GB2444411A

GB2444411A - Pile installation method

Info

Publication number: GB2444411A
Application number: GB0723550A
Authority: GB
Inventors: John Richard Yorke Gleadowe
Original assignee: Fugro Seacore Ltd
Current assignee: Fugro Seacore Ltd
Priority date: 2006-12-05
Filing date: 2007-12-03
Publication date: 2008-06-04
Also published as: GB0624285D0; GB0723550D0

Abstract

A method for facilitating the installation of a pile or column 1 in a supporting medium 2 comprises creating spaces or voids (7, Fig 2) within the medium, adjacent to the lower end 3 of the pile. These spaces or voids receive or accommodate material displaced by the lower end of the pile or column, as it is caused to penetrate said medium as it descends to a required depth. The pile or column may be advanced by using successive stages of forcibly driving the pile or column downwards into the supporting medium. The spaces or voids may take the form of a ring or radial array (6, Fig 2) of relatively spaced holes around the central axis of the pile or column. The spaced holes may be produced by indexing or rotating a drilling head 4 around the central axis.

Description

METHODS AND APPARATUS FOR THE

iNSTALLATION OF COLUMNS/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 5-orthe like.

The erection of many structures andlor 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 mounted to a pile or column, or an array of piles on a supporting hollow mono-column it is clearly of great importance that any associated foundation pile or column(s) or the supporting column(s) should be very firmly mounted in the supporting ground what ever its nature i.e., in a sea/water bed.

A conventional method of mounting such piles/columns is to drill or otherwise remove a column of the seabed, 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 or column the intended function of the pile or column, the diameter of the pile or column, the overall height of the pile or column the weight loading to be carried/supported by the pile or column (i.e.,) of an electricity generating turbine and associated rotor and housing mounted to the

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column, the expected wind forces acting upon the exposed regions of the column, and the water pressures acting upon the submerged regions of the 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 for the mounting of support columns presently commonly used. These techniques have conventionally involved the drilling or other mode of production of the bore involving removing a core of waste material produced by the action of the drilling apparatus involved thereby to produce an appropnate cylindrical bore for subsequently receiving the pile or column/support 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 increase the demands for greater and greater diameters for the 1 5 piles/columns at least at the base regions of such piles/columns has likewise increased.

The increases of such demands has in turn had the result that as the diameters of the piles/ columns become greater the amount of core material to be removed from the ground, sea bed etc., also becomes greater and greater.

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 substantially least reduce the amount 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.

Broadly, according to a first aspect of the present invention there is provided a method of installing/sinking a tubular/hollow pile or column into a support medium by downwards displacement of the pile or column to a required depth, including the step of displacing material in the vicinity of the lower regions of the pile or column, during its downward displacement in such manner as to produce a space/void within the for receiving at least a portion of material displaced by the downwards motion of the pile or column, A second aspect of the invention provides a method of installing/sinking a tubular pile or column in a support medium by by downward displacement of t he pile or column to a required depth, including forming in the medium space for receiving material displaced at the lower end of the pile or column during its downward movement.

A further aspect of the invention provides a method of installing/sinking a tubular pile or column forcible downwards displacement of the pile or column including the step of providing a ring/radial array of relatively angularly spaced bores for receiving/accommodating material displaced by the lower end of the pile or column as the latter is caused to descend to a required depth.

Conveniently, the ring/array of bores is produced by a drilling or the like sequence arranged to produce a ring/array of spaced holes just internally of the inner diameter of the pile or column in the vicinity of the lower end of the pile or column.

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Conveniently the ring of holes is produced by indexing or rotating the drills/drilling head around the central axis of the pile.

Preferably the ring/radial array of holes are drilled so as to be positioned internally of the lower end of the pile or column in the immediate vicinity of the inner diameter of the pile or column.

Alternatively, the ring/radial array can be located externally of the pile or column or a combination of holes position both internally and externally of the pile or column may be provided.

In accordance with a still further aspect of the invention there is provided a method for facilitating the installation of a pile or column in a supporting medium, including using successive stages of forcibly driving the pile or column/downwards into the supporting medium for a predetermined distance and producing a ring/radial array of relatively spaced holes around the central axis of the pile or column for receiving/accommodating material displaced by the lower end of the pile or column as the latter is caused to penetrate said medium as it descends a required depth.

Preferably the method includes the step of providing a guide casing within the generally still exposed upper regions of the pile the pile or column during the installation of the pile or column 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 a first phase in a first method involved in the installation of a tubular column in a sea or other submerged bed; and S -5-.

Figure 2 is a schematic representation of the ring/radial array of holes.

Referring now to Figure 1, a pile or column 1 is required to be installed in a supporting bed 2. This bed 2 can comprises a variety of materials such as likely to be found as a sea river or other bed of a natural volume of water or as likely to be found on dry land..

As shown the lower end 3 of the pile or column I is positioned at the location at which the pile or column is required to be positioned.

The pile or column is then forceably driven into the ground (i.e., soft ground, weathered rocks) for short distance determined by the nature of the material into which the pile or column 1 is being installed by an appropriate means such as hammenng or driving, at the upper end of the pile or column so as effectively firmly to locate the leading end of the pile or column.

Once this position has been reached a drilling head/system 4 is mounted to the top/head 5 of the pile 1. The drilling head is operated in such manner as to produce a ring 6 of holes 7 of small diameter as compared to that of the pile or column is drilled. The drilling is such that the holes are just inside the inner diameter of the pile or column.

The Figure 1 schematically indicates the holes extending beneath the position of the pile or column following its initial introduction into position.

The ring can be produced by rotating/indexing the drills of the drilling head 4 around the central axis of the pile or column.

A guide casing 8 with appropriate casing supports 9 is provided within the pile or column 1 during the installation processes As will be noted the guide casing

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provides guiding support for the still exposed regions of the pile or column, and that the lower part of the guide casing is inserted into the uppermost layers of the medium into which the pile or column is being installed.

Once the holes have been produced the pile or column is further forced downwards..

In practice the ring/radial array 6 of holes 7 that had been produced in advance of the leading end of the pile or column provides a series of voids or spaces into which material is displaced as a result of the hammering or driving in of the pile or column.

It will be understood that the number of holes 7 and their diameters would be selected in relation to the nature of the material into which the pile or column 1 is being driven.

This process of driving the pile or column I downwards and small hole drilling is continued until the pile or column has been set to a required depth in the surrounding ground 2.

The consequence of mounting the pile or column I as above mentioned by the provision of the ring/radial array of small holes 7 both weakens the ground in the vicinity of the leading end 3 of the pile or column and generate spaces in to which material displaced by the descending pile or column can enter By means of the method of the invention piles or columns I may be driven into the ground i.e., weak rock with significant lowered driving or hammering energies as compared with directly driving or hammering in the absence of the small holes. 1 -7-

It will be apparent that with the method of the quantities of material actually removed are lower than the quantities involved in removing a core of material from the interior of the pile or column as presently commonly performed reduces problems arising from the dispersal of such core material since at least a proportion of the drilled material can remain within the pile of column. S -8-

Claims

CLArMS 1. A method of installing/sinking a tubular/hollow pile or

column into a support medium by downwards displacement of the pile or column to a required depth, including the step of displacing material in the vicinity of the lower regions of the pile or column, during its downward displacement in such manner as to produce a space/void within the for receiving at least a portion of material displaced by the downwards motion of the pile or column,
2. A method of installing/sinking a tubular pile or column in a support medium by by downward displacement of t he pile or column to a required depth, including i 0 forming in the medium space for receiving material displaced at the lower end of the pile or column during its downward movement.
3. A method of installing/sinking a tubular pile or column forcible downwards displacement of the pile or column including the step of providing a ring/radial array of relatively angularly spaced bores for receiving/accommodating material displaced by the lower end of the pile or column as the latter is caused to descend to a required depth.
4 A method as claimed in claim 3, and in which the ring/array of bores is produced by a drilling or other form of removing of material from the vicinity of the lower end of a pile or column in such manner as to produce a ring/array of spaced holes located internally of the inner diameter of the pile or column.

column.
5. A method as claimed in claim 4, and including the step of removing material from the drilled region to provide space for material subsequently displaced by the action of displacing the pile or column downwards. S -9-
6 A method as claimed in claim 5, and in which the ring of holes is produced by indexing or rotating a drills/drilling head involved in the formation of the bores forming the ring/array of bores around the central axis of the pile or column being installed.
7 A method as claimed in claim 4, 5 or 6, and in which the ring/radial array of holes are drilled so as to be positioned internally of the lower end of the pile or column in the immediate vicinity of the inner diameter of the pile or column.
8 A method as claimed in claim 4,5 or 6, and in which the ring/radial array of holes is located externally of the pile or column or as a combination of holes positioned both internally and externally of the pile or column.
9 A method for facilitating the installation of a pile or column in a supporting medium, including using successive stages of forcibly driving the pile or column/downwards into the supporting medium for a predetermined distance and producing a ring/radial array of relatively spaced holes around the central axis of 1 5 the pile or column for receiving/accommodating material displaced by the lower end of the pile or column as the latter is caused to penetrate said medium as it descends a required depth.
10. A method as claimed in any one of the preceding claims, and including the step of providing a guide casing within the generally still exposed upper regions of the pile the pile or column during the installation of the pile or column
11. A method of installing a pile or column, substantially as herein before described with reference to the Figures of the accompanying drawing.