Method and Apparatus for Driving a Pile into a Substrate

Abstract

A pile guide for supporting a pile as it is driven into a substrate, comprises: a base frame having a planar substrate-engaging surface; and a pile guide member mounted on the base frame, the pile guide member being configured to guide a pile in a predetermined direction therethrough as it is driven into a substrate. The pile guide member is pivotally mounted on the base frame, with pivotal movement of the pile guide member varying the predetermined direction relative to the planar substrate-engaging surface of the base frame.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for driving a pile into a substrate, particularly, but not exclusively an inclined underwater substrate, such as the inclined side of a seabed canyon.

It is known to provide pile guides for underwater piling, see, for example, Sea Steel Limited's range of pile guides as described in WO 99/11872 (Fast Frame pile guide), WO 01/92645 (Finned Frame/Follower pile guide) and WO 03/074795 (Orientation Control pile guide). However, such pile guides are not ideally suited for driving a pile into an inclined substrate, such as the inclined side of a seabed canyon, not least because they would each guide the pile into the substrate in a non-vertical orientation. The present invention has been devised specifically to allow for pile driving into an inclined substrate.

In accordance with a first aspect of the invention, there is provided a pile guide for supporting a pile as it is driven into a substrate, comprising: a base frame having a planar substrate-engaging surface; and a pile guide member mounted on the base frame, the pile guide member being configured to guide a pile in a predetermined direction therethrough as it is driven into a substrate, characterised in that the pile guide member is pivotally mounted on the base frame, with pivotal movement of the pile guide member varying the predetermined direction relative to the planar substrate-engaging surface of the base frame.

In this way, the orientation of the pile guide member may be adjusted to suit inclined substrates. For example, if the pile guide is to be used on a substrate which is inclined at about 20° to the horizontal, the pile guide member may be pivotally moved relative the base frame into a precise guide angle so that it guides piles in a vertical orientation as they are driven into the substrate. The pile guide member may be shaped as a simple hollow cylinder, or may be as disclosed in WO 01/92645 for use with piles with stabilising fins, or WO 03/074795 for use with piles with orientation control tabs, or WO 2007/066078 for use with piles with profiles which interact with corresponding profiles in the pile guide member to resist bursting pressures in the latter.

The pile guide member may be pivotally movable relative to the base frame between a first position and a second position, with the first and second positions being angularly spaced by at least about 30°. The first position may be substantially perpendicular to the substrate-engaging surface of the base frame. Thus, the pile guide could be used in a conventional way on a horizontal substrate.

The pile guide may further comprise a releasable locking device for preventing pivotal movement of the pile guide member relative to the base frame. In use, the releasable locking device allows a precise guide angle to be maintained between the pile guide member and the base frame during pile driving. The releasable locking device may comprise a variable length strut or piston pivotally coupled between the pile guide member and the base frame. The variable length strut may be hydraulically driven. Such a hydraulically driven variable length strut may be adjusted in situ, e.g. by a ROV, in order to control alignment of the pile guide member relative to the base frame in dependence upon underlying substrate inclination. The variable length strut may even be configured to force the pile guide member into a new orientation relative to the base frame part way through driving a pile into the substrate.

The pile guide member may further comprise a releasable anchor for stabilising positioning of the pile guide on a substrate during pile driving. When driving a pile in a vertical direction on an inclined slope, a component of the pile driving force acts to push the pile guide down the incline. However, once deployed, the anchor is configured to resist this position de-stabilising force component.

The releasable anchor may be pivotally coupled to the base frame, with the releasable anchor being deployed/released through pivotal movement relative to the base frame. The releasable anchor may be positioned to one lateral side of the pile guide member's pivot axis. In this way, the releasable anchor may be best placed to resist the position de-stabilising force component. The pivotal movement of the releasable anchor may be hydraulically driven, and may be controlled by a ROV.

In accordance with a second aspect of the present invention, there is provided a method of driving a pile into an inclined substrate, comprising: providing a pile guide comprising a base frame and a pile guide member pivotally mounted on the base frame; positioning the base frame of the pile guide on the inclined substrate; and pivotally moving the pile guide member relative to the base frame so that the pile guide member is configured to guide the pile into the substrate underlying the base frame at an acute angle relative to the substrate during pile driving.

The acute angle may be configured such that the pile is in a substantially vertical orientation once driven into the substrate.

The method may further comprise: initially positioning the pile guide member to guide the pile in a non-vertical orientation, the non-vertical orientation being selected to reduce or avoid forces generated by pile driving a pile in a vertical orientation which urge the pile guide down the inclined substrate; and partially driving the pile into the inclined substrate before pivotally moving the pile guide member to guide the pile at the acute angle during subsequent pile driving. The initial pile driving in the non-vertical orientation (which may be perpendicular to the inclined substrate) may serve to anchor the pile guide in position before driving the pile in the vertical orientation.

The method may further comprise providing the pile guide with a releasable locking device, and locking pile guide member orientation relative to the base frame when pile driving. The method may further comprise providing the pile guide with an anchor, and anchoring the pile guide to the substrate when pile driving.

An embodiment of the invention will now be described by way of example, and with reference to the accompanying figures in which:

FIG. 1 illustrates schematically a pile guide embodying the present invention;

FIG. 2 illustrates a partial side view of the pile guide of FIG. 1; and

FIG. 3 illustrates a plan view of the pile guide of FIG. 1.

The pile guide 10 of FIGS. 1 to 3 comprise a base frame 12 having a planar substrate-engaging surface 14, and a pile guide member 16 pivotally mounted on the base frame 12.

The pile guide member 16 is configured to guide a pile 20 in a predetermined direction therethrough (i.e. the pile 20 pass along the longitudinal axis of the pile guide member 16 which may be substantially cylindrical as shown). The pile guide member 16 is configured to move pivotally about its pivot axis AA from a first position 30 to a second position 32 (shown in phantom lines). The first and second positions 30,32 are angularly spaced by about 30°. In this way, the direction in which a pile 20 will be guided into the substrate 40, relative to the planar substrate-engaging surface, may be varied from D₁ to D₂ as the pile guide member 16 moves from the first to the second positions 30,32.

The pile guide 10 includes a releasable locking device 50 for locking the pile guide member 16 in a set orientation relative to the base frame 12. The releasable locking device 50 comprises a pair of variable length struts or pistons 52, each pivotally coupled at one end to the pile guide member 16 and pivotally coupled at its other end to the base frame 12. The variable length struts 52 each include a hydraulic cylinder which can be controlled by a ROV. For example, so-called “hot stabs” may be provided in a ROV interface panel for ROV-controlled activation of the hydraulic cylinders.

The pile guide 10 further includes a releasable anchor 60 for anchoring the base frame 12 to the surrounding substrate 40. The anchor 60 comprises blade 62 mounted on arms 64 which are pivotally coupled to the base frame 12. Hydraulic pistons 66 are pivotally coupled at each end to the base frame 12 and the arms 64. As the pistons 66 extend, the blade 62 is urged into the substrate 40. Thereafter, if the pistons contract, the blade 62 is retracted from the substrate 40.

The pile guide member 10 may be deployed on an inclined underwater substrate 40. The pile guide member 16 may be initially orientated to guide a pile 20 substantially perpendicularly to the inclined underwater substrate 40. Once the pile 20 is partially embedded in the inclined underwater substrate 40, the variable length struts 52 may be used to rotate the pile guide member 16 about pivot axis AA, forcing the pile 20 into a vertical orientation (dragging the pile guide 10 along the inclined underwater substrate 40 as it does so). Once in the vertical orientation, the pile 20 may be driven fully into the inclined underwater substrate 40. On the other hand, use of anchor 60 obviates the need to initially orientate the pile guide member 16 in such a way as to guide the pile 20 substantially perpendicularly to the inclined underwater substrate 40.

Claims

1. A pile guide for supporting a pile as it is driven into a substrate, comprising: a base frame having a planar substrate-engaging surface; and a pile guide member mounted on the base frame, the pile guide member being configured to guide a pile in a predetermined direction therethrough as it is driven into a substrate, characterised in that the pile guide member is pivotally mounted on the base frame, with pivotal movement of the pile guide member varying the predetermined direction relative to the planar substrate-engaging surface of the base frame.

2. A pile guide according to claim 1, in which the pile guide member is pivotally movable relative to the base frame between a first position and a second position, with the first and second positions being angularly spaced by at least about 30°.

3. A pile guide according to claim 2, in which the first position is substantially perpendicular to the substrate-engaging surface.

4. A pile guide according to claim 1, further comprising a releasable locking device for in use preventing pivotal movement of the pile guide member relative to the base frame.

5. A pile guide according to claim 4, in which the releasable locking device comprises a variable length strut pivotally coupled between the pile guide member and the base frame.

6. A pile guide according to claim 5, in which the variable length strut is hydraulically driven.

7. A pile guide according to claim 1, further comprising a releasable anchor for in use stabilizing position of the pile guide during pile driving.

8. A pile guide according to claim 7, in which the releasable anchor is pivotally coupled to the base frame, with the releasable anchor being deployed/released through pivotal movement relative to the base frame.

9. A pile guide according to claim 8, in which the releasable anchor is positioned to one lateral side of the pile guide member's pivot axis.

10. A pile guide according to claim 8, in which pivotal movement of the releasable anchor is hydraulically driven.

11. A method of driving a pile into an inclined substrate, comprising: providing a pile guide comprising a base frame and a pile guide member pivotally mounted on the base frame; positioning the base frame of the pile guide on the inclined substrate; and pivotally moving the pile guide member relative to the base frame so that the pile guide member is configured to guide the pile into the substrate underlying the base frame at an acute angle relative to the substrate during pile driving.

12. A method according to claim 11, further comprising: initially positioning the pile guide member to guide the pile in a non-vertical orientation, the non-vertical orientation being selected to reduce or avoid forces generated by pile driving a pile in a vertical orientation which urge the pile guide down the inclined substrate; and partially driving the pile into the inclined substrate before pivotally moving the pile guide member to guide the pile at the acute angle during subsequent pile driving.

13. A method according to claim 11, further comprising: providing the pile guide with a releasable locking device, and locking pile guide member orientation relative to the base frame when pile driving.

14. A method according to claim 11, further comprising: providing the pile guide with an anchor, and anchoring the pile guide to the substrate when pile driving.