Patent Publication Number: US-2023151577-A1

Title: Device for pushing four piles into the ground

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for pushing four piles into the ground or into a seabed in a square configuration or in a diamond configuration or for pulling four piles out. Devices for pushing piles into the ground are known in the field of the art. 
     BACKGROUND OF THE INVENTION 
     Offshore structures are generally grounded to the seabed with large diameter piles. The piles may be installed through the legs of the structure, so called main piles, or may be installed adjacent to the structure and connected with pile sleeves, so called skirt piles, to the structure. In order to insert these piles into the seabed, hydraulic impact hammers are typically used. The impact of the hydraulic hammer on the pile during a blow radially expands the pile. This expansion in turn results into a pressure wave in the water and soil column. 
     The noise generated by the pressure wave may be harmful for marine mammals. In some areas regulatory bodies limit the allowed sound levels. Such regions are for instance Germany, where the allowed sound levels are limited to 160 dB SEL5% at 750 m. In order to reduce the sound levels bubble curtains can be deployed prior to installation. These curtains are hoses with holes which lay on the seabed. Air is blown through these hoses, which escapes through the holes. Due to the difference in impedance between the air bubbles and the seawater part of the pressure wave is reflected and energy is dissipated reducing the noise levels significantly. 
     In order to blow enough air from the bubble curtain, many compressors are required. These are typically positioned on an auxiliary vessel. This is an expensive operation and has a large carbon footprint. Furthermore, the noise during pile driving is only reduced, never fully mitigated. Finally, these bubble curtains only work effectively in shallow water depths and become less efficient at larger depths. Therefore a silent alternative would be preferred both from a sustainability and technical perspective. 
     A further disadvantage of hammering piles into the ground or seabed is that the shockwaves typically are so strong that they damage electronic equipment which could be used to measure the position and orientation (inclination) of the piles. 
     There are several options to silently install piles. Typical examples are helical piles installed by torque or piles which are pushed into the ground. The push-in pile is often used on land where multiple piles are installed at the same time. One pile is pushed down while the other piles are used as a reaction force. These piles are installed in one line, to form a row. In the present invention, it was recognized that this is not economical for offshore piles, because the distance between the outermost pile and the jacket would become too large. Currently, there is no viable technology available to drive piles into the seabed in a silent manner. 
     On land, hammering piles into the ground is common technology and widely used for foundations of buildings and in general structures. However, similar issues apply with regard to noise. The hammering has a disadvantage in that a lot of noise is generated, which provides serious inconvenience to people in the surrounding. The hammering may also form a cause of damage to other buildings, in particular by causing cracks in other buildings. 
     As indicated above, systems for pushing piles into the ground in a silent matter exist. However, such systems generally have a limitation that the piles need to be positioned in a row. Furthermore, these systems generally require a separate reaction frame for the first few piles, because the system requires a support position in order to be able to start working. Only after a few piles are inserted into the ground, the reaction frame is no longer necessary. 
     Another system for silently driving piles into the ground exists. This system is applied by a British company called Dawson, called a Dawson system. With this system, four interlocked sheet piles can be driven into the ground. See the website of this company: http://www.dcpuk.com/productspress.html. This system is considered to form the closest prior art for the present invention. 
     It was recognized in the present invention that a disadvantage of this Dawson system is that the Dawson system is not capable of driving regular tubular piles into the ground. In the Dawson system, the piles needs to be interlocked, and for this reason need to have a specific design which allows for the interlocking of the piles. Such specially made piles are quite costly. 
     Other systems for driving piles into the ground in a silent manner also exist. For instance, systems exist for driving piles having a helical shape into the ground. This is essentially screwing a pile into the ground. Although these systems work, the piles need to be specifically designed and manufactured, and are quite costly. 
     Other systems exist which are based on vibrating piles into the ground. Such systems have a specific disadvantage that the vibrations may also cause inconvenience to people in the surroundings and may be a cause of damage to surrounding buildings. Furthermore, these systems do not work under all circumstances. 
     OBJECT OF THE INVENTION 
     It is an object of the invention to provide a device for driving a plurality of piles into the ground or into a seabed in a silent manner wherein the piles do not need to be interlocked. 
     It is an object of the invention to provide a device for driving a plurality of piles into the ground or into a seabed in a silent manner wherein the piles can be regular tubular piles. 
     It is an object of the invention to provide a device for driving a plurality of piles into the ground or into a seabed which allows better and/or more accurate measuring of the loads, positions and orientations of the piles, and with less risk of damage to electronic measuring equipment. 
     SUMMARY OF THE INVENTION 
     In order to achieve at least one objective, the present invention provides a device for pushing four piles into the ground or into a seabed in a square configuration or in a diamond configuration, the device comprising:
         a bridge assembly which when seen in top view defines a first, second, third and fourth connecting location which are arranged in a square configuration or in a diamond configuration,   a first, a second, a third and a fourth pile connection assembly via which in use each of the four piles is connected to the bridge assembly, wherein each pile connection assembly comprises:
           an actuator which extends downward from the respective connecting location, wherein each actuator comprises an upper actuator part and a lower actuator part, wherein the upper actuator part is connected to the bridge assembly, wherein the actuator is configured to
               extend in order to move the lower actuator part downward relative to the upper actuator part, and/or   retract in order to move the lower actuator part upward relative to the upper actuator part,   
               a pile connector connected to the lower actuator part, wherein each pile connector is configured to be connected to an upper end of a pile which is to be pushed into or pulled out of the ground or seabed, wherein the pile connector is configured to move downward or upward relative to the upper actuator part together with the associated lower actuator part during the respective extension or retraction,   
           a control device configured for alternately pushing in each pile by
           keeping one actuator substantially stationary while retracting the remaining actuators, wherein the control device is configured for regulating at least the vertical force exerted by the retracting actuator opposite the substantially stationary actuator in order to have the pile corresponding to the substantially stationary actuator receive a greater vertical force than each of the remaining, stationary piles for pushing the pile which is associated with the substantially stationary actuator into the ground or seabed, or combining said alternately retracting of the remaining actuators by   alternately having each of the actuators extend, wherein the control device is configured for regulating at least the force which is exerted by the actuator which extends and the force which is exerted by the opposite actuator in order to let the pile which is pushed into the ground or seabed receive a greater force than the opposite pile of the square or diamond configuration,
               and/or wherein the control device is configured for alternately pulling out each pile by   
               keeping one actuator or two opposite actuators substantially stationary while extending the remaining actuators, wherein the control device is configured for regulating at least the vertical force exerted by the extending actuator opposite the substantially stationary actuator or the vertical force exerted by the two opposite actuators in order to have each pile corresponding to the substantially stationary actuator or the two substantially stationary actuators receive a greater vertical force than each of the remaining, stationary piles for pulling each pile which is associated with the substantially stationary actuator or the two substantially stationary actuators out of the ground or seabed, and/or by   alternately having each of the actuators or pairs of opposite actuators retract, wherein the control device is configured for regulating at least the force which is exerted by a retracting actuator ( 18 ) and the force exerted by the opposite actuator ( 18 ) in order to let the pile or piles being pulled out of the ground or seabed receive a greater force than the remaining piles of the square or diamond configuration,   wherein the actuator which is associated with the pile being pushed in or pulled out transfers the exerted push force or pull force into the bridge assembly and wherein said push force or pull force is transferred at least partially from the bridge assembly as a respective tension force or a compression force, and a bending moment into the two adjoining piles via the two adjoining pile connection assemblies.   
               

     The present invention is based on the general idea that in order to push one pile into the ground, a push force (or compression force) is provided by an actuator connected to the bridge assembly. This push force results in a reaction force of the pile into the bridge assembly. This reaction force is at least partially transferred as a combination of a tension force and a bending moment into both of the piles which adjoin the pile which is pushed into the ground or seabed. 
     The device is configured to actively maintain the push force on the pile opposite the pile which is to be pushed into the ground at a lower level than the pile which is to be pushed into the ground or seabed. This prevents a situation in which it is unknown which of the two piles will actually be pushed downward. In order to control the forces of the individual actuators, the device comprises a control unit which actively controls the forces in the four actuators. If the actuators are hydraulic actuators, the control unit controls the hydraulic pressures in the four hydraulic actuators. 
     An advantage of the invention is that the device can be “stand alone”. In other words, the device does not generate external loads as land based systems generally do, which external loads have to be carried by a separate crane or structure or foundation. 
     Another advantage of the device according to the invention is that, in contrast to piles that are installed by pile driving, measurement tools can remain on the equipment. This is normally not possible as the measurement system cannot survive the blows from the hammer. This allows direct read-out of the depths and orientations of the independent piles and/or the tool itself and of the loads which are exerted on the piles. 
     The device according to the invention is configured to distribute the load over the piles in such a way that one of the piles alternatingly has a significantly larger push force than the opposite pile on the diagonal (of the square of diamond configuration) and a balance of forces is achieved by transferring a part of the load as a combination of tension and bending moments into the piles on the opposite diagonal. 
     In an embodiment the bridge assembly comprises:
         a first pivotable frame which is pivotable about a first pivot axis,   a second pivotable frame positioned below the first pivotable frame and being pivotable about a second pivot axis which extends at an angle, in particular at right angles, to the first pivot axis, wherein when seen in top view the first pivotable frame crosses the second pivotable frame,
           wherein the first actuator and the second actuator are positioned below the first pivotable frame and are connected with the respective upper actuator parts thereof to the first pivotable frame at the first and second connecting locations wherein the third actuator and the fourth actuator are positioned below the second pivotable frame and are connected with the respective upper actuator parts thereof to the second pivotable frame at the third and fourth connecting locations,   wherein each pile connection assembly comprises a pair of connector rods, each pair comprising a right connector rod and a left connector rod, wherein:
               the right and left connector rod of the first pile connection assembly are connected to the lower actuator part of the first actuator and to the second pivotable frame,   the right and left connector rod of the second pile connection assembly are connected to the lower actuator part of the second actuator and to the second pivotable frame,   the right and left connector rod of the third pile connection assembly are connected to the lower actuator part of the third actuator and to the first pivotable frame,   the right and left connector rod of the fourth pile connection assembly are connected to the lower actuator part of the fourth actuator and to the first pivotable frame,   
               wherein each right connector rod is connected to a right side of the associated actuator and each left connector rod is connected to a left side of the associated actuator, wherein each pair of connector rods is configured to transfer a tension force and a bending moment from the bridge assembly into the associated pile.   
               

     In an embodiment, each pile connection assembly comprises a sliding assembly which is rigidly connected to the bridge assembly, wherein the sliding assembly comprises a sleeve and one or more gripper actuators which can be switched between a gripping state and a released state, wherein:
         in the released state the pile and/or pile connector can slide through the sleeve,   in the gripping state the sleeve is rigidly connected to the pile and/or pile connector, allowing a tension force and a bending moment to be transferred from the bridge assembly into the pile which is in the sleeve.       

     In an embodiment, the pile connection assemblies are rigidly connected to one another via a base frame which is positioned below the bridge assembly and which is rigidly connected to the bridge assembly via at least one column, wherein the sliding assemblies are connected to the base frame. 
     In an embodiment each actuator comprises:
         a cylinder, a piston rod and a first piston and second piston positioned inside the cylinder and mounted on the piston rod at a distance from one another, and/or   a plurality of linear guides positioned at a lateral distance from one another and extending parallel to the direction in which the cylinder actuator extends wherein the linear guides are configured to transfer a bending moment from the upper actuator part to the lower actuator part,   a cylinder in which a minimum distance between a piston guide and a rod guide is equal to or greater than a diameter of the cylinder, and/or   a first sub-actuator, in particular a cylinder, and a second sub-actuator, in particular a cylinder, positioned adjacent one another.       

     In an embodiment, in top view the bridge assembly has a square or diamond shape and comprises a central opening, wherein the bridge assembly extends around this central opening. 
     In an embodiment, the device is configured for pushing piles into the ground or seabed which are not interlocked. 
     In an embodiment, the device is configured for pushing piles which are positioned at a horizontal distance from one another and do not contact one another. 
     In an embodiment, each pile connector comprises an insertable part which is configured to be inserted into, the upper ends of tubular piles. 
     In an embodiment, each pile connector comprises one or more gripper actuators to grip the upper end of the tubular piles. 
     In an embodiment, the device comprises exactly four connecting assemblies and exactly four pile connectors. 
     In an embodiment, the device is configured to drive all piles vertically into the ground or seabed, wherein in particular the four actuators and the four pile connectors are oriented vertically. 
     In an embodiment, the right and left connector rod of each pair are connected to a same side of the associated pivotable frame and to opposite sides of the associated lower actuator part. 
     In an embodiment, each connector rod is connected to the associated cylinder actuator via a lower hinge, and wherein each connector rod is connected to the associated pivotable frame via an upper hinge. 
     In an embodiment, the first pivotable frame is pivotable in a first plane and the second pivotable frame is pivotable in a second plane which extends at right angles to the first plane, wherein the first and second plane extend in particular vertically. 
     In an embodiment, the first, second, third and fourth connecting location are adjustable between an outer location and an inner location respectively with respect to a centre of the bridge assembly. 
     In an embodiment, a spacing distance between the pile connectors is approximately 0.5 times the diameter of the piles configured to be connected thereto. 
     In an embodiment, a spacing distance between the pile connectors is 2 times the diameter of the piles configured to be connected thereto or less. 
     In an embodiment, a spacing distance between the pile connectors is between 2 and 4 times the diameter of the piles configured to be connected thereto. 
     The present invention further relates to a method of pushing four piles into the ground or into a seabed in a square configuration or in a diamond configuration, the method comprising:
         positioning four piles on the ground or on a seabed, in a square or diamond configuration when seen in top view, and connecting the device according to the invention to the upper ends of the piles, wherein each pile connection assembly is connected to an associated pile,   alternately pushing each one of the four piles over a distance into the ground or seabed by alternately
           keeping one actuator substantially stationary while retracting the remaining actuators, wherein the control device regulates the vertical force exerted by the retracting actuator opposite the substantially stationary actuator in order to have the pile corresponding to the substantially stationary actuator receive a greater vertical force than each of the remaining, stationary piles for pushing the pile which is associated with the substantially stationary actuator into the ground or seabed,   or combining said alternately retracting of the remaining actuators by alternately   extending the actuator which is associated with said pile, wherein during the extension the control device regulates the force exerted by the actuator which extends and the force exerted by the opposite actuator in order to let the pile which is pushed into the ground or seabed receive a greater force than the opposite pile of the square or diamond configuration, and wherein an exerted push force is transferred from the respective actuator   
           which is associated with the pile being pushed in into the bridge assembly and transferred at least partially from the bridge assembly as a tension force and a bending moment into the two adjoining piles via the two adjoining pile connection assemblies.
 
The method provides the same advantages as the device.
 
In an embodiment, the method comprises:
   connecting the device according to the invention to the piles,   alternately pushing in each one of the four piles over a distance into the ground or seabed by extending the cylinder actuator which is associated with said pile or by retracting the remaining actuators, wherein during each pushing step the required push force is transferred from the respective cylinder actuator into the pivotable frame to which the cylinder actuator is connected and from said pivotable frame at least partially as a tension force and a bending moment into two adjacent piles by the connector rods which are connected to said pivotable frame and to the two adjacent piles.
 
In an embodiment of the method, the piles are tubular piles.
       

     In an embodiment of the method, the piles are not interlocked and are in particular positioned at a horizontal distance from one another. 
     In an embodiment of the method, the bridge assembly moves downward together with the piles as they are pushed into the ground. 
     In an embodiment of the method, during the extension of an actuator the pivotable frame which is connected to the upper part of said actuator is maintained stationary and the other pivotable frame pivots. 
     In an embodiment, the method comprises:
         positioning four piles in an square or diamond configuration in a temporary location,   connecting the device according to the assembly to the four upper ends of the four piles,   lifting the combination of the device and the four piles connected thereto to a target location on a seabed or on the ground.       

     In an embodiment of the method each cycle comprises the following steps in the sequence as indicated:
         pushing the first pile over a distance into the ground or seabed,   pushing the second pile which is opposite to the first pile over a distance into the ground or seabed,   pushing the third pile over a distance into the ground or seabed,   pushing the fourth pile which is opposite to the third pile over a distance into the ground or seabed.       

     In an embodiment of the method, the first pile or the fourth pile of a cycle can be pushed in by keeping the actuator associated with said first pile or fourth pile substantially stationary while retracting the remaining actuators. The other piles in the cycle can be pushed in by alternately extending the respective actuators. This embodiment allows for a faster cycle compared to only extending the actuators one by one. 
     In an embodiment of the method, the device is lifted by a crane on an installation vessel at sea. 
     In an embodiment of the method, four piles are pushed into the ground through piles sleeves at each leg of a jacket. 
     The present invention also relates to a method for pulling four piles out of the ground or a seabed in a square configuration or in a diamond configuration, the method comprising:
         connecting the device according to any of the preceding claims to the upper ends of the piles, wherein each pile connection assembly is connected to an associated pile,   alternately pulling one or two piles of the four piles over a distance out of the ground or seabed by alternately
           keeping one actuator or two opposite actuators substantially stationary while extending the remaining actuators, wherein the control device regulates the vertical force exerted by the extending actuator opposite the substantially stationary actuator or the vertical force exerted by the two opposite actuators in order to have each pile corresponding to the substantially stationary actuator or the two substantially stationary actuators receive a greater vertical force than each of the remaining, stationary piles for pulling each pile which is associated with the substantially stationary actuator or the two substantially stationary actuators out of the ground or seabed,   and/or by   retracting the one actuator or two actuators associated with respective said pile or piles, wherein during the retraction the control device regulates the force exerted by a retracting actuator and the force exerted by the opposite actuator in order to let the pile or piles being pulled out of the ground or seabed receive a greater force than the remaining piles of the square or diamond configuration,
 
and wherein an exerted pull force is transferred from the respective actuator which is associated with the pile being pulled out into the bridge assembly and transferred at least partially from the bridge assembly as a compression force and a bending moment into the two adjoining piles via the two adjoining pile connection assemblies.
   
               

     The present invention further relates to a pile support frame, wherein the pile support frame is configured to support four piles in a square or diamond pickup configuration and in a substantially vertical orientation and parallel to one another, wherein the pile support frame is open at an upper side, allowing the four piles to be gripped by the device according to any of claim  1 - 15 . 
     In an embodiment, the pile support frame comprises pile supports which are configured to support the piles at a distance from one another and with the upper end faces of the piles substantially flush. 
     The present invention further relates to a vessel comprising:
         the device according to the invention,   a pile support frame, and   a crane.       

     In an embodiment of the vessel, the pile support frame:
         positioned on deck,   is located at least partially below a deck,   comprises a cantilever platform which extends outwardly away from the hull or deck of the vessel,   located at least partially in a column of a semi-sub, wherein the column connects a deck structure with a floater.       

     These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG.  1    shows an isometric view of a first embodiment according to the invention. 
         FIG.  2    shows a front view of the embodiment of  FIG.  1   . 
         FIG.  3    shows a side view of the embodiment of  FIG.  1   . 
         FIG.  4    shows an isometric view of an embodiment of the invention in action. 
         FIG.  5    shows an isometric view of another embodiment of the invention in action. 
         FIG.  6    shows an isometric view of a step in the method according to the invention. 
         FIG.  7    shows an isometric view of another step in the method according to the invention. 
         FIG.  8    shows an isometric view of the embodiment of  FIG.  1    in action. 
         FIG.  9 A  shows a top view of the embodiment of  FIG.  8   . 
         FIG.  9 B  shows an isometric view showing forces and moments present in the situation of  FIGS.  8  and  9   . 
         FIG.  10    shows an isometric view of the embodiment of  FIG.  1    in action. 
         FIG.  11    shows a top view of the situation shown in  FIG.  10   . 
         FIGS.  13 - 16    show side views and front views of the embodiment of  FIG.  1    in action. 
         FIG.  17    shows another isometric view of the device in action. 
         FIG.  18    shows a top view associated with  FIG.  17   . 
         FIG.  19    shows another isometric view of the embodiment of  FIG.  1    in action. 
         FIG.  20    shows a top view associated with  FIG.  10   . 
         FIG.  21 A  shows the device according to the invention in action. 
         FIG.  21 B  shows an isometric view of a swaging tool. 
         FIG.  22 A  shows an isometric view of another embodiment of the invention. 
         FIG.  22 B  shows the embodiment of  FIG.  22 A , wherein three of the four actuator are about to retract in order to push the other pile into the ground. 
         FIG.  22 C  shows the embodiment of  FIG.  22 A , wherein one of the piles is disconnected from its associated pile connector. 
         FIG.  23 A  shows a side view of the embodiment of  FIG.  22    after a pushing or pulling step. 
         FIG.  23 B  shows a side of the embodiment of  FIG.  22    prior to pushing the left pile in by retracting the other actuators of the remaining piles. 
         FIG.  24    shows a top view of the embodiment of  FIGS.  22 - 23   . 
         FIG.  25    shows a sectional side view of a detail of the embodiment of  FIGS.  22 - 24   . 
         FIG.  26    shows a side view of another embodiment of the invention. 
         FIG.  27    shows a top view of the embodiment of  FIG.  26   . 
         FIG.  28    shows an isometric view of the embodiment of  FIGS.  26 - 27   . 
         FIG.  29 A  shows an isometric view of a further embodiment of the invention. 
         FIG.  29 B  shows an isometric view of the embodiment of  FIG.  29 A , wherein three of the four actuator are about to retract in order to push the other pile into the ground. 
         FIG.  30 A  shows a side view of the embodiment of  FIG.  29   . 
         FIG.  30 B  shows a side view of  FIG.  29 B . 
         FIG.  31    shows a top view of the embodiment of  FIGS.  29 - 30   . 
         FIG.  32    shows a sectional view of a hydraulic cylinder configured to take bending moments. 
         FIG.  12    shows a sectional view of another embodiment of a hydraulic cylinder configured to take bending moments. 
         FIG.  33    shows a perspective view of another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE FIGURES 
     Turning to  FIGS.  1 ,  2  and  3    a first embodiment of the device  10  is shown. The device  10  comprises a bridge assembly  12 . The bridge assembly  12 —when seen in top view—defines a first, second, third and fourth connecting location  14 . 1 ,  14 . 2 ,  14 . 3 ,  14 . 4  (generally designated as  14 ) which are arranged in a square configuration or in a diamond configuration. It is noted that the numbering of the connection locations is chosen such that 14.1 and 14.2 are located opposite one another and  14 . 3  and  14 . 4  are also located opposite one another. 
     Typical centre to centre of the piles (or distance between the connecting locations  14 ) would be 2 m to 3 m. The pile diameter can be in the order of 1.5 m (1500 mm). The pile length may be 42 m. Obviously, other sizes, diameters and distance are also possible. 
     During operation part of the piles are loaded in tension and part of the piles are loaded in compression. It was surprisingly found that when the piles are spaced more closely together the increase in tension capacity is larger than the increase in compression capacity. As the compression capacity of piles is generally larger than the tension capacity of piles a result of spacing the piles more closely together is that the difference between the compression capacity and the tension capacity of the piles is reduced. The difference between the compression and tension capacities is compensated by the weight of the device itself and the moment that is taken up by the piles. So an advantage of placing the piles closer together is that either the deadweight of the device can be significantly reduced or the moment acting on the piles can be reduced, or a combination thereof. 
     The piles may be spaced as closely together as possible. A pile spacing  95  is however limited by the minimum required spacing  96  between the cylinders  18  and the fabrication of the device according to the invention, see  FIG.  33   . The spacing is  95  limited to approximately half a pile diameter. The pile spacing is substantially equal to the distance between the pile connectors. 
     It was found that the tension and compression capacity of the piles increase exponentially at a pile spacing of 2 pile diameters and less, wherein the tension capacity has a steeper exponential increase with decreasing pile spacing  95  compared to the compression capacity. 
     It was further found that a spacing  95  between 2 to 4 pile diameters already has a more or less linearly increasing effect on the difference between tension and compression capacity, with the same advantage of allowing the deadweight of the device to be reduced. 
     The device  10  comprises a first, a second, a third and a fourth pile connection assembly  16 . 1 ,  16 . 2 ,  16 . 3 ,  16 . 4  (generally designated as  16 ) via which in use each of the four piles 1, 2, 3, 4 is connected to the bridge assembly  12 . In  FIGS.  1 ,  2 , and  3    the piles 1, 2, 3, 4 are not shown. 
     Each pile connection assembly  16 . 1 ,  16 . 2 ,  16 . 3 ,  16 . 4  comprises an actuator  18  (individually designated as:  18 . 1 ,  18 . 2 ,  18 . 3 ,  18 . 4 ) positioned (when seen in top view) at a respective connecting location and extending downward from the associated connecting location  14 . The actuators may be hydraulic actuators. This is the preferred embodiment for offshore use. 
     However, the actuators  18  may also be electric or pneumatic or be operated on steam. This may in particular be suitable for use on land, and may be suitable for smaller versions of the device  10 . 
     The actuators  18  may be of cylinder type or of a spindle type. In case of a spindle, the spindle may be driven by hydraulic, pneumatic or electric force. 
     Each actuator  18  comprises an upper actuator part  20  and a lower actuator part  21 . The upper actuator part  20  is connected to the bridge assembly  12 . The actuator  18  is configured to extend (in length) in order to each time move the lower actuator part  21  downward relative to the upper actuator part  20  in order to push the associated pile over a distance into the ground or seabed. 
     Each pile connection assembly  16  further comprises a pile connector  22  (individually designated as  22 . 1 ,  22 . 2 ,  22 . 3 ,  22 . 4 ) connected to the lower actuator part  21 . Each pile connector  22  is configured to be connected to an upper end of a pile which is to be pushed into the ground or seabed. 
     The pile connector  22  is configured to move downward together with the associated lower actuator part  21  relative to the upper actuator part  20  during the extension of the actuator  18 . 
     For the hydraulic and pneumatic embodiment, the device  10  further comprises a source  25  of hydraulic/pneumatic fluid connected to the four actuators  18  and a control device  100  configured for alternately letting each of the actuators extend. The control device is configured for individually controlling the hydraulic/pneumatic pressures in the actuators  18 . The control device  100  is configured for regulating the hydraulic/pneumatic pressures inside the actuator  18  which extends and inside the opposite actuator  18  in order to let the pile which is pushed into the ground or seabed receive a greater force than the opposite pile of the square or diamond configuration. In case of electric actuators, the source or pressurized fluid is obviously not required, and the control device  100  simply controls the forces in the electric actuators  18 . 
     The device  10  may comprise measuring equipment for measuring the position and orientation of the piles 1, 2, 3, 4 relative to the device  10 . The measuring equipment may comprise electronic, optic mechanical or acoustic sensors. The sensors may be connected to the control unit  100  for effective control of the entire process. The measuring equipment may further comprise load sensors for measuring the loads which are exerted on the piles. 
     In the embodiment of  FIGS.  1 ,  2    and,  3 , the bridge assembly  12  comprises:
         a first pivotable frame  26  which is pivotable about a first pivot axis  27 , and   a second pivotable frame  28  positioned below the first pivotable frame and being pivotable about a second pivot axis  29  which extends at an angle, in particular at right angles, to the first pivot axis, wherein when seen in top view the first pivotable frame crosses the second pivotable frame,       

     The first pivotable frame  26  is pivotable in a first plane which extends at right angle to the first pivot axis. The second pivotable frame  28  is pivotable in a second plane which extends at right angles to second pivot axis and to the first plane. The first and second pivot axis extend horizontally. The first and second plane extend vertically. 
     It is noted that the first and second connection locations  14 . 1  and  14 . 2  define outer ends of the first pivotable frame  26 . The third and fourth connection locations  14 . 3  and  14 . 4 . define outer ends of the second pivotable frame  28 . In the embodiment of  FIG.  1   , the first and second pivot axis  27 ,  29  extend orthogonal to one another, when seen in top view. 
     The first actuator  18 . 1  and the second actuator  18 . 2  are positioned below the first pivotable frame  26  and are connected with the respective upper actuator parts  20  thereof to the first pivotable frame at the connection locations  14 . 1 ,  14 . 2 . In top view, both connection locations  14 . 1 ,  14 . 2  are located on the first pivot axis  27 . The connections locations  14 . 1 ,  14 . 2  are located on opposite sides of the first pivotable frame. 
     The third actuator  18 . 3  and the fourth actuator  8 . 4  are positioned below the second pivotable frame  28  and are connected with the respective upper actuator parts  20  thereof to the second pivotable frame on opposite sides of the second pivotable frame  28 , Each pile connection assembly  16  further comprises a pair  30  of connector rods  31 . 
     The pairs are individually designated as  30 . 1 ,  30 . 2 ,  30 . 3  and  30 . 4 . The connector rods  31  are designated with a digit indicating the connecting assembly  16  to which the connector rod belongs, i.e.  31 . 1 ,  31 . 2 ,  31 . 3 ,  31 . 4 . Further, each pair  30  comprises a right connector rod  31 A and a left connector rod  31 B, indicated with  31 . 1 A,  31 . 1 B, etc. For the pairs  30 . 1  and  30 . 2 , “right” is defined as the right side when looking at the device  10  from the side of connecting assembly  16 . 1 . For the pairs  30 . 3  and  30 . 4 , “right” is defined as the right side when looking at the device  10  from the side of connecting assembly  16 . 3 . 
     The right and left connector rod  31 . 1 A,  31 . 1 B of the first pile connection assembly  16 . 1  are connected to the lower actuator part  21  of the first actuator  18 . 1  and to the second pivotable frame  28 . The first and second pivotable frame  26 ,  28  each comprise upper rod mounting positions  33 ,  34  for the connector rods  31 . The first pivotable frame  26  comprises four upper mounting positions  33 , two upper mounting positions  33  for the connector rods  31 . 3 A and  31 . 3 B extending to the lower actuator part  21 . 3  of the third connecting assembly  16 . 3  and two upper mounting positions  33  for the connector rods  31 . 4 A and  31 . 4 B extending to the lower actuator part  21 . 4  of the fourth connecting assembly  16 . 4 . The second pivotable frame  28  comprises four upper mounting positions  34 , two upper mounting positions  34  for the connector rods  31 . 1 A,  31 . 1 B extending to the lower actuator part  21 . 1  of the first connecting assembly  16 . 1  and two upper mounting  34  positions for the connector rods  31 . 2 A,  31 . 2 B extending to the lower actuator part  21 . 2  of the second connecting assembly  16 . 2 . 
     The upper rod mounting positions  33  of the first pivotable frame  26  are located at opposite sides of the first pivot axis  27 . The upper rod mounting positions  34  of the second pivotable frame  26  are located at opposite sides of the first pivot axis  29 . 
     Each lower actuator part  21  comprises lower rod mounting positions  35 ,  36 . 
     Each rod mounting position  33 ,  34 ,  35 ,  36  may comprise a hinge. 
     The right and left connector rod  31 . 1 A,  31 . 1 B of the first pile connection assembly  16 . 1  are connected to the lower actuator part  21 . 1  of the first actuator  18 . 1  and to the second pivotable frame  28  at the upper rod mounting positions  34  thereof. 
     The right and left connector rod  31 . 2 A,  31 . 2 B of the second pile connection assembly  16 . 2  are connected to the lower actuator part  21 . 2  of the second actuator  18 . 2  and to the second pivotable frame  28  to the upper rod mounting positions  34  thereof. 
     The right and left connector rod  31 . 3 A,  31 . 3 B of the third pile connection assembly  16 . 3  are connected to the lower actuator part  21 . 3  of the third actuator  18 . 3  and to the first pivotable frame  26  to the upper rod mounting positions  33  thereof. 
     The right and left connector rod  31 . 4 A,  31 . 4 B of the fourth pile connection assembly  16 . 4  are connected to the lower actuator part  21 . 4  of the fourth actuator  18 . 4  and to the first pivotable frame  26  to the upper rod mounting positions  33  thereof. 
     Each right connector rod  31 A is connected to a right side of the associated actuator  18  and each left connector rod  31 B is connected to a left side of the associated actuator  18 . 
     The right and left connector rod  31 A,  31 B of each pair  31  are connected to a same side of the associated pivotable frame  26 ,  28  and to opposite sides of the associated lower actuator part  21 . 
     Each connector rod  31 A,  31 B is connected to the associated pivotable frame via an upper hinge. Each connector rod  31 A,  31 B is connected to the lower part  21  of the associated cylinder actuator  18  via a lower hinge. 
     Each pair  30  of connector rods  31 A,  31 B is configured to transfer a tension force and a bending moment from the bridge assembly  12  into the associated pile. The transfer of the tension force and the bending moment takes place via the lower actuator part  21 . Because the connector rods  31  are connected to the upper and lower pivotable frames and to the lower parts  21  of the actuators via hinges, the bending moments can only be transferred into the piles in one plane (or about one axis). Due to the hinges, no bending moments about an axis which is parallel to the pivot axis  27 ,  29  of the respective pivotable frame can be transferred by the connector rods. This allows pivoting of the pivotable frame about the pivot axis. 
     Each pile connector  22  comprises an insertable part  40  which is configured to be inserted into a pile. Each a pile connector  22  comprises a shoulder  48  configured to rest on the end face of a pile and to transfer the push force to the pile. 
     Each pile connector comprises one or more grippers  42  configured to grip the upper end of the tubular piles. The grippers  42  can move between an outer, gripping position and an inner, released position as indicated by arrow  44 . The grippers  42  may be operated by one or more actuators situated within the insertable part  40 . The grippers  42  can be embodied as a lock which fits underneath a ring which is attached to the pile or as separate blocks with teeth which grip into the inside of the pile or systems with similar functionalities. 
     The grippers  42  may grip the piles from the inside, but may also grip the piles from the outside, or both from the inside and from the outside. In this last embodiment, Hoop stresses are avoided. The grippers  42  can be fixed to the pipes by clamping, gripping (friction), pinning, load carrying ridge(s) etc. or a combination thereof. All of these methods can be internal, external or a combination of internal and external gripping. 
     The device comprises a suspension organ  46  in the form of an eye which allows suspension of the device from a crane. 
     Operation—First Embodiment 
     Turning to  FIG.  4   , when the device  10  is to be used in an offshore environment, the device  10  may be operated from a vessel  112 . The vessel may be a semi-submersible, regular vessel, barge or any other type of vessel. 
     A pile support frame  116 , may be provided on the vessel. The pile support frame is configured to support  4  piles in a pickup configuration. In the pickup configuration, the four piles are positioned parallel to one another at mutual interspacing which corresponds to the interspacing between the connecting locations  14 . 1 - 14 . 4 . Preferably the piles ore oriented vertically or substantially vertically. In the embodiment of  FIG.  4   , the pile support frame  116  is located inside a column  111  of the semi-sub vessel and an upper end of the pile support frame  116  is located at the deck level. In case of a regular hull, the pile support frame  116  may be located inside the hull. 
     In the embodiment of  FIG.  5   , the pile support frame  116  further comprises a platform  117  provided at a side of the vessel  112 . The pile support frame  116  cantilevers over the water. 
     Obviously, other embodiments of the pile support frame  116  are also possible. For instance the pile support frame  116  may be positioned on deck  110  and rise upward from the deck or may be positioned in a moonpool. 
     In operation, the vessel  112  is positioned at a target location  118 , for instance at a base  120  of a leg  121  of a jacket  122 . The target location  118  may obviously be any location at which piles need to be driven into the seabed. The device  10  can for instance be used for installing piles into an already installed (part) of a structure (e.g. jacket or template or any other structure) or for so-called “pre-piling”, in case the structure or part thereof is not yet in place and eventually is placed over the pre-installed piles. 
     It is noted that pre-piling can be done with an intermediate template on the sea-floor, the use of a spacer frame could however act as a guidance frame that comes with the piles rather than pre-installing a temporary guidance frame. This would result in a reduction of execution time. 
     This could, when used for pre-piling, eliminate having a complex pre-pilling template with adjustable inclination systems. 
     Four piles 1, 2, 3, 4 are positioned in the pile support frame  116 . The piles may be tubular. In case of the platform of  FIG.  5   , the piles may be connected near their upper ends to the pile support frame  116  and be suspended therefrom. The upper end faces of the four piles are flush with respect to one another. 
     The device  10  may be lifted from the deck  110  of a vessel  112  with a crane  114 . The crane  114  lifts the device  10  and subsequently places the device  10  on the four piles 1, 2, 3, 4 as is shown in both  FIGS.  4  and  5   . Next, the grippers  42  are moved outward and grip the upper ends of the tubular piles, thereby connecting each pile connection assembly  16  to an associated pile. The device  10  is now connected to the four piles. 
     Turning to  FIG.  6   , the crane  114  subsequently lifts the combination  150  of the device  10  and the four piles 1, 2, 3, 4 from the pile support frame  16  and moves the combination  150  to the target location  118 . In order to improve the stability of the combination, temporary wires, braces, brackets, stops or similar device may be provided to prevent the four piles from colliding during the lift, to maintain a required spacing of the lower ends of the piles and to prevent the moving parts of the device  10  from moving. 
     Optionally, the device  10  can be equipped with a spacer frame to limit relative movement between the piles and between the piles and the device  10 . This spacer frame can be hung off underneath the device  10  or be suspended on the piles itself, allowing to install and remove it in one lift or in two separate lifts. 
     The connection between the spacer frame and the device  10  can for instance be formed by either slings, chains or rigid materials. 
     Turning to  FIG.  7   , the combination  150  is subsequently lowered into the base  120  of a leg of a jacket. The base  120  comprises a base plate  123  and pile sleeves  124  which extend upwardly from the base plate. The four piles 1, 2, 3, 4 are lowered into the four pile sleeves  124 . This requires a certain degree of control and accuracy. The bottom ends  126  of the piles are maintained at the required distance from one another by any of the temporary devices discussed above. The pile sleeves  124  may comprise tapered pile guides  125  at their upper ends to facilitate the positioning of the piles into the pile sleeves. 
     In an embodiment, the initial start-up loads can be transferred to the pile sleeves by providing a rigid connection between the pile connection assemblies of the piles which are under tension and the associated pile sleeves  124 . This allows to be able to (partly) omit the use of ballast weight for the start-up weight during the time that limited soil capacity is activated. 
     It is noted that in an alternative embodiment, the piles may be positioned and lowered into the pile sleeves individually and sequentially, for instance by the crane  114 , and prior to the device  10  being positioned on top of the piles 1, 2, 3, 4. Next, the device  10  is then positioned on top of the four piles. In this embodiment, no pile support frame  116  is required. 
     When the bottom ends of the piles 1, 2, 3, 4 contact the seabed, initially the piles will sink into the seabed under their own weight and the weight of the device  10  over a certain distance, e.g. 50 cm. Additional ballast weight may be provide on top of the device  10  to increase this distance and to improve the overall functioning of the device  10 . 
     Turning to  FIGS.  8 ,  9 A and  9 B , when all piles are inside the pile sleeves and the device  10  is on top of the piles and has gripped the piles (which in top view are in square or diamond configuration), the device  10  can start operating. In a first step, pile 1 is pushed downward. This is done by increasing the hydraulic pressure inside the first actuator  18 . 1  with the control device. At the same time, the hydraulic pressure inside the second actuator  18 . 2  is maintained at a lower level. 
       FIG.  9 A  shows the resulting forces in the four piles 1, 2, 3 and 4. The force exerted on pile 1 is raised to 3000 mt (for example), the force exerted on pile 2 is maintained at 1600 mT. 3000 mt is an example which is realistic for very dense North Sea sands. Pile 1 will then be pushed downward. 
     As a result the piles 3 and 4 will be put under tension, each at—2300 mT. The minus indicates that the force is a tension force. The four forces result in a balance of forces, but in an imbalance of moments on the bridge assembly  12  and in particular on the first pivotable frame  26 . It is noted that during the extension of the first actuator, the first pivotable frame  26  is held stationary. 
     Turning to  FIG.  9 B , the same forces F1, F2, F3 and F4 are shown in an isometric drawing. When pile 1 is pushed downward, these four forces will result in an imbalance of bending moments about axis  29 . In order to restore equilibrium the piles 3 and 4 need to exert a bending moment M 1  (=1400*d) about axis  29  on the upper pivotable frame  26 . 
     Turning to  FIGS.  8 ,  9 A,  9 B,  13  and  14   , the tension forces and the bending moment are exerted from the piles 3, 4 on the upper pivotable frame  26  via the connector rods  31 . 3 A,  31 . 3 B,  31 . 4 A and  31 . 4 B which extend between the lower actuator parts  21 . 3 ,  21 . 4  and the upper pivotable frame  26 . Because action=−reaction, the force of pile 1 on the first pivotable frame will be 3000 mT and the force exerted by pile 2 will be 1600 mT. In order to provide equilibrium, the tension force in connector rod  31 . 3 B (indicated in  FIG.  14   ) of connection assembly  16 . 3  will be greater than the tension force in connector rod  31 . 3 A of connection assembly  16 . 3 . 
     As can be seen in  FIG.  8   , during the insertion stroke of pile 1, the first pivotable frame  26  remains stationary while the second pivotable frame  28  pivots about its pivot axis  29  and becomes tilted. This is caused by the connector rods  31  which extend between the lower actuator part  21  and the second pivotable frame  28 . These connector rods pull the second pivotable frame  28  down on the side of the first pile 1. 
     Returning to  FIGS.  13  and  14   , the occurring forces are shown during the insertion of pile 1. The combined tension force occurring in the two right connector rods  31 . 3 A,  31 . 4 A which are connected to respectively the lower actuator part  21 . 3  and the lower actuator part  21 . 4  is shown in  FIG.  14    as 1150 mT, i.e. 625 mT for the right connector rod  31 . 3 A and 625 mT for the right connector rod  31 . 4 A. The combined tension force occurring in the two left connector rods  31 . 3 B,  31 . 4 B which are connected to respectively the lower actuator part  21 . 3  and the lower actuator part  21 . 4  is shown in  FIG.  14    as 3450 mT, i.e. 1725 mT for the left connector rod  31 . 3 B and 625 mT for the left connector rod  31 . 4 B. Together, these forces transfer a tension force and a bending moment into piles 3 and 4. 
     Turning to  FIGS.  10  and  11   , when pile 1 has been inserted over the distance of the stroke of actuator  18 . 1  into the ground or seabed, the same process is carried out for the opposite, second pile 2. The hydraulic pressure in the second actuator  18 . 2  is raised and the hydraulic pressure in the first actuator  18 . 1  is lowered until F1=1600 mT and F2=3000 mT. F3=F4=−2300 mT. As a result, the second actuator  18 . 2  makes an extension stroke and pushes pile 2 into the ground or seabed. Pile 1 remains stationary during this time. The second pivotable frame  28  tilts back to a horizontal orientation. The piles 3, 4 are again put under tension while at the same time a moment M 2  is imparted onto piles 3 and 4. M 2  is opposite to M 1 . 
     Turning to  FIGS.  17  and  18   , the same process is repeated for pile 3. Actuator  18 . 3  is extended and as a result, pile 3 is inserted into the ground or seabed over a distance. Now, the second pivotable frame  28  remains stationary while the first pivotable frame  26  pivots about its pivot axis  27 . F3 is now +3000 mT, F1 and F2 are −2300 mT and F4 is +1600 mT. 
     Turning to  FIGS.  19  and  20   , the same process is repeated for pile 4. Pile 4 is inserted over a distance into the ground by extending actuator  18 . 4 . The first pivotable frame  26  pivots back to its horizontal orientation. 
     Turning to  FIG.  21 A , when all four piles have been inserted into the ground or seabed over a distance once, a full cycle has been completed. Each cycle comprises the following steps in the sequence as indicated:
         pushing the first pile over a distance into the ground or seabed,   pushing the second pile which is opposite to the first pile over a distance into the ground or seabed,   pushing the third pile over a distance into the ground or seabed,   pushing the fourth pile which is opposite to the third pile over a distance into the ground or seabed.       

     All four piles are now (assuming that everything went well) inserted into the ground or seabed over a same distance, and the method can continue with inserting pile 1 over a next distance. 
     A number of cycles are carried out until all four piles are inserted into the ground or seabed over the required depth. The device  10  moves downward together with the piles. Alternately each one of the four piles 1, 2, 3, 4 is pushed over a distance into the ground or seabed by extending the actuator  18  which is associated with said pile. During the extension the control device  100  regulates the hydraulic pressures inside the actuator which extends and inside the opposite actuator in order to let the pile which is pushed into the ground or seabed receive a greater force than the opposite pile of the square or diamond configuration. The exerted push force is transferred from the respective actuator into the bridge assembly  12  and transferred at least partially from the bridge assembly as a tension force and a bending moment into the two adjoining piles via the two adjoining pile connection assemblies. 
     During the extension of an actuator  18 , the pivotable frame  26 ,  28  which is connected to the upper part  20  of said actuator is maintained stationary and the other pivotable frame pivots. The actuator  18  which extends transfers an exerted push force into the bridge assembly and wherein said push force is transferred at least partially from the bridge assembly as a tension force and a bending moment into the two adjoining piles via the two adjoining pile connection assemblies. 
     Optionally, the device  10  can be equipped with a gripper or a lock system at the bottom of the lower bridge. 
     With reference to  FIG.  21 B , the device  10  can be further equipped with one or more swaging tools  80 . The swaging tool  80  can be integrated with the insertable part  40  or can be provided as an add-on. This swaging tool itself is known from the prior art and allows to plastically deform the pile in radial direction by applying a pressure. This deformed shape than fits into one or more internal cavities  82  in the pile sleeve to form a mechanical connection. The cavity may extend circumferentially around the central passage. This removes the need to grout the pile to the sleeve. 
     The gripper or lock system can engage with the pile sleeve  124  ensuring a connection between the two. If all the actuators  18  are then extended the device  10  can pull up the pile sleeve and tilt the jacket. This can be used on the lowest corner of the jacket to adjust the jacket level. Afterwards the swaging tool can be used to mechanically connect the pile sleeves with the pile to ensure that the jacket stays level. 
     The proposed system can be used for installing piles into an already (part) of a structure (e.g. jacket or template or any other structure) or for the pre-piling where the structure is not yet in place and eventually is placed over the pre-installed piles. 
     Pre-piling can be done with an intermediate template on the sea-floor, the use of a spacer frame could however act as a guidance frame that comes with the piles rather than pre-installing a temporary guidance frame. This results in a reduction of execution time. 
     Measurements 
     When driving piles it is generally advantageous to monitor the process with measurement equipment. There are several reasons for this. 
     One reason is that it is a requirement for the German authorities to have an indication of capacity of the pile after installation. In piles which are hammered, normally additional measurement systems have to be placed on the pile after the pile has been hammered into the ground. This is due to the fact that the blows are so hard that electronic equipment becomes damaged. An advantage of the device  10  is that it, because it requires no hammering, electronic equipment can be placed on the device  10  and the piles 1, 2, 3, and 4. This enables a constant read-out of the pile capacity through the pressures in the cylinders, therefore no additional measurements are required. 
     By measuring the depth of the piles independently, the top of the piles can be placed level or within a desired inclination even if the piles are at an offset of the desired inclination. 
     This could, when used for pre-piling, eliminate having a complex pre-pilling template with adjustable inclination systems. 
     Pulling Out 
     In addition to the first embodiment of the invention being capable of pushing piles into the ground or the seabed, the device is also configured for pulling piles out of the ground or the seabed. When, for example, the installed piles have met their life expectancy, it can be beneficial to remove them from the ground or seabed for economic and ecological reasons, 
     In essence, the operation of removing the piles resembles the installation operation in backwards order. After connecting the device  10  to the upper end of the piles, wherein each pile connection assembly  16  is connected to an associated pile, either one pile or two piles are alternately pulled out of the ground or seabed over a distance. 
     By keeping one actuator or two actuators substantially stationary while extending the remaining actuators, the corresponding pile or piles can be pulled out. During the extension, the control device is used to regulate the vertical force exerted by the extending actuator opposite the substantially stationary actuator or the vertical force exerted by the two opposite actuators. In doing so, each pile corresponding to a substantially stationary actuator receives a greater vertical force than each of the remaining, stationary piles. This results in pulling each pile associated with the substantially stationary actuator or the two substantially stationary actuators out of the ground or seabed. 
     Additionally or alternatively, it is also possible to retract the one or two actuators associated with respective pile or piles. During the retraction, the control device  100  can then regulate the force exerted by a retracting actuator  18  and the force exerted by the opposite actuator  18 . This way, the pile or piles being pulled out of the ground or seabed may receive a greater force than the remaining piles of the square or diamond configuration. 
     An exerted pull force can be transferred from the respective actuator which is associated with the pile being pulled out into the bridge assembly  12 . It can then, at least partially, be transferred from the bridge assembly as a compression force and a bending moment into the two adjoining piles via the two adjoining piles connection assemblies. 
     Second Embodiment—Sliding Assembly 
     Turning to  FIGS.  22 - 25   , a second embodiment is shown. In this embodiment, each pile connection assembly  16  ( 16 . 1 ,  16 . 2 ,  16 . 3 ,  16 . 4 ) comprises a sliding assembly  50  ( 50 . 1 ,  50 . 2 ,  50 . 3 ,  50 . 4 ) which is rigidly connected to the bridge assembly  12 . 
     This embodiment does not have any pivotable frames. The actuators  18  are connected with their upper parts  22  the bridge assembly  12 . 
     In this embodiment, the bridge assembly  12  comprises an upper bridge part  55 . In this embodiment, the pile connection assemblies  16  are rigidly connected together via a base frame  53 . The base frame is rigidly connected to the upper bridge part  55  via four columns  51 . The base frame  53  is rigidly connected to each of the four columns  51 , and the columns are rigidly connected to the bridge assembly  12 . The overall construction has the configuration of a box frame. The connecting locations  14  are at the upper bridge part  55 . The base frame  53  defines four sleeves  52 . 
     Each sliding assembly  50  comprises a sleeve  52  ( 52 . 1 ,  52 . 2 ,  52 . 3 ,  52 . 4 ) and one or more gripper actuators  54  ( 54 . 1 ,  54 . 2 ,  54 . 3 ,  54 . 4 ) which can be switched between a gripping state and a released state. In  FIG.  25   , two gripper actuators  54  are shown above one another. The gripper actuators  54  may act on the pile, or on the pile connector  22 , or both. 
     In the released state of the gripper actuators  54 , the pile 1, 2, 3, 4 and/or pile connector  22  can slide through the sleeve  52 . The sleeve  52  can exert a bending moment on the pile and/or the pile connector  22 , and vice versa, the pile and/or the pile connector  22  can exert a bending moment on the sleeve. This bending moment can be transferred to one or more of the other three piles via the base frame  53  and the other three sleeves  52 . 
     In the gripping state of the gripper actuators  54 , the pile in question is firmly gripped and cannot move upward or downward relative to the base frame  53 . The base frame  53  can exert both a bending moment and an upward (or downward) force on the pile 1, 2, 3 or 4. Typically, the upward force is primarily relevant for the operation of the device  10 , because with the upward force, the pile can be put under a tension force. 
     The operation of the second embodiment is very similar to the operation of the first embodiment. 
     Each cycle comprises the following steps in the sequence as indicated:
         pushing a first pile over a distance into the ground or seabed,   pushing a second pile over a distance into the ground or seabed,   pushing a third pile over a distance into the ground or seabed,   pushing a fourth pile which is opposite to the third pile over a distance into the ground or seabed.
 
The piles can be pushed into the ground or seabed by carrying out multiple cycles.
       

     In contrast to the operation of the first embodiment, the pushing of the first pile or the fourth pile in the second embodiment may also be done by keeping one actuator substantially stationary while retracting the remaining actuators. The control device can be configured for regulating at least the vertical force exerted by the retracting actuator opposite the substantially stationary actuator. In doing so, the pile corresponding to the substantially stationary actuator can receive a greater vertical force than each of the remaining, stationary piles. The pile which is associated with the substantially stationary actuator can then be pushed into the ground or seabed. This can be repeated for all four piles. 
     In  FIGS.  22 B and  23 B , the operation is shown wherein the actuator of the first pile 1 is kept substantially stationary and the actuators of the remaining piles 2, 3, 4 are about to be retracted. 
     Another possible operation of the second embodiment, but also of the third and fourth embodiment, is the combination of alternately retracting the actuators and having each of the actuators extend. Herein, the control device can also be configured for regulating at least the force which is exerted by the actuator which extends and the force which is exerted by the opposite actuator. In doing so, the pile which is pushed into the ground or seabed can receive a greater force than the opposite pile of the square or diamond configuration, 
     By combining the pushing through the extension and retracting of the actuators, the time necessary pushing of all four piles can be reduced because every movement of the actuators can be used to push the piles. 
     Both during the retracting and extension of the actuators, the actuator which is associated with the pile being pushed in can transfer the exerted push force into the bridge assembly. Additionally, said push force can be transferred at least partially from the bridge assembly as a tension force and a bending moment into the two adjoining piles via the two adjoining pile connection assemblies. 
     A method for the pushing of four piles into the ground or into a seabed may then comprise the pushing in of the first pile or the fourth pile of a cycle by keeping the actuator associated with said first pile or fourth pile substantially stationary while retracting the remaining actuators, the other piles in the cycle can then be pushed in by alternately extending the respective actuators. 
     In the second embodiment, the first, second third and fourth pile can be chosen in any order. In other words, the order can be, when seen in top view, clockwise, anticlockwise, or similar to the order used in the first embodiment. 
     The regulating of the hydraulic pressures in the actuator which makes the stroke and in the opposite actuator remains the same as for the first embodiment. In other words, for the actuator which is to be extended the hydraulic pressure is higher than for the opposite actuator. This will create a bending moment which needs to be transferred into the two piles on the other diagonal. 
     Similarly to the first embodiment, the device can also be used to pull out the piles when they have served their purpose. Generally speaking, the operation of removing the piles can be done by reversing the operational steps of installing the piles. 
     In particular, after having connected the device  10  to the upper ends of the piles, the pulling out is done by keeping one actuator or two actuators substantially stationary while extending the remaining actuators; the corresponding pile or piles can then be pulled out. During the extension, the control device is used to regulate the vertical force exerted by the extending actuator opposite the substantially stationary actuator or the vertical force exerted by the two opposite actuators. In doing so, each pile corresponding to a substantially stationary actuator receives a greater vertical force than each of the remaining, stationary piles. This results in pulling each pile associated with the substantially stationary actuator or the two substantially stationary actuators out of the ground or seabed. 
     Additionally or alternatively, it is also possible to retract the one or two actuators associated with respective pile or piles. During the retraction, the control device  100  can then regulate the force exerted by a retracting actuator  18  and the force exerted by the opposite actuator  18 . This way, the pile or piles being pulled out of the ground or seabed may receive a greater force than the remaining piles of the square or diamond configuration. 
     An exerted pull force can be transferred from the respective actuator which is associated with the pile being pulled out into the bridge assembly  12 . It can then, at least partially, be transferred from the bridge assembly as a compressions force and a bending moment into the two adjoining piles via the two adjoining piles connection assemblies. 
     Third Embodiment 
     Turning to  FIGS.  26 ,  27  and  28   , a third embodiment is shown. This embodiment is quite similar to the second embodiment, with a difference in that the bridge assembly  12  comprises a single frame  58 , which in top view has a square or diamond shape, and which has a central opening  60 . 
     The sliding assemblies  50  of the third embodiment are essentially the same as for the second embodiment. 
     The operation of the third embodiment is also essentially the same as the operation of the second embodiment. 
     With reference to  FIG.  28   , the single frame  58  can be positioned over a jacket which has been placed on the seabed earlier. This positioning manoeuvre can be carried out with a crane  114  on board the installation vessel  112 . The four piles can be prepositioned before the device  10  is positioned on top of the piles. Alternatively, the four piles can be lifted over the jacket and be positioned on the seabed together with the device  10 . 
     The operation of the third embodiment is the same as the operation of the second embodiment. 
     Fourth Embodiment 
     With reference to  FIGS.  29 - 32  and  12   , in a fourth embodiment, the four actuators  18  are each configured to transfer both an axial force (compression force and tension force) and a bending moment from the bridge assembly  12  to the respective piles 1, 2, 3, 4 and vice versa. 
     This configuration has less mechanical parts, but the actuators  18  need to be specifically designed and constructed in order to be able to transfer the bending moments. 
     In one variant, shown in  FIG.  32   , each actuator  18  comprises a cylinder  84 , a piston rod  87  and a first piston  88  and second piston  89  positioned inside the cylinder and mounted on the piston rod at a distance from one another. The two pistons at a distance from one another allow the transfer of a bending moment. 
     In another variant, shown in  FIG.  12   , the piston  88  comprises a piston guide  92  and the rod end  90  of the cylinder comprises a rod guide  93 . The piston guide  92  and the rod guide  93  are configured to transfer the lateral forces. A minimum distance  94  between the piston guide  92  and the rod guide  93  (at the outermost position of the rod) is equal than or greater to the diameter of the cylinder. The minimum distance  94  is at least 50 cm at a minimum diameter of the cylinder of 50 cm. 
     In another variant, each actuator comprises a plurality of linear guides positioned at a lateral distance from one another and extending parallel to the direction in which the actuator extends. The linear guides are rigidly fixed to the upper actuator part  20 . The lower actuator part  21  is slideably connected to the linear guides. The linear guides are configured to transfer a bending moment from the upper actuator part to the lower actuator part. 
     In another variant, each actuator ( 18 ) comprises a first sub-actuator and a second sub-actuator positioned adjacent one another. 
       FIG.  33    shows a variant, wherein the connecting locations  14  are adjustable between an outer location  97  and an inner location  98  respectively with respect to a centre  99  of the bridge assembly. 
       FIGS.  29 B and  30 B  show actuators  18 . 1 ,  18 . 2  and  18 . 3  which are about to retract while actuator  18 . 1  is kept substantially stationary. This way the pile associated with actuator  18 . 1  receives a greater force than the remaining piles and is pushed into the ground. 
     General Aspects 
     The device  10  according to the present invention may be used both on land and at sea. 
     The device  10  according to the present invention is configured for pushing piles into the ground or seabed which are not interlocked. 
     The device  10  is configured for pushing piles into the ground or seabed which are positioned at a horizontal distance from one another and do not contact one another. Generally, the piles will be tubular piles having a circular cross-section. 
     The device  10  may be equipped with suction pumps to reduce friction of the pile being pushed downward and/or to increase the tension capacity of the piles under tension by increasing or decreasing the internal pressure in each pile. In particular, the device  10  may be equipped with valves to increase the tension capacity at the pull side by creating an under pressure inside the piles which are under tension when pulling on the pile. 
     The device according to the present invention may comprise exactly four pile connectors. 
     The device according to the present invention is in particular suitable to drive all piles vertically into the ground or seabed. The four actuators and the four pile connectors may be oriented vertically. However, depending on the conditions, the device  10  may also be used to drive piles into the ground or seabed in an inclined orientation. 
     The bridge assembly moves downward together with the piles as they are pushed into the ground. Ultimately, the bridge assembly may contact the ground, seabed or pile sleeve. 
     The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising i.e., open language, not excluding other elements or steps. 
     Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention. It will be recognized that a specific embodiment as claimed may not achieve all of the stated objects. 
     The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 
     White lines between text paragraphs in the text above indicate that the technical features presented in the paragraph may be considered independent from technical features discussed in a preceding paragraph or in a subsequent paragraph.