The invention relates to a vibratory pile driver comprising a vibratory system and at least a clamping mechanism for attaching the vibratory pile driver to a pile. The invention further relates to a method of using a vibratory pile driver .

Such vibratory pile drivers are known for example from United States Patent Number 5,088,565 which discloses a vibratory pile driver having a vibratory system and a means for clamping onto a pile or similar structure to be driven or extracted substantially linearly, e.g. vertically.

A disadvantage of the vibratory pile drivers of the prior art are that they can be used only once a pile has been positioned vertically at a surface into which the pile is to be sunk; this is typically done using a crane. Once the pile has been positioned, the vibratory pile driver can then be clamped to the pile and the pile driving operation begun. Connecting a pile to a crane, raising and positioning the pile and disconnecting the pile from the crane is a time consuming and hence costly process, in particular for off-shore pile driving operations.

It is an object of the invention to provide a vibratory pile driver according to the appended claims that over- comes the problems of the vibratory pile drivers of the prior art .

In a first aspect, the invention relates to a vibratory pile driver comprising a vibratory system and at least a clamping mechanism for attaching the vibratory pile driver to a pile, wherein the vibratory pile driver is provided with a pivoting mechanism such that at least the vibratory system is rotatable from a loading position wherein the vibratory system is horizontal to a pile driving position wherein the vibratory system is vertical.

For practical reasons piles are typically provided horizontally, in particular for off-shore operations where piles can be several meters in diameter and tens of metres in length. By providing the vibratory pile driver with a pivoting mechanism, the pile can be coupled directly to the vibratory pile driver, thus avoiding the need to use a crane to first position the pile vertically at a surface into which the pile is to be sunk. Since the time-consuming steps of first coupling and then disconnecting the pile from the crane can be avoided, the pile driving operation requires less time and hence costs are reduced accordingly.

It is preferred that the vibratory pile driver is suspendable, for example from a crane or other winching mecha- nie. In accordance therewith, the vibratory pile driver is preferably provided with a feature from which the vibratory pile driver is suspendable. This enables hoisting of the vibratory pile driver and the pile suspended therefrom.

The nature of the feature from which the pile driver is suspendable is not particularly limited and includes for example, a cradle, a bracket, a hoisting beam etc.

In a preferred embodiment, the pivoting mechanism comprises the feature from which the vibratory pile driver is suspendable. A person skilled in the art can envisage many ways in which this can be achieved; a non limiting example of such a system is given in the drawing which will be discussed hereinafter. Such an arrangement is advantageous since the whole vibratory pile driver can simply be rotated about the pivoting mechanism whilst the vibratory pile driver is suspended .

The vibratory pile driver is provided with a clamping mechanism for clamping the vibratory pile driver to a pile at least during pile driving. Clamping the vibratory pile driver to the pile permits the pile to be vibrated efficiently. During a pile driving operation the pile is typically vertical and in contact with a surface; wherein the clamping mechanism is used only during a pile driving operation, it is not necessary and even undesirable for the clamping mechanism to be able to support the entire weight of a pile. In a preferred embodiment, the vibratory pile driver is provided with a pickup mechanism for raising and positioning a pile ready to be driven e.g. for raising the pile from a horizontal position into a vertical position at a surface into which the pile is to be driven, and thus to release load from the clamping mechanism. The pick-up mechanism optionally (partly) in combination with the clamping mechanism is preferably able to hold the entire weight of a pile and can distribute the forces ap- plied on the pile during raising and positioning of the pile e.g. from a horizonatal to a vertical position such that neither the pile nor the clamping mechanism is damaged.

In an alternative embodiment, the clamping mechanism is further suitable both for raising and positioning a pile e.g. from a horizontal position to a vertical position at a surface into which the pile is to be driven, and for clamping the vibratory pile driver to a pile during a pile driving operation .

In a further preferred embodiment, the vibratory pile driver preferably comprises an upending mechanism for rotating at least the vibratory system from the loading position to the pile driving position. In its broadest sense, the upending mechanism is any system that may be used to rotate at least the vibratory system of the vibratory pile driver between the loading and pile driving positions; many possibilities will occur to a person skilled in the art and include for example use of a motor or hydraulic system. An important consideration however is that the upending mechanism must be robust enough to endure vibrations.

In a preferred embodiment, the upending mechanism preferably comprises a line or cable fixed or fixable to a fixing point at an extremity of the vibratory pile driver distant from the feature from which the vibratory pile driver is suspendable. By applying a force to the line or cable at a particular angle, such as by using a winch, the vibratory pile driver may be rotated. Such an upending mechanism is advantageous since moving parts such as of the winch are external and are not subject to significant vibrations during a pile driv- ing operation.

In a further preferred embodiment, the upending mechanism preferably further comprises: (i) a brace connected or connectable to and extending from the feature from which the vibratory pile driver is suspendable, and (ii) a pulley mount- ed or mountable to the brace, wherein the line is passable through the pulley such that by applying and/or releasing a pulling force on the line or cable, the vibratory system is rotatable between the loading position and the pile driving position .

The vibratory pile driver preferably also comprises a locking mechanism for locking at least the vibratory system in one or both of the loading position and the pile driving position. A locking mechanism is desireable for the safe operation of the vibratory pile driver.

In a second aspect, the invention relates to a method for using a vibratory pile driver comprising a vibratory system and at least a clamping mechanism, wherein with the vibratory pile driver further comprising a pivoting mechanism such that at least the vibratory system is rotatable from a loading position wherein the vibratory system is horizontal to a pile driving position wherein the vibratory system is vertical, the method comprises: (i) providing a pile, (ii) with the vibratory system in the loading positon, coupling the vibratory pile driver to the pile, (iii) raising the pile and rotat- ing the vibratory system from the loading position to the pile driving position (iv) activating the vibratory system of the vibratory pile driver to sink the pile, (v) stopping the vibratory system when the pile has reached a required depth, (vi) removing the vibratory pile driver from the pile, (vii) returning the vibratory pile driver to the loading position.

The invention will hereinafter be clarified with reference to the drawing of Figures 1-4 showing a preferred embodiment of the invention which is not limiting of the appended claims .

With reference to the drawing:

-Figure 1 shows three views from different angles of a preferred embodiment of the invention in a loading position;

-Figure 2 shows three views from different angles of a preferred embodiment of the invention in a pile driving po- sition;

-Figure 3 shows several views of the first and second clamping mechanisms of a preferred embodiment of the invention;

-Figure 4 shows a preferred embodiment of a method for using a vibratory pile driver.

Whenever in the figures the same reference characters or numerals are applied, these characters or numerals refer to the same parts.

Figure 1 shows three alternative views of a preferred embodiment of the vibratory pile driver 1 in a loading posi- tion wherein the vibratory system 2 is horizontal and is coupled to a head end of a pile 13. The vibratory pile driver comprises: a vibratory system 2, and a clamping mechanism 3. The clamping mechanism 3 is provided in order to clamp the vi- bratory pile driver 1 to a pile 13 at least during a pile driving operation. In this preferred embodiment, the clamping mechanism 3 grips the edge of a pile 13 via a series of pin- cer-type grips 3 ' . At least the vibratory system 2 should be mounted to a pile 13 via the first clamping mechanism 3 in or- der to be able to vibrate the pile 13 efficiently. The vibratory pile driver 1 is further provided with a pivoting mechanism 4 such that the vibratory system 2 is rotatable from a loading position as shown if Figure 1 wherein the vibratory system 2 is horizontal, to a pile driving position wherein the vibratory system 2 is vertical or about vertical as shown in Figure 2.

Figure 2 shows three views from different angles of a preferred embodiment of the vibratory pile driver 1 in a pile driving position wherein the vibratory system 2 is vertical and is coupled to a pile 13.

A person skilled in the art can envisage many possible pivoting mechanisms; in this preferred embodiment, the pivoting mechanism 4 is embodied as a shackle A and bolt B provided on either side of the vibratory pile driver 1 and mounted to a hoisting beam C. The hoisting beam C is one example of a feature 5 from which the vibratory pile driver is suspendable . Other suitable examples include: a bracket mounted to the vibratory pile driver 1 e.g. on the underside or upperside; a beam passing through the vibratory pile driver 1 or brackets mounted to the side of the vibratory pile driver 1. Coupling the pivoting mechanism 4 and the feature 5 from which the vibratory pile driver is suspendable constitutes a simple means for achieving an object of the invention i.e to provide a vibratory pile driver wherein at least the vibratory system 2 is rotatable from a loading position wherein the vibratory system 2 is horizontal to a pile driving position wherein the vibratory system 2 is vertical, whilst the construction allows the hoisting of the pile 13.

The vibratory pile driver of this preferred embodi- ment further comprises a pick-up mechanism 6, which is further detailed with reference to Figure 3 to be discussed hereinafter; an upending mechanism 7, and; a locking mechanism 12. The upending mechanism 7 comprises a line or cable 8 attached or attachable to a fixing point 9 at an extremity of the vibrato- ry pile driver 1. By applying a pulling force with the line or cable 8 at a particular orientation, the vibratory system, and in use, a pile 13 attached to the vibratory pile driver 1 is rotatable from a loading position in which the vibratory system 2 (and the pile 13) are horizontal, to a pile driving pos- iton in which the vibratory system 2 (and the pile 13) are vertical. In this preferred embodiment, the upending mechanism further comprises a brace 10 comprising a pair of beams D extending from the feature 5 from which the vibratory pile driver is suspendable, a pulley 11 attached or attachable to the brace 10 such that with the line or cable 8 passed through the pulley and attached to a (not shown) winch, the vibratory system 2, and in use, a pile 13 attached to the vibratory system 2 via the clamping mechanism 3 and/or pick-up mechanism 6, is movable from a loading position according to Figure 1, to a pile driving position according to Figure 2, by applying or releasing a pulling force on the line or cable 8. The locking mechanism 12 is embodied for instance as a locking brace that fits the beams D of the brace 10 which is shown in Figure 2. With the locking mechanism 12 locked around the beams D the vibratory system 2 is locked in the pile driving positon. A person skilled in the art can envisage many ways of locking the vibratory system 2 in either a loading or in a pile driving position.

Figure 3 shows in Figure 3.1 a simplified side-view of the vibratory pile driver 1. In addition to the clamping mechanism 3 and pick-up mechanism 6 the upending mechanism 7 is clearly shown. Figures 3.2 and 3.3 focus on the clamping mechanism 3 and in particular to the pick-up mechanism 6. Figure 3.2 is a view of the base of the vibratory pile driver. The clamping mechanism 3 comprises a series of pincer-type grips 3' for gripping an upper edge of a pile at least during a pile driving operation. The pick-up mechanism 6 comprises a hydraulic support that forces against an inside surface of a pile during raising and positioning; this is demonstrated in Figure 3.3. The pick-up mechanism 6 is provided to release load from the clamping mechanism 3 during raising and positioning. By separating the functions of the clamping mechanism 3 from the pick-up mechanism 6 each can be optimised for its particular purpose.

Figure 4 shows a preferred embodiment of a method for using a vibratory pile driver such as the the vibratory pile driver 1 of the preferred embodiment shown in Figures 1-3. The method comprises: In panel 1: providing a pile 13, preferably in a horizontal position; in panel 2: with the vibratory sys- tern 2 in the loading positon, coupling the vibratory pile driver 1 to the pile 13, using the clamping mechanism 3 and pick-up mechanism 6; in panel 3: raising the pile 13 and rotating the vibratory system 2 from the loading position to the pile driving position in panel 4 such that the pile 13 is raised to a vertical position; in panel 4: activating the vibratory system 2 of the vibratory pile driver 1 to sink the pile 13 ; in panel 5: stopping the vibratory system 2 when the pile 13 has reached a required depth; in panel 6: removing the vibratory pile driver 1 from the pile 13; in panel 7: return- ing the vibratory pile driver 1 to the loading position; in panels 8,9: readying the vibratory pile driver to repeat the method with a new pile 13.