The invention relates to a vibrating device for inserting a foundation element, such as a foundation pile or sheet pile profile or tube, into the ground. Such foundation elements can be inserted into the ground on land or at sea.

Diverse vibrating systems are known in practice which make use of a vibrating device and more particularly of a vibrator block provided with a number of eccentrics. Such a vibrator block exerts vibrations on the foundation element, whereby this element is vibrated into the ground. Such vibrator blocks are usually arranged on the upper side of the foundation element during insertion thereof. These vibrating systems known in practice are usually driven hydraulically, wherein use is made of a so-called power pack comprising a diesel engine and a hydraulic pump. This hydraulic pump drives the hydraulic motor of the vibrating device.

A problem with existing vibrating systems is that due to the ground resistance great power is usually required to insert the foundation element into the ground. The great resistance entails the danger of overloading of the hydraulic system and/or makes it necessary for great power to be provided for the vibrating system. This increases the insertion time of the foundation element and/or entails higher costs.

An object of the present invention is to obviate or reduce the above stated problems and to provide an effective vibrating system for inserting a foundation element into the ground.

This object is achieved with the vibrating system according to the present invention for inserting a foundation element into the ground, wherein the vibrating system comprises:

a vibrating device;

a drive operatively connected to the vibrating device and comprising a motor; and - a foundation element to be inserted into the ground or removed from the ground, comprising a closing means arranged in the interior of the foundation element for realizing a pressure chamber in the interior of the foundation element. In a currently preferred embodiment the pressure chamber is created between the closing means and the ground into which or on which the foundation element is inserted or is situated.

Providing the vibrating device, also referred to as vibrator block, with a number of eccentrics in particular enables a vibration to be exerted on a foundation element, such as a foundation pile, a foundation tube, a tube and a sheet pile profile.

The drive of the vibrating device is formed by the motor, in a currently preferred embodiment comprising a hydraulic motor. This is preferably provided in combination with a pump, in a currently preferred embodiment comprising a hydraulic pump. This produces a quantity of hydraulic fluid which determines the frequency of the vibrating device. The effective frequency of the vibrating device is determined in practice by the relation between the quantity of hydraulic fluid and the so-called stroke volume of the hydraulic motor, together with the transmission ratio inside the vibrating device. The frequency of the vibrating device together with the eccentric moment of the vibrating device determine the impact force, i.e. the power produced by the vibrating device.

The maximum available power of the drive for the vibrating system is determined by the (hydraulic) pump, which is operatively connected to the (hydraulic) motor, together with the drive unit for the (hydraulic) pump. Such a drive unit is preferably a diesel engine, although an electrically driven hydraulic pump is also possible.

The hydraulic pressure determines the drive force which can be realized with the vibrating system. The drive force of the vibrating device is substantially used to overcome the resistance which is encountered during insertion into the ground of the foundation element, and some losses. Providing the drive with an adjusting device which is configured to set the drive force of the system achieves an optimal use of the available power, while the power which can be supplied by the vibrating device to the foundation element remains substantially constant.

By providing according to the invention a closing means, comprising one, two or more plugs or closing means, a pressure chamber is provided in the interior of the foundation element.

An overpressure can be provided in the pressure chamber during insertion into the ground of the foundation element. This achieves that the stability of the foundation element, particularly a tube, is increased. Providing an underpressure in the pressure chamber during the vibration process achieves that the foundation element will penetrate further into the ground than in a similar situation without pressure chamber. This significantly increases the effectiveness of the process, and enables a number of foundation elements to be inserted into the ground in less time. Besides installation being accelerated, an additional advantage is that a sound-reducing effect is achieved whereby the total amount of sound produced can remain limited. The risk that the foundation element may or may not reach its destination depth can in addition also be limited further. If desired, in a possible embodiment according to the invention it is also possible to provide a type of spring action with the pressure chamber during installation of the foundation element.

During removal of the foundation element from the ground the pressure chamber is preferably brought to an overpressure, whereby an upward force is achieved. This removal of a foundation element from the ground is also referred to as decommissioning. One of the advantages herein is that the crane used has to lift the foundation element and possible vibrator block, but need not overcome the full resistance of the ground. This is because the upward force contributes to the decommissioning of the foundation element. Decommissioning of the foundation element is for instance applicable during removal of the foundation element after use and/or testing of the load- bearing capacity of the foundation element. The pressure chamber in addition increases the buoyancy of the foundation element. This is particularly advantageous when the foundation element is transported over water, which element can hereby be displaced in floating manner. This simplifies transport of the foundation element.

Multiple effects are achieved in the above stated manner with the pressure chamber according to the invention, which can be advantageously combined in the whole process of insertion of the foundation element into the ground or decommissioning thereof. This can hereby be performed in more effective manner, preferably using a lighter vibrating device.

In an advantageous preferred embodiment according to the invention the closing means is positioned between two outer ends of the foundation element.

By providing the closing means in the interior of the foundation element instead of at the outer end thereof in a possible embodiment an interior pressure chamber is provided inside the foundation element. The above stated effects are hereby better guaranteed.

In an advantageous preferred embodiment according to the invention the closing means is provided with one or more expanders for moving the closing means between an insertion configuration and a closing configuration in which the closing means is expanded.

Applying expanders enables the closing means to be placed in the foundation element in relatively simple manner. In the case that round foundation piles or tubes are applied, the closing means is inserted and carried to the desired position while having a relatively small diameter. At the desired position the closing means is brought to a relatively large diameter with the expanders such that the closing means is fixed against the internal surface of the pile or tube, preferably water and/or air-tightly. Expanders can be formed in diverse ways, for instance using an element extendable with a cylinder, and/or an inflatable element.

The closing means is preferably removable. This allows the closing means to be reused.

In a further embodiment according to the invention the closing means can be provided with a valve for for instance carrying air or water (passively) out of or into the pressure chamber. If desired, a medium such as air or water can additionally or alternatively be carried into the pressure chamber or removed therefrom in a more active manner using a pump or compressor.

In an advantageous preferred embodiment according to the invention the vibrating system further comprises a control system for modifying the pressure in the pressure chamber.

By providing a control system for modifying the pressure in the pressure chamber the pressure in this pressure chamber can be monitored and preferably controlled. Use is preferably made here of one or more pressure sensors. By making use of a control system according to the invention the desired effects to be achieved with the pressure chamber can be provided in effective manner. The control system is preferably suitable for controlling the above described passive and/or active manner of introducing or removing a medium, such as water or air, into or from the pressure chamber. In an advantageous preferred embodiment according to the invention the foundation element further comprises a cutting tool configured to cut off the foundation element.

Providing a cutting tool is particularly advantageous during decommissioning of a foundation element. If a foundation element cannot be wholly removed from the ground, a part can be cut off so that at least a part of the foundation element can be removed.

In a currently preferred embodiment optimal use is made of the available power, and the power which can be transmitted by the vibrating device to the foundation element is kept substantially constant herein during use. The insertion time required and the overall amount of energy required to insert the foundation element into the ground is hereby minimized. The power taken up by the foundation element is determined here by the frequency and the drive force of the vibrating device.

By optimizing the taken-up power with an adjusting device in such a preferred embodiment a foundation element can be inserted into the ground in effective manner. It is here possible in practice to dispense with a conventional safety valve, or at least with the practical use thereof, whereby in conventional systems the maximum operating pressure is limited. Hydraulic fluid is carried via such a safety valve back to the reservoir, while the drive force of the vibrating device remains the same. This results in loss of power. The adjusting device according to the invention increases the drive force, while the frequency is reduced. No power is hereby lost, and an effective process is achieved.

The invention further relates to a method for inserting a foundation element into the ground or decommissioning it, comprising the steps of:

providing a foundation element to be inserted into the ground or decommissioned; providing a closing means in the foundation element for the purpose of providing a pressure chamber;

- providing a vibrating device at or on the foundation element; and

inserting or removing the foundation element.

The method provides the same advantages and effects as described for the vibrating system.

During providing of the closing means, this closing means is preferably arranged in the interior of the foundation element between the two outer ends thereof. Use is preferably made here of expanders for varying the diameter of the closing means. The method also preferably comprises the step of removing the closing means.

In a possible application the method comprises the step of transporting the foundation element over water, wherein the pressure chamber created by the closing means provides buoyancy. This enables efficient transport. During or prior to insertion into the ground the pressure chamber is preferably placed under an overpressure such that the stability of the foundation element is increased. This preferably improves the stability such that the foundation element can stand independently. This simplifies the insertion process. Increasing the stability prior to insertion into the ground is in a possible embodiment also possible when the foundation element is not yet positioned on the ground or ground layer by making use of two closing means. The pressure chamber is then situated therebetween. For insertion into the ground one of the closing means can then be opened or removed, so that the ground will once again function as second closing means and an

underpressure in the pressure chamber allows the vibration process to run more efficiently, as already described above. The pressure chamber is here preferably filled with a gas or liquid which is lighter than water, for instance air, for the purpose of increasing the stability.

In a possible advantageous embodiment the pressure chamber is placed under an underpressure for the purpose of insertion, such that the power of insertion into the ground is increased during insertion of the foundation element into the ground. A smaller vibrating device can hereby suffice and/or the foundation element can be inserted into the ground more quickly.

In a further advantageous preferred embodiment the pressure chamber is placed under an overpressure such that an outward pressing or outward driving force is achieved during decommissioning of the foundation element. A smaller vibrating device can hereby suffice and/or the foundation element can be decommissioned more quickly. A cutting tool is preferably provided in this application. In the case that not the whole foundation element need or can be removed from the ground, the foundation element is cut off with a cutting tool during decommissioning of the foundation element.

In the discussed applications the pressure in the pressure chamber is preferably monitored and preferably controlled with a control system.

Further advantages, features and details of the invention are elucidated on the basis of a preferred embodiment thereof, wherein reference is made to the accompanying figures in which:

Figure 1 shows a view of a vibrating system according to the invention.

Foundation element 2 (Figure 1) is held on the upper side by clamping system 4 using one or more clamps 6. Arranged above clamping system 4 is vibrator block 8 which in the shown embodiment is provided with hydraulic motor 10. Further arranged above vibrator block 8 is a so- called suppressor 12 which ensures inter alia that vibrations are not transmitted via connection 14 to for instance the boom of a lifting device.

In the shown embodiment vibrating system 16 comprises in addition to vibrator block 8 with hydraulic motor 10 a power pack 18, wherein hydraulic hoses 20 carry hydraulic fluid, for instance an oil, to connections to suppressor 12 and back via hoses 22, wherein via suppressor 12 hydraulic fluid is carried via hydraulic hoses 24 to hydraulic motor 10 and back via hydraulic hoses 26. A different configuration of hydraulic hoses 20, 22, 24, 26 is of course likewise possible.

In the shown embodiment power pack 18 comprises diesel engine 28 and hydraulic pump 30, which are mutually coupled using connection 32.

Provided in foundation element 2 is closing means or plug 34 whereby pressure chamber

36 is provided. In the shown embodiment foundation pile 2 is situated partially in air 38, under water 40 and in ground 42. A pile cutter 44 is further optionally provided.

Pressure sensor 46, whereby pressure signal 48 is sent to controller 50, is shown schematically. On the basis of the operation to be performed on foundation element 2, instruction 52 can hereby be sent to actuator 54, for instance a pump, which modifies the pressure in pressure chamber 36, if required, with control action 56.

When foundation pile 2 is installed in ground 42 an underpressure is preferably applied in chamber 36 during transport and upending. When pile 2 is positioned upright an overpressure is preferably applied in chamber 36 for the purpose of stable positioning. During vibration for the purpose of installation an underpressure is preferably applied in chamber 36 using controller 50.

When pile 2 is decommissioned from ground 42 an overpressure is preferably applied in chamber 36. If desired, a part of pile 2 can be cut off using pile cutter 44.

During insertion of foundation element 2 power pack 18 is set into operation to supply available power. Hydraulic oil is carried to motor 10 with a set stroke volume. Vibrator block 8 is hereby driven and operated at a determined frequency and drive force. In the case of an increase of the resistance to a foundation element 2 being inserted into the ground, the drive force is increased according to the invention, while the frequency of vibrator block 8 decreases.

It is noted for the sake of completeness that the closing means according to the invention can be both placed in the foundation element as separate component or can be integrated therein.

According to the invention, the pressure chamber can optionally be filled with both liquid which cannot be compressed in practice, or hardly so, and/or gas which can be compressed in practice. In an advantageous embodiment use is for instance made of water or air. The choice can be made on the basis of for instance the specific application, such as insertion of the foundation element into the ground, decommissioning of the foundation element, increasing the pile stability and/or testing the load-bearing capacity.

In a possible embodiment the closing means can also be used to test the load-bearing force of the pile. The downward load-bearing capacity of the pile can be tested by creating

underpressure. The upward load-bearing capacity can be tested by creating overpressure. This testing is for instance possible immediately after installation with the vibrating system. It is also possible to perform the tests at a later time, for instance in order to map the change in load-bearing capacity in the course of time. Increasing the stability and/or testing the load-bearing capacity with the closing means in a possible embodiment can be done in combination with the vibrating system, but also by using only the closing means.

A number of the possible embodiments or possible applications according to the invention is stated below. These can be applied individually or in different combinations, optionally in combination with other aspects.

In a first embodiment the stability is increased using in particular two closing means, wherein the pressure chamber is filled with a gas or liquid lighter than the surrounding liquid, optionally in combination with an above described vibrating device.

In a second embodiment the stability is increased using one closing means, wherein the pressure chamber is filled with a gas or liquid lighter than the surrounding liquid, optionally in combination with an above described vibrating device.

In a third embodiment a foundation element is inserted into the ground more efficiently by applying underpressure in the pressure chamber, in combination with vibration, wherein the pressure chamber is filled with liquid, gas or a combination of the two.

In a fourth embodiment a foundation element is decommissioned more efficiently, in combination with vibration, wherein the pressure chamber is filled with air, water or a combination of the two.

In a fifth embodiment the upward load-bearing capacity is tested by means of applying an overpressure, wherein the pressure chamber is filled with liquid, gas or a combination of the two, optionally in combination with a vibrating device.

In a sixth embodiment the downward load-bearing capacity is tested by applying an underpressure, wherein the pressure chamber is filled with liquid, gas or a combination of the two, optionally in combination with a vibrating device.

In a seventh embodiment an optional so-called pile run during installation of the pile is prevented or avoided, wherein the closing means can be closed in the case of such a pile run, wherein the pressure chamber is filled with liquid.

The invention is by no means limited to the above described preferred embodiments thereof. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged.