Improved caisson emplacement system and method Field of the invention

[001] The present invention relates to the use of caissons or casings to place structural elements into soft ground without disturbing the surrounding environment. For the purpose of this specification and attached claims, the word "caisson" is meant to describe a hollow structure, which can be pressurized, that is, able to bear hydrostatic pressure either as water is evacuated from inside, or air is pumped in, whereas the word "casing" is meant to describe a hollow structure which is not pressurized, that is, water may be on the inside of the hollow structure. The following invention applies to both types. .

Background of the invention

[002] There are various requirements to place structural elements below the existing ground level.

[003] One such requirement relates to the placement of precast concrete panels in front of an existing seawall requiring replacement.

[004] Placement of the new panels using known methods such as percussion, vibration, pre drilling or other methods may disturb the surrounding environment and induce premature failure of the existing sea wall.

[005] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

Summary of the invention

[006] A solution to this problem is to push, pull, hammer or lower a caisson or casing to a predetermined depth. The caisson or casing is a hollow box shaped to accept a new panel.

[007] After the caisson or casing is pushed, pulled, hammered or lowered to a depth the new panel can be inserted and or formed inside the caisson or casing.

[008] After the new panel is inserted in the caisson or casing, the caisson or casing is able to be removed and can be withdrawn leaving the new panel in place.

[009] The present invention provides a drilling assembly for insertion of a caisson or casing, the drilling assembly having two or more drill bits which are adapted to be driven by a drilling or rotation motive device, the drill bits being adapted to be arranged with respect to the caisson or casing in use, so as form a hole or bore which substantially conforms to, or substantially overlaps with, the shape of the caisson or casing. [010] The drill bits can be adapted to be positioned ahead of a leading edge of the caisson or casing.

[011] The drill bits can be expanding drill bits.

[012] The drilling assembly is such that it is one or a combination of more than one of the following:

the expanding drill bits when in a retracted condition, allows the drilling assembly to be withdrawn from the caisson or casing;

the expanding drill bits when in an expanded condition, ground engaging bits extend beyond part of a leading edge of the caisson or casing;

the expanding drill bits when in an expanded condition, ground engaging bits extend beyond all of the leading edge of the caisson or casing;

the drill bits are rotated by hydraulic motors located within the caisson or casing;

the drill bits are rotated by hydraulic motors located outside the caisson or casing;

the drill bits are rotated by other mechanical means whether individually or in unison;

the drilling assembly is mounted for being pulled towards or pushed away from the caisson or casing;

the drilling assembly is provided with a means of flushing by air, liquid, slurry, mud or a combination of all.

[013] The drilling bits can be adapted to be positioned ahead of a leading edge of the caisson or casing.

[014] The drilling assembly can be adapted to be attached to the caisson or casing.

[015] The drilling assembly can be releasably attachable to the caisson or casing.

[016] The caisson or casing does not rotate as it advances downwardly.

[017] The caisson or casing can have a first edge, and a first edge projection which surrounds it at the first edge.

[018] The caisson or casing further includes a second edge opposite the first edge, and a surrounding projection located at the second edge, the surrounding projection being adapted to cooperate with the first edge projection of an adjacent caisson or casing.

[019] The caisson or casing can be constructed from two or more vertical sections.

[020] The drilling assembly can substantially close off an opening formed by an inner periphery of the caisson or casing.

[021] Multiple drilling heads can be used for each opening. [022] The drilling assembly can disturb, plasticize, fluidize, or worry a bed drilled by the drilling assembly, allowing the caisson or casing to be positioned to a predetermined or required depth.

[023] There can be a gap between an interior surface of the caisson or casing and a body of the drilling assembly.

[024] The gap can be on the order of 5 to 10 millimeters.

[025] The present invention also includes a method of inserting a caisson or casing into a friable terrain, the method including the steps of:

arranging a drilling assembly as described in the paragraphs above with respect to a caisson or casing;

positioning the drilling assembly and the caisson or casing over a location for insertion of the caisson or casing;

operating the drilling assembly from another location, until sail caisson or casing has been situated as desired.

[026] The method can also include the steps of:

retracting the expanding bits, and

withdrawing the drilling assembly from the caisson or casing.

[027] The method can include the step of inserting or forming a structural element into the caisson or casing.

[028] The method can include the step of withdrawing the caisson or casing.

[029] The structural element can include a through aperture via which grout is received to grout the structural element.

[030] The method can include the step of separately drilling a hole into a hard ground at a position which corresponds with the through aperture.

[031] The through aperture can be adapted to receive a reinforcing dowel.

[032] The method can be repeated to insert or form further structural elements.

[033] The method can provide grouting spaces between adjacent structural elements.

[034] Lateral vertical sides of the structural elements can be shaped so that the grout between adjacent structural elements forms a grout key.

[035] A stocking made from canvas, plastic, any appropriate nylon, or geo-fabric can be placed over a grout line used to grout spaces between adjacent structural elements.

[036] The method can include the step of securing a capping beam to the structural element.

[037] The capping beam and structural element can be bolted or screwed together. [038] The method can further have one of the below features:

the capping beam includes one or more inserted or pre-cast reinforcement bars, each to be inserted into a corresponding aperture in the structural element; or

the structural element includes one or more inserted or pre-cast reinforcement bars, whereby each reinforcement bar is received by a corresponding aperture in the capping beam; or the structural element includes one or more inserted or pre-cast reinforcement elements, and the capping beam is cast onto the structural element and around the reinforcement elements.

[039] The method can include the step of including an anchoring tie in the capping beam.

[040] The method can include the step of attaching a subsequent caisson or casing to the caisson or casing.

[041 ] The present invention also provides an apparatus that allows a caisson or casing to be pushed, pulled or lowered to a required depth.

[042] There can be a two or more expanding drill bits.

[043] The expanding drill bits can be located within a caisson or casing inner drilling assembly.

[044] The expanding drill bits can be arranged so as to conform to the shape of the caisson or casing.

[045] The caisson or casing inner drilling assembly can be located so that the drill bit cutting edges extend below the leading edge of the caisson.

[046] The expanding drill bits utilised can be constructed using known bits. The expansion and retraction of the cutting edges can be achieved by mechanical, hydraulic, or other means, as well as by rotation.

[047] When rotated in a primary direction of rotation the expanding drill bit cutting edges are retracted and remain wholly within the caisson or casing. In this retracted position the inner assembly can be removed from the caisson casing.

[048] When located in the caisson or casing and rotated in the opposite direction to the primary direction, the expanding drill bit cutting edges extend beyond the outer extremities of the caisson or casing.

[049] When rotated in the extended or expanded position the expanding drill bits will disturb or drill the ground and allow the caisson or casing to be pushed, pulled or lowered into the disturbed or drilled ground.

[050] The drill bits can be provided with a means of flushing by the introduction of either, liquid or air, or a combination of both, to assist the advance of the caisson or casing. [051] The inner drilling assembly can be made to advance ahead of the caisson or casing.

[052] Once the inner drilling assembly is advanced the caisson or casing can be made to advance by retracting the inner drilling assembly and pushing, pulling or lowering the caisson or casing. This process can then be repeated.

[053] When the caisson or casing has reached the required depth the rotation of the expanding drill bits is reversed, retracting the cutting edges. The inner drilling assembly can then be detached from the caisson or casing and then removed from the caisson or casing. Once the required depth of caisson/casing is reached, a structural element, such as a poured concrete element (such as a wall, a block, retainer), or a preformed concrete shape, can then be placed inside the caisson or casing and the caisson or casing removed leaving the structural element in position, and allowing the caisson to be re-used. The caisson or casing could also be left in situ, as a final structural element. Furthermore, the caisson or casing could also be used as formwork, to e.g. form or cast in place a concrete structural element.

[054] The structural elements placed inside the caisson or casing can be made from concrete steel or any other material, including reinforcing made from fibre glass or non- corroding reinforcing material.

[055] The structural element can be provided with a drain hole, or drainage holes.

[056] The drainage holes in the element can be provided with a strip drain.

[057] The strip drain can be protected by geo fabric.

[058] The structural element can be provided with a lifting eye, or lifting eyes.

[059] The structural element can be provided with a grout tube, or tubes to allow grout, or other medium, to be pumped to the base. The grouting can be done before during or after the withdrawal of the caisson or casing.

[060] The structural element can be provided with a void or a multiple of voids to allow a jet grouted pile, or piles to be constructed below the element.

[061] The structural element can be provided with a void, or voids to allow the installation of a grouted rock dowel, or dowels below the element. The structural element can also be provided with reinforcement bars to allow attachment of a capping beam. The structural element can also be provided with cast in place penetrations to allow the reinforcement bars to be grouted in place after casting. [062] After the element is placed in the caisson or casing, a free flowing material either granular or liquid can be placed in the caisson as it is withdrawn to fill the void left by the caisson.

Brief description of the drawings

[063] A detailed description of a preferred embodiment will follow, by way of example only, with reference to the accompanying figures of the drawings, in which:

[064] Figure 1.1 is a side elevational view of a caisson/casing and drilling assembly with the drill bits in a retracted condition;

[065] Figure 1.2 is a front elevational view of the apparatus of figure 1.1 ;

[066] Figure 1.3 is a plan view of the apparatus of figure 1.1 ;

[067] Figure 2.1 is a side elevational view of a caisson/casing and drilling assembly with the drill bits in an extended or expanded condition, showing how a substantial portion of the periphery of the caisson/casing is overlapped by the drill bits;

[068] Figure 2.2 is a front elevational view of the apparatus of figure 2.1 ;

[069] Figure 2.3 is a plan view of the apparatus of figure 2.1 ;

[070] Figure 3.1 is a side elevational view of a caisson/casing and drilling assembly with the drill bits in an extended or expanded condition with the middle bit lower than the outer bits and the whole of the periphery is overlapped by the footprint of the drill bits in extended or expanded condition;

[071 ] Figure 3.2 is a front elevational view of the apparatus of figure 3.1 ;

[072] Figure 3.3 is a plan view of the apparatus of figure 3.1 ;

[073] Figure 4.1 is a side elevational view of a caisson/casing and drilling assembly with the drill bits in an extended or expanded condition, similar to Figs 3.1 to 3.3, with the middle bit being at same height as the outer bits, but 90 degrees out of phase, and the whole of the periphery is overlapped by the footprint of the drill bits in extended or expanded condition;

[074] Figure 4.2 is a front elevational view of the apparatus of figure 4.1 ;

[075] Figure 4.3 is a plan view of the apparatus of figure 4.1 ;

[076] Figure 5 illustrates a plan view of an embodiment similar to that of figure 2.3, where the caisson/casing has a hollow T-shape;

[077] Figure 6 illustrates a plan view of an embodiment similar to that of figure 2.3 or 5, where the caisson/casing has a hollow arcuate or half round shape; [078] Figure 7 illustrates a plan view of an embodiment similar to that of figure 2.3, 5 or

6, where the caisson/casing has is a relatively large hollow square shape, utilising some 9 expanding bits;

[079] Figure 8.1 illustrates a side elevational view of a caisson/casing and drilling assembly with two drill bits, both in an extended or expanded condition;

[080] Figure 8.2 illustrates a plan view of the caisson/casing shown in Figure 9.1 , where the caisson/casing is generally shaped like the number "8" ;

[081] Figure 8.3 illustrates a front or rear elevational view of the caisson/casing and drilling assembly shown in Figure 8.1 ;

[082] Figure 8.4 illustrates a plan view of an embodiment similar to that of figure 2.3, 5,

6, or 7 where the caisson/casing has the shape shown in Figure 8.2;

[083] Figure 9 illustrates a vertical cross section through the embodiment of figure 1.1 to 2.3 showing the assembly of a caisson/casing and a drilling assembly with expanding drill bits which are driven by hydraulic motors;

[084] Figure 10 are photographs of examples of two drill bits and their specifications which can be utilised with the embodiments of the invention;

[085] Figure 11 illustrates a dual section view of the drilling assembly and its disengagement and retraction mechanism;

[086] Figure 12 illustrates a schematic view similar to Figure 9, except that intervening the between the lifting assembly and latches is a hydraulic ram system to push the drilling assembly downward relative to the caisson or casing;

[087] Figure 13.1 is a front or rear view of a plurality of structural panels, drilling assembly, and grout between the panels;

[088] Figure 13.2 is plan view of the panels of the apparatus of Figure 13.1 ;

[089] Figure 13.3 is a cross section through line 1-1 of Figure 13.2;

[090] Figure 14.1 is a schematic front view of a plurality of structural panels showing toe grouting of some of the panels;

[091] Figure 14.2 is a schematic plan view of Figure 14.1 ;

[092] Figure 14.3 is a cross section through line 2-2 of Figure 14.1 ;

[093] Figure 15.1 is a schematic cross sectional view of a plurality of structural panels being attached to rock or hard ground;

[094] Figure 15.2 is a plan view of Figure 15.1 ; [095] Figure 15.3 is a cross section through line 3-3 of Figure 15.2;

[096] Figure 16.1 is a schematic cross sectional view of a plurality of structural panels and a capping beam attached to some of the panels;

[097] Figure 16.2 is a schematic plan view of Figure 16.1 ;

[098] Figure 16.3 is a cross section taken through line 4-4 of Figure 16.2;

[099] Figure 17.1 is a front view of two caissons in situ, one of which showing reinforcement bars;

[0100] Figure 17.2 is a plan view of Figure 17.1 , schematically showing concrete poured into the caisson as formwork

[0101] Figure 18 is a schematic depicting a capping beam with land anchors or ties attached;

[0102] Figure 19.1 is a schematic depicting the initial positions of a drilling assembly and a caisson on a friable bed, preferably under water;

[0103] Figure 19.2 is a schematic depicting the movement of plasticised or disturbed bed matter;

[0104] Figure 19.3 is a schematic depicting the upward movement and accumulation of plasticised bed matter as the caisson sinks;

[0105] Figure 19.4 is a schematic depicting the downward movement of plasticised bed matter once the caisson is removed;

[0106] Figures 20.1 to 20.8 are cross sections showing the method where by a caisson inserted into a hole formed by the drill assembly, and a second caisson is attached and inserted into the hole;

[0107] Figure 21 is a schematic view of a caisson which can be vertically attached to another caisson;

[0108] Figure 22 is a schematic view of a caisson which can be lowered by the application of pulling forces.

Detailed description of the embodiment or embodiments

[0109] While the following description is in respect of an unpressurised caisson or casing, driven vertically in marine sediment it will be readily understood that the present invention and embodiments thereof can be applied to pressurized caissons, and in directions other than vertical and other ground types. [0110] Illustrated in figures 1.1 to 1.3 is a generally rectangular caisson or casing 1 , which can be of any desired height and or wall thickness. Inside of the caisson or casing 1 is mounted an inner drilling assembly 3 with thee drill bits 4, being in a retracted condition. Not shown in these figures are the attachment of the inner drilling assembly to the caisson or casing, or the bit drive, or flushing mechanism, but they are illustrated and described in respect of Figure 9. The drill bits 4 are mounted for rotation in the drilling assembly 3, as described later in respect of Figure 9. It will be noted from Figures 1.1 , 1.2 and 1.3 that the retracted size or diameter of the drill bit 4 that is selected for use with the caisson/casing 1 , is such as to fit within the inner wall dimension of the caisson/casing 1. The expansion and retraction of the cutting edges can be achieved by rotation, or by mechanical, hydraulic, or other means.

[011 1] Illustrated in figures 2.1 to 2.3 are a similar figures to figures 1.1 to 1.3 respectively, showing the relative positioning of the caisson/casing 1's wall with the drill bits 4.1 being the same as drill bits 4, except in an extended or expanded condition. It should be noted that the drill bits now labeled 4.1 in their extended or expanded condition do not cover the complete leading edge 2 of the caisson/casing 1 , as is visible in each of figures 2.1 to 2.3. However, it will be noted that a substantial portion of the periphery of the caisson/casing perimeter is overlapped by the outside diameter of the extended or expanded drill bits 4.1. In soft ground or highly friable terrain, this will not hinder the advance, downward movement or insertion of the caisson/casing 1's into such ground.

[0112] The caisson or casing 1 does not rotate whilst it is advanced or inserted into the ground. The terrains in which the embodiments are used are friable ground whereby the "cuttings" or bed are disturbed or plasticized, fluidised or worried, and are displaced by the drilling assembly and/or the caisson or casing. The embodiments do not drill or function when rock is encountered. The cuttings in these terrains are simply disturbed or moved away, and mixed with water by the rotation action of the drilling bits 4, especially in e.g. a river bed. This enables the caisson or casing to sink into the ground and reach the required or predetermined depth, under the influence of gravity, by a pushing or a pulling force, or by hammering. For instance, as shown in Figure 22, workers can apply a tension rather than a compressive force to lower the caisson. This can be done by pulling on a rope, cable or similar 38, which is arranged around pulleys 40 to transmit the pulling force into a downward force upon the caisson or casing 1.

[0113] The drill assembly 3 effectively closes off, or substantially closes off, the opening formed by the inner periphery at the leading ledge of the caisson or casing.

[0114] It will be noted from figure 2.2 and 2.3, that the outside diameter of the expanded drill bits 4.1 do not overlap, ensuring the easy operation and obviates the need to synchronise the bits 4.1 in their cutting action. [0115] As the bits 4.1 when expanded, can be contracted to the positions shown in figures 1.1 to 1.3, this means that when the caisson/casing 1 is in the desired position in the earth, river or harbour bed, or other location, once brought to the retracted condition can be withdrawn from the caisson/casing 1 , with the friction with the caisson/casing 1 outer wall, ensuring that it does not move when the drilling assembly 3 is withdrawn from the caisson/casing 1.

[0116] Illustrated in figure 3.1 to 3.3 are respectively similar views to that of figures 2.1 to 2.3 with the drill bits 4.1 and 4.2 in their extended or expanded conditions covering the complete leading edge 2 or the whole periphery of the caisson/casing 1. Drill bit 4.2 is vertically positioned lower with respect to the bits 4.1 , so that the rotation of bit 4.2 does not conflict with the rotation of other bits 4.1. Alternatively, the bit 4.2 can be positioned above other bits 4.1 , in order to achieve a similar functional effect.

[0117] Illustrated in figures 4.1 to 4.3 are respectively similar illustration to that of figures

3.1 to 3.3, with the drill bits 4.3 in their extended or expanded position, but the outer bits 4.3 being at a 90 degrees phase difference to the inner bit 4.3. The rotation of the drill bits in this assembly would need to be synchronized to avoid conflict or inter-engagement. The

synchronization could be achieved by chains, gears or any other appropriate means.

[0118] Illustrated in figures 5, 6 and 7 are caissons 1 and inner drilling assemblies 3 of various shapes. The location of the drill bits 4.1 are as detailed in figures 2.1 to 2.3. The drill bits

4.1 of figures 5, 6 and 7, could also be arranged as described in figures 3.1 to 3.3 or 4.1 to 4.3.

[0119] Illustrated in Figures 8.1 to 8.4 are a caissons/casing 1 and an inner drilling assembly 3 of the shape which generally corresponds to the number "8". Two drilling bits 4.1 ,

4.2 are provided in the drilling assembly 3. The drilling bits 4.1 , 4.2, in their expanded condition overlap with each other. Therefore, one drill bit 4.2 is positioned lower than the other drill bit 4.1.

[0120] It will be readily understood that structural elements of other shapes than those illustrated in the Figures 1.3, 3.3, 4.3, 5 to 7, and 8.3 will require caissons/casings 1 of other corresponding or matching shapes.

[0121] As illustrated in Figures 1.1 to 8.4, there is a gap 2.1 between the body of the inner drilling assembly 3 and the interior surface of the caisson or casing 1. The body of the inner drilling assembly 3 can further generally conform to the shape of the interior of the caisson 1. This gap is usually of the order of 5 to 10 millimetres, but variations from this range are possible. When the embodiment is used in a watery environment such as the ocean, harbour, or river, water is allowed to ingress into the interior of the caisson/casing 1 through the gap 2.1. Water ingress into the caisson or casing 1 is also possible through any other apertures or holes provided on the wall of the caisson or casing 1. Thus in circumstances where the embodiment is used in a watery environment, water is allow to enter and may fill the caisson/casing 1. The water ingress helps the caisson/casing to sink into the friable ground.

[0122] Illustrated in Figure 9 is a caisson/casing 1 and an inner drilling assembly 3 with

3 expanding drill bits 4 driven by hydraulic motors 5. The motors 5 are kept in approximate synchronization by the hydraulic flow divider 7. The flow divider 7 can be located within the Inner drilling assembly 3 or as shown in Figure 9 where it is external to the caisson/casing 1. The motors 5 have drive shafts 6 that pass through bearings 8 to the bits 4.

[0123] Flushing hoses 14 supply air or liquid to the bits 4 through the bearing 8 and the shaft 6 to a location past the base 9 of the bearing 8, and out through the flushing hole 15. Hydraulic hoses 13 connect the divider 7 with the motors 5. A latch assembly 10 on the drilling assembly 3 locates the inner drilling assembly 3 with the caisson/case 1 , and engages apertures 1 1 in the caisson or casing 1. A lifting assembly 12 is provided to remove the inner drilling assembly 3 from the caisson/casing 1 when the bits 4 are retracted. The lifting assembly 12 is connected to the latch assembly 10 so that when tension is applied to the lifting assembly the latch 10 will automatically detach from the caisson 1. This attachment is not shown on the drawings.

[0124] In operation, the periphery of the body of the drilling assembly 3 conforms as close as practical to the internal rim of the leading edge of the caisson 1 , which will preferably, on its inside, be of a constant cross section. This relationship of conformity precludes or reduces the entry of material into the caisson 1. The drill bits 4, by their rotation, will worry, plasticise, fluidise, or disturb the ground. The disturbance can be also helped or enhanced by the injection of fluids through the flushing hole 15. The ground, so disturbed, is forced by the combined mass of the caisson 1 and the drilling assembly 3 to move outward from underneath the drilling assembly 3 and upward as the assembly sinks.

[0125] Illustrated in Figure 10 are examples of two drill bits which are available and can be used with the embodiments described above. Other types of expanding drill bits, some called under the name 'reamers" or "under reamers" which may or may not require rotation to cause expansion or counter-rotation to cause contraction, are also known which can also be used with the embodiments of the present invention as described above.

[0126] In respect of the above embodiments, when the caisson or casing 1 has reached the required depth, the rotation of the expanding drill bits 4, 4.1 , 4.2, 4.3 are reversed in the direction 16 of Figure 10, retracting the cutting edges. The inner drilling assembly 3 can then be detached from the caisson/casing 1 and then removed from the caisson/casing 1. Once the required depth of caisson/casing 1 is reached, a structural element, such as a poured concrete element (such as a wall, a block, retainer), or a preformed concrete shape, can then be formed or placed inside the caisson/casing 1 and then caisson/casing 1 removed leaving the structural element in position, and allowing the caisson/casing 1 to be re-used.

[0127] The structural elements placed inside the caisson/casing 1 can be made from concrete, steel or any other material, and may include reinforcing made from fibre glass or non- corroding reinforcing material.

[0128] The structural element can be provided with a drain hole, or drainage holes.

[0129] The drainage holes in the structural element can be provided with a strip drain.

The strip drain can be protected by geo fabric.

[0130] The structural element can be provided with a lifting eye, or lifting eyes so it can be lifted and deposited into position in the caisson/casing 1.

[0131] The structural element can be provided with a grout tube, or tubes to allow grout, or other medium, to be pumped to the base. The grouting can be done before during or after the withdrawal of the caisson/casing 1.

[0132] The structural element can be provided with a void or a multiple of voids to allow a jet grouted pile, or piles to be constructed below the element.

[0133] The structural element can be provided with a void, or voids to allow the installation of a grouted rock dowel, or dowels below the element. The structural element can also be provided with reinforcement bars to allow attachment of a capping beam. The structural element can also be provided with cast in place penetrations, i.e. through apertures, to allow the reinforcement bars to be grouted in place after casting.

[0134] After the structural element is placed in the caisson/casing 1 , a free flowing material either granular or liquid can be placed in the caisson as it is withdrawn to fill the void left by the caisson/casing 1. The caisson or casing could alternatively be left in situ, as a final structural element. Furthermore, the caisson or casing could also be used as formwork, to e.g. form or cast in place a concrete structural element.

[0135] In respect of the description of what is positioned inside the caisson/casing 1 , after it has achieved a desired depth, as described above in paragraphs [067] to [075] has not been described in any detail, nor illustrated, as these aspects are not part of the invention described in this specification, and further will be commonly and widely known by a person skilled in this art.

[0136] Illustrated in Figure 1 1 is a manual release system to separate the drilling assembly 3 from the caisson/casing 1. In this manual release system the lifting cable 12 connects to a lifting flange 12.1. The left side of Figure 1 1 shows the system when the drilling assembly 3 is locked by latches 10 to latch holes 1 1 thus locking the two together. The lifting flange 12.1 has a lifting bolt 12.3 which passes through an upper frame member or component of the drilling assembly 3, and is secured in place with an intervening compression spring 12.2, washer 12.4 and nut 12.5. The lifting flange 12.1 has a pivot connection 10.3 to pivotally connect the latch body 10.1 , and the latch body 10.1 is pivotally connected by pivot 10.2 to the mounting plate 10.4 which is secured to the drilling assembly 3. Thus, according to the right hand side of Figure 1 1 , when the lift assembly 12 applies sufficient force to the lifting flange 12.1 , so as to overcome the spring force of the spring 12.2, this will move the bolt 12.3 upward relative to the drilling assembly 3, which causes a rotation of the latch body 10.1 around relatively stationary pivot 10.2, thus withdrawing the latch 10, out of latch hole 1 1 , thus allowing the drilling assembly 3 being able to be withdrawn from and relative to the caisson/casing 1.

[0137] Illustrated in Figure 12 is a caisson/casing 1 and drilling assembly 3, which is similar to that of Figure 9, and like parts have been like numbered. The difference is that the drilling assembly 3 is able to be moved downward relative to the caisson/casing 1 , by means of spaced hydraulic or pneumatic cylinders 100, which push or pull against the lifting frame 12, which is held in place by the latches 10 in latch holes 1 1 in the caisson/casing 1. The same pushing and pulling force could be provided by a similar apparatus external to the caisson or casing 1. At a desired depth, the cylinders 100 are energised to extend so as to push (or pull) the drilling assembly 3 downward. By retracting the cylinders 100, the caisson/casing 1 can be pulled downward into the drilled hole. Then the drills active again, pushed downward by the extending cylinders 100 etc.

[0138] It will be noted from Figures 1 to 11 that the body of the drilling assembly 3 is of a shape and size which effectively, or substantially, closes off the opening formed by the inner periphery of the caisson or casing 1. This is the case whether the caisson or casing 1 is of a rectangular or curved shape, or whether of a more complex shape such as an arc or T-shape.

[0139] It is to be noted, from the embodiments depicted, that there are two or more drilling heads used to create an area that generally overlaps with the opening or footprint of a caisson or casing having a single opening.

[0140] Figures 13.1 to 13.3 depict a method of grouting the vertical spaces between inserted precast panels. Figure 13.1 shows a casing or caisson 1 which is advancing downwardly, aided by the action of the drill bits 4. As discussed previously, once the drilling bits 4 and caisson/casing 1 advance to the required depth, the drill bits 4 are retracted and removed. The caisson or casing 1 supports any pre-existing sea-walls nearby or adjacent, while a preformed structural panel 17 is inserted into the caisson/casing 1 , before the caisson/casing 1 is removed. When this process is repeated and a further panel is inserted adjacent the first panel, a gap in the form of a vertical space 17.1 will be left between the panels 17. [0141] To seal or close the gaps 17.1 , the panels 17 will be grouted. To do this, a stocking 18 is placed over a grout line 19 to be inserted in a gap 17.1 between the panels 17. The stocking 18 can be chosen from materials such as canvas, plastic, any appropriate nylon, or geo-textile. The grout line 19 is then pushed to the bottom of the gap 17.1. As the grout material is being pumped into the gap 17.1 , the grout line 19 is withdrawn. As shown in Figure 13.2, the panels 17, on their vertical side edges, have grooves or formations. As the grout is pumped, the material conforms to the space formed by the grooves or formations between adjacent panels 17, and forms a key 20 between adjacent panels 17.

[0142] Figures 14.1 to 14.3 depict a method of grouting the toes or lower portions of the structural panels 17. The drilling assembly 3 and the caisson/casing 1 are larger than the panels 17. Therefore, after the caisson/casing 1 is withdrawn, the panel 17 is encapsulated by the disturbed ground. Grouting the toes or lower portions of the panels 17 in the ground will enhance the stability of the panels 17. A grout tube 21 is precast in each panel 17. The grout tube 21 runs the whole length of height of the panel 17. Grout 22 is pumped into the grout tube 21. The grout 22 used for toe grouting generally has a specific gravity of approximately 2, which is higher than the specific gravity of the disturbed, plasticised, worried, or fluidised portion of the friable ground. As the grout 22 is denser than the disturbed, plasticised, worried, or fluidised ground, the pumped grout will displace the disturbed ground to encapsulate the corresponding panel 17. The grout 22 is pumped after the casing is taken out to at least the desired grout height. . The volume of the grout 22 to be pumped will therefore be determined by the difference between the desired grout height multiplied by the difference between the cross sectional area of the resulting hole and the cross sectional area of the panel. Once this is done, the grouting procedure of Figures 13.1 to 13.3 can be employed to key in or lock adjacent panels together.

[0143] As shown in Figures 15.1 to 15.3, in some situations, one or more of the panels will be placed over rocks or hard-ground 24 which is not friable or not friable enough. The caisson/casing 1 will not sink into the hard ground 24. A panel 17 suitable for placement over hard ground 24 can have cast into it a penetration 23, i.e. a through aperture. The penetration 23 is usually centrally located with respect to the panel 17. The rock cutting drill bit 4 is then operated to drill a hole 25 into the hard ground 24 through the penetration 23, so that a hole 25 is drilled to coincide with the penetration 23. A reinforcement dowel 26 can be placed into the hole 25, and grouted in place through the grout line 27 which extends to the bottom of the hole 25.

[0144] Any reinforcements are preferably of a non-corrodible type material, such as glass fibre, reinforcing carbon fibre rods or stainless steel, etc.

[0145] Figures 16.1 to 16.6 depict securing or casting a capping beam 28 to the tops of the structural panels 17. As shown in Figures 16.1 to Figure 16.3, the structural panels 17 can have blind apertures or penetrations 29 accessible from the tops of the panels 17 Separate reinforcement bars 30 adapted to be partially received by the blind apertures 29 are grouted into place in the apertures 29. Alternatively, the panels 17 can have reinforcement bars 31 cast into them. A capping beam 28 which has been pre-cast is then attached to the dowels 30, or alternatively the capping beam is cast onto the dowels 30. The capping beam 28 will have holes which correspond to the reinforcement bars 30, 31. The reinforcement bars 30, 31 are fitted into the corresponding holes in the capping beam 28 as the capping beam 28 is attached. Figure 16.4 depicts the reverse scenario, where inserted dowels 30 or precast dowels 31 are provided in a pre-cast capping beam 28. The capping beam 28 is then attached to the panels 17 which have the required apertures to accept the dowels 30, 31.

[0146] More preferably, as shown in Figure 16.5, the capping beam 28 can cast directly into a formwork provided around the tops of the panels 17, in which case the capping beam 28 will be cast around the dowels 30, 31 and the panels 17. As shown in Figure 16.6, it is alternatively possible to cast a capping beam 28 onto the panels 17 or attach a precast beam 28 to the panels 17, and then drill securing bolts to secure the beam 28 and panels 17 together.

[0147] Figures 17.1 and 17.2 depict concrete caissons or casings 1 that are formed with reinforcements 1.3 and that are left in situ rather than removed, after the drilling assembly 3 has been retracted. The caissons are left as structural elements. The caisson/casing 1 may or may not have a structural core. It can be left in situ as a structural element itself, or it may have a cast in place concrete structural core 1.2 that is formed inside the caisson 1.

[0148] Referring to Figures 18.1 to 18.3, the panels 17 or capping beams 28 further include anchoring ties 32 to stable land which is adjacent the panels 17. In Figure 18.1 , holes are drilled into the adjacent stable land to insert the ends of the ties that are distal from the panels 17. The proximal ends of the ties are bolted or otherwise secured to the capping beams 28 or panels 17. The anchoring ties 32 helps secure the panels 17 against the weight of the friable land pushing directly or indirectly against the panels 17. In Figure 18.2, the panels 17 are installed next to wall members 17.2 which are pre-existing and deteriorating, with the panels 17 being put in place to shore up or take over from the old pre-existing retaining panels 17.2. In this case, an old anchor 32.2 is already in place and tied to adjacent land. An extension 32.1 is linked to the old anchor 32.2 to extend the tie 32 to the capping beam 28 for the new panel 17. The extension 32.1 can be precast into the beam 28, or the capping beam 28 for the new panel 17 is post tensioned to the existing capping beam 28.2.

[0149] Figures 19.1 to 19.4 depict the movement of the bed dirt, mud, or other matter which is displaced by the drilling assembly 3. As discussed before, as the drilling assembly 3 drills into the friable ground, the weight of the caisson/casing 1 enables the caisson 1 to sink down to the drilled level. As mentioned above, the caisson 1 is also able to sink because the cuttings tend to be displaced upwards. Together the actions and weight of the drilling assembly 3 and caisson 1 progressively cause portions of the friable ground to become plasticised, which allows the action of gravity to sink the caisson to a desired depth.

[0150] The assembly 3 and caisson 1 displace the disturbed or drilled matter 33, which tends to accumulate upwards as shown in the arrows included in Figures 19.2 and 19.3. The arrows of Figure 19.3 depict the process whereby, as the caisson and drilling assembly advance deeper into the hole, more disturbed or drilled matter 33 is accumulated upwardly. The previously displaced cuttings or matter is pushed upwards by newly displaced matter. Once the drill assembly is retracted, and a structural element such as a panel 17 is inserted into the caisson 1 , the caisson can be removed. Upon the removal of the caisson 1 , the previously piled displaced matter 33 (if toe grouting is not done) now flows downwardly, in the direction indicated by the arrows in Figure 19.4, to fill the space vacated by the caisson 1. Due to the friable nature of the environment, the drillings and cuttings are plasticized. Therefore, there is no requirement to actively pump the bed matter out of the drilled hole to prevent blockage.

[0151] Referring to Figures 20.1 to 20.8, in some circumstances, the depth of the hole to be drilled will be greater than the length or height of a caisson 1 that can be used with the drilling equipment. In this situation, additional caissons 1 ' can be added to follow the initial or leading caisson 1 which has been inserted or partially inserted into the hole, in an end-to-end fashion. Here, the attachment of the caissons 1 , 1' is done whilst the trailing edge of the first inserted caisson 1 is still accessible. Preferably, the neighbouring caissons 1 , 1 ' will be attached together. This way, the plurality of caissons 1 , 1' is able to be removed in a single operation. The skilled person will appreciate that more caissons can be added for insertion into holes of greater depths as needed.

[0152] Figure 21 is a schematic view of one manner of attachment between neighbouring caissons. As shown, the lower or leading caisson 1 has a rim, flange, bead, or generally a projection 34 around its trailing edge. The adjacent, subsequently inserted caisson 1' which trails the other caisson 1 includes a cooperating projection 35 at its leading edge. The cooperating projection 35 includes a groove 36 which is adapted to receive the trailing projection 34 of the previous caisson 1. The upper or subsequent caisson 1' is further constructed from two halves 1 '-1 , 1'-2, respectively having the grooves 36-1 , 36-2. The two halves 1 '-1 , 1 '-2 are two vertical halves of the subsequent caisson 1 '. The halves 1 '-1 , 1'-2 have a vertical parting plane S and are initially spaced apart from each other. The vertical halves 1'-1 , 1'-2 are moved toward the trailing edge of the first or previously inserted caisson 1 , then closed toward each other and onto the previously inserted caisson 1 , so that the grooves 36-1 , 36-2 together are fitted onto the projection 34, attaching the caissons 1 , 1 ' together. The two vertical haves 1'-1 , 1 '-2 of the subsequent caissons 1' can further be secured together by e.g. bolts. The skilled person will appreciate that although the subsequent caissons or casings V are described as having two half sections, they can each be constructed of three or more vertical sections, and then assembled in the manner described above.

[0153] When the caissons 1 , V need to be removed, the upper most caisson V is hooked or otherwise attached to a lifting device, and then both caissons 1 , V will be lifted together because of the attachment between the caissons 1 , 1 '.

[0154] The caissons 1 , 1 ' can have identical features - that is each caisson 1 has a leading projection 35 and a trailing projection 34 as described above, and is constructed from two vertical halves. This construction allows the subsequent caisson 1' to be added unhindered by the support or cables for the drilling assembly. Alternatively, the skilled person will appreciate that the first inserted caisson does not need to have a leading edge projection 35 or be constructed from multiple sections.

[0155] Figures 1.1 , 1.2, 1.3, 2.1 , 2.2, 2.3, 3.1 , 3.2, 3.3, 4.1 , 4.2, 4.3, 5 to 10,

have the following feature's legend:

1 -Caisson

1.2 -structural core cast inside a caisson to be left in situ

2 -Caisson leading edge

2.1 -Gap between caisson/casing and the body of the drilling assembly

3 -Inner assembly

4 -Drill bit retracted

4.1 -Drill bit extended or expanded

4.2 -Drill bit extended or expanded

4.3 -Drill bit extended or expanded

5 -Rotation motor

6 -Drive shaft

7 -Hydraulic flow divider

8 -Bearing housing with flushing hole

9 -Base of Bearing with flushing hole

10 -Latch assembly

10.1 -Latch body

10.2 -Latch pivot stationary relative to drill assembly 3

10.3 -Latch pivot moveably pivoted and mounted to lift flange 12.1

10.4 -Mounting plate attached to drill assembly 3

11 -Recess in caisson to accept latch

12 -Lifting assembly

12.1 -Lifting flange or eye

12.2 - Compression spring

12.3 -Mounting bolt

12.4 -Mounting washer

12.5 -Mounting nut

13 -Hydraulic hoses

14 -Flushing hoses

15 -Flushing hole in drill bit

16 -Normal direction of rotation to keep retracted

17 -structural panels

17.1 -vertical gap between adjacent panels

17.2 -pre-existing structural panel in the ground

18 -stocking 19 -grout line

20 -grout key

21 -grout tube for toe grouting

22 -toe grout

23 -penetration for dowel

24 -hard ground or rock

25 -hole drilled into hard ground or rock

26 -dowel

27 -grout line for down penetration hole

28 -capping beam

28.2 -existing capping beam

29 -apertures for capping beam reinforcement bars

30 -reinforcement bars inserted into apertures in the panel

31 -reinforcement bars cast into the panel

32 -anchoring ties

32.1 -extended portion of an anchoring tie linking new and existing capping beams

32.2 -anchoring tie to an existing capping beam

r -trailing caisson

33 -displaced plasticized ground matter

34 -trailing edge projection for end-to-end attachment between caissons

35 -leading edge projection for end-to-end attachment between caissons

36 -groove in the leading edge projection to accommodate the trailing edge projection of an adjacent caisson

38 -rope used in a pulling operation to lower the caisson

40 -pulley used in a pulling operation to lower the caisson

S -parting plane between sections of a caisson

100 -Hydraulic or pneumatic cylinder

[0156] Where ever it is used, the word "comprising" is to be understood in its "open sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of". A corresponding meaning is to be attributed to the corresponding words "comprise", "comprised" and "comprises" where they appear.

[0157] It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text. All of these different combinations constitute various alternative aspects of the invention.

[0158] While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, and all modifications which would be obvious to those skilled in the art are therefore intended to be embraced therein.