WO2007020445A1

WO2007020445A1 - Methods and apparatus for the installation of foundation piles

Info

Publication number: WO2007020445A1
Application number: PCT/GB2006/003074
Authority: WO
Inventors: Peter Geoffrey Clutterbuck
Original assignee: Fugro Seacore Limited
Priority date: 2005-08-18
Filing date: 2006-08-17
Publication date: 2007-02-22
Also published as: GB2429229A; GB0516906D0; GB0616338D0

Abstract

A method of establishing a tubular slot (14) in a support medium (13) for receiving a tubular pile/column (1) in which the need to remove a central core of material from the interior of the pile/column (1) is avoided by drilling in the medium a downwards directed tubular slot (14) having internal and external diameters that allows the pile/column (1) to be introduced into the annular slot down to a required depth (15) to which it is required to introduce the lower end (2) of the pile/column into the medium (13) the drilling being effected either in the absence of the pile/column or after the latter has been positioned at the location at which it is to be erected, and following drilling enabling the lower end of the pile/column to reach the required depth (15).

Description

METHODS AND APPARATUS FOR THE INSTALLATION OF FOUNDATION PILES

This invention relates to the methods and apparatus for use in the installation of foundation piles for buildings structures and for the erection of support columns or the like.

The erection of many structures and/or columns requires the positioning of the piles and/or said columns in a ground area and/or in submerged areas such as sea beds, river estuaries, lakes etc.

In particular, the present invention relates' to the production of bores in the ground, bedrock, sea beds, river beds or lake beds that are required to receive upstanding piles or columns that are required to be provided as a predetermined arrangement of a number of piles or columns or as individual piles or columns.

With the development of various present day technologies such as the installation of submerged turbines and/or the establishment of so-called wind farms in coastal or other waters that involve turbine installations each mounted to hollow pile, oτ an array of piles on a supporting hollow mono-column it is clearly of great importance that any associated foundation pile(s) and/or supporting column(s) should be very firmly mounted in the supporting ground what ever its nature i.e., in a sea or river water bed.

A conventional method of mounting such piles/columns is to drill or otherwise remove a column of the sea or river bed, what ever its geological nature, down to a depth considered to be a correct depth in relation to expected environmental conditions at the location of the pile/column, the intended function of the pile/column, the diameter of the pile/column, the overall height of the pile/column., the weight loading to be carried/supported by the pile/column (i.e., the weight of an electricity generating turbine and associated rotor and housing mounted to the column, the expected wind forces acting upon the exposed regions of the pile/column, and the water pressures acting upon the submerged regions of the pile/column,

Techniques for the drilling of bores for receiving such columns have developed in the main from those used in connection with the production of bores for geological sampling, oil well drilling and similar requirements and have hitherto proved adequate in drilling bores intended for the mounting of support columns presently commonly used. These techniques have conventionally involved the drilling or other mode of production of the bore requiring removing a core of waste material produced by the action of the drilling apparatus being used thereby to produce an appropriately dimensioned cylindrical bore for subsequently receiving the lower end of the pile/column.

However, it has been found that as present day increasing demands with respect to the accommodation of greater and greater load resistance's etc., by the piles/columns increases the requirement for greater and greater diameters for the piles/columns at least at the base regions of such piles/columns has likewise increased.

In practice, such piles/columns can be of considerable diameters such as for example two or more metres in diameter. With the present day requirements for larger and larger piles/columns diameters of four metres are becoming more and more necessary.

As the diameters of the piles columns have become greater the amount of core material be removed from the ground, sea bed etc. to enable erection of the pile/column, has also correspondingly increased.

This increase in the amount of material to be removed has been found to introduce increased material handling problems during the bore producing operations together with costs and problems arising in ensuring stability of the thus produced bores which way be regarded as centring around the logistics of removing very large quantities of the ground/seabed as a result of drilling a wide diameter elongate bore, for example, several metres in length whilst maintaining the integrity of the walls of the bores involved..

It is an object of the present invention to at least reduce the amounts of material that needs to be displaced/removed when drilling or otherwise excavating a bore in the ground or elsewhere such as a sea, river or lake bed for purposes such as the mounting of piles, tubular columns or the like.

According to a first aspect of the invention there is provided a method of establishing a tubular bore in a bed for receiving and supporting a tubular pile/column in which the need to remove a central core of material from the interior of the pile/column is avoided during installation is avoided.

A second aspect of the invention provides a method of mounting a tubular piie/coiumn in a supporting bed, including the steps of producing a downwards directed tubular slot in the bed having internal and external diameters that allows the pile/column to be introduced into the annular slot to a depth to which it is required to introduce the lower end of the pile/column into the bed.

Preferably, the method includes the steps of locating the tubular pile/column in an upstanding position at the location at which it is to be located, enabling the pile/column lower end to sink under its own weight to an initial depth determined by the nature of the upper levels of the bed into which the pile/column is to be mounted, producing the tubular slot having said required depth, and subsequently enabling the iower end of the pile/column to reach said required depth.

Conveniently, the method includes the step of introducing internally of an upstanding tubular pile/column mean for producing the annular slot, operating the slot producing means to produce the slot having the required depth, removing the means for producing the slot from the pile /column and causing the pile/coiumn to lower from its initial position to said required depth.

Conveniently the pile/column is driven downwards to said required depth by the application of impact forces to the top regions of the pile/column.

In a particular method the pile/column is vibrated, oscillated and/rotated in such manner that the forces produced as a result of such vibration, osculation and/or rotation in combination with the weight of the pile/column causes the latter to descend to said required depth.

Additionally the method includes the step of applying a combination of downwards directed impact forces and vibrating, osculating and/rotating the pile/column in such manner that the forces produced as a result of such vibration, oscillation and/or rotation in combination with the weight of the pile/column causes the latter to descend to said required depth.

Preferably the walls of the slot are stabilised to the displacement of the pile/coiumn to said required depth.

According to a further method of the invention an annular slot is produced in the absence of the pile/column in the bed into which a pile/column is required to be upstanding materia! produced by the formation of the slot, being removed and following introduction of the pile/column into the slot any space within the slot not occupied by the pile/column is filled with a grouting medium.

In a further aspect of t he method the pile/column is initially positioned at the location at which the pile/column is to be positioned, and means for producing the

pile/column is able effectively to follow the downwards formation of the slot until the bottom of the pile or column attains said required depth, and thereafter removing the means for producing the slot to leave the pile/column upstanding within the slot..

Conveniently the drilling means includes a plurality of sections that are successively connectabϊe to each other to enable the drilling head to attain a required drilling depth.

Preferably, the sections are of annular formation and of such internal diameter as to be able to descent into the slot cut by the drilling head.

Preferably, the sections are of such construction as to enable ongoing removal of material removed by the driiiing head

For a better understanding of the invention and to show how to carry the same into effect reference will now be made to the accompanying drawings in which

Figure 1 schematically illustrates in section a first phase in a first method involved in the installation of a tubular pile/column in a sea or other submerged bed;

Figure 2 schematically illustrates in part section the initial positioning of a seabed driiiing unit for the drilling of an annular slot within a previously positioned the positioned tubular pile/column;

Figure 3 schematically illustrates in part section the drilling head unit when the cutting head of the unit has drilled the slot to a required depth for the lower end of the tubular pile/column;

Figure 4 schematically illustrates the column following withdrawal of the drilling unit from the slot produced in the sea bed and the attachment of means for displacing the tubular pile/column downwards to the required depth; Figure 5 schematically illustrates in part section the tubular pile/column when finally positioned..

Figure 6 schematically illustrates a first phase in a second method involved in the installation of a tubular piie/column in a sea or other submerged bed; and 5 shows the drilling unit in position on the submerged bed.

Figures 7 to 9 schematically illustrate in part section successive phases in the production of an annular siot in a the seabed in preparation for receiving the tubular pile/column to be erected;

Figure 10 schematically illustrates in part section the tubular pile/column when in 10 position,

Figure 11 schematically illustrates in part section a first phase involved in a third method in the installation of a tubular pile/column in a sea or other ϋ cτuιluvirvu-cvvirgnrovu/1 kjxsKi u-nwi ϋi iυ n u + kiniow ~i

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Figures 12 to 14 schematically illustrates in part section successive stages ^{1 5} involved in the installation of a tubular pile/column by said third method;.

For convenience in the Figures the seabed is indicated at SB and the sea level is indicated at SL.

Referring now to Figure 1 as mentioned this Figure illustrates a first stage in the installation of a tubular pile/column 1. This stage essentially involves positioning

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precise location in the seabed SB at which it is required to locate the pile/column. The pile/column is initially enabled to sink into the usually soft upper levels of the sea bed SB under its own weight to the position shown in this Figure.. At this stage if deemed necessary or convenient the pile/column can be hammered (by means not shown) further downwards to a distance at which a predetermined resistance to further downwards displacement is encountered.. Λt this stage in the method the lower end 2 of the pile/column 1 is at the position in the seabed schematically indicated by the reference 3.

At this point, as is illustrated in Figure 2, a drilling head/apparatus 4 that is designed to produce an annular cut is lowered into the interior of the column i . The drilling head/apparatus \ is dimensioned so as to to produce a slot having an external diameter that is equal to or a little less than that of the internal wall of ° the previously positioned column 1 ,

In the Figure 2 the drilling head/apparatus 4 is schematically illustrated as including a head unit 5 that is such as to be connectable/associated with means (not shown) for rotating the head unit. 5 and thus the drilling apparatus associated therewith. The head unit 5 is connectable to a cutter barrel 6 that is formed from a plurality of separable annular ring sections 7 having an outer diameter that is a 5 clearance diameter with respect to the internal surface 8 of the column and an internal diameter which effectively define the inner wall 9 of the slot being produced by a drilling head arrangement 10 provided at the lower end 1 1 of the lowermost ring section 7 . It should be noted that the ring sections 7 each have an axial length that is convenient to handle. These sections can be successively connected between the head unit A and the next adjacent ring section until the actual drilling arrangement 10 connected to the lowermost section 7 reaches a required target depth 15 for the slot 14 in the sea bed SB as is indicated in Figure 3.

The drilling head unit 4 is rotated and operated as to cause the cutting arrangement 10 to remove seabed material 13 in such manner to produce the annular slot 1^Λ. (Figures 4/5) The seabed material 13 is thus progressively removed so as progressively to lengthen the slot 14 until the slot reaches the target depth 15 at which the lower end 2 of the column 1 is required to be positioned. This stage in the method is schematically illustrated in Figure 3..

In practice, the nature and constructional arrangements for the cutting teeth/members 16 of the actual drilling arrangement 10 are chosen to suit the ground/seabed type within which it is required to install the column.

During the cutting operation the material 13 that has been loosened to form the siot 14 i.e., detritus from the drilling operation is removed by a flushing operation involving the use of a pressurised flushing medium i.e., a water/air mixture. . Thus arrangements (not shown) are provided for introducing the requisite flushing medium into the slot and its removal with entrained detrius material 13 from the slot cutting operation. It will understood that the ring sections 7 are suitably designed as to enable the requisite flows of the flushing material and entrained detrius material 13..

Once the target depth 15 has been attained the drilling head 4 and the ring sections 7 coupled thereto are removed from the interior of the column leaving the column 1 in the position attained at the time the drilling head was introduced. This stage is illustrated in Figure 4. During this stage the slot 14 can be filled with drilling mud or some other fluid to stabilise the ground in the vicinity of the wails of the slot walls if such stabilising is deemed necessary to prevent collapse of the walls of the slot

..

As may be noted from Figure 4 the slot 14 extends below the tubular pile/column bottom 2 down to the target depth i5.

Following removal of the drilling heaφ means 17 are connected with the top of the column whereby the pile/column can be displaced downwards until the bottom 2 thereof reaches the target depth 15 as is indicated in Figure 4 . This lowering of the column can be effected by forcible hammering and/or by subjecting the pϋe/column to rotational and/or oscillatory or vibration movements.. It will be understood that the weight of the pile/column will also be involved in the production of the downward movement of the pile/column..

⁵ Those regions of the slot 14 not occupied by the pile/column following the installation of the pile/column i to the target depth 15 are then filled with an appropriate grouting medium.

Referring now to Figures 6 to 10, these Figures as has been mentioned disclose very schematically the stages involved in a second method of installing a hollow * ° pile/column 1 into the ground, sea bed or the like.

For convenience in relation to the Figures 6 to 10 references that have been used in relation to Figures 1- to 5 will also be used where applicable in relation to Figures 6 to 10

.Since the construction of the drill head 4 of Figures 6 to 10 is the same as that 5 previously discussed further discussion thereof is not thought necessary in relation to Figures 6 to 10

In this second method the procedure involved is to produce the annular slot 14 to the required target depth 15 and then to introduce the pile/column 1 into the completed slot.

0 In this second method since the pile/column locating slot 14 is to be produced in the absence of the pile/column the drill head 4 is lowered so as to engage with the sea bed SB at the location at which the pile/column 1 is to be sited. It will be understood that the drill head slot producing arrangements 10/16 are required to produce an annular slot 14 having inner and outer diameters such that the pile/ 5 column i is able to engage there within. The drilling head 4 is operated until the slot 14 attains the target depth 15, the position indicated in Figure 7, namely the depth at which the bottom 2 of the column 1 is required to be embedded in the seabed SB.

Once this depth has been attained the drilling head 4 is, as indicated by the upwards directed arrow 18 in the Figure 8, withdrawn leaving the annular slot

14 in the sea bed. During this process of the upwards lifting of the drill head 4 drilling mud or some other fluid is pumped into the slot 14 at a pressure that acts as to stabilise the seabed material forming the slot walls so as to prevent collapsing of the walls of the slot 14. This 'hollow cylinder of drilling mud is schematically indicated at 19. It will be understood that the detrius arising from the drilling operation will be removed during the drilling operation as previously discussed.

Figure 9 schematically illustrates the stage at which the drilling head 4 has been removed and the slot 14 filled with the drilling mud 19.

Following total removal of the drilling head unit 4 the pile/column 1 is inserted into mud filled slot 11 . As will be appreciated that since the width of the slot 14 is intended to afford an operational clearance for the tubular pile/column tl the lowering of the pile/column progressively forces the drilling mud out from the slot. When the column reaches the target depth 15 any remaining mud is pumped out This setting of the pile/column 1 after lowering is shown in Figure iθ. To firmly mount the pile or column in its installed position the unfilled space i.e., the remainder of the slot is filled with grout 20 the latter commonly being a cementicious material.

The finally installed pile/column 1 is illustrated in Figure 10. Referring now to Figures 11 to 14, these Figures as has been mentioned disclose very schematically stages involved in a third method of installing a hoiϊow pile/column 1 into the ground, sea bed or the like.

For convenience in relation to the Figures 10 to 13 references used in relation to previous Figures will aiso be used where applicable in relation to Figures iO to 13.

Since in this third method the drilling arrangements are as previously discussed further description is not thought necessary.

In this third method the pile or column 1 is lowered so as to engage with the sea bed SB at the location at which the pϋe or column 1 is to be sited. This stage is illustrated by Figure 11.

The drill head 4, the associated sections and the slot cutting members 16 are lowered into the piϊe/coiumn and slot cutting is commenced.

With this embodiment the internal and external diameters of the slot being cut are such that as the drilling of the slot 14 is effected the pϋe/column i chases or

sea bed. Figure 12 illustrates the formation of the slot 14 and the lowering of the pile/column from the position shown in Figure 1 1

In other words as the drilling head head 4 and thus the depth of the slot 14 is increased towards the target depth i5 the pile/column 1 moves progressively downwards towards the required target depth 15. This stage in the method is represented by the Figure 13..

It will be appreciated that the pile or column 1 itself will be effectively aiding the formation of the slot.. In practice the weight of the pile or support will produce be assisting the slot producing process in that the pile/column with be providing support for the wails of the of the siot.

It will be understood that the detrius 13 producing during slot production will be removed in the manner previously discussed

Once the slot 14 has reached the requisite target depth 15 the drilling head 4 is removed, and once the pile/column has descended to the target depth any region of the slot not occupied by the pile or column is then grouted in so as firmly to secure pile or column in position. This is illustrated in Figure 14.

If deemed necessary the cutter arrangements may be connected to the column using, for example, friction pads to facilitate the required downward column movement.

It will be understood that the drilling sequence can be such that the overall length of the drilling arrangements 4,7,iϋ,iό can be such that the slot depth capability of the arrangements can be equal to the required, target depth whereby continuous drilling can take place. Alternatively the overall length of the drilling arrangements can be progressively extended by the appropriate addition of sections 7 to lengthen the cutter barrel ό..

It will be noted that in the installation of a pile/column by the above discussed methods in each method that only material removed from the supporting bed i.e., seabed SB is that required to produce the tubular slot thereby leaving the cylinder of sea bed material defined by the inner wall of the slot undisturbed. Baring in mind the pile/column diameters contemplated i.e., 4 metres, the amount of material to be handled is greatly reduced as compared with the removal of all of

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be installed the quantity and the logistics associated with the handling material when drilling in a sea bed are greatly reduced..

Claims

CLAJMS

1. A method of establishing a tubular bore in a bed for receiving and supporting a tubular pile/column in which the need to remove a central core of material from the interior of the pile/column during installation is avoided.

2. A method of mounting a tubular pile/column in a supporting bed, characterised by the steps of producing a downwards directed tubular (14) the bed (SB) having internal and external diameters that allows the pile/column (1) to be introduced into the annular slot (14) to a depth (15) to which it is required to introduce the lower end of the pile/column (1) into the bed.

3. A method as claimed in claim 2, characterised by the steps of locating the tubular pile/column (1) in an upstanding position at the location at which it is to be located, enabling the pile/column lower end (2) to sink under its own weight to an initial depth (3) (1) is to be mounted, producing the tubular slot (14) having said required depth (15), and subsequently enabling the lower end (2) of the pile/column to reach said required depth.

4. A method as claimed in claim 2 or 3, and characterised by the step of introducing internally of an upstanding tubular pile/column (1) mean (45,6,9) for producing the annular slot (I⁷I), operating the slot producing mean (1,5 ,6,9) to produce the slot having the required depth, removing the means for producing the slot from the pile /column (1) and causing the pile/column to lower from its initial position (30 to said required depth.

5. A method as claimed in claim 2 or 3 and characterised by the step of driving the piie/coiumn (1) downwards to said required depth by the application of impact forces to the top regions (5) of the pile/colurnn (1).

6. A method as claimed in claim 3, or 4, and characterised by the step of vibrating, oscillating and/rotating the pile/column ( i ) in such manner that the forces produced as a result of such vibration, oscillation and/or rotation in combination with the weight of the pile/column (1) causes the latter to descend to said required depth (15).

7. A method as claimed in claim 4 and characterised by the step of applying a combination of downwards directed impact forces and vibrating, oscillating and/rotating the pile/column (1) in such manner that the forces produced as a result of such vibration, oscillation and/or rotation in combination with the weight of the pile/column causes the latter to descend to said required depth (15).

8. A method as claimed in any one of claims 2 to 7, and characterised by the step of stabilising the waits of the siot (i4) prior to the displacement of the pile/column (1) to said required depth (15).

9. A method as claimed in claim 2, and characterised by the step of producing an annular slot (14) in the bed (SB) into which a piie/coiumn (I) is required to be upstanding in the absence of the pile/column, removing material (13) produced by the formation of the slot (14) , introducing the pile/column (1) into the slot, and filling any space within the slot not occupied by the pile/column.

10 A method of mounting a tubular pile/column in a supporting bed as claimed in claim 2, and characterised by the steps of producing a downwards directed tubular slot (Ii) in the (SB) bed in the absence of the pile/column (1) the slot having internal and external diameters that allows the pile/column (1) to be mounted to be introduced into the slot (14) , forming the slot to the required depth (15) for the lower end of the pile/column, and introducing the pile/column (i) to be mounted into the slot after the formation of the slot. .

11. A method as claimed in claim 2, and characterised by the steps of initially positioning the piie/coiυmn (I) at the iocation at which the pile/coiumn is to be positioned, introducing means (/1 ,5,6,9) for producing the slot into the pile/column, (1) operating said means at a rate at which the pile/column effectively follows the downwards formation of the slot (14) until the bottom (2) of the pile or column attains said required depth (15) , and removing the means for producing the slot to leave the pile/column upstanding within the slot..

12. A method as claimed in any one of the preceding claims characterised by the step of removing material (13) produced by the formation of the slot (13) by use of introduction of flushing into the slot (1^) during its formation

13. A method as claimed in any one of the preceding claims and characterised by the step of grouting the pile/column (1) within the slot (i 4).

14. A method as claimed in claim 9, and characterised n that a grouting medium includes a cementicious material

15. Apparatus for producing a slot( 14) for receiving the lower end of a pile/column (i) required to be upstanding from a support bed (SB) comprising a drilling head structure (4) that produces a slot, on advance of the drilling head into the bed CSBO that conforms to the form/shape of the bottom (T) of the pile/column.

16. Apparatus as claimed in claim 15, in which the drilling means includes a plurality of sections that are successively connectabϊe to each other to enable the drilling head to attain a required drilling depth.

17. Apparatus as claimed in claim 15, and wherein the drilling sections (7) are of annular formation and of such internal diameter as to be able to descent into the slot (H) cut by the drilling head (9) .

18. Apparatus as claimed in claim 15 or 16, and wherein the sections (7) of such construction as to enable ongoing removal of materia(13) removed by the drilling head