AU3762297A

AU3762297A - Piling system

Info

Publication number: AU3762297A
Application number: AU37622/97A
Authority: AU
Inventors: Ian Grant Macdonald; Ian Robert Macdonald
Original assignee: Tristanagh Pty Ltd
Current assignee: Tristanagh Pty Ltd
Priority date: 1996-08-13
Filing date: 1997-08-12
Publication date: 1998-03-06
Anticipated expiration: 2017-08-12
Also published as: AU748919B2

Description

TITLE PILING SYSTEM

FIELD OF THE INVENTION

THIS INVENTION relates to a piling system. The invention also relates to a land reclamation and/or protection system using the piles of the piling system.

The invention relates further to a method for underpinning structures.

BACKGROUND OF THE INVENTION Piles are commonly used to support and/or stabilise building structures, retaining walls, revetments and the like in soils which have low, or insufficient, structural strength. Examples of such soils include sandy coastal soils and reclaimed swamplands.

In many situations, conventional pile driving methods are not applicable, eg., due to lack of access or likelihood of damage to surrounding structures due to the transmitted vibrations from the piles.

It is an object of the present invention to provide a piling system where the piles can be formed in situ.

It is a preferred object of the present invention to provide a piling system where a structural core or body for the pile can be simply and inexpensively manufactured and can be assembled on site.

It is a further preferred object of the present invention to provide a piling system where the structural strength can be increased by the addition of additional reinforcing.

SUMMARY OF THE INVENTION It is also an object of the invention to provide an improved method for underpinning structures for reinforcement and/or stabilization purposes.

Other preferred objects of the present invention will become apparent from the following description.

In one aspect, the present invention resides in a method of manufacturing a pile, including the steps of: forming a borehole a hole in a soil formation; at least substantially filling the borehole with grout; inserting a pile core into the grout, preferably centrally within the grout; and allowing the grout to set.

Preferably, the hole is drilled with its longitudinal axis directed substantially vertically, although the axis may be inclined to the vertical to increase the maximum shear strength of the pile in a given load direction or plane.

Preferably, the grout is a cementitious, structural grout. (The mechanical strength of the grout may be varied to suit the particular intended application.)

Preferably, the core is hollow, and is preferably of triangular cross-section. Alternative cross-sections include square, rectangular, hexagonal, circular, star or the like.

The core, when triangular, may be formed in two parts, ie, (I) a substantially V-shaped body member and (ii) a locking member having a web interconnecting a pair of inclined side flanges.

The core member may be formed from, eg., steel, aluminium, plastics (including fibre-reinforced plastic or carbon fibre) and/or any other suitable material, and may be formed from, eg., sheet or mesh material and, eg., folded or roll-formed to shape.

Additional reinforcement fabric (eg., rods, mesh) may be provided internally and/or externally of the core.

When the grout has set, a portion of the hole may be excavated, eg., to expose one side of the pile, to enable the pile to support structural member(s), eg., retaining wall panels.

In a second aspect, the present invention resides in a pile manufactured by the above method.

In a third aspect, the present invention resides in a core for a pile, including: a substantially V-shaped body member; and a locking member having a web interconnecting a pair of inclined side flanges; so arranged that the opposed edges of the body member are respectively engaged in the junction of the web and one of the side flanges of the locking member to form a structural element. Welds may be provided, eg., at spaced intervals to retain the body member and locking member together, as the core is inserted in the grout.

Alternatively the core may comprise an extruded hollow plastics member having a substantially triangular cross section. While it is preferable that the core can be driven into the grout, the core may be placed in the hole before the grout is, eg., pumped or poured into the hole.

Formations may be formed into, or fixed to, the body member and locking member to increase their "keying" with the grout. When one side of the borehole is to be excavated after the grout has set, it is preferable that the apex of the body member is directed towards the soil which will be undisturbed, ie., away from the direction of the excavated soil.

In a fourth aspect, the present invention resides in a method of manufacturing a pile, including the steps of forming a borehole in a soil foundation; inserting or drilling a hollow pile body into the hole, as or after the hole is drilled or formed; and filling the body with grout, soil or like material. Preferably, the body has the cross-sections hereinbefore described and is formed of the same materials as hereinbefore described for the core member.

A cap may be provided at the top of the body to enclose the material within the body.

In sand or like soil, the body may be "jet-drilled" to the desired depth.

In a fifth aspect, the present invention resides in a pile having a hollow (preferably triangular) body member filled with grout, soil or like filling material and optional reinforcing material.

In a sixth aspect, the present invention resides in a land reclamation and/or protection system wherein: a plurality of piles are arranged in an array or matrix, where piles in alternative rows are offset from the piles in the remaining rows.

Preferably, the piles are triangular in cross-section, and the apexes of the piles in a given row lie substantially at the intersection of lines defined by the side faces of the piles in the preceding row.

Preferably, the piles dissipate any wave energy in the waves washing on the beach or land protected by the piles.

In a seventh aspect, the invention resides in a method of underpinning a structure, said method comprising the steps of: forming a borehole in an earth formation adjacent a foundation for said structure, said borehole being inclined from the vertical and extending beneath the foundation; forming a cementitious pile in said borehole, said cementitious pile including a cap formation extending beneath the foundation; and, inserting in a cavity between said foundation and an upper surface of said cap support means to allow the building load to be transferred to said pile.

If required the borehole may include a casing liner. Suitably a source of pressurised fluid is injected into said borehole to form an enlarged cavity at the base thereof, said cavity when filled with cementitious material forming a support base for said pile.

Preferably said pile includes reinforcing means.

Suitably said reinforcing means comprises a pile core as hereinbefore described. The pile may also include one or more steel reinforcing rods.

If required at least one of said reinforcing rods may have at a remote end thereof, retractable flukes which, in an extended position form a reinforced base for said pile.

Suitably said cap formation includes reinforcing means. If required said cap may include a load bearing surface.

The load bearing surface may comprise a metal reinforcing member.

Suitably said support means comprises an extendable member. Preferably said extendable member comprises a jacking means.

The cavity between said foundation and the upper surface of said cap formation may be filled with a cementitious material when said foundation is located in a desired position. BRIEF DESCRIPTION OF THE DRAWINGS

To enable the invention to be fully understood, preferred embodiments will now be described with reference to the accompanying drawings, in which:

FIG 1 is a perspective view of the components of the pile core;

FIG 2 is a perspective view of the pile core when assembled;

FIG 3 is a top plan view of a completed pile; FIG 4 is a perspective view of an earth formation supported by a plurality of the piles in accordance with the present invention; and

FIG 5 is a schematic plan view of a pile, in accordance with a second embodiment, in use to support a sheet pile;

FIG 6 is a schematic side cross sectional view of a beach protected by the reclamation system; and

FIG 7 is a schematic plan view of the layout of the piles for the system of FIG 6.

FIG 7 shows schematically a method for underpinning a structure in accordance with the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIGS 1 and 2, the pile core 10 has a substantially V-shaped body member 20, eg., rolled from sheet steel, and a locking member 30 with a central web 31 interconnecting a pair of inwardly-inclined side flanges 32, 33 (also formed from sheet steel).

As shown in FIG 2, the locking member 30 is slid onto the body member 20 so that the opposed edges 21 , 22 of the body member are engaged with the junction of the web 31 and the inclined side flanges 32, 33, respectively.

Welds 40 can be provided at spaced intervals along the core 10 to lock the body member 20 and lock member 30 together when the core 10 is inserted into the grout in the hole. Formations (eg., grooves, slots, deformations) may be roll formed or pressed into the body member 20 and/or the locking member 30; or formations, eg., ribs, plates, may be welded to the body member 20 and/or locking member 30; to increase the keying of the pile core 10 to the grout when the grout has set. Referring to FIGS 3 and 4, a borehole 50 is drilled into the soil formation 60 and is substantially filled with a cementitious structural grout 70.

A pile core 10, as hereinbefore described, is driven into the grout 70 substantially centrally thereof and additional reinforcing rods 80 may also be driven into the grout internally and/or externally of the pile- core 10. When the grout has set, the resultant pile 100 may be used, eg., to support the foundations of a building structure.

Alternatively, as shown in FIG 4, a portion of the soil formation 60 may be excavated to leave an exposed face or wall 61 interconnecting adjacent piles 100. It will be noted that the pile core 10 is arranged in the pile 100 so that the apex 23 of the body member 20 is directed in the direction of arrow A in FIG 4 and that the locking member 30 is adjacent the exposed side of the pile 100.

Structural formations, eg., retaining walls, may be mounted on and/or supported by, the piles 100.

The dimensions of the pile core 10, eg., length, metal thickness, height and base width may be varied to suit the particular intended application, eg., as indicated in dashed lines in FIG 3.

While the components 20, 30 of the pile core 10 may be formed from sheet steel, they may also be formed from steel mesh, plastics sheet or mesh (preferably being fibre-reinforced for increased strength) or a combination of two or more of these, eg., the body member 20 may be formed from sheet material and the locking member 30 formed from mesh material or vice versa. Referring now to FIG 5, the pile 200 has a hollow body 210, of triangular cross-section, extruded from PVC plastics (which may be fibre-reinforced).

The body 210 is driven into the ground using a jet-drill to form the hole in the sandy soil formation in which the pile 200 is placed. Grout or sand 211 is used to fill the interior of the body 210 and a cap (not shown) can be placed to enclose the top of the body 210. The pile 200 can be used to support a corrugated sheet pile 250, being bolted thereto using bolts 260 and reinforcement plates 261.

It will be readily apparent to the skilled addressee that the body 210 could be formed of steel or other suitable material, and that the wall thickness and included angles between the adjacent sides can be varied to suit the particular intended applications for the piles.

Referring now to FIGS 6 and 7, a land reclamation and/or protection system 300 uses the piles 200 to protect, or reclaim, a beach 301 adjacent a building 302. The piles 200 are arranged in alternating rows extending substantially parallel to the water line. The apex 211 of each pile 200 lies substantially on the intersection of the lines 212, 213 projected from the sides 214, 215 of the piles 200 in the preceding row of piles 200.

From preliminary tests with a model, it appears that the first row of piles 200 breaks up the wave action and "funnels" the wave towards the second row of piles, which further breaks up the wave action. Each successive row of piles acts similarly. While the incoming waves moving towards the apices 211 of the piles will carry sand to the beach 301 , the dissipation of the wave energy prevents, or minimises, the amount of sand drawn from the beach on the back flow of the waves. The sand progressively builds up behind, and then around, the piles and the beach is reclaimed.

To protect a beach from erosion, the piles can be installed as shown in FIG 6, just below ground level. While large waves (eg., in cyclonic conditions) may remove the top layer 303, the piles 200 will prevent further scavenging of the sand from the beach. When a beach has been reclaimed, the piles can be removed, eg., to a new site, or can be left in place to protect the reclaimed sand. The spacing between "adjacent piles in a row, and between adjacent rows", and the actual relationship between the rows, can be varied to suit the intended application.

It will be readily apparent to the skilled addressee that the present invention provides a method for manufacturing piles with good structural characteristics without the need for heavy pile-driving equipment and/or the likelihood of damage to surrounding structures due to generated vibrations in the soil. It further provides a range of applications for the piles.

Various changes and modifications may be made to the embodiment described and illustrated without departing from the present invention. FIG 8 illustrates a method of underpinning a building according to the invention.

Where for example due to soil subsidence the structural integrity of a building is at risk, it may be necessary to reinforce or elevate portions of a building's foundations. In such circumstances, it is not possible to excavate large amounts of soil from underneath the building foundations or footings or to employ earth working machinery which induces vibratory forces into the earth mass as this can worsen the situation.

According to the present invention a borehole is drilled into an earth formation 510 by a rotary drill or the like, the borehole being inclined to the vertical and extending beneath the foundation or footings 520 of a building structure 530.

Depending upon the nature of the earth formation a steel casing (not shown) may be inserted into the borehole to prevent collapse of the bore wall.

When the borehole is formed to a desired depth, an enlarged cavity 540 may be formed at the base of the borehole 500 by compressed air or pressurized water.

A cementitious grout of say 70-80 Mpa is introduced into the borehole to fill the bore 500 and cavity 540.

Thereafter a triangular pile core 550 is inserted into the grout mass 560 while still fluid, the pile core extending to a region adjacent the base cavity 540.

If additional reinforcing is required, reinforcing bars and/or a steel rod 570 carrying a plurality of pivotally mounted flukes 580 is inserted down the middle of the pile core and when the flukes reach the region of the cavity they are extended into the grout mass in cavity 540 to provide additional reinforcing therefor.

When the grout has set, a selected region 590 beside and beneath the footing structure 520 is excavated and any reinforcing bars 600 extending from the pile core are bent over the region beneath the footing 520.

A pile cap 610 is then formed by pouring a further mass of cementitious material into the lower portion of cavity 590 leaving a space 620 beneath the exposed portion of footing 520. A screw jack 630 is then placed beneath footing 520 with its base 640 embedded in the cementitious cap 610.

When the cementitious grout has cured sufficiently the jack 630 and other similarly strategically placed jacks around the building can be extended to elevate the subsided portions of building to a sufficient level to restore the structural integrity to the building.

After the building has been aligned the remaining portion of the excavation 590 is filled with cementitious material and allowed to set thus providing full support for the building foundations.

It will be readily apparent to a skilled addressee that many modifications and variations may be made to the various aspects of the invention without departing from the spirit and scope thereof.

Claims

1. A method of manufacturing a pile, including the steps of: forming a borehole a hole in a soil formation; at least substantially filling the borehole with grout; 5 inserting a pile core into the grout, preferably centrally within the grout; and allowing the grout to set.

2. A method as claimed in claim 1 wherein the grout is a cementitious, structural grout. 0

3. A method as claimed in claim 1 wherein the pilecore is hollow and has a cross sectional shape selected from rectangular, hexagonal, circular, star or triangular.

4. A method as claimed in claim 3 when the pile core is of triangular cross section and comprises a substantially V-shaped body member and 5 a locking member having a web interconnecting a pair of inclined side flanges.

5. A method as claimed in claim 1 wherein additional reinforcing means is provided internally and/or externally of the core.

6. A method as claimed in claim 1 wherein after curing the grout, a 0 portion of the borehole is excavated to expose one side of the pile to enable the pile to support structural members.

7. A method as claimed in claim 1 wherein the core is placed in the borehole before the grout is admitted.

8. A core for a pile, including: 5 a substantially V-shaped body member; and a locking member having a web interconnecting a pair of inclined side flanges; so arranged that the opposed edges of the body member are respectively engaged in the junction of the web and one of the side o flanges of the locking member to form a structural element.

9. A core as claimed in claim 8 wherein said body member and said locking member are secured at spaced intervals to retain the body member and locking member together.

10. A core as claimed in claim 8 wherein formations are formed into, or fixed to, the body member and locking member to increase their "keying" with the grout.

11. A core as claimed in claim 8 wherein a cap is provided at the top thereof to enclose material therewithin.

12. A sand bench reclamation and/or protection system wherein: a plurality of piles are arranged in a sand base in an array or matrix, where piles in alternative rows are offset from the piles in the remaining rows.

13. A system as claimed in claim 12 wherein the piles are triangular in cross-section, and the apexes of the piles in one row lie substantially at the intersection of lines defined by the side faces of the piles in an adjacent row whereby the piles dissipate any wave energy in the waves washing on the beach or land protected by the piles and reduce water velocity to permit sedimentation of entrained sand in the region of the piles.

14. A method of underpinning a structure, said method comprising the o steps of: forming a borehole in an earth formation adjacent a foundation for said structure, said borehole being inclined from the vertical and extending beneath the foundation; forming a cementitious pile in said borehole, said cementitious pile 5 including a cap formation extending beneath the foundation; and, inserting in a cavity between said foundation and an upper surface of said cap support means to allow the building load to be transferred to said pile.

15. A method as claimed in claim 14 wherein the borehole includes a 0 casing liner.

16. A method as claimed in claim 14 wherein a source of pressurised fluid is injected into said borehole to form an enlarged cavity at the base thereof, said cavity when filled with cementitous material forming a support base for said pile.

17. A method as claimed in claim 15 wherein said pile includes reinforcing means.

18. A method as claimed in claim 17 wherein said reinforcing means comprises a pile core as hereinbefore described.

19. A method as claimed in claim 18 wherein the pile includes one or more steel reinforcing rods.

20. A method as claimed in claim 19 wherein at least one of said reinforcing rods has at a remote end thereof, retractable flakes which, in an extended position form a reinforced base for said pile.

21. A method as claimed in claim 14 wherein said cap formation includes reinforcing means.

22. A method as claimed in claim 14 wherein said support means comprises an extendable member.

23. A method as claimed in claim 22 wherein extendable member comprises a jacking means.

24. A method as claimed in claim 14 wherein the cavity between said foundation and the upper surface of said cap formation may be filled with a cementitious material when said foundation is located in a desired position.