GB2364078A - Apparatus for a ground treatment device - Google Patents

Abstract

A ground treatment apparatus (10) operates by repeatedly dropping a weight (12) onto the ground (14). The weight (12) is lifted between drops by a crane (16) via winches (30) and cables (32 Fig2). The weight (12) falls between leaders (18) which guide the drop. The leaders (18) have an upper portion (22) mounted at their lower end to the crane (16) by an articulated jib (24) allowing them to rock toward or away from the crane (16). They are also connected to the crane (16) at the top of the upper portions (22) by a telescopic arm (26) to control this rocking. The rocking allows the leaders (18) to be set in an upright position despite variations in the ground surface. A cradle (20 fig5) having flared channels (70 fig6) is attached to the lower end of the upper portion (22) to allow a degree of movement of the weight (12) after it hits the ground and therefore reduce the severity of the impact on the apparatus (10).

Description

2364078 Ground Treatment The present invention relates to ground treatment

and in particular, to the treatment of ground by means of dropping weights.

Our International Patent Application W 099/09261 describes various methods and apparatus for ground treatment by means of dropping weights.

The weights are of considerable size (typically at least 2 5 tonnes) in order to achieve adequate ground treatment for preparing the ground for subsequent building In consequence, substantial lifting gear in the form of cranes, or the like, is required for lifting the weights prior to dropping For consistency of results and for safety reasons, it is desirable to retain control over the motion of the weights, for instance by using leaders to guide the weights as they fall, as described in our previous patent application.

The present invention provides ground treatment apparatus comprising at least one leader providing at least one guide surface which, in use, guides a falling weight, the guide surface being further spaced in a horizontal direction from the line of fall of a weight at the lowermost end of the guide surface than at a position further up the leader, whereby to provide greater freedom to the weight as the weight impacts the ground.

The guide surface preferably forms part of a guide channel The channel preferably comprises walls between which a portion of a falling weight is retained, the separation of the walls being greater at the lowermost end of the channel than higher up the channel The channel preferably has a terminal portion at its lowermost end, the wall separation being increased within the terminal portion The channel walls preferably flare away from each other within the terminal portion, whereby to continuously increase the separation of the walls The channel may also comprise a floor extending between the walls, to constrain a falling weight in a direction substantially perpendicular to the constraint provided by the walls The channel floor is preferably further spaced in a horizontal direction from the line of fall of a weight at the lowermost end of the guide channel than at a position further up the leader Preferably the channel floor flares away from the line of fall within a terminal portion at the lowermost end of the guide channel, whereby to continuously increase the separation of the floor from the line of fall.

Preferably the apparatus comprises a plurality of leaders between which a weight is constrained to fall, each leader providing a guide channel as aforesaid The leaders preferably each have at least one surface which cooperates with the surface of another leader to constrain a falling weight against movement in two substantially opposite directions.

Examples of apparatus according to the invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which:

Fig 1 is a side elevation, partly schematic, of apparatus according to the invention and in position for use; Fig 2 is a front elevation corresponding with Fig 1, omitting the crane in the interests of clarity; Fig 3 is a greatly enlarged schematic section in plan through the apparatus of Fig 2 and taken at the height indicated at 3-3 in Fig 2; Figs 4, 5 and 6 are a plan, side elevation and front elevation, respectively, on an enlarged scale, of a cradle incorporated at the lowermost end of the apparatus of Fig 2; and Figs 7 and 8 are greatly enlarged side and front elevations of guide channel arrangements of the apparatus of Figs 4, 5 and 6, shown on an enlarged scale.

Fig 1 shows ground treatment apparatus 10 which operates by repeatedly dropping a weight 12 onto the ground 14 The weight 12 is of the type shown in Figs 9 to 11 of our previous patent application The weight 12 is lifted between drops by means of power supplied by a crane 16 The weight 12 falls between leaders 18 which guide the falling weight.

The leaders 18 incorporate guide channels, to be described and including, at their lowermost end, guide channel portions provided by a cradle arrangement indicated generally at 20 Within this terminal portion of the guide channels, the guide channels are of increased width in a manner to be described and for reasons which will become apparent.

In more detail, the crane 16 can be of any conventional type capable of meeting the performance requirements of load-bearing and power output The leaders 18 have an upper portion 22 mounted on the crane 16 at their lower end by means of an articulated jib 24 allowing them to rock toward or away from the crane 16 (to the left or right as illustrated in Fig 1) A telescopic arm 26 is connected between the crane 16 and the top of the upper portions 22 to control this rocking to allow the leaders 18 to be set in a vertical orientation despite variations in ground level which may affect the orientation of the crane 16.

Appropriate sensors (not shown) and interlocks, if desired, are provided to assist the operator in ensuring that the leaders 18 are vertical before a weight is dropped.

This ability to rock the leaders 18, and the hinged arrangement of the boaders are optional and could be omitted if the consequent adaptabklity is not requied.

Fig 1 illustrates schematically at 28 an alternative position of the leaders 18, in which the arm 26 has been extended to rock the leaders 18 forward from the crane 16 as may be required to bring the leaders 18 to a vertical position when the crane 16 is on sloping ground.

The weight 12 can be raised and dropped by means of winches 30 mounted at the top of the leaders 18 to wind (in or out) cables 32 (Fig 2) from which a grab mechanism 34 is hung The winches could alternatively be mounted elsewhere The grab 34 carries a releasable coupling 36 operated by a hydraulic cylinder 38 to close on a second coupling member 40 carried by the weight 12, or to open to release the member 40.

Before describing the apparatus in further detail, it is helpful to provide a brief description of the operating cycle of the apparatus thus far described.

Initially, the weight 12 will be resting on the ground, having been dropped The cables 32 are then played out from the winches 30 to lower the grab 34 until the coupling 36 reaches the member 40 The cylinder 38 is then operated to close the coupling 36 to grab the member 40 The winches 30 are then reversed to haul the grab 34 back up the leaders 18, with the weight 12 hanging from the coupling 36 Once the grab 34 has been raised to bring the weight 12 to the desired height (according to the energy required to be imparted to the ground 14 by a single drop of the weight 12), the cylinder 38 is operated to open the coupling 36, releasing the member 40 and allowing the weight 12 to drop back to the ground 14 Once the weight 12 has come to rest, this cycle is repeated until the ground has been adequately treated The crane 16 may then be moved to a new position, carrying the rest of the apparatus with it, whereupon the cycle can again be executed repeatedly to treat the ground at the new location.

In an alternative, the grab could be omitted, with the weight being released by allowing the winch to run freely.

The features remaining to be described are related primarily to the guidance of the weight 12 while it is falling Turning to Fig 3, the drawing illustrates the weight 12 while it is at a height part way up the upper leader portions 22 The weight 12 has an upper plate 42 carrying the second coupling member 40 Two guide columns 44 are provided on opposite sides of the square of the plate 42, midway along those sides The guide columns 44 project beyond the boundary (in plan) of the plate 42 to provide projections on opposite sides of the plate 42 The upper portion 22 provides a vertical channel 46 having two vertical opposed walls 48 and a vertical floor 50, leaving a vertical mouth 52 along the full height of the upper portion 22, for receiving the corresponding guide column 44 in a loose fit As the weight 12 is hauled up or drops down the leader 18, the column 44 runs in the channels 46 of the two portions 22 The walls 48 prevent the weight 12 deflecting significantly in a horizontal direction parallel with the floor 50 The floors 50 of the channels 46 cooperate to prevent substantial movement of the weight 12 in a horizontal direction parallel with the walls 48 Finally, the channels 46 prevent substantial twisting of the weight 12 about a vertical axis through the centre of the plate 42 In this manner, the weight 12 is guided as it falls (and also as it is hauled up), the freedom of the weight being set by the clearance between the columns 44 and the channels 46.

It is desirable for these clearances to be kept small (perhaps in the region of about 6 mm) in order to precisely direct the weight 12 as it falls, thus ensuring consistency in the ground treatment process, and minimising safety risks arising from such large weights falling in an uncontrolled or loosely controlled manner from a significant height (perhaps 5 m) However, we have realised that close constraint of this nature will give rise to operational problems if the channels 46 are extended down to the ground, thus continuing to guide the weight throughout its fall and during the impact In particular, differences in ground condition across the area of impact, or the effect of various shapes of the weight 12, can cause the weight 12 to twist violently about horizontal axes as it impacts, and perhaps bounces, on the ground In view of the weight and drop height involved, the resulting forces exerted on the leaders 18 are very considerable and likely to cause damage to the leaders 18, which may then give rise to inadequate guidance during future drops, with the results of reduced precision and increased dangers Features of the cradle 20 address these problems, as can now be described.

The cradle 20 has legs 54 which hang from the lower ends 56 of the upper leader portions 22, by means of pivot connections at 58 Frame members 60, 62, 64 are carried by the legs 54 Viewed in plan (Fig 4) these form a generally square frame having the legs 54 positioned midway along opposite sides of the square so formed The rear frame member 60 is adapted for attachment at 66 to the crane 16 and is suitably braced to the legs 54 by braces 68 The other frame members 62, 64 extend forwardly of the legs 54 (away from the crane 16) primarily for safety reasons to prevent workmen straying into the area on which the weight 12 will be dropped, or placing articles in that area.

Viewed from above, it can be seen that the legs 54 provide channels 70, similar in form to the channels 46 of the upper portions 22 Indeed, the channels 70 are positioned to lie directly underneath the lower end of the channels 46 so that when the columns 44 leave the lower ends of the vertical channels 46 as the weight 12 falls, the columns 44 will enter the upper end of the channels 70 The channels 70 may be slightly flared at their upper end to form a mouth 72 guiding the columns 44 down to a vertical, straight-sided channel section generally at 74 The straight channel section 74 ends at its lower end at a height indicated by a line at 76 By the time the column 44 has reached the lower end at 76, the weight 12 will be close to the ground 14, but will not yet have impacted the ground Impact does not occur until the columns 44 have left the lower end 76 and entered the lowermost terminal portion 78 of the channels 70 The terminal portions 78 are flared in two senses, as follows First, as can be seen from Fig 7, the walls 80 of the channel flare apart, the separation of the walls 80 being greater at the lowermost end of the channel 70 than higher up the channel This flaring may be linear (that is, each wall may be straight and sloping), or the walls 80 may be curved.

In similar manner, the floor 82 of the channel 70 is also flared away from the line of fall of the weight within the terminal portion 78.

Consequently, as the weight 12 approaches impact, the columns 44 are increasingly less constrained either by channel walls 80 or between the two channel floors 72 but it is important to recognise that they are not wholly unconstrained Thus, as the weight 12 impacts on the ground, some greater degree of bounce, twisting and mis-alignment is possible but is confined.

Consequently, the severity of impacts between the weight 12 and the guiding structures is reduced (because the guidance imposed is less severe), but safety is not unacceptably prejudiced (because the weight 12 remains confined at all times).

Many variations and modifications can be made to the apparatus described above, without departing from the scope of the invention The form of the guidance arrangements can be changed considerably, particularly in accordance with the form of the weight In alternatives to the guide channels described, other forms of guide members could be used These could be beams or hollow sections having surfaces between which the guided portion may pass, or alternatively, the guided portion could have an eye or other surface located around a guide member, such as a bar, rope or cable In the example, the weight is constrained against deflection or twisting in all or most directions and senses, but in some circumstances, it may be adequate to provide guidance in only some directions or senses, for instance by providing a guide channel down one side of the fall line of the weight, but not both Alternatively, additional security might be required, for instance by providing more than two leaders and guide channels The leaders described above could be replaced by fixed, onepiece leaders which define the whole height of the drop.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims (12)

1 Ground treatment apparatus comprising at least one leader providing at least one guide surface which, in use, guides a falling weight, the guide surface being further spaced in a horizontal direction from the line of fall of a weight at the lowermost end of the guide surface than at a position further up the leader, whereby to provide greater freedom to the weight as the weight impacts the ground.

2 Ground treatment apparatus according to claim 1 in which the guide surface forms part of a guide channel.

3 Ground treatment apparatus according to claim 2 in which the channel comprises walls between which a portion of a falling weight is retained, the separation of the walls being greater at the lowermost end of the channel than higher up the channel.

4 Ground treatment apparatus according to claim 3 in which the channel has a terminal portion at its lowermost end, the wall separation being increased within the terminal portion.

Ground treatment apparatus according to claim 4 in which the channel walls flare away from each other within the terminal portion, whereby to continuously increase the separation of the walls.

6 Ground treatment apparatus according to any of claims 2 to 5 in which the channel comprises a floor extending between the walls, to constrain a falling weight in a direction substantially perpendicular to the constraint provided by the walls.

7 Ground treatment apparatus according to claim 6 in which the channel floor is further spaced in a horizontal direction from the line of fall of a weight at the lowermost end of the guide channel than at a position further lip the leader.

8 Ground treatment apparatus according to claim 7 in which the channel floor flares away from the line of fall within a terminal portion at the lowermost end of the guide channel, whereby to continuously increase the separation of the floor from the line of fall.

9 Ground treatment apparatus according to any of claims 2 to 8, in which the apparatus comprises a plurality of leaders between which a weight is constrained to fall, each leader providing a guide channel as aforesaid.

Ground treatment apparatus according to claim 9 in which the leaders each have at least one surface which cooperates with the surface of another leader to constrain a falling weight against movement in two substantially opposite directions.

11 Ground treatment apparatus substantially as herein described and with reference to the accompanying drawings.

12 Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.