveable member is biased in a rearward direction to a closed position in which the at least one grout outlet is obstructed by the moveable member and wherein fluid supplied to the assembly flows through the central bore and the central fluid passage and acts on a forward pressure area of the moveable member to urge the moveable member in the rearward direction to the closed position; the grout valve assembly further comprising an opening member, insertable into the central bore to occlude the central fluid passage of the moveable member such that fluid supplied to the assembly urges the moveable member in a forward direction from the closed position to an open position in which the grout outlets are in fluid communication with the central bore.

2. A grout valve assembly as claimed in claim 1, wherein the forward pressure area of the moveable member comprises an annular end face of the moveable member.

3. A grout valve assembly as claimed in claim 1 or claim 2, further comprising a shoulder provided on an outer surface of the moveable member, wherein the forward pressure area comprises a forwardly-directed annular face of the shoulder.

4. A grout valve assembly as claimed in any of claims 1 to 3, wherein an area of the forward pressure area is greater than an area of a rear pressure area of the moveable member such that fluid flowing through the moveable member exerts a net rearward force on the moveable member.

5. A grout valve assembly as claimed in claim 3 or claim 4, further comprising at least one port provided in the moveable member, the at least one port extending from the central fluid passage to the outer surface of the moveable member forward of the shoulder, wherein the at least one port provides a fluid path between the central fluid passage and a forward portion of the valve chamber.

6. A grout valve assembly as claimed in any preceding claim, wherein the opening member is spherical.

7. A grout valve assembly as claimed in any preceding claim, further comprising a biasing element arranged in the valve chamber, wherein the biasing element is arranged to bias the moveable member in the rearward direction to the closed position.

8. A grout valve assembly as claimed in any preceding claim, wherein the grout valve assembly is integrally formed with a backhead assembly of a down-the-hole hammer.

9. A grout valve assembly for a hydraulic down-the-hole hammer, the grout valve assembly comprising: a body having a central bore therethrough, for supply of fluid to the hammer; a grout valve, comprising a moveable member mounted in a valve chamber in the central bore; at least one grout outlet extending from the central bore to an outer surface of the grout sub; wherein the moveable member is biased in a rearward direction to a drilling position in which the at least one grout outlet is obstructed by the moveable member; and wherein the moveable member comprises a central fluid passage therethrough for supply of fluid to the hammer and wherein a fluid path extends between the central fluid passage and a forward portion of the valve chamber such that, when fluid is supplied to the assembly, a portion of the fluid supplied to the assembly flows through the central fluid passage into the forward portion of the valve chamber to urge the moveable member in the rearward direction to the drilling position.

10. A drilling assembly, comprising a hydraulic down-the-hole hammer connectable to a supply of working fluid for drilling a hole of a desired depth and connectable to a supply of grout while located in the hole to allow the hole to be at least partially filled with grout, the drilling assembly further comprising a grout valve assembly as claimed in any preceding claim, upstream of the hammer.

11. A drilling assembly as claimed in claim 10, wherein a working fluid of the hammer is water.

12. A method for operating a drilling assembly, comprising: drilling a hole of a desired depth using a drilling assembly as claimed in claim 10 or claim 11, wherein the hammer of the drilling assembly is operated by supplying working fluid to the drilling assembly via the grout valve assembly.

13. A method as claimed in claim 12, further comprising: while the hammer is located in the hole, ceasing supply of working fluid to the hammer; inserting the opening member into the central bore of the grout valve assembly to occlude the central fluid passage of the moveable member and open the grout valve; supplying grout to the drilling assembly, wherein grout supplied to the drilling assembly urges the moveable member in a forward direction from the closed position to the open position, in which the at least one grout outlet is in fluid communication with the central bore to at least partially fill the hole in which the hammer is located with grout.

14. A grouting assembly for grouting a bore hole, comprising: at least one elongate pipe section, having a central bore therethrough; at least one grout valve assembly as claimed in any of claims 1 to 8, upstream of the at least one elongate pipe section, the central bore of the grout valve assembly coaxially arranged with the central bore of the elongate pipe section.

15. A grouting assembly as claimed in claim 14, comprising: a plurality of elongate pipe sections; and a corresponding plurality of grout valve assemblies as claimed in any of claims 1 to 8, each grout valve assembly arranged upstream of the corresponding pipe section, the central bore of each grout valve assembly coaxially arranged with the central bore of each elongate pipe section; wherein the central fluid passage of each grout valve assembly has a larger inner diameter than a grout valve assembly immediately downstream thereof.

16. A grouting assembly as claimed in claim 15, wherein: the opening member of each grout valve assembly is dimensioned to occlude the central fluid passage of the moveable member of that grout valve assembly, but is dimensioned to pass through the central fluid passage of the moveable member of each upstream grout valve assembly and the central bore of each upstream pipe section.

17. A grout valve assembly substantially as hereinbefore described with reference to and / or as illustrated in any of Figures 1 to 5 of the accompanying drawings.

18. A drilling assembly substantially as hereinbefore described with reference to and / or as illustrated in any of Figures 3 to 5 of the accompanying drawings.

19. A grouting assembly substantially as hereinbefore described with reference to and / or as illustrated in Figure 6 of the accompanying drawings.