GB2260776A

GB2260776A - Pile driving apparatus

Info

Publication number: GB2260776A
Application number: GB9122672A
Authority: GB
Inventors: Lean Teik Ong
Original assignee: SUM CHEONG MACHINERY Pte Ltd
Current assignee: SUM CHEONG MACHINERY Pte Ltd
Priority date: 1991-10-25
Filing date: 1991-10-25
Publication date: 1993-04-28
Also published as: GB9122672D0

Abstract

Mobile pile driving apparatus comprises a pile driving tower (2) mounted on a vehicle (1) and equipped with a long stroke hydraulic pile driving ram (13) powered by hydraulic drive means on the vehicle. Such a pile driver can drive piles in a steady-hydraulic stroke rather than relying on percussive pile driving with high noise levels and vibration levels. <IMAGE>

Description

PILE DRIVING APPARATUS The present invention relates to pile driving apparatus, and in particular to a mobile pile driver.

Traditionally, pile driving apparatus has been mobile by virtue of the use of a percussive action to hammer the piles home into the ground. The impulse imparted to the pile as a result of the impact of a descending hammer head has enabled the weight of the hammer head to be relatively low as compared with the pile driving force required to be generated, and this has enabled the pile driver to be easily manoeuvrable between locations of use. However, such mobile pile drivers have suffered from the disadvantage that the percussive action of hammering the piles causes noise which limits the times of the day when pile driving can be carried out in populated areas, and furthermore the vibration of the impact, transmitted into the surrounding ground by the descending pile can cause damage to nearby structures such as buildings.

It is an object of the present invention to provide a mobile pile driver capable of being used close to existing buildings and without unacceptable noise pollution of the surroundings.

Accordingly, the present invention provides mobile pile driving apparatus comprising a vehicle, a pile driving tower carried by the vehicle, pile driving means adapted to drive a pile downwardly relative to said vehicle, and pile guide means for guiding a pile being driven by said pile driving means, wherein said pile driving means comprise a hydraulic ram for driving a ram head downwardly against a pile guided by said pile guide means and able to retract said ram head clear of said pile guide means for insertion of a fresh pile to be driven.

In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to the accompanying drawings, in which: FIGURE 1 is a side elevational view of one embodiment of a mobile pile driver in accordance with the invention, during erection after arrival at a new location of use; FIGURE 2 is a view of the pile driving tower of the vehicle of Figure 1, when viewed from behind (i.e. from behind the driving cab); FIGURE 2A is a top plan view of the apparatus of Figure 2; FIGURES 2B, 2C and 2D are sectional views taken on the line B-B, C-C, and D-D of Figure 2; FIGURE 3 is a sectional view of the ram for pressing the piles home, and illustrates the ram head attached thereto by a ball-and-socket coupling;; FIGURE 4 is a side elevational view of the apparatus during lifting of the first pile at the start of a pile driving operation; FIGURE 5 shows the apparatus of Figure 4 during the pile driving operation, showing the first pile just being inserted into the ground; FIGURE 6 is a view of the equipment of Figures 4 and 5, at a still later stage when the first length of piling has been driven home and a second length of piling has just been hoisted in place and welded to the first; FIGURE 7 is a detail of the pile cap attached to the ram head; FIGURE 8 is a side elevational view of an alternative form of ram allowing a much more compact ram structure and hence a shorter (lower) pile driving tower to be used; and FIGURE 9 is a sectional view showing the ram of Figure 8.

As shown in Figure 1, the pile driving vehicle 1 comprises a tower 2 supported at its lower end on a beam 3 of the pile driving vehicle, and steadied by a telescopic strut 4 allowing the tower to be pivoted into an inclined position for transport between locations of use.

The rear of the vehicle is equipped with groundengaging jacks 5, and the front of the vehicle is likewise equipped with ground-engaging jacks 6, which can be hydraulically extended and retracted, when desired.

The vehicle includes, at the rear end of the beam 3, a counterweight 7 which counterbalances the weight of the pile driving tower 2 during transport.

Figure 1 also shows a pile hoisting cable 8 which can be retracted by a hoist 9 on the vehicle 1, and extends upwardly and over a pair of pulleys 10 so that the free end of the hoist cable 8 can be deployed in front of the tower for lifting piling as will be evident from the later Figures.

Figure 1 also illustrates two ballast weights 11 in position on the tower 2. In practice the pile driving vehicle will be equipped with sixteen of these ballast weights, each weighing 5 tons, thereby allowing a ballast of 80 tons to be mounted on the tower for deep piling operations.

The ram head 12 is lifted and lowered by means of a hydraulic ram 13 mounted between upper and lower supports 14 and 15, respectively, on the pile driving tower.

Figure 2 illustrates the tower 2 in more detail and shows that it comprises two parallel vertical tubular casing leaders 16 which are spaced apart at their upper end by the pile driving tower head 17, and over their lower halves by diagonally extending bracing struts 18.

Additional spacer plates 19 at intervals along the length of the tower provide further support both to space the casing leaders 16 and to centre the ram 13 to hold it parallel to the casing leaders 16.

The top plan view of Figure 2A shows the top of each stack of ballast weights 11, and also the various spacing plates 19, as well as the pile guide 20.

The pile guide 20 is shown in more detail in Figure 2B as having a square pile guiding aperture 21 to receive the piling during pile driving operations therethrough. At the start of such a pile driving operation, the lower end of the pile 37 (Figure 5) will be guided in the square aperture 21 while the upper end will be carried by the pile cap which gradually descends with the pile to approach the pile guide 20 towards the end of the operation of driving in one length 37 of piling (by which time that piling will have been sufficiently far inserted into the ground to be steadied by its contact with the ground).

The sectional view of Figure 2C illustrates the lowermost spacer plate 19 which steadies the piston rod of the ram 13.

The sectional view shown in Figure 2D illustrates one of the bracing struts 18 between the casing leaders 16, and also shows a C-section channel 22 along the front of each of the casing leaders 16, for guiding the cylinder rod.

The ram 13 shown in Figure 3 comprises a piston rod 23 supporting at its upper end a piston 24, and carries at its lower end a ball 25 of a ball-and-socket coupling to support the ram head 12 swivellably in relation to the axis of the ram. The socket section of the ram head can be released from the ball 25 by undoing the screws 26 and removing the concave spherical retaining nut 27.

The lower end of the ram cylinder 28 carries a plug 29 through which the piston rod 23 is sealingly slidable.

The ram 13 is thus divided into an upper working chamber 30 having a hydraulic port 31, and a lower working chamber 32 having a hydraulic port 33, the piston 24 being located between the two chambers 30 and 32.

The stroke of the ram 23 is preferably 6 meters, in order to allow a 6 meter length of piling to be driven into the ground during one stoke.

The attachment of the piling cap 34 to the ram head 12 is illustrated in Figure 7 as being by way of wire slings 35 which support the pile cap at a given spacing below the driving face 36 of the ram head 12.

The pile driving operation using the apparatus of Figures 1 to 3 and 7 will now be described with reference to Figures 4 to 6.

Figure 4 shows the mobile pile driving apparatus with the ground-engaging jacks 5 and 6 retracted and the hoisting cable 8 attached to the first length 37 of piling.

With the jacks still retracted, the winch 9 is operated to raise the length of piling 37 into the position shown in Figure 4.

Before start of operations, the appropriate number of ballast weights 11 will have been stacked on the piling tower, so that the total weight of the vehicle 1, the pile driving tower 2, and the ballast weights 11 will exceed the expected piling resistance force.

Figure 5 shows the first piling length 37 as having been lifted into a vertical position, and its bottom end has been inserted into the square aperture 21 (Figure 2B) of the pile guide 20. The hoisting cable 8 is shown as still being attached to the length 37 of piling, and may either remain attached with all tension removed by paying out from the hoist 9, or be removed from the piling in order to rely on the steadying effect of the pile guide 20 on the one hand and the pile cap 34, on the other hand.

The rear pair of hydraulic jacks 5 are then extended (lowered) to contact the ground and to raise the rear end of the vehicle 1 slightly.

To steady the vehicle 1, the front pair of jacks 6 is also extended, in order to engage the ground and thereby to be able to steady the front of the apparatus.

Starting from a retracted configuration of the ram 13, the hydraulic pump (not shown) of the vehicle 1 is operated to pump hydraulic fluid through the inlet port 31 to the upper working chamber 30, while hydraulic fluid from the lower working chamber 32 returns to the vehicle through the port 33. This drives the piston rod 23 downwardly and brings the ram head working face 36 into contact with the pile cap to drive the pile cap 34, and the length of piling 37, downwardly to insert the piling length 37 into the ground as shown in Figure 6. If desired, during this operation the front pair of hydraulic jacks 6 may be slowly retracted in order to allow greater force to be exerted downwardly on the pile.

When the Figure 6 configuration is reached, the first 6 meter length of piling 37 has been driven into the ground and a second similar length 37' has been lifted into position and has been welded to the first length at 40. As in the case of Figure 5, the hoist cable 8 is still shown as being attached to the second piling length 37', but it could instead be released as by now the second piling length 37' is steadied by having been welded at its lower end to the first length 37, and by engagement of its upper end with the pile cap 34.

This operation is continued until sufficient length of piling have been welded and driven home, or until the ultimate pile resistance force has been achieved.

It will of course be appreciated that the number of ballast weights 11 can be selected to suit the expected piling resistance, and that the mounting of too many ballast weights will be avoided in order to impede stability of the vehicle.

As will be clear from the above description, the pile driving tower needs to be long enough to accommodate a ram in excess of 6 meters overall length, in order for the ram stroke to be 6 meters and thereby sufficient to drive home a 6 meter length of piling.

However, in order to provide for a shorter piling tower 2, it may be desirable to replace the single cylinder ram 13 shown in Figures 3 and 8 by a multi-cylinder ram 42 of telescopic design. This alternative variant has a plurality of telescopically interfitting cylinders 43, 43a, 43b, 43c and 43d, each having a length which is only a portion of the overall ram stroke required, and the smallest diameter cylinder 43d carrying the ball 25 of the ball-andsocket coupling. The same ram structure is shown in crosssection in Figure 9 which shows seals A and B, the cylinder end caps C, and cylinder steadying ribs D to give the ram 42 the necessary rigidity and resistance to buckling in use.

The pile driving apparatus described above and illustrated in the drawings is much more compact than existing mobile pile drivers because there is no longer the need for the pile driving tower to be tall enough to permit the necessary drop of the pile driving hammer to accumulate the impulse energy necessary for the pile driving action.

Furthermore, the device can be readily and rapidly deployed as the hoist cable 8 remains attached and it is simply necessary to extend the hydraulic strut 4 to erect the pile driving tower 2 once the vehicle has arrived at a location of use.

Furthermore, all the components of the pile driving equipment can be mounted on the same vehicle which therefore avoids the need for a number of accompanying vehicles to transport components of the pile driving equipment.

Furthermore, the design of hydraulic ram 13 shown in Figure 3 can allow for a pile driving force of 150 tons, and thus provided a sufficient number of ballast weights 11 has been attached to the pile driving tower 2, the maximum pile driving resistance which can be overcome by the steady hydraulic stroke of the ram 13 will be of the order of 150 tons. This will allow larger cross-sections of piles to be driven home for a given total length of piling (or equally a longer pile for a particular cross-sectional size), subject to the maximum stroke of the ram 13.

Claims

1. Mobile pile driving apparatus comprising a vehicle, a pile driving tower carried by the vehicle, pile driving means adapted to drive a pile downwardly relative to said vehicle, and pile guide means for guiding a pile being driven by said pile driving means, wherein said pile driving means comprise a hydraulic ram for driving a ram head downwardly against a pile guided by said pile guide means and able to retract said ram head clear of said pile guide means for insertion of a fresh pile to be driven.

2. Mobile pile driving apparatus according to claim 1, and including means attaching a pile cap to said ram head.

3. Mobile pile driving apparatus according to either of the preceding claims, wherein said hydraulic ram comprises a single cylinder longer than the expected length of a pile to be driven by said pile driving apparatus, and a ram piston able to travel along said cylinder through a stroke long enough to drive a single pile through said pile guide means.

4. Mobile pile driving apparatus according to either of claims 1 and 2, wherein said pile driving means comprise a telescopic ram comprising a plurality of cylinders telescopically interfitting with one another whereby the length of each of said cylinders is less than the stroke of a ram piston contained within said telescopic assembly of cylinders.

5. Mobile pile driving apparatus according to any one of the preceding claims, and including a swivel coupling connecting said ram head to said ram to allow said ram head to align itself with the upper end of a pile supported by said guide means.

6. Mobile pile driving apparatus according to any one of the preceding claims, and including means for attaching ballast weights to said pile driving tower and/or said vehicle.

7. Mobile pile driving apparatus according to any one of the preceding claims, and including a winch and a hoist cable for lifting a length of piling for loading into said pile guide means.

8. Mobile pile driving apparatus according to any one of the preceding claims, wherein said pile driving tower comprises a pair of spaced columns with spacing means therebetween and support means for said power driving ram and for said pile guide means.

9. Mobile pile driving apparatus according to any one of the preceding claims, and including a telescopic strut pivotably interconnecting a location on said tower to a first location on said vehicle, and wherein said tower is pivotally connected to a further location on said vehicle whereby contraction and extension of said strut permit lowering and raising of said tower from and to a vertical position relative to said vehicle.

10. Mobile pile driving apparatus according to claim 9 wherein said first location is on a cantilevered extension at one end of said vehicle and said other location is cantilevered at the opposite end of said vehicle, and including ground-engaging jacks able to engage the ground at said first cantilevered location.

11. Mobile pile driving apparatus constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 to 7 of the accompanying drawings.

12. Mobile pile driving apparatus according to claim 11, when modified substantially as hereinbefore described with reference to, and as illustrated in, Figures 8 and 9 the accompanying drawings.