AU785079B2 - Stone column construction for ground improvement - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): Ho Choon AW Invention Title: STONE COLUMN CONSTRUCTION FOR GROUND IMPROVEMENT The following statement is a full description of this invention, including the best method of performing it known to me/us: 14 STONE COLUMN CONSTRUCTION FOR GROUND IMPROVEMENT The present invention relates to a method and apparatus for constructing ground columns to improve ground conditions for building foundations.

BACKGROUND OF INVENTION Before the introduction of stone columns for reinforcing grounds, construction on soft grounds was avoided as the expense for reinforcing soft grounds using traditional foundation techniques, such as driven piles and caissons, was too great. The differences between traditional foundation piles and stone columns is that foundation piles take on the imposed load exclusively while stone columns provide a general improvement of the soil's bulk modulus and redistribution of imposed stresses. Stone columns additionally assist in accelerating consolidation of the ground by allowing a freer and quicker path for pore water pressure to dissipate. This strengthens the soil parameter.

o Stone columns have become widely used to improve the soil beneath roadways, soft soil under road 25 embankments, soil in former mining areas and generally improve soil against liquification caused by seismic action.

Stone columns are presently constructed using the vibro-flotation method. This method includes mounting a vibroflot onto a hydraulic crawler crane having a 40 ton capacity. A vibroflot is a long, thin vibrating tool having a calibre along its length. The vibroflot is positioned above the ground where a stone column is to be constructed. As the vibroflot is set to vibrate transversely to the ground a jet of pressurised water is sent through the calibre and expells through the head of the vibroflot. This has the effect of temporarily liquefying the soil in its vicinity allowing the vibroflot to sink into the soil by displacing the soil. When the vibroflot reaches the required depth the water jet is switched off. With the vibroflot still vibrating the surrounding soil densely packs into a funnel-shaped hole which is then filled with granular filling material such as stone. Extraction of the vibrating vibroflot from the ground continues to shape the hole still filling with material and also compacts the material in the hole.

While the vibroflot method is a satisfactory technique for constructing stone columns, it is an expensive technique with some drawbacks. The vibroflot technique can never produce stone columns which are 100% 15 stone and free from mud and soil contamination. It requires large quantities of water since the vibroflot can only penetrate the ground deeply by temporarily liquefying the surrounding soils. Further, there is a danger of losing the expensive vibroflot if it fails to vibrate when 20 it has sunk to a great depth. If the vibroflot does not resume vibrating, especially at a depth greater than there is a high possibility of it burying itself in the ground.

25 Once a stone column is installed using the vibroflot method the exact size of the column is not ascertainable. The technique further requires highly skilled and conscientious operators in order to produce a high quality stone column. Precision and experience is important in penetrating the vibroflot at the correct rate and correctly pouring the stone. Further, short term load bearing capacity is not able to be tested immediately on the finished stone columns.

SUMMARY OF THE INVENTION 3 According to the present invention there is provided a method of constructing ground columns for ground improvement comprising: inserting a hollow tube into the ground, the tube having a leading end which is closed during insertion so as to form a hole in the ground; filling the tube with fill material withdrawing the tube from the ground, the leading end being open during withdrawal such that fill material in the tube fills the hole as the tube is withdrawn thereby creating a ground column; characterized by inserting said tube into the ground by using insertion means, closing the leading end by attaching to it a retrievable collapsible gate or detachable cover, and vibrating the fill material during withdrawal of the tube with a vibrator located at the leading end of the tube to increase density of the fill material in the column.

20 According to a present invention there is further provided an apparatus for constructing ground columns for ground improvement comprising: a frame including a base supporting counter-weights; a hollow tube adapted to receive fill material and moveable relative to the frame, the tube having a leading end which is capable of being open or closed; an insertion means mounted to the frame, the insertion means being adapted to insert the tube with a closed leading end into the ground thereby creating a hole adapted to be filled with fill material which is provided through the tube when o the leading end is open; characterized in that retrievable collapsible gate or detachable cover is provided at the leading end to close the leading end and allowing the retrievable collapsible gate to rotate downwards automatically or detaching the cover from the leading end opens the leading end, and H:\joannem\keep\26159-02 Ho Choon.doc 27/07/06 3a a vibrator is located at the leading end which vibrates to condense the fill material BRIEF DESCRIPTION OF THE DRAWINGS An embodiment, incorporating all aspects of the invention, will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 illustrates an apparatus for constructing stone columns according to the present invention; Figure 2 is a plan view of Figure 1; H:\joannem\keep\26159-02 Ho Choon.doc 27/07/06 Figure 3 is a close view of the jacking front of the apparatus of figure 1; Figure 4 illustrates one embodiment of the jacking system of the apparatus of figure 1; Figure 5 is a sectional bottom view of figure 4 Figure 6 illustrates the apparatus of figure 1 in a first position; Figure 7 illustrates the apparatus of figure 1 in a second position; i0 Figure 8 illustrates a first step in a method of constructing stone columns according to the invention; Figure 8 (ii) illustrates a second step in the method; Figure 8 (iii) illustrates a third step in the

S..

15 method; S• Figure 8 (vi) illustrates a fourth step in the method; Figure 8 illustrates a fifth step in the method; 20 Figure 9 illustrates a second embodiment of the jacking system of the apparatus of figure 1 in an engaged position; p Figure 10 is a plan view of figure 9; Figure 11 illustrates the jacking system of 25 figure 9 in a disengaged position; Figure 12 is a plan view of figure 11; Figure 13 is a side view of a third embodiment of the jacking system of figure 1 in an engaged position; Figure 14 is a plan view of figure 13; Figure 15 illustrates the jacking system of figure 13 in a disengaged position; and Figure 16 is a plan view of figure DETAILED DESCRIPTION OF PREFERRED EMBODIMENT It is understood that the fill material used in making stone columns according to the present invention is not restricted to stone but also includes other granular materials such as sand, concrete etc. When sand is used, it is a sand column.

When concrete is used, it is a concrete pile.

Figures 1 and 2 illustrate an apparatus used in constructing stone columns according to the present invention. Essentially, the apparatus consists of counter weights 15 of thirty tons or more, a jacking frame 21, a jacking system 57 including a pair of hydraulic jacks 6 and wedging elements 22, and a jacking tube 7.

The jacking frame 21 includes a horizontal base member 2 supported off the ground by locking wheels 23 or the like. Provided on the jacking frame base 2 are two vertical members 1 and cross members 3 and 5 forming a stable three-dimensional frame. Two counter-weights 15 are 15 provided on the base 2 on either side of the jacking frame 21. The counter-weights provide a counteracting force to the jacking action of the jacking tube 7 and ensure the apparatus remains stable throughout operation. The jacking tube 7 is provided centrally of the frame and is insertable 20 through an opening (not shown) in the base 2 to gain access to the ground below.

The jacking tube 7 is a long hollow steel tube having a longer length than the intended length of the 25 stone column. The leading, end of the jacking tube 7 widens in diameter to form a bell-shaped jacking front 8 as illustrated in figure 3. Since the jacking front 8 has a greater diameter than the rest of the jacking tube 7 it determines the diameter of the stone column which will thus be larger than the jacking tube 7.

A detachable head 16 is attached to the jacking front 8 which has an open end. As the jacking tube 7 is jacked into the ground to form a column for filling with stones or other granular material, the detachable head 16 prevents soil from entering tube 7.

The bell-shaped jacking front 8 has an additional application in that it overcomes soil collapse problems which occur when the surrounding soft soil partially collapses into the hole formed by the jacking tube 7.

Overcoming soil collapse is achieved by the collapsed soil being pushed back to the side wall of the hole by the bellshaped jacking front as it is extracted from the hole.

Inside the jacking tube 7 is a centrally located passage in the form of a steel tube 13. Steel tube 13 allows a hydraulic vibrator 14 access to the jacking front 8. The hydraulic vibrator 14 is operated from a top end 24 of the jacking tube 7. Hydraulic hoses 55 connecting the hydraulic vibrator 14 to a power source (not shown) runs through the steel tube 13. During ground penetration of 15 the jacking tube, the vibrator 14 is protected from soil movement by the steel tube 13 and its outer casing provided on the collapsible gates 16. The vibrator's "outer casing 25 is also the jacking tube's first ponit of contact with the ground. Hinges 26 spanning between the vibrator's casing (25) and a base 27 of the collapsible gates provide a means for closing tube 7 during penetration and opening it during withdrawal.

Stones S for filling the column are poured into the annular space 27 between the steel tube 13 and the interior of the jacking tube 7. Pouring of stones begins when the jacking tube 7 had reached its required depth.

See figures 8(i) The tube is then slowly extracted by jacking upwards and, under the weight of the tube filled with stones, the collapsible gate 16 opens up by rotating downwards about hinges As the jacking front moves upwardly with the collapsible gate open the hydraulic vibrator 14 and its casing (25) becomes exposed to the surrounding stones S and is set to vibrate. The vibration densifies the stones which continue to be poured into the jacking tube 7. The bell-shaped jacking front ensures that the hole is immediately relined with soil during the withdrawal process. Relining the hole ensures the column is completely filled with stones at the correct diameter. Meanwhile, the hydraulic vibrator ensures compaction of the stones. Thus, a perfect stone column is formed without contamination from soil or mud.

As illustrated in figures 4 and 5 the jacking system 57 is secured to the jacking frame 21.

Specifically, one end of each hydraulic jack 6 is fixed, by way of a cross member, to one of the bracing members 3.

The other end of each hydraulic jack is fixed, by way of another cross member 4a, to a movable horizontal guide 4.

The ends 54 of guide 4 are grooved to receive a vertical member 1 on which guide 4 moves. The jacking tube 7 is provided through an opening in the guide 4. Wedging 15 elements 22 act as an interface between horizontal guide 4 and jacking tube 7 such that when a hydraulic pack (not shown) powers the hydraulic jacks 6 to displace the horizontal guide 4, the wedging elements grip the jacking tube and move it accordingly upward or downward. The S 20 wedging elements comprise two annular barrels 10 and 11 and two semi-circular wedges 9 and 12.

S.

The wedging elements are divided into a top wedge system W1 and a bottom wedge system W2. The top wedge system W1 comprises barrel 10 and wedge 9 while the bottom wedge system W2 comprises barrel 11 and wedge 12. The bottom wedge system engages. with the jacking tube 7 for penetrating the jacking tube 7 into the ground. To withdraw the jacking tube from the ground the bottom wedge system W2 is disengaged and the top wedge system W1 is engaged. In each wedge system the annular barrel 10 and 11 are bolted to the horizontal guide 4. Top barrel 10 is bolted to the upper surface of guide 4 while bottom barrel 11 is bolted to the underside of guide 4. The openings in the barrels are in coaxial alignment with the opening in guide 4 through which jacking tube 7 extends. The jacking tube is free to move through top and bottom barrels 10 and 11. The internal wall 50 of the barrels is inclined so as To provide an opening at an outer end having a greater diameter than the opening at the bolted end 51 of each barrel. The bolted end 51 of the barrel is provided with an annular flange 52 which provides a bolting surface for the barrel.

The semi-circular wedges, 9 and 12, are adapted to each wedge into a space between the surface of the jacking tube 7 and the internal inclined wall 50 of barrel 10 10 and 11 respectively. Two wedges are provided with each ibarrel. Each wedge extending around approximately half the circumference of the jacking tube. The inner surface of the wedge has a saw-tooth texture so as to form a gripping surface contacting the jacking tube.

In summary, the wedging systems W1 and w2 are responsible for translating the vertical jacking movement of guide 4 to axial jacking of jacking tube 7. For example, to drive the jacking tube into the ground the bottom wedges 12 are inserted between bottom barrel 11 and .jacking tube 7, their textured surface facing the tube 7.

This has the effect of locking movement of guide 4 caused by extending hydraulic jacks 6 translates to tube 7 forcing it too to move downwardly. Before hydraulic jacks 6 retract moving guide 4 upwardly, wedges 12 are loosened from their wedged position so that upward movement of guide 4 is not translated to the tube 7. The reverse is true with the withdrawing process of tube 7, that is, bottom wedges 12 are disengaged from bottom barrel 11 and top wedges 9 are engaged between top barrel 10 and tube 7.

Figure 6 illustrates the construction apparatus at the first stage of construction. The collapsible gate 16 is closed and positioned over the point on the ground where the stone column is to be constructed. Figure 8 is a closer view of the jacking front 8 with the collapsible gate closed.

Before penetration of the jacking tube 7 can begin, the two top wedges are removed from the top wedge system W1 leaving only the bottom wedge system W2 operational. When the hydraulic power pack extends the pair of hydraulic jacks 6, the bottom wedges 12 in the bottom wedge system W2 firmly grip onto the jacking tube 7 forcing, it together with closed collapsible gates 16 into the soil. The jacking tube and closed collapsible gates are advanced a distance into the soil equal to the hydraulic jack extension. The hydraulic jacks 6 are retracted to repeat the jacking motion. Before the next jacking cycle bottom wedging system W2 is loosened of its grip on the jacking tube. This is done by lightly tapping the two bottom wedges 12 causing them to fall away from the bottom wedge barrel 11. The hydraulic jacks 6 are then safely retracted S• without imparting any motion on the jacking tube 7.

Once the hydraulic jacks 6 are fully retracted, the two bottom wedges 12 are again inserted into the bottom wedge barred 11. Extension of the hydraulic jacks 6 pushes the jacking tube 7 and closed collapsible gates further into the soil. This process is repeated until the required depth is reached or when a sufficiently hard bearing stratum is encountered. This can be determined by reading a hydraulic :..o:pressure gauge (not shown) provided on the apparatus. The bearing capacities of the soil at various depths can be S"immediately identified by a pressure gauge reading from which an accurate determination of the required length of a stone column in a particular area of soil can be calculated. Figure 7 illustrates the jacking tube 7 at a required depth and jacks 6 fully extended.

During the insertion process, the only resistance to penetration is from the closed front bearing onto the soil and a small amount of surface friction from the bell shaped jacking head as a result of it having a greater diameter than the jacking tube 7.

Figure 8 (ii) illustrates a fully inserted jacking tube 7. The steel tube 13 is shown centrally located along the axis of the jacking tube 7. The closed jacking front is the retrievable collapsible gates or sacrificial detachable head.

Figure 8 (iii) illustrates the jacking tube being filled with stone having the required grading for providing fill. The hydraulic vibrator 14 is protected from the stones by steel tube 13. When the jacking tube 7 is full with stones it is ready to be withdrawn from the ground.

To withdraw the jacking tube the bottom wedge 15 system W2 is disengaged and the top wedge system W1 is engaged. Top wedges 9 are therefore inserted into top barrel 10 while bottom wedges 12 are removed from bottom barrel 11. Retraction of the hydraulic jacks 6 lifts S horizontal guide 4 which in turn lifts jacking tube 7 by 20 way of the gripping interface of the top wedge system W1 As the jacking tube is retracted, the stones previously in space 27 in the tube 7 discharge into the hole created by the jacking front 8. See figure 8 (iv).

25 More stones are added at the top of the jacking tube as those at the bottom discharge into the hole. The collapsible gates collapse downwards at the jacking front as the tube 7 is lifted and remains at the lowest point of the jacking tube. As the tube is retracted, the bellshaped jacking head assists in relining the soil in the side wall of the hole back to the hole's original diameter.

The hydraulic vibrator 14 commences vibration as the tube 7 is first retracted. The vibration causes the discharging stones to align closer and compact to a suitable density. Vibration occurs during the whole extraction process of the tube 7.

11 Alternatively loosening and engaging top wedge system W1 respectively with extension and retraction of the hydraulic jacks completely withdraws the jacking tube. The final result is a well compacted stone column as illustrated in figure 8(v).

The finished stone column can be immediately loaded to determine its short term bearing capacity. The entire load capacity test takes not more than ten minutes as the test set up is a kentledge.

The type of stone columns discussed so far have a constant diameter along their length. Another embodiment of the stone column is produced with an enlarged upper end ooeoo: which provides an increased bearing capacity compared with the constant diameter columns. For example, a 18m stone column with a diameter of 600mm at the upper 2m of the column and a diameter of 300mm for the remaining lower 16m, ""has a bearing capacity of more than three times than an 18m 20 stone column having a constant diameter of 300m. It is therefore foreseeable that a stone column having an enlarged upper end can be made shorter than a uniform cross-section column whilst providing equivalent or better structural performance.

Figures 9, 10, 11 and 12 illustrate a second embodiment 30 of the jacking system. This embodiment is similar to the first embodiment wherein the hydraulic jacks 6 are located between a fixed cross member of the jacking frame and a moveable horizontal guide 4. However, rather than a top and bottom wedge system, the second jacking system embodiment 30 requires lifting studs 31 to be welded onto the jacking tube 7a at regular intervals. Two small hydraulic jacks 32 are mounted to lifting boxes 33 which in turn are bolted to horizontal guide 4. Lifting blocks B are horizontally slidable in and out of the lifting boxes 33 and are driven by hydraulic jacks 32. Each jack piston 34 and an outer end of each block B are connected in parallel to a vertical plate 35. In this way, horizontal movement of jack 32 is translated into the horizontal movement of the corresponding block B.

If, for example, it is required to withdraw a jacking tube 7a from the ground, the hydraulic jacks 32 are retracted which causes lifting blocks B to move towards of the jacking tube 7a so that inner ends of the blocks B are positioned underneath lifting studs 36. Hence when the main hydraulic jacks 6 (two main jacks are used in this embodiment) are retracted, horizontal guide 4 is forced upwards which in turn lifts jacking tube 7a by way of hooking lifting blocks B underneath lifting studs 36.

ooooo s 15 Extending small jacks 32 disengages or removes lifting blocks b from the lifting studs 36 thus allowing guide 4 to freely move downwards and prepare engagement o with the next, lower set of studs 36. Figures 11 and 12 illustrate the extended jacks 32 and correspondingly retracted lifting blocks b. Sliding lifting blocks b towards tube 7a once more positions them under the next set of lifting studs to repeat the lifting process until the jacking tube 7a is fully withdrawn. The opposite applies with inserting the jacking tube 7a into the ground.

Lifting blocks B are moved towards tube 7a to loosely grip the jacking tube 7a at an engaged position above the lifting studs 36.

A third embodiment 38 of the jacking system is illustrated in figures 13 to 16. Conceptually, the third embodiment is similar to the second embodiment in that it operates on the principle of engaging lifting blocks B on either an upper or lower side of lifting studs 36 to produce incremental lifting or downward pushing actions.

In this embodiment the lifting, or more accurately reaction, studs 36a are welded onto each vertical leg 1 of the jacking frame. The reaction studs 36a engage with lifting blocks B extendable by small jacks 32 in a similar assembly to the second embodiment 30. The small jacking assembly is bolted to a horizontal guide member 40 provided between and guided by two adjacent vertical legs 1. Bolted to the underside of the horizontal guide 40 is a single main hydraulic jack 41. The extendable piston 42 of the hydraulic jack 41 abuts against a lower horizontal member 43 which is also moveable in the vertical direction and guided between vertical legs i. Fixed to the underside of this second horizontal guide 43 is the top of the jacking tube 7. Therefore, jacking of the tube 7 into the ground is effected at the top of the jacking tube 7. The vertical legs 1 of the jacking frame are necessarily higher than the .:length of the tube 7.

15 Figure 13 illustrates the jacking system in preparation for jacking the tube 7 into the ground.

Lifting block B is extended by small jack 32 towards vertical leg 1 and positioned under a first reaction stud .36. This has the effect of fixing the upper horizontal guide 40 for use as a reaction surface for hydraulic jack 41. Extension of hydraulic jack 41 directly forces jacking tube 7 downwards. Hydraulic jack 41 and jacking tube 7 are in coaxial alignment. The lower horizontal member 43 between the hydraulic jack and jacking tube 7, guides movement of the jacking tube 7 ensuring it correctly extends transversely to the ground. Upon reaching the full extension of the hydraulic jack 41, the small jacks 32 are operated to retract lifting blocks B from the vertical leg i. Retraction of hydraulic jacks 41 then pulls the horizontal guide 40, and thus the jacking assembly, in a downwardly direction to a position level with the next, lower set of reaction studs 36. Extension of lifting blocks B brings them directly underneath the reaction stud 36. The jacking system is ready to once again thrust against the underside of the reaction stud 36 to repeat jacking and penetration of tube 7.

To withdraw the jacking tube from the ground, 14 lifting blocks B bear on the upper surface of reaction studs 36 rather than the underside. The jacking system moves incremently up along each group of level studs 36 until the jacking tube 7 is fully withdrawn.

There are many advantages associated with the present invention over the prior art, an important of which is that water is not needed in the operation. A dry and clean jacking operation is thus performed. This results in a 100% displacement of soil, as opposed to part displacement and part replacement of known techniques.

•Better densification of soil results and the resulting stone column consists 100% of clean stones without soil or ooooo: mud contamination. There is further no environmental pollution which can result from water based installation methods wherein mud pushed above ground eventually washes into drains and rivers.

The capital outlay of the construction apparatus is, for example, less than 10% of the vibroflot method and there is no possibility of losing an expensive vibroflot.

The cross-sectional shape of the hole created is uniform and automatically and accurately controlled. The process does not require high operator skill to produce a high quality stone column. In fact, the whole process is mechanically controlled and monitored. Additionally, the finished stone column can be immediately loaded to determine its short term bearing capacity. This is not possible with previous methods.

For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the word "comprises" has a corresponding meaning.

It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invent ion.

Claims (17)

1. A method of constructing ground columns for ground improvement comprising: inserting a hollow tube into the ground, the tube having a leading end which is closed during insertion so as to form a hole in the ground; filling the tube with fill material withdrawing the tube from the ground, the leading end being open during withdrawal such that fill material in the tube fills the hole as the tube is withdrawn thereby creating a ground column; characterized by inserting said tube into the ground by using insertion means, closing the leading end by attaching to it a retrievable collapsible gate or detachable cover, and vibrating the fill material during withdrawal of the tube with a vibrator located at the leading end of the tube to increase density of the fill material in the column. :e 2. The method of constructing ground columns for ground improvement of claim 1 wherein said leading end is in the form .0of a bell-shaped jacking front. oooo

3. The method claimed in claim 2 further characterised by opening the leading end by detaching and keeping the detachable cover at a bottom of the hole as the tube is withdrawn. oeooo

4. The method claimed in any one of the preceding claims further 30 characterised by adding further fill material to the tube as .000 •oD the tube is being withdrawn. 0.

5. The method claimed in any one of the preceding claims further characterised by relining the hole as the tube is withdrawn to prevent soil collapse. H:\joannem\keep\26159-02 Ho Choon.doc 27/07/06 17

6. The method claimed in any one of the preceding claims further characterised by reducing resistance to insertion of the tube by enlarging the leading end of the tube.

7. The method claimed in any one of the preceding claims further characterised by gauging a pressure at the leading end so as to determine the strength of soil in the ground and the required length of the columns.

8. The method claimed in any one of the preceding claims wherein the insertion means is a jacking system.

9. The method claimed in any one of the preceding claims in that the fill material is stone (S) The method claimed in any one of claims 1 to 8 in that the fill material is sand.

11. The method claimed in any one of the preceding claims 20 further characterised by forming an upper portion of the ground column having a greater cross-section than a lower portion of oeo the column.

12. An apparatus for constructing ground columns for ground improvement comprising: a frame including a base supporting counter-weights; a hollow tube adapted to receive fill material and moveable relative to the frame, the tube having a leading end which is capable of being open or closed; an insertion means mounted to the frame, the insertion means being adapted to insert the tube with a closed leading end into the ground thereby creating a hole adapted to be filled with fill material which is provided through the tube when the leading end is open; characterized in that a retrievable collapsible gate or detachable cover is provided at the leading end to close the leading end and H:\joannem\keep\26159-02 HO Choon.doc 27/07/06 18 allowing the retrievable collapsible gate to rotate downwards automatically or detaching the cover from the leading end opens the leading end, and a vibrator is located at the leading end which vibrates to condense the fill material (S)

13. The apparatus claimed in claim 12 characterised in that the leading end has a greater cross-sectional area than the rest of the tube such that the cross-sectional area of the hole is determined by the leading end.

14. The apparatus claimed in claim 13 characterised in that the leading end is bell-shaped.

15. The apparatus as claimed in any one of claims 12 to 14 further characterised in that an internal tube is provided inside the hollow tube.

16. The apparatus claimed in claim 12 characterised in that the vibrator is connected to a power source through the internal tube and is protected from fill material by the internal :e tube and the retrievable collapsible gate or detachable cover. 0***00

17. The apparatus claimed in any one of claims 12 to 16 characterised in that the insertion means is a jacking systems S" 25 comprising at least one hydraulic jack mounted to the frame and adapted to move a guide member which in turn is adapted to move, by way of an interface assembly, the tube in an upwardly or downwardly direction. 30 18. The apparatus claimed in claim 17 characterised in that the 0000 goo interface assembly is a top and bottom wedge system, each wedge system (W1, W2) having a barrel fixed to the guide member. .0 S. 19. The apparatus claimed in claim 18 characterised in that a wedge segment is adapted to wedge between the barrel and the tube, the tube extending through the barrel, such that the wedge system (Wl, W2) moves the tube in the direction of the guide member. H:\joannem\keep\2619-02 Ho Choon.doc 27/07/06 19 The apparatus claimed in claim 17 characterised in that the interface assembly is a pair of small hydraulic jacks mounted on the guide member and adapted to move a sliding block towards the tube and adjacent lifting studs fixed on the tube.

21. The apparatus as claimed in any one of claims 12 to 16 characterised in that the insertion means is a jacking system comprising at least one hydraulic jack mounted between a moveable guide member and an upper end of the tube, the guide member providing a reaction surface against which the hydraulic jack operates to move the tube upwardly or downwardly.

22. The apparatus claimed in claim 21 characterised in that small hydraulic jacks are mounted on the guide member and are adapted to move sliding blocks towards the frame and adjacent reaction studs fixed onto the frame so as to secure the guide member against upward or downward movement thus providing the hydraulic jack with the reaction surface. 20 23. The apparatus as claimed in any one of claims 12 to 22 wherein the fill material is stone (S) wherein the fill material is sand. The apparatus as claimed in any one of claims 12 to 22 wherein the fill material is concrete. o o o "XX" Dated this 27th day of July 2006 HO CHOON AW oo By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H;\Joannem\keep\26159-02 HO Choondoc 27/07/06