GB2093511A

GB2093511A - Improvements in or Relating to a Method and Device for Automatically Controlling the Pile- driving of an Elongated Element into the Ground

Info

Publication number: GB2093511A
Application number: GB8204687A
Authority: GB
Original assignee: Frankignoul Pieux Armes
Current assignee: Frankignoul Pieux Armes
Priority date: 1981-02-19
Filing date: 1982-02-17
Publication date: 1982-09-02
Also published as: DK73282A; AU8044482A; DE3205855A1; FR2500026A1; LU83951A1; AU546771B2; PT74445B; NZ199772A; SE8200974L; YU37882A; BR8200925A; NL8200613A; FI820489L; IT1190692B; PT74445A; CH646482A5; CA1210600A; GB2093511B; HK100284A; FR2500026B1

Abstract

The present invention relates to a method and a device for the automatic pile-driving of an elongated element into the ground. The device of the present invention includes a pile-driving plant (1) with the free fall of a monkey (7) to drive a pile (2) into the ground, including a load pick-up for measuring the load applied by the monkey hanging cable (8) on a pulley (6), and a winch angular movement pick-up (15). These several pick-ups are connected to an electronic analysis device (13) of the signals generated by said pick-ups so as to automatically control the unclutching, pre-clutching or clutching of the winch (9) by automatic detection of the impact moment of the monkey (7) on the pile (2), of the monkey lifting height and of stop or immobilization moment of the monkey on the pile, respectively. The invention is used in civil engineering. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to a Method and Device for Automatically Controlling the Piledriving of an Elongated Element Into the Ground The present invention relates generally and has essentially for a subject matter a method and a device for automatically controlling the driving of an element such as a pile, a sheet pile or the like, for example into the ground.

Several pile-driving plants including a hammer or a monkey hung from a cable which is coiled around a winch, are already known. In these known pile-driving plants, the control of the hammer lifting and/or the release of the hammer free fall was manually achieved. Accordingly, these plants show great draw-backs. Indeed, the operator had to follow with attention the displacement of the monkey so as to optimize the efficiency of the pile-driving which is a function of the pile-driving speed and the lifting height of the hammer. More especially, when the pile-driving speed is high, the attention of the operator quickly became unbearable, and consequently, the efficiency of the plant considerably decreased.

The main purpose of the invention is to overcome these drawbacks by providing a method and a device for automatically controlling the lifting of the monkey and the release of the monkey free fall. The invention, which avoids any manual operation of the operator, permits to optimize the efficiency of the pile-driving plant whatever the pile-driving speed.

The invention therefore has for its object a method for realizing the driving of a pile for example into the ground such as a pile, a sheet pile or the like, with a pile-driving plant with the free fall of a hammer, such as a pile-driving rig or the like, including the following steps:- drop, in free fall, the hammer onto the pile; lifting the hammer to a predetermined height which is adjustable with regard to the pile; repeating these operations.

The method of the invention is characterized in that the release of the free fall of the hammer and the hammer lifting are automatically controlled by the detection of the impact moment of the hammer on the pile and the hammer lifting height.

According to another characteristic of the invention, said detection of said impact moment controls the recoiling of the hanging cable under a recoiling strength of the cable at most substantially equal to the weight of said hammer, the release of the hammer lifting being controlled by the detection of the stop moment of the hammer on the pile.

So, according to this characteristic, after that, the hammer comes into collision with the pile, said cable is substantially maintained in a stretched condition, but no strength permitting to lift the hammer, is applied on said hammer.

Accordingly, the totality of kinetic energy of the hammer, at the said impact moment, will be substantially imparted to the pile.

The present invention has also for object a device for carrying out the above method, this device being of the type comprising a pile-driving plant or a pile-driving rig including a frame, a raking strut, a hammer or a monkey hung from a cable coiling around a winch, said winch being connected to driving means such as, for example, electric, thermic, hydraulic, pneumatic engines or the like, through clutching and unclutching means, characterized in that it comprises sensor means for detecting the impact moment of the monkey on the pile, and sensor means for detecting the lifting height of the monkey, both these sensor means being connected to said clutching and unclutching means respectively.

So, this device permits, on the one hand, to control the clutching of the winch and the driving means as soon as the monkey has come into collision with the pile, and on the other hand to control the unclutching of said winch in order to release the monkey free fall as soon as said monkey is lifted to a predetermined height with respect to the pile. Thus, the pile-driving is automatically controlled without the operator's intervention.

According to another characteristic of the invention, said impact moment sensor means includes a load pick-up for measuring the load applied by the monkey hanging cable on a guiding pulley of said cable, said pulley being mounted at the upper end of said raking strut, and an analysis device of the variations of the signal generated by said pick-up. This signal variations analysis device is constituted with an analysis element of the signal and a control element of said clutching and unclutching means of the winch.

According to another characterizing feature of the invention, the impact moment sensing means comprises pick-ups for detecting the location, the speed, or the acceleration of the monkey during its free fall, and an analysis device of the value of the signal generated by these pick-ups, said analysis device including an analysis element of said signal and a control element of said clutching and unclutching means.

According to another characteristic of the invention, this impact moment sensing means comprises a sound pick-up and an analysis device of the'signal generated by said pick-up, said analysis device being the same as the foregoing analysis device.

According to another characterizing feature of the invention, the monkey lifting height sensing means comprises a pick-up for measuring the angular movement of the winch, and an analysis device for analyzing and comparing the signal generated by said pick-up with an adjustable and predetermined value corresponding to the predetermined height of the monkey lifting, said analysis and comparison device including an analysis and comparison element of the signal and a control element for controlling said unclutching and clutching means.

Advantageously, this winch angular movement pick-up comprises several marks substantially regularly fixed on the winch according to a circle, a detector generating a signal corresponding to each passage of one of said marks in front of at least one fixed reference element, and a totalizer counter of said signals.

Besides, these several analysis devices of signals generated by the several pick-ups are advantageously a unity with electronic circuits.

According to another important characterizing feature, the device comprises a sensing means for detecting the moment of the stop or immobilization of the monkey on the pile, said sensing means being connected to the clutching or unclutching means through said power control element, said clutching means comprising a first position called "pre-clutching" wherein a driving force at most substantially equal to the weight of the monkey is imparted to the winch, and a second position called "clutching" wherein a driving force capable of lifting the monkey, is imparted to the winch.

Besides, said impact moment sensing means generates a signal corresponding to this impact moment which is applied to the power control element for controlling the change-over of the clutching means from its unclutching position to its first position of pre-clutching, the said sensing means of the stop moment of the monkey on the pile generating a signal corresponding to this immobilization of the monkey, said signal being applied to said power control element for controlling the change-over of said unclutching means from its first position of pre-clutching to its second position of clutching.

Advantageously, said stop moment sensing means is constituted by said monkey lifting height sensing means, the signal generated by this means being analyzed into an analysis device in order to determine the moment corresponding to a zero rotation speed of the winch and to generate the said signal applied to said power control element.

Other advantages, characterizing features and details of the invention will appear more clearly from the following explanatory description made with reference to the appended drawings given solely by way of example and wherein Figure 1 is a schematic view of a pile-driving plant including the automatic control device of the pile-driver, according to the invention; Figure 2 shows graphically the variation of the load applied by the cable on the pulley as a function of the time, during the pile-driving, according to a first embodiment of the invention; and Figure 3 shows graphically the coiling and uncoiling speed of the cable around the winch as a function of the time, during the pile-driving, according to a second embodiment of the invention.

By referring to the Figure 1, a pile-driving plant 1 of an elongated element 2 such as a pile, a sheet pile or the like into the ground 3 conventionally comprises a frame 4, a raking strut 5 and a guiding pulley 6 mounted at the upper end of the raking strut 5. In addition, this piledriving plant comprises a hammer 7 or a monkey hung from a cable 8 guided by the pulley 6. This cable 8 is coiling around a winch 9. The winch 9 is fixed on the frame 4 and comprises driving means (not illustrated) for example hydraulic or pneumatic driving means. According to the invention, the connection between the winch 9 and said driving means is controlled by clutching or unclutching means schematically illustrated at 11. This clutching or unclutching means is constituted, according to a preferred embodiment of the invention, by a system of hydraulic jacks, for example.

Moreover, according to the invention, said unclutching or clutching means 11 are controlled and actuated by an hydraulic power control element 10, known per se and schematically including a distributor 1 Oa, a pump 1 Ob and a hydraulic fluid tank 1 Oc, the several connecting lines between the elements 11, 1 Oa, 1 Ob, 1 Oc, illustrated in strong lines, correspond to hydraulic connections.

According to a first preferred embodiment of the invention, the pile-driving plant 1 is provided with an automatic control system of the driving of the pile into the ground 3. This automatic control system comprises a pick-up 12 of the load applied by the cable 8 on the pulley 6. This load pick-up 12 is connected to an analysis device 13 of the signal generated by said pick-up 12.

Furthermore, according to the invention, several marks 14 are fixed substantially regularly according to a circle on the winch 9. When the winch 9 rotates, these marks 14 rotate past two fixed reference elements 1 spa, 1 sub constituting a unity of detection 1 5 of the direction and the value of the angular movement of the winch 9.

Indeed, each passage of a mark 14 in front of the fixed reference elements 1 spa, 1 sub is detected and totalized by a counter of pulsions, the generated signal is transmitted to the analysis device 1 3.

This analysis device 13 treating the signals generated by pick-ups 12 and 1 5 respectively, generates a control signal actuating the power control element 10 of the clutching or unclutching means 11 of the winch 9. In Figure 1, the thin lines connecting the pick-ups 12, 1 sub, 1 5a, the analysis device 1 3 and the power control element 10 respectively, illustrate the connecting circuits for transmitting the signals between these several elements. According to the preferred embodiment of this invention, said connecting circuits are electric circuits.

By referring to Figures 1 and 2, and according to a first preferred embodiment of the present invention, the running of the automatic control system is explained herebelow.

More especially, by referring to Figure 2, which schematically shows the variations of the value of the load applied by the cable 8 on the pulley 6 and which is measured by the load pick-up 12 during two cycles of pile-driving, this signal is analyzed by the analysis device 13 in order to determine the impact moment of the monkey 7 on the pile 2.

Along the curve represented by the letters a, b, c, d, e, f, g, b', during the portion of the cycle a-b the signal of the load pick-up 12 is substantially constant and corresponds to a high value of the load applied on the pulley 6, this portion corresponds to the lifting of the monkey, thus the winch 9 and the driving means are clutched. At the moment b, the load rapidly drops, the portion of the curve b-c corresponding to the release of the free fall of the monkey. Then there is a substantial stabilization of the load during the portion of cycle c-d, and a new diminution of this load at point d. This new diminution corresponds to the impact moment of the monkey 7 on the pile 2. Indeed, at this impact moment, the cable 8 continues to uncoil and has a great slack thus, the load applied on the pulley 6 decreases.The analysis device 13, which is, according to a preferred embodiment of the invention, constituted by electronic circuits, comprises an analysis element of the signal generated by the load pick-up and illustrated by the Figure 2, and a control element for actuating the power control element 10 of the clutching or unclutching means 11. The analysis element detects the diminution of the charge, at the point d, and energizes at this moment, said control element for actuating the power control element 10 of clutching means 11 in order to clutch the winch 9 with the driving means.Thus, the portion of the curve e-f substantially corresponds to the coiling of the slack of the cable 8, and the load abruptly increases from f to g, corresponding to the beginning of the lifting of the monkey 7, the portion g-b' corresponding to the lifting of the monkey 7 to a predetermined height.

Furthermore, according to the invention, the release of the free fall of the monkey 7, substantially corresponding to points b and b' of the diagram of Figure 2, is controlled in function of a signal generated by the sensing means 1 5 and analyzed by the device 1 3. Indeed, the number of pulsions generated by the means 1 5 and totalized corresponds to the number of the passages of the marks 14 in front of the detectors 1 5a, 1 5b and thus to the length of the cable 8 which is coiled around the winch 9, therefore to the height of the monkey lifting with regard to the pile 2.This number of pulsions is analyzed and compared in an element of analysis and comparison of the analysis device 13, to a predetermined and adjustable value corresponding to the predetermined height of the monkey lifting 7. When the totalized number of pulsions is equal to the predetermined value, the element of analysis and comparison energizes a control element to actuate the power control element 10 of the clutching or unclutching means 11 in order to unclutch the winch 9 and the driving means whereby the release of the free fall of the monkey 7 is automatically controlled.

Therefore, the device of the invention permits to automatically control the lifting of the monkey 7 to a predetermined height and the release of its free fall, with a double detection of the impact moment of the monkey 7 on the pile 2 and of the monkey lifting height, respectively. So, the method and the device of the present invention permit to use a pile-driving plant with a good efficiency of the monkey free fall, whatever the pile-driving speed, and independently from the attention and the professional qualification of an operator, since the manual control of the displacement is suppressed.

According to a second preferred embodiment of the invention, the clutching or unclutching means 11 comprises an unclutched position and two clutched positions: a first position called "pre-clutching" wherein a driving strength at most substantially equal to the weight of the monkey 7 is transmitted to the winch 9; and a second position called "clutching" wherein a driving force capable of lifting the monkey 7 is imparted to the winch 9. In this embodiment, the sensing means 1 5 of angular displacement of the winch 9 permits advantageously on the' one hand, to determine the lifting height of the monkey 7 and on the other hand, to determine the stop moment of the monkey 7 on the pile 2 By referring more particularly to Figure 3, the operation of the automatic control device according to this second embodiment of the invention is described herebelow.

The diagram, in continuous lines shows the variation of the speed of coiling Ve or uncoiling Vd of the cable around the winch 9 in function of the time during a cycle of pile-driving, the diagram in broken lines illustrates the variations of the uncoiling Vd or coiling Ve speed of the cable 8 during the following cycle of pile-driving, this latter diagram being substantially identical to the first diagram.

The pile-driving cycle according to the second embodiment of the present invention is as follows: at point a the monkey being lifted to a height corresponding to the predetermined height, the winch is unclutched in order to release the monkey free fall this period corresponding to the zone 1, the uncoiling speed of the cable is illustrated by the portion of diagram a-b. At the impact moment of the monkey 7 on the pile 2, detected by the load pick-up 12, the clutching means 11 are actuated to their first position called "pre-clutching" in order to drive the winch 9 under a driving force at most substantially equal to the weight of the monkey 7. On Figure 3, this portion of cycle corresponds to the zone II.

Therefore, the cable is recoiling around the winch 9 until it is in a stretched condition. This recoiling of the cable corresponds to the portion bc of the curve. Since the driving force applied on the cable is not sufficient for lifting the monkey 7, when the cable is in a stretched condition, the downward displacement of the monkey 7 provides a small uncoiling of the cable, illustrated by the portion cd of the curve.

The monkey 7 stops on the upper end of the pile 2 when the totality of its kinetic end of the pile 2 when the totality of its kinetic energy is applied on the pile 2. According to this invention, since the cable 8 is always maintained in a stretched condition by the preclutching of the clutching means 11, this stop or immobilization moment is detected and determined by the winch angular displacement sensing means 15, and corresponds to the point d of the diagram, when the winch is stopped.

At this moment, the signal generated by the sensing means 15, and analyzed by the analysis device 13 generates a control signal for actuating the power control element of the clutching means 11 in order to actuate said means from its first position of preclutching to its second position of clutching wherein the driving force imparted to the winch 9 is capable of lifting the monkey 7.

This portion of the cycle corresponds to zone Ill and the portion of the diagram d-e-f.

The monkey is lifted to a height measured by the sensing means 1 5 and corresponding to a predetermined height, then, the winch 9 is unclutched to begin a new pile-driving cycle.

Thus, according to this second embodiment of the invention, after the impact moment of the monkey on the pile 2, the force applied by the cable 8 to the monkey 7 is weak enough so that, the cable 8 is maintained in a stretched position only, and accordingly, the totality of the kinetic energy of the monkey 7 is substantially applied to the pile 2.

The method of the invention permit to automatically control the pile-driving and increase the efficiency of the pile-driving.

Of course, the invention comprises all devices permitting to automatically detect the said impact moment of the monkey on the pile 2, for automatically controlling the lifting of said monkey. For example, the device may comprise sensing means for detecting the position, the speed or the acceleration of the monkey 7 during its free fall, or a sound pick-up. All these sensing means generate a signal showing a variation corresponding to this impact moment of the monkey 7 onthe pile 2, this variation being analyzed in an analysis device 13 for controlling the power control element of the clutching means of the winch.

On the other hand, the winch angular displacement sensing means 1 5 is given by way of example only.

Of course, the invention is by no means limited to the forms of embodiment which have been given by way of example only. Thus, the driving means, the clutching or unclutching means, the power control element of said clutching or unclutching means can be in any form.

Claims

1. A method for realizing the driving of an element for example into the ground, such as a pile, a sheet pile or the like, with a pile-driving plant with the free fall of a hammer, such as a pile-driving rig or the like, including the following steps drop, in free fall, of the hammer onto the pile; lifting the hammer to a predetermined height which is adjustable with respect to the pile; repeating these operations: characterized in that the release of the free fall of the hammer and the hammer lifting are automatically controlled by the detection of the hammer lifting height and the impact moment of the hammer on the pile, respectively.

2. A method according to claim 1, characterized in that the said release of the hammer lifting is controlled by the detection of the stop or immobilization moment of the hammer on the pile, the said detection of said impact moment controlling the recoiling of the hanging cable of the hammer under a recoiling force of the cable at most substantially equal to the weight of said hammer.

3. A device for carrying out the method according to claim 1 or 2, comprising a piledriving plant or a pile-driving rig including a frame, a raking strut, a hammer or a monkey hung from a cable coiling around a winch, said winch being connected to driving means such as, for example, electric, thermic, hydraulic or pneumatic engine or the like, through clutching and unclutching means, characterized in that it comprises sensor means for detecting the impact moment of the monkey on the pile, and sensor means for detecting the lifting height of the monkey, both these sensor means being connected, through a power control element to said clutching and unclutching means respectively.

4. A device according to claim 3, characterized in that it comprises sensor means for detecting the stop or immobilization moment of the monkey on the pile, said sensor means generating a signal corresponding to said stop moment to control through said power control element the actuating of said clutch or unclutching means, said clutching or unclutching means comprising a first position called "pre-clutching" wherein a driving force at most substantially equal to the weight of said monkey is imparted to said winch, and a second position called "clutching"wherein a driving force capable of lifting the monkey is imparted to said winch.

5. A device according to claim 4 characterized in that said impact moment sensor means generates a signal corresponding to said impact moment which is applied to said power control impact for actuating the changeover of said clutching or unclutching means from its unclutching position to its first position of preclutching, said stop moment sensor means generating a signal corresponding to said stop moment, which is applied to said power control element for actuating the changeover of said unclutching and clutching means from said first position of preclutching to said second position of clutching.

6. A device according to claim 4 or 5, characterized in that said stop moment sensor means is constituted by said monkey lifting height sensor means.

7. A device according to any one of claims 3 to 6 of the type comprising a guiding pulley of the cable mounted at the upper end of said raking strut, characterized in that said impact moment sensor means includes a load pick-up for measuring the load applied by the monkey hanging cable on said guiding pulley, and an analysis device of the variations of the signal generated by said pick-up, said analysis device being constituted with an analysis element of the signal and a control element connected to said clutching and unclutching means of the winch.

8. A device according to any one of the claims 3 to 6, characterized in that said impact moment sensor means comprises pick-ups for detecting the location, the speed, or the acceleration of the monkey during its free fall, and an analysis device of the value of the signal generated by these pickups, said analysis device including an analysis element of said signal and a control element connected to said clutching and unclutching means.

9. A device according to any one of claims 3 to 6, characterized in that said impact moment sensor means comprises a sound pick-up, and an analysis device of the signal generated by said pick-up, said analysis device including an analysis element of said signal and a control element connected to said clutching and unclutching means.

1 0. A device according to any one of the claims 3 to 9, characterized in that said monkey lifting height sensing means comprises a pick-up for measuring the angular movement of the winch, and an analysis device for analyzing and comparing the signal generated by said pick-up with an adjustable and predetermined value corresponding to the predetermined height of the monkey lifting, said analysis and comparison device including an analysis and comparison element of the signal and a control element connecting through said power control element to said clutching and unclutching means.

1 A device according to claim 10, characterized in that said winch angular movement pick-up comprises several marks substantially regularly fixed on the winch according to a circle, a detector generating a signal corresponding to each passage of one of said marks in front of at least one fixed reference element and a totalizer counter of said signals.

12. A device according to any one of claims 4 to 6 and 10 or 1 characterized in that said stop moment sensor means comprises said marks and references elements of said winch angular movement pick-up, an analysis device of the generated signals which generates in response a signal applied to said power control element, corresponding to the moment of zero rotation speed of the winch.

13. A device according to any one of claims 3 to 12, characterized in that the analysis devices are a unit including electronic circuits.

1 4. A method of pile driving substantially as herein described with reference to the accompanying drawings.

1 5. Apparatus for pile driving substantially as herein described with reference to and as shown in the accompanying drawings.