Driving into the Ground or Pulling from the Ground

Elongated Construction Elements Technical field

[0001 ] The invention concerns a device, a system, and methods for driving an elongated construction element, for instance a pile, a tubular post, or a sheet pile segment, into a ground layer, and/or for pulling the elongated construction element from the ground layer using a number of elongated auxiliary elements.

Background Art

[0002] Prior to the construction of buildings, earthworks, or infrastructure, elongated construction elements such as piles, tubular posts and/or sheet pile segments are often placed in the underlying ground layer to provide a supporting and/or reinforcing function. Various techniques are known for driving such piles, tubular posts or sheet pile segments into the ground. Piling technology uses hammering or vibrating methods, in which a series of abrupt or periodically repeated impulses is exerted on an upper end portion of the elongated construction element. This causes noise pollution as well as an increased risk of earth slides and damage to nearby buildings or other constructions.

[0003] Alternative techniques are known, in which such construction elements are driven gradually into the soil by exerting more constant forces. These techniques involve less noise pollution and less risk of earth slides, but they require much heavier and more complex pressing machines. In all cases the friction that the surrounding soil exerts on the construction element must be overcome in order to drive the construction element deeper into the ground. Such friction includes both the resistance against driving apart the soil below the construction element and the friction forces exerted by the soil on the side surfaces of the construction element. Conversely, when the elongated construction element is to be extracted from the ground, friction along the element’s side surfaces and potentially also the underpressure (vacuum) at a bottom end portion of the construction element need to be overcome.

[0004] British Patent GB-A-2218722 describes a system and a method for driving a tube with a mandrel into the ground, using reactive forces of auxiliary elements previously placed in the ground layer. Use is made of two T-shaped steel auxiliary elements that are initially driven into the ground. Subsequently, a pressing machine is coupled to these auxiliary elements, after which the tube is driven into the ground layer by both the pressing machine’s weight and the friction forces that the soil exerts on the auxiliary elements. Then the pressing machine is coupled to the tube and the auxiliary elements are driven further into the ground by both the pressing machine’s weight and the friction forces that the soil exerts on the tube.

[0005] Document GB-A-2218722 provides virtually no details on the design of the pressing machine or on the manner in which the machine engages the tube and the auxiliary elements. It is desirable to provide a device and a method with which driving in and/or pulling out elongated construction elements may be adapted to the soil’s local characteristics, so as to render the driving in and/or pulling out easier to achieve.

Summary of Invention

[0006] According to a first aspect of the invention, there is provided a device for driving an elongated construction element, like a pile, tubular post, profiled beam, or sheet pile segment, into a ground layer and/or for pulling such a construction element from the ground layer, using a number of elongated auxiliary elements that may be placed in the ground layer in order to generate reactive forces. These reactive forces are friction forces exerted by the soil in a substantially vertical direction on and along the outer surface of the auxiliary elements. The direction of these reactive forces is equal to the direction of the pressing or pulling forces that the device exerts on the construction element during operation. The device comprises a number of actuators and a base including an aperture and a clamping member. Each of the actuators is adapted to couple the actuator to a respective auxiliary element, and for exerting both vertical pushing forces and pulling forces on the auxiliary element, along an axial direction and with respect to the base. Such a pushing force is exerted in order to drive the relevant auxiliary element deeper into the ground, and such a pulling force is exerted in order to pull the auxiliary element from the ground. The aperture defines a passageway extending along the axial direction through the base and terminating on two opposed sides of the base. This aperture is adapted for receiving a part of the elongated construction element, such that the construction element extends substantially along the axial direction through the base. The clamping member is arranged on or around the aperture, and is configured to temporarily fix and prevent translation of the construction element in the axial direction relative to the base.

[0007] The device according to this first aspect may be used in regular earthworks machinery that includes a wheeled chassis and a lead column, and enables pressing or pulling elongated construction elements into/out of the ground using a combination of the machine’s own weight and reactive forces exerted by auxiliary elements placed in the ground (i.e. friction forces between the soil and the auxiliary elements directed along the pressing/pulling direction of the construction element). The machine’s own weight may initially be used to drive the construction element as far as possible into the ground. The auxiliary elements can subsequently be driven into the ground, to provide reactive forces. The reactive forces and pushing force caused by the machine’s own weight jointly allow the construction element to be driven deeper. The auxiliary elements are pulled statically, and the cycle may be repeated. The device enables the auxiliary elements and the construction element to be pressed into (or pulled from) the ground in alternating steps, ensuring that the reactive forces on the auxiliary elements increase (or decrease) gradually and symmetrically, the further down (less deep) the auxiliary elements are in the ground. The characteristics of the auxiliary elements used (such as their shape, dimensions, mechanical properties, number, and spatial distribution) as well as the stroke lengths of the actuators and the forces exerted between the auxiliary elements and the construction element may be selected and adapted on site, based on the soil’s local properties. This provides a method for driving construction elements into and/or pulling them out of the ground, which can be adapted to the soil’s characteristics. The device and method described here are especially suited for use in softer, cohesive soil types, such as clay, peat and loam.

[0008] ‘Elongated’ is used herein to refer to a length of the object that is much larger than its characteristic lateral dimensions, for instance at least one order of magnitude larger. For an elongated construction element with a length Lc and lateral dimensions AXc, AYc, this means that Lc » AXc, AYc, for instance that Lc > 10-AXc and Lc > 10-AYc. Examples of elongated construction elements are piles (e.g. driving piles or supporting piles), tubes (e.g. tubular posts), profiled beams (e.g. steel beams with IPE, HEM or HEB profiles), wall segments (e.g. sheet pile walls), or other elongated elements with sufficient rigidity to function as foundation for buildings and/or to solidify the subsoil. Pressing in or pulling out construction elements is performed in a substantially vertical downward or upward direction. The longitudinal axis of the construction element then lies substantially parallel with the direction of the force of gravity.‘Substantially vertical’ is used in this context to refer to a pushing/pulling direction under an angle of less than 20°, preferably less than 15°, or even less than 10°, relative to the vertical direction Z.

[0009] The auxiliary elements may for instance be formed as elongated segments of a segmented tubular post, or as drill spindles. Placing or removing the auxiliary elements into (or from) the ground also takes place along a substantially vertically downwards (upwards) direction, with the auxiliary elements’ longitudinal axes directed substantially parallel with the pushing or pulling direction of the construction elements.

[0010] In an embodiment, each of the actuators is fixedly mounted to the base and is provided with a coupling member for releasably coupling the actuator with a respective auxiliary element. Each coupling member may preferably be coupled with a respective auxiliary element, such that movement between this coupling member and the coupled auxiliary element in the two opposite directions along the longitudinal axis of the auxiliary element is prevented. In addition, the actuators and the corresponding coupling members are sufficiently rigid so as to allow both pushing and pulling forces to be exerted in opposite directions along the longitudinal axis of the auxiliary element (i.e. the axial direction Z) from the base onto the auxiliary elements, by driving the actuators. The coupling provided by the coupling member preferably is releasable, so that auxiliary elements may be removed and exchanged when desired.

[001 1 ] The aperture in the base defines a passageway extending along the axial direction through the base, which may enclose the construction element along an axial part of it. The presence of this aperture allows the use of construction elements with a length Lc that is greater than the length Lh of the auxiliary elements, and allows the provision of a clamping member arranged on or around the aperture, such that the construction element may be temporarily but robustly fixed relative to the base during pressing or pulling operations. More specifically, the base may have a length Lb, the extended actuators may project below the base to a maximum length La, and the length Lc of the construction element may be greater than or equal to the lengths of the base, the actuators, and the auxiliary elements together (i.e . Lc > Lb + La + Lh). This device can be used for construction elements of various lengths, without the need to adapt or exchange the device when switching to other element lengths.

[0012] In embodiments, the base comprises a side aperture defining a passageway between an outer circumference of the base and the central aperture. The side aperture has a lateral dimension that equals at least a smallest lateral dimension of the construction element, and that allows the construction element to be placed in the central aperture by a lateral movement through the side aperture. In further embodiments, the base comprises two base members and a hinge. The base members may be movably coupled to each other by the hinge, such that the base members may swivel relative to one another, between:

- a closed state, in which distal portions of the base members touch, and are held together such that the base surrounds the aperture in lateral directions, and

- an open state, in which de distal portions are spaced apart from each other, defining a side aperture in between, which is in communication with the central aperture.

[0013] The hinge is arranged on a lateral side of the central aperture, and the distal portions are arranged at a distance from the hinge and on free ends of the base members that are located on laterally opposite sides of the aperture. The side aperture, temporarily formed between the distal portions in their open state, is in communication with the central aperture, such that a construction element may be placed in the central aperture by a lateral movement through the side aperture. After placement, the base may be brought back to its closed state.

[0014] The articulated base may be provided with a latch mechanism for latching and mutually fixing the base members in the closed state. In the closed state the clamping member may be activated to clamp the construction element and temporarily fix it relative to the base. The latch mechanism is strong enough to compensate for the outward forces (or torques) that are generated as a result of the inward clamping forces of the clamping member on the construction element. The latching mechanism may for instance be formed of hydraulically driven hooked rims extending over the full height along the distal portions, and capable of interlocking in the closed state.

[0015] In a further embodiment, the base members are formed substantially mirror-symmetrically with respect to a sagittal plane of the base and the lead column. In this case, the device may be provided with an even number of actuators, and these actuators may be arranged around the aperture in a distribution that is both mirror-symmetrical and rotation-symmetrical relative to a nominal central axis of the aperture, and in which none of the actuators is in the sagittal plane. In the open state, this keeps the route through the side aperture and to the central aperture fully free, whereas in the closed state the actuators and the base may generate optimum linear forces between the auxiliary elements and the construction element.

[0016] In an embodiment, the device comprises at least two actuators, and preferably at least four actuators. The actuator may be arranged around the aperture on the base. The phrase ‘around the aperture’ refers in this context to actuators being arranged on opposite sides near the aperture, each at a lateral displacement relative to the central axis of the aperture. This arrangement allows the auxiliary elements on opposite sides of the construction element to be forced into or out of the ground, so that the reactive forces generated by the auxiliary elements may be maximally converted into linear pressing and/or pulling forces that are exerted on the construction element parallel with its nominal longitudinal axis, while generation of lateral forces and/or torques on the construction element is mostly avoided. The device may be configured to move a desired selection of auxiliary elements up or down relative to the base, while

simultaneously keeping all other, non-selected auxiliary elements stationary relative to the base, and to subsequently repeat the procedure of selective movement for another selection of auxiliary elements. In one example, a device each time moves just one auxiliary element while keeping all other auxiliary elements stationary, and selects and moves another one auxiliary element in consecutive stages. In another example, a device each time selects two auxiliary elements located at laterally opposite sides relative to the axial center of the aperture in the base, and that moves the pair simultaneously while keeping all other auxiliary elements stationary.

Subsequently, this device selects another pair of mutually opposite auxiliary elements for simultaneous moving.

[0017] In a further embodiment, the actuators are arranged in a regularly spaced distribution around the aperture, and mounted on the base. The term‘regularly spaced distribution’ refers in this context to actuators being placed in a mirror-symmetrical and/or discrete rotation-symmetrical distribution around a center of the aperture. In one embodiment with four actuators, a first set of two actuators may for instance be arranged on opposite sides of the aperture, symmetrically with respect to the central axis of the aperture, while another set of two actuators is arranged on opposite sides of the aperture and symmetrically with respect to the central axis of the aperture, but rotated 90° around the central axis relative to the first pair. The four actuators may for example be arranged in a + shaped or x shaped distribution, relative to a sagittal plane of the base that coincides with the central axis of the aperture.

[0018] In some embodiments, the aperture has characteristic lateral dimensions perpendicular to the central axis. In order to keep the torques between an auxiliary element and the base, as well as twisting of the lead column, small during driving of the auxiliary elements, the actuators around the aperture may be positioned at lateral distances from the nominal axis, such that these lateral distances are maximally two times the characteristic lateral dimension of the aperture.

[0019] In some embodiments, the actuators project downward from a lower end portion of the base during operation, and these actuators are adapted to hold the auxiliary elements along their upper rim using the coupling members.

[0020] In a further embodiment, each of the actuators comprises an elongated body extending along a nominal actuator axis parallel with the axial direction.

[0021 ] According to further embodiments, each actuator comprises an elongated body that extends at least partially inside the base, so that the coupling members may be retracted up to the bottom of the base. De actuator may for instance be formed as a screw spindle or an assembly of piston cylinder and a piston rod that may be retracted into the base, for instance hydraulically.

This retractability may minimalize the distance between the base and the auxiliary elements, thereby minimizing undesired lateral forces or torques that may occur when the auxiliary elements are selectively pressed or pulled.

[0022] According to embodiments, the auxiliary elements are formed as elongated blades or beams having an outer circumference that is substantially identical at various positions along the longitudinal axis. The auxiliary elements may for instance have a linearly symmetrical form along their longitudinal axis. In that case, the actuators may be formed as linear actuators, each of which is configured to be coupled to a respective auxiliary element and to move this auxiliary element up or down relative to the base independently of the other auxiliary elements.

[0023] Alternatively the auxiliary elements may be formed as elongated drill spindles, and the actuators may be formed as threaded actuators. These threaded actuators may be adapted to be coupled to a respective auxiliary element, and to rotate this auxiliary element independently of the other auxiliary elements, relative to the base, and simultaneously move it up or down.

Combinations of various auxiliary elements and their corresponding actuators are also possible. For example, two linear actuators may be coupled with beam-shaped auxiliary elements and arranged on opposite sides of the central aperture, and two threaded actuators may likewise be coupled with drill spindles and arranged on other opposite sides of the central aperture, rotated over 90°.

[0024] According to some embodiments, the clamping member is arranged along the aperture in the base, and is provided with at least one inwardly movable engagement surface for clamping the elongated construction element inside the aperture.

[0025] In some embodiments, the base comprises a movable carrier that is adapted to hold the base by a part of a pressing system, at adjustable positions above the ground layer. This carrier may for instance be formed as a sled, mounted to a lead column of an earthworks machine, whic may be moved upward and downward along the lead column by means of a transversally enclosing rail engagement and a driving device. Base and carrier may also be provided with collaborating clamp coupling members formed to temporarily fix the base to the carrier. These clamp coupling members may be formed in a standardized manner to allow the exchange of the base with other operating devices.

[0026] In order to be able to subject a construction element, during or directly after driving it into the ground layer, to a measurable test load, the device may be provided with a sensor system for measuring a pushing force exerted on the construction element by the base and de actuators.

[0027] According to a second aspect, and in accordance with the advantages and effects discussed above, the invention provides a system for pressing an elongated construction element into a ground layer and/or for pulling the elongated construction element from the ground layer. The system comprises an undercarriage that can be placed on the ground layer, a lead column moveably coupled to the undercarriage, which may be placed in an operational position with a vertical component relative to the ground layer, and a device according to the first aspect, which may be coupled to the lead column.

[0028] According to a third aspect, and in accordance with the advantages and effects discussed above, the invention provides a method for pressing an elongated construction element into a ground layer, using a number of elongated auxiliary elements that are placed in the ground layer in order to generate reactive forces, as well as a device according to the first aspect, or a system according to the second aspect. The method comprises:

- placing the elongated construction element through the aperture of the base;

- coupling each of the auxiliary elements to a corresponding actuator, for instance by means of a respective coupling member;

- successively activating and extending one or more selected actuators, while holding the other actuators in position, in order to drive into the ground the corresponding auxiliary element, over a first distance relative to the base (52), the construction element, and the other auxiliary elements;

- fixing the construction element relative to the base by means of the clamping member, followed by

- simultaneously activating and shortening all actuators while holding the construction element in position, in order to drive into the ground the construction element, over a distance relative to the auxiliary elements. That distance may be identical to the first distance.

[0029] Preferably, successively activating and extending selected actuators each time concerns activating and extending a single actuator, while keeping the other actuators in position, or simultaneously activating and extending two actuators on opposite sides of the central aperture, while keeping a greater number of other actuators in position. After powering the selected actuator or selected actuator pair, the same procedure is repeated for another actuator respectively another actuator pair (i.e. an alternating method of selecting and powering actuators).

[0030] In one embodiment the method further comprises:

- fixing the construction element relative to the base by means of the clamping member, before or during successively activating and extending one or more selected actuators, in order to drive into the ground the corresponding auxiliary element over a first distance relative to the base (52), the construction element, and the other auxiliary elements.

[0031 ] During the pressing operation, the vertical positions of the bottom rims of the auxiliary elements in the ground remain always higher than the lower end portion of the pile. The pile thus projects below the auxiliary elements at all times, which prevents that soil will be caught locally between the auxiliary elements and that driving the pile further in would generate excessive outward transversal pressure on the auxiliary elements.

[0032] According to a fourth aspect, and in accordance with the advantages and effects discussed above, the invention further provides a method for pulling an elongated construction element from a ground layer, using a number of elongated auxiliary elements that are placed into the ground layer to generate reactive forces, and a device according to the first aspect, or a system according to the second aspect. The method comprises:

- coupling each of the auxiliary elements to a corresponding actuator, for instance by means of a respective coupling member;

- placing the device above the construction element positioned in the ground layer and placing the auxiliary elements with bottom rims adjacent to and around the construction element; - successively activating and extending one or more selected actuators, while holding the other actuators in position, in order to drive into the ground the corresponding auxiliary element over a first distance relative to the base and the other auxiliary elements;

- after driving in all auxiliary elements, simultaneously activating and shortening all actuators in order to drive the base downwards over the first distance relative to the auxiliary elements;

- continuously repeating the previous two steps until the elongated construction element extends with an projecting upper end portion through the aperture of the base;

- fixing the construction element relative to the base by means of the clamping member;

- simultaneously activating and lengthening all actuators while holding the construction element in position, in order to urge the base and the construction element upwards over a distance relative to the auxiliary elements. This distance may be identical to the first distance.

The method may further comprise the following:

- releasing the clamping member and releasing the construction element relative to the base, and

- simultaneously activating and shortening all actuators in order to urge the base downwards over the first distance relative to the construction element and the auxiliary elements.

The previous four steps may be repeated until the construction element is removed from the ground.

Brief Description of Drawings

[0033] In the following, embodiments of the invention will be described, merely as examples and using the accompanying schematic drawings. In these figures, corresponding parts are indicated by corresponding reference symbols. The various instances of a part may be indicated by a letter added to the reference symbol. Two instances of a certain part‘40’ may then be indicated as‘40a’ and‘40b’. The reference symbol may be used without the added letter to refer in general to an unspecified instance or to all instances of that part, while the reference symbol with the added letter refers to a specific instance.

[0034] Figure 1 shows a machine for pressing in elongated construction elements free of vibrations, according to an embodiment;

[0035] Figure 2a shows an embodiment of the device for use in the machine of Figure 1 ;

[0036] Figure 2b shows a top view of a cross section of the base and four actuators of Figure 2a;

[0037] Figure 2c shows a top view of a cross section of a construction element and surrounding auxiliary elements of Figure 2a;

[0038] Figures 3a - 3c show an alternative embodiment of a device;

[0039] Figure 4 shows a yet another embodiment of a device;

[0040] Figures 5a - 5f illustrate a method for pressing in an elongated construction element according to an embodiment.

[0041 ] These drawings are for illustration purposes only, and do not limit the scope of the invention as defined by the claims. Description of Embodiments

[0042] Figure 1 shows an example of an embodiment of a mobile machine 10 for pressing in and/or pulling out an elongated construction element 34 into and/or from a ground layer 30. The machine 10 is provided with a wheeled undercarriage 12 with caterpillar treads 14, and with an upper carriage 16 with control cabin 18 rotatably mounted on the undercarriage. To this upper carriage 16 a lead column 20 is mounted in an adjustable manner. The lead column 20 is provided on its upper end portion with a cathead 26 with pulleys 28a, 28b. The lead column 20 may be oriented relative to the upper carriage 16 by means of a hydraulic piston device 24, for instance from a substantially horizontal position corresponding to a movement mode of the machine 10, to a substantially vertical position corresponding to an operational mode of the machine 10 (as seen in Figure 1). In the operational mode, undercarriage 12 and upper carriage 16 are mutually fixed and arranged in a stabilized manner on a surface 32 of a target ground layer 30, and the lead column 20 extends substantially vertically relative to the ground surface 32.

[0043] The machine 10 comprises a specially configured auxiliary device 50 with a base 52 that is mounted by means of a movable carrier 56 to the lead column 20. In this example the carrier is configured as a sled 56, which may be moved upward and downward along the lead column 20 by means of a transversally locking rail clamp. The movement of the sled 56 with base 52 along the lead column 20 is driven by a pulley system, which is arranged vertically along the lead column (not indicated). The base 52 and the sled 56 are provided with cooperating clamp coupling members 57, adapted to temporarily fix the base 52 to the sled 56. By moving the sled 56 along the lead column 20, the fixed base 52 may be positioned at a desired height DZ relative to the local ground surface 32.

[0044] By means of the machine 10, a pile 34 may be pressed into the ground layer 30, or removed from the ground layer 30. In these examples, the use of the machine 10 and the driving in and pulling out operations are described with reference to a pile 34, but it will be clear that the principles and actions described herein may equally be applied to a tubular post, a profiled beam, a sheet pile segment, or any such slim/elongated structure.

[0045] The machine 10 is provided with a lifting system with a winch 22 on the upper carriage 16. This winch 22 is adapted for rolling in and out a cable 29 running over pulleys 28 on the cathead 26. The cable 29 may be temporarily coupled near an end portion thereof to an upper end portion

36 of the pile 34, such that the pile 34 may be lifted from a horizontal rest position on the surface 32 to a vertical operating position in which the pile 34 is enclosed by the base 52.

[0046] To this end, the base 52 is provided with an aperture (element 58 in Figures 2a - 2b) that defines a passageway extending through the base 52, and which terminates on opposed sides 54, 55 of the base 52. In the operational mode the first and second sides 54, 55 of the base 52 are substantially directed upwards (i.e. away from the ground surface 32) respectively downwards (i.e. towards the ground surface 32).

[0047] On the second side 55 of the base 52 four cylinder actuators 62 are mounted. Each of these actuators 62 is provided on its lower side with a coupling member 64, which it is adapted for holding a corresponding auxiliary element 40 along the pile 34. [0048] The presence of aperture 58 in the base 52 enables using a pile 34 or another construction element with a length Lc that is greater than the length Lh of the auxiliary elements 40. More specifically, the base 52 may have a length Lb and the actuators 40 may extend over a maximum length La below the base 52, such that the length Lc of the pile 34 is greater than or equal to the total length of the base 52, the actuators 62, and the auxiliary elements 40 together, i.e. Lc > Lb + La + Lh.

[0049] Figure 2a shows an example of an embodiment of the device 50 of Figure 1 in more detail. The base 52 forms a single body, including the aperture 58 that extends around a nominal central axis B through the entire base 52. The aperture 58 is adapted for receiving a part of the pile 34, such that the pile 34 extends through the base 52, and that the central axis B of the aperture 58 is substantially aligned with the nominal longitudinal axis C of the pile 34. In this example, the longitudinal axis C and hence the desired pressing direction of the pile 34 is chosen substantially parallel with the vertical direction Z.

[0050] The cable 29 that is (temporarily) coupled to an upper end portion 36 of the pile 34 may be used to initially lift the pile 34 into the aperture 58 of the base 52. This embodiment with a unitary base 52 is well suited for use with piles 34 or other slim construction elements having a relatively short length Lc. When lifting and placing longer construction elements into the aperture 58, use may be made of an auxiliary crane.

[0051 ] Along an inner surface of the aperture 58 a clamping construction 60 is mounted, which in this example has contact surfaces that may be moved inwards and outwards along transversal directions X, Y. This clamping construction is configured to temporarily clamp and fix the enclosed pile 34 relative to the base 52, such that the movement of the enclosed pile 34 relative to the base 52 along central axis B is prevented.

[0052] The device 50 comprises four actuators 62a, 62b, 62c, 62d, each of which is fixed with an upper end portion to the base 52. These actuators 62 are arranged in a regular, 90°-symmetrical, plus-shaped distribution around the aperture 58. Two actuators 62b, 62d are located on opposite sides of the aperture 58 and in a sagittal plane P of the base 52 (and the lead column 20), while the other two actuators 62a, 62c are located on other opposite sides of the aperture 58 and are located on equal lateral distances from this sagittal plane P. In this example each of the actuators 62 is formed by a hydraulic piston, the cylinder of which being fixed to and part of the base 52, and the cylinder rod of which being extendable downwards from a bottom 55 of the base 52 along a nominal actuator axis Ai (i = a, b, c, d) substantially parallel with the central axis B of the aperture 58. Since the cylinders extend at least partially inside the base 52, the coupling members 64 may be retracted up to the lower side 55 of the base 52.

[0053] In this example, each of the actuators 62i is provided on its lower side with a coupling member 64 for releasably coupling the actuator 62i to an upper rim 42i of a corresponding auxiliary element 40i. Each actuator 62 is adapted to exert both vertical pushing forces and pull forces on the coupled auxiliary element 40.

[0054] Figure 2b shows a cross section of the base 52 and four actuators 62 in a top view along the vertical direction Z. This shows that the aperture 58 is centered with the central axis B around the longitudinal axis C of the pile 34, and has lateral dimensions DCo, DUo that are slightly greater than the characteristic lateral dimensions DCo, DUo of the pile 34. Concrete driving piles, for instance, may have characteristic lateral dimensions in which DCo en DUo are identical and each are within a range of 180 - 500 mm. The actuators 62 are arranged around the aperture 58, such that the actuator axes Ai are located at respective lateral distances AXa, AYa from the central axis B. In this example each of these lateral distances AXa, AYa is smaller than twice the characteristic lateral dimension DCo, DUo of the aperture 58, to prevent undesirably great torques from being exerted on the actuators 62, the construction element 34, and the lead column 20 during the selective pressing of auxiliary elements 40.

[0055] Figure 2b shows a top view along the vertical direction Z of a cross section of a construction element 34 and four auxiliary elements 40a - 40d that are arranged in the ground in a continuous manner around the construction element 34. The elements 34 and 40 are placed in the ground layer 30, such that the construction element 34 is directly encircled by an interior part 30a of the ground layer 30. The auxiliary elements 40 are interlinked along their side rims 46, in order to form an articulated tube, which in cross section defines a closed contour that completely surrounds the construction element 34 and the inner ground layer part 30a in a regular distribution. In order to improve the mutual stability of the auxiliary elements 40 and the accuracy of the placement of these auxiliary elements 40, side rims 46 may be provided with interlocking sliding connections that allow mutual longitudinal displacement between the auxiliary elements 40, but that resist mutual transversal movement of the auxiliary elements 40. The auxiliary elements 40, once positioned, are in their turn encircled by an outer part 30b of ground layer 30. It will be clear that construction elements and auxiliary elements of different shape and composition may be used, such as cylinder-shaped construction element and/or auxiliary elements shaped as cylinder shell segments such that these may be linked along their sides to form a continuous (round) cylinder shell around the construction element.

[0056] Figured 3a - 3c show an alternative device 150. Elements and properties of the device described above (Figures 1 - 2c) may also be included in the device 150 in Figures 3a - c and will not be discussed here again. Like elements are indicated with like reference numbers, but preceded by a number 100 to distinguish between embodiments.

[0057] In this example the device 150 comprises two base members 152a, 152b configured substantially mirror-symmetrically relative to a sagittal plane P of the base 152 and the lead column 120. These base members are coupled movably relative to one another by means of a hinge 168, such that the base members can swivel relative to one another in the XY-plane between i) an open state (Figures 3a - b) in which the distal ends 172a, 172b of the base members 152 interlock and are held together with a latching mechanism 174, and ii) an open state (Figure 3c) in which the distal ends 172 are temporarily spaced apart to define a side aperture 170.

[0058] The temporary side aperture 170 that is formed in the open state communicates with the central aperture 158, so that a pile 134 may be placed through the side aperture 170 into the central aperture 158. After placement, the base 152 may be returned to the closed state and be locked, after which the clamping members 160 may be activated to fix the pile 134 temporarily relative to the base 152. The latching mechanism 174 must be sufficiently strong to compensate for the outwardly directed forces and/or torques that are generated as a result of the inwardly directed clamping forces of the clamping members 160a - b on the pile 134. The latching mechanism 174 may for instance be formed of hydraulically actuated hooking rims that extend over the entire height along the side aperture 170 and that may interlock in the closed state.

[0059] Also in this example, the actuators 162 are arranged in a regular 90°-symmetrical distribution around the aperture 158, although in this case this is in a cross-shaped distribution, i.e. a distribution rotated over 45° relative to the sagittal plane P. As a result, none of the actuators 162 is in the sagittal plane P, so that the way through the side aperture 170 to the aperture 158 remains unobstructed.

[0060] Due to the two-part implementation of the base 152 with hinge 168, the use of a crane is not needed, because the pile 134 may be lifted from a horizontal rest position by means of the winch 122 and with the cable 129 coupled to the upper end portion 136 of the pile 134, through the side aperture 170, into the central aperture 158 inside the base 152. This embodiment with a two-part base 152 is suitable for employment with piles 134 and other elongated construction elements with various lengths.

[0061 ] Figure 4 shows a further alternative device 250. Elements and properties of the devices described above (Figures 1 - 3c) may also be included in the device 250 of Figure 4, and will not be discussed here again. Like elements are indicated with like reference numbers preceded a number 200.

[0062] In this device 250, the auxiliary elements are formed by elongated drill spindles 240, and the actuators are formed by screw spindles 262. Each screw spindle 262 is adapted to be coupled to a respective drill spindle 240, and to rotate this drill spindle independently of the another drill spindles around a respective actuator axis Ai and relative to the base 252, and to simultaneously move them up or down in the ground. If desired, screw spindles 262 may simultaneously be driven to screw the drill spindles 240 in or out of the ground in pairs.

[0063] Figures 5a - 5f illustrate an example of a method for driving a pile 34 into the ground, using a machine such as for instance the machine 10 discussed with Figures 1 - 2c. The method employs a combination of the weight of the machine 10 (i.e. the force of gravity Fz exerted on the machine 10) and reactive forces (i.e. friction forces) that the ground 30 exerts on the (partially) inserted auxiliary elements 40.

[0064] Figure 5a shows a first stage of the pressing method. Initially the pile 34 is placed vertically and with a lower end portion 37 on the ground. Near an upper end portion 36, the pile 34 protrudes substantially vertically through the aperture 58 of the base 52, and the clamping member 60 is activated to fix the pile 34 and base 52 temporarily together. A middle portion of the pile 34 that is located between the upper and lower end portions 36, 37 is surrounded by four bent blade-shaped auxiliary elements 40. The coupling members 64 of the actuators 62 are each fixed to an upper rim 42 of a respective auxiliary element 40, so that the actuators 62 keep the auxiliary elements 40 in a vertical orientation along and around the pile 34, and at a fixed distance from the base 52. In this state, the pile 34 is driven into the ground 30 by the machine 10 under its own force of gravity Fz directed along its own longitudinal axis C and over an initial distance DZ1 (Figure 5a).

[0065] Figure 5b illustrates a second stage of the pressing method, in which the auxiliary elements 40 are powered one by one and driven into the ground over a first distance AZa. To this end, one actuator 62a is first powered and extended by a distance AZa, for instance by the maximum stroke length of the actuator 62a, while the clamping member mutually holds the pile 34 and base 52, and the other three actuators (62j (j ¹ a) are held at a constant length. As a result, the coupling member 64 with the coupled auxiliary element 40a will be driven downwards over a distance AZa into the ground 30, relative to the base 52 with the pile 34 and other auxiliary elements 40j, while the pile 34, the base 52, and the other three auxiliary elements 40j remain at substantially the same distances relative to the ground 30. This selective pressing operation is repeated with each of the actuators 62 separately, until all are driven into the ground 30 over substantially equal distances AZa.

[0066] During the pressing operation, the vertical positions of the bottom rims 43 of the auxiliary elements 40 in the ground 30 always remain higher than the lower end portion 37 of the pile 34. As a result the pile 34 always extends below the auxiliary elements 40, thus preventing soil from being caught locally between the auxiliary elements 40, and preventing that driving the pile 34 further down will generate an excessive transversally outwards pressure on the auxiliary elements 40.

[0067] Figure 5c shows a result of a third stage of the pressing method. In this third stage, the powering of the clamping member 60 is removed, so that the base 52 becomes moveable relative to the pile 34, while the pile 34 can be moved freely through the aperture 58. Now all actuators 62 are simultaneously powered and shortened over a distance substantially equal to AZa, so that the base 52 is moved integrally downwards over the distance AZa along the pile 34 and relative to both the pile 34 and the stationary auxiliary elements 40. The procedure with separate powering and lengthening of each of the actuators 62i (i = a, b, c, d) and the separate driving into the ground of the auxiliary elements 40i may now be repeated several times. If this part of the procedure is performed N times, the auxiliary elements 40 will be driven into the ground 30 over a distance N AZa relative to the pile 34. The result of N steps is shown in Figure 5c, which shows that the lower end portion 37 of the pile 34 remains extended below the bottom rims 43 of the auxiliary elements 40. The total friction force Fwt exerted by the ground 30 on the four auxiliary elements 40 driven into the ground thus equals four times the friction force Fwh on every individual auxiliary elements 40 (Figure 5d). In a next stage, this total friction force Fwt exerted on the auxiliary elements 40 that are already (partially) driven in may be used together with the weight Fz of the machine 10 itself to drive the pile 34 one stroke deeper into the ground.

[0068] Figure 5d illustrates a fourth stage of the pressing method. Here, the clamping member 60 is powered to mutually fix the pile 34 and the base 52. Subsequently, all actuators 62 are simultaneously powered and shortened over a distance substantially equal to AZa, so that the base 52 is moved together with the pile 34 over the distance AZa downwards relative to the stationary auxiliary elements 40. As a result, the pile 34 is driven into the ground over a distance AZa. Subsequently the clamping member 60 is released again such that the pile 34 is no longer clamped, and all actuators 62 are simultaneously powered and lengthened over a distance substantially equal to AZa, so that the base 52 is integrally moved upwards over the distance AZa along the pile 34 and relative to both the pile 34 and the stationary auxiliary elements 40.

Subsequently, the clamping member 60 may again be powered to mutually fix the pile 34 and the base 52 and to drive down the pile again over a distance AZa.

[0069] More specifically, Figure 5d shows an intermediary result of the fourth stage, in which, by performing this part of the procedure M times, the pile 34 has been driven into the ground 30 over a distance M AZa relative to the auxiliary elements 40. This part of the procedure is preferably repeated until the maximum force Fmax by which pile 34 can be pressed into the ground 30 is reached. This maximum force Fmax equals the total friction force on the auxiliary elements 40 already driven in, plus the force of gravity exerted on the machine 10 (i.e. Fmax = Fwt + Fz). This maximum force Fmax is determined experimentally during the pressing operation. It will be clear that the distance traveled during the last and/or intermediate steps may be selected to be smaller than AZa, to ensure that the total driving distance AZt achieved for the pile 34 corresponding to the soil friction force Fp exerted on the pile in this fourth stage approaches the maximum achievable pushing force Fmax as closely as possible.

[0070] As long as pile 34 has not yet been driven down to the desired depth in the ground 30, the second, third and fourth stages may be repeated in sequence. The total force with which every inserted auxiliary element 40 may be driven further into the ground 30 equals three times the friction force Fwh on the remaining three auxiliary element 40 plus the force of gravity Fz on the machine 10. After repeating the second and third stages, the total friction force Fwt’ exerted by the ground 30 on the further inserted auxiliary elements 40 is substantially increased, such that the pile 34 may be driven into the ground with a further maximum force Fmax’ = Fwt’ + Fz . It must be noted that the maximum distance over which each auxiliary element 40 may be driven into the ground 30 and the resulting friction force exerted on each individual auxiliary element 40 will be limited by the strength and maximum pressing power that can be delivered by each of the corresponding actuators 62. A maximum pressing power that may be delivered by a commercially available hydraulic cylinder actuator may for instance amount to 60 tons, 80 tons, or 100 tons.

[0071 ] During or after driving the pile 34 into the ground 30, the device 10 may exert a test pressing force on the pile 34 that is driven in. This test pressing force may be measured by means of a sensor system 65. This force may serve as a test load with which the pile 34 that is driven in may be tested for its load capacity, without a separate measurement system being necessary.

[0072] Some foundation constructions may require that the pile 34 is driven completely into the ground, for instance with the upper end portion 36 at the same level as the ground surface 32 or even deeper into the ground layer 30. Figure 5e illustrates an optional fifth stage, in which the pile 34 has been driven almost entirely into the ground 30, such that the upper end portion 36 of the pile 34 remains just within the aperture 58 of the base 52, and may be clamped by the clamping member 60. Subsequently decoupling the clamping member 60 and simultaneously powering and lengthening the actuators 62 will cause the aperture 58 and the base 52 to extend above the pile 34. In this optional stage, a pile-shaped auxiliary segment 66 may be inserted through the aperture 58, which is placed on the upper end portion 36 of the pile 34. By clamping this auxiliary segment 66 by means of the clamping member 60, and by subsequently simultaneously powering and shortening the actuators 62, the pile 34 may be driven downwards by means of the auxiliary segment 66 over a last distance AZe relative to the stationary auxiliary elements 40, fully into the ground 30, such that the upper end portion 36 of the pile 34 ends up at the same level or even slightly below the ground surface 32. In alternative methods in which the pile 34 does not need to be driven completely into the ground, this optional fifth stage may be skipped, and the use of an auxiliary segment 66 may be omitted. The pressed-in pile 34 may for instance remain with its upper end portion 36 above the ground surface 32, or may be cut off.

[0073] Figure 5f illustrates a last stage, in which the auxiliary elements 40 are pulled from the ground 30 one by one. In this case, each individual element 40i is each time moved upwards over a stroke length AZa relative to the other three elements 40j (j ¹ i), during which the pulling force upon shortening the corresponding actuator 62i will each time remain smaller than the resulting friction force on the remaining three elements 40j. After all four elements 40 have been pulled upwards over a stroke length AZa, all actuators are simultaneously powered and lengthened over a stroke length AZa, so that the base 52 is in its entirety moved upwards over AZa relative to the auxiliary elements 40. This cycle is repeated until the base 52 and auxiliary elements 40 are all substantially removed from the ground 30, whereas the pile 34 remains in the ground 30.

[0074] It will be clear that the embodiments described above are only given as examples and not with the purpose of limiting the scope of the invention in any way, and that various changes and adaptations are possible without passing outside the scope of the invention, the scope being determined only by the appended claims.

[0075] For instance, in the exemplary method described above, during the stage of selectively driving down an auxiliary element, only the combination of the machine’s own weight and the friction forces exerted by the ground on the other auxiliary elements in the ground was used, without clamping the construction element and utilizing the friction force exerted by the ground on the partially inserted construction element. Not clamping the construction element when the auxiliary elements are selectively and alternatingly pressed in further is preferable in the case that the construction element has a low resistance to twisting forces directed transversally to the longitudinal direction of the construction element. In alternative methods however, it is possible to also use the friction force exerted by the ground on the construction element partially driven into the ground, during the pressing of the selected auxiliary elements, by fixing the construction element in this stage to the base using the clamping mechanism. This may be considered if the construction element has a high strength (mechanical resistance) against shear stresses and/or bending forces transversal to the longitudinal direction of the construction element. This applies to for instance auxiliary elements formed from steel profile beams. List of Reference Symbols

10 pressing system

12 undercarriage

14 drive members (e.g. caterpillar treads)

16 upper carriage

18 control cabin

20 lead column

22 winch

24 actuator (slope cylinder)

26 cathead

28 pulley

29 cable

30 ground layer

32 ground surface

34 pile or tubular post

36 upper end portion

37 lower end portion

38 side surface (of pile or tube)

40 auxiliary element

42 upper rim (of auxiliary element)

43 bottom rim (of auxiliary element)

44 side surface (of auxiliary element)

46 side edge (of auxiliary element)

50 device

52 base

54 first side (e.g. upper side of base)

55 second side (e.g. bottom side of base)

56 movable carrier

57 sliding-clamping connection

58 aperture

59 inner surface

60 clamping member (e.g. locking shoe or expandable collar)

62 actuator

63 piston

64 coupling member (of actuator)

65 sensor

66 auxiliary segment

168 hinge

170 side aperture

172 distal portion 174 latch

A nominal axis of the actuator

B nominal axis of the aperture

C nominal axis of the construction element

P sagittal plane

X first direction (longitudinal direction)

Y second direction (transversal direction)

Z third direction (vertical direction)

AXa first lateral distance from actuator

AYa second lateral distance from actuator

DCo first lateral dimension of aperture

DUo second lateral dimension of aperture

AXc first lateral dimension of construction element

AYc second lateral dimension of construction element

DZ distance between base and ground

AZa stroke length

DZ1 starting height

AZt driving depth

Lc length (of construction element)

Lb length (van base)

La length (of stretched actuator)

Lh length (of auxiliary element)

a cylinder angle