US3832859A

US3832859A - Method and apparatus for spread-foot piles

Info

Publication number: US3832859A
Application number: US00043917A
Authority: US
Inventors: R Kanjanavanit
Original assignee: Individual
Current assignee: DIONIAN INDUSTRIES Ltd
Priority date: 1968-05-10
Filing date: 1970-06-05
Publication date: 1974-09-03
Anticipated expiration: 1991-09-03

Abstract

A hollow core pile has a cap on the lower end enclosing the lower ends of hinged spread feet. When the pile has been driven to depth, a rod or plunger is extended down the hollow core of the pile and is impacted to drive the cap down clear of the lower ends of the feet. The pile is then driven further so that the inclined ends of the spread feet engage the edges of the cap which forces them outwardly into the spread position.

Description

[ Sept. 3, 1974 United States Patent [1 1 Kanjanavanit [56] References Cited UNITED STATES PATENTS METHOD AND APPARATUS FOR SPREAD-FOOT PILES Bilhorn.......................... 6l/53.68 X 61/53 68 Primary Examiner-Jacob Shapiro [22] Filed:

[21] Appl. No.: 43,917 Attorney, Agent, or FirmStanley G. Ade

Related US. Application Data Continuation-impart of Ser. No. 818,325

ABSTRACT A hollow core pile has a cap on the lower end enclos- April 22,

ing the lower ends of hinged spread feet. When the pile has been driven to depth, a rod or plunger is exabandoned.

[30] Foreign Application Priority Data Apr. 24, 1968 Great Britain....................

tended down the hollow core of the pile and is impacted to drive the cap down clear of the lower ends of the feet. The pile is then driven further so that the inclined ends of the spread feet engage the edges of the cap which forces them outwardly into the spread position.

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METHOD AND APPARATUS FOR SPREAD-FOOT PILES This invention relates to new and useful improvements in methods and apparatus for spread foot piles and constitutes a continuation-in-part application of Ser. No. 818,325 dated Apr. 22, 1969 and now abandoned.

Piles are normally precast and then driven into the ground or, alternatively, the ground is drilled and then filled with concrete or the like thus forming the pile.

Conventionally, such piles should extend down to bedrock or hardpan but often this is of too great a depth for convenient pile installation. When the ground is predrilled, it is conventional to provide a spread foot base for the lower end of these drillings but use of an expanding bit or the like so that when the pile is poured in place, the excavation at the base of the drilling is also filled with concrete thus forming a spread foot or enlarged lower end.

For cohesivesoil where there is no hardpan or firm strata for the tip of the pile to be driven into, the bearing capacity of the pile is entirely the function of the shear values of the soil through which it passes.

To this should be added the relatively small support provided by the lower end of the pile and it is the combination of these two which maintains the pile in position. This means have to be of a considerable depth in order to obtain sufficient frictional adherence so that the pile is stabilized against downward movement.

It is not always convenient or expedient to predrill such areas and use the conventional spread foot system so that the present device can be utilized under these conditions.

I provide a base cap to a hollow cored pile upon which are hingedly secured a plurality of metal spread feet. A drive shoe engages over the lower ends of these spread feet thus maintaining them parallel to the longitudinal axis of the pile while same is being driven. When the desired depth is reached, the drive shoe is driven further downwardly by the insertion of a plunger or rod through the hollow cored pile. The pile is then driven donwardly so that the chamfered inner ends of the spread feet engage the upper edges of the drive shoe which thus drives these hinged spread feet outwardly thereby increasing considerably the bearing support or bearing area of the lower end of the pile.

The invention is applicable to either precast concrete piles or steel piles and can easily be attached to the lower end thereof. Furthermore, I form the drive shoe with conical lower tip or end so that the soil penetration of the pile being driven is improved considerably.

When the pile has been driven into position and the spread foot members have been extended radially from the lower end thereof, concrete can be poured down the hollow cored pile and rammed into position so that it freezes the lower end together with the radially extending spread foot members.

The device is simple in construction, economical in manufacture, and otherwise well suited to the purpose for which it is designed.

With the foregoing in view, and such other or furher purposes, advantages or novel features as may become apparent from consideration of this disclosure and specification, the present invention consists of, and is hereby claimed to reside in, the inventive concept which is comprised, embodied, embraced, or included in the method, process, construction, composition, arrangement or combination of parts, or new use of any of the foregoing, of which concept, one or more specific embodiments of same are herein exemplified as illustrative only of such concept, reference being had to the accompanying figures in which:

FIG. 1 is a side elevation of the lower end of a pile with my device in the driving position.

FIG. 2 is a sectional view along the line 22 of FIG. 1.

FIG. 3 is a similar figure to FIG. 1, but showing the drive shoe moved downwardly by the plunger or rod.

FIG. 4 shows the lower end of the pile in section with the spread foot members having been spread apart by the drive shoe.

FIG. 5 is a cross-sectional view similar to FIG. 4 but showing consolidation of the lower end by poured concrete.

FIG. 6 is a side elevation of the lower end of a pile showing an alternative embodiment, sectioned in part.

FIG. 7 is a view similar to FIG. 6 but showing the spread foot members being spread apart.

FIG. 8 is a fragmentary sectional view of the lower end of the base cap showing one method of hinging the spread foot members thereto.

FIG. 9 shows an alternative method of forming a spread foot pile.

FIG. 10 is a side elevation of the lower end of a pile with an alternative embodiment of my device in the driving position.

FIG. 11 is a partially sectional view similar to FIG. 10, but showing the drive shoe moved downwardly by the plunger or rod.

FIG. 12 is a partially sectional view similar to FIG. I, with the spread foot members having been spread apart by the drive shoe.

In the drawings like characters of reference indicate corresponding parts in the different figures.

Proceeding therefore to describe the invention in detail, reference should first be made to FIGS. 1 to 5 inclusive.

Reference character 10 illustrates a hollow cored concrete pile having a central vertically extending aperture or drilling 11 extending therethrough. The pile is shown as being of square cross-section but of course, it will be appreciated that any external configuration can be used as desired.

Frictionally engaged over the lower end 12 of the concrete pile is a base cap or socket 13 formed preferably of cast steel or the like. This consists of side plates 14 corresponding to the sides of the pile 10 and a centrally apertured base member 15, said central aperture corresponding to the aperture or core 11 of the concrete pile.

The lower end of the pile seats within this cap or socket and the socket is adapted to hold a plurality of spread foot members 16 in hinging relationship thereto.

In the present embodiment, a pair of such members are provided but it will be appreciated that more can be provided if desired.

The spread foot members 16, in the present embodiment, consist of lengths of channel having side flanges 17 and web 18 extending therebetween. In the present embodiment, two such members are illustrated consisting of an outer member 16A and an inner member 168 and reference to FIG. 2 will show that the flanges 17 of the outer member 16A are wider apart than then flanges of the inner member 16B so that they can nest one within the other when in the position shown in FIGS. 1, 2 and 3.

The two

members

16A and 16B are secured to opposite sides of the socket 13 by means of pivot pins 19 as clearly shown in FIG. 1 and 2, said pivot pins engaging through the flanges l7 adajcent one end 20 thereof which, in the present drawings, can be characterized as the upper end.

When in the position shown in FIGS. 1 and 3, the spread

foot members

16A and 16B are closed or parallel to the longitudinal axis 21 of the pile 10.

The lower or other ends 22 of the flanges 17 are angulated or chamfered to form camming surfaces 23 upon the inner sides of these flanges, said surfaces inclining upwardly and inwardly from the web 18 when the members are in the position shown in FIGS. 1 and 3.

A mild steel drive shoe 24 is frictionally engageable over the other ends 22 of the members 16, said shoe having side plates 25 and a conical soil penetrating lower end or tip 26. Projections 27 are formed upon the inner surfaces of the plates 25 and engage the webs 18 of the members frictionally to assist in maintaining the shoe in position until driving takes place.

This drive shoe encloses the lower or other ends 22 of the members 16 and maintains them in the position shown in FIG. 1 during the driving operation.

TI-Ie upper portion 27 of the webs 18 of the

members

16A and 16B are cut away to allow pivotal or hinging action of the members radially outwardly and downwardly when in the spread foot position shown in FIG. 4 so that the upper edge 28 of the remainder of the webs 18 engages the sides of the socket 13 as clearly shown thus limiting the outward movement.

In operation, the device is assembled on the lower end of the pile 10 as shown in FIG. I and it should be stressed at this point that pile 10 can either be of reinforced concrete or of steel.

The pile is then driven downwardly in the normal fashion until the lower end thereof reaches the location desired whereupon a plunger or rod 29 is inserted downwardly through the core 11 and through the base of the socket 13 until it engages within the drive shoe 24 as clearly shown in FIG. 3.

The plunger is then driven downwardly disengaging the drive shoe from the lower ends of these spread foot members 16 until it takes up the position shown in FIG. 3 whereupon the plunger may be withdrawn.

The pile is then driven further downwardly and I have found that the chamfered or cam surfaces 23 engage the sides of the hole formed by the downward movement of the shoe 24 thus causing them to move outwardly slightly and to an extent sufficient to ensure that these cammed surfaces 23 engage the upper edges 30 of the drive shoe 24 immediately therebelow. This camming action, as the pile is driven further downwardly, causes the spread foot members 16 to move outwardly to the fullest extent limited by the engagement of the edge 28 with the sides of the socket 13 until they take up the position shown in FIG. 4.

This increases considerably the load bearing capacity of the pile due to the channel formation and angle of inclination of the spread foot members 16.

If desired, concrete may then be poured down through the core 11 as indicated by reference character 31 in FIG. 5. This concrete may then be rammed by the plunger 29 until it fills the area all around the spread foot members as clearly shown. This freezes the spread foot members in position and protects the mechanism against corrosion.

FIGS. 6, 7 and 8 shown an alternative construction wherein the base cap or socket 32 receives the lower end 12 of the hollow cored pile 10 within a socket portion 33 formed in the upper end of this cap 32.

Two pairs of spread foot members 34 (one pair of which only is illustrated) are formed with hooked upper ends 35 engageable within apertures 36 formed in the lower comers 37 of the socket 32. These comers are inset with respect to the sides 38 of the socket so that the spread foot members 34 are flush with the sides 38 when in the parallel position shown in FIG. 6.

The drive shoe 24 engages over the lower or other ends 39 of the spread foot members 34 in a way similar to that hereinbefore described so that the assembly takes up the position shown in FIG. 6.

A flexible link 40 extends between each pair of spread foot members 34 and in the present embodiment, this flexible link takes the form of a pair of tie rod links 41 pivotally secured together by the inner ends 42 thereof and being pivotally secured to adjacent the ends 39 of the members 34, by the other ends 43, through the agency of pivot pins 44 as clearly shown.

Hereagain the inner surfaces 45 of the lower ends 39 are chamfered or cammed.

The operation of this embodiment is exactly the same as heretofore with the exception that the tie rods or flexible links 41 limits the outward movement of the spread foot members 34 as clearly shown in FIG. 7.

FIG. 9 shows a final embodiment in which the drive cap can be driven downwardly clear of the lower end of the pile whereupon an explosive or some similar means can excavate an area adjacent the lower end and drive cap which can then be filled with concrete through the hollow core and rammed into position.

In fine particle cohesive soil, when the shoe is pushed down by the plunger, it does not leave a clean bore parallel sided hole equal to the size of the shoe, but always obtains a smaller dimension due to the soils plasticity and the external pressure acting thereupon. Therefore, when the pile is driven further down after the shoe has been moved clear of the spread foot members, the tips of the spread foot members will engage with the sides of the reduced and curve sided hole which deflects them out progressively so that the cammed surfaces engage over the edges of the shoe which continues to deflect them fully to the expanded position.

However, when used in sandy clay, the granular material tends to prevent the clay from flowing so that a clean bore hole equal to the size of the shoe may result. Under these circumstances, of course, the spread feet will not have an initial outward movement so that they will not engage the outer sides of the shoe in order that the spreading action may take place.

Under these circumstances, the arrangement or embodiments shown in FIGS. 10, 11 and 12 should be utilized.

A cam 46 is formed on the inner surface of each of the spread foot shoes 16 as shown clearly in FIGS. 10,

.11 and 1 2. The plunger or rod 29A used in this embodiment is shouldered or stepped as at 47 so that the lower end 48 is of a reduced diameter to that of the remainder indicated by reference character 49, above the step or shoulder 47. The reduced diameter portion 48 passes between the closing cams 46 and engages the shoe 24 as hereinbefore described. As the shoe is driven clear of the lower ends of the spread foot members 18, the shoulder 47 engages the cams 46 and moves them outwardly together with the attached spread foot portions 18. This causes or ensures that the camming surfaces 23 engage the outer edges of the sides 30 of the shoe 24 thus ensuring that they are spread as the pile is driven deeper.

This action of the spread foot portions 16B moved outwardly by the enlarged diameter portion 49 of the plunger is shown clearly in FIGS. 11 and 12 shows the spread foot portions 16 in the fully expanded positions.

Various modifications can be made within the scope of the inventive concept which is herein disclosed and- /or claimed.

What I claim as my invention:

1. A spread foot assembly for hollow cored piles comprising in combination a plurality of spread foot members having enclosed lower ends, pivotally connected at the upper ends thereof to the lower end of the associated pile for hinging action from a position substantially parallel to the longitudinal axis of said pile to a position extending radially outwardly and downwardly from said lower end, means to operatively secure said enclosed lower ends of said spread foot members to said lower end of the associated pile and means to spread said feet outwardly and downwardly as aforesaid, and a drive shoe engageable over the other ends of said spread feet to enclose said other ends and maintain same in the said parallel position while being driven, said drive shoe having a soil penetrating lower end.

2. The assembly according to claim 1 in which said means to spread said feet outwardly and downwardly includes a cam surface on said other ends of said spread feet and on the inside thereof engageable with the upper end of said drive show when in the foot spreading position.

3. The assembly according to claim 1 which includes means to limit the degree of spread of said spread foot members.

4. The assembly according to claim 2 which includes means to limit the degree of spread of said spread foot members.

5. The assembly according to claim 3 in which said means to limit the degree of spread of said spread foot members includes a pair of tie rod links pivotally secured together by the inner ends thereof and pivotally secured to adjacent the other end of said spread'feet.

-6. The assembly according to claim 4 in which said means to limit the degree of spread of said spread foot members includes a pair of tie rod links pivotally secured together by the inner ends thereof and pivotally secured to adjacent the other end of said spread feet.

7. The assembly according to claim 1 in which said means to spread said feet outwardly and downwardly as aforesaid includes a plunger rod extending through said pile and engaging said drive shoe for moving said drive shoe downwardly clear of said spread foot members, and further means to initiate outward movement of said spread foot members.

8. The assembly according to claim 7 in which said means to spread said feet outwardly and downwardly includes a cam surface on said other ends of said spread feet and on the inside thereof engageable with the upper end of said drive shoe when in the foot spreading position.

9. The assembly according to claim 7 which includes means to limit the degree of spread of said spread foot members.

10. The assembly according to claim 8 which includes means to limit the degree of spread of said spread foot members.

11. The assembly according to claim 7 in which said further means includes a cam formed on the inner surface of each of said spread foot members, said plunger rod having a shoulder formed towards the lower end thereof whereby the portion above said shoulder is of a greater diameter than the portion below said shoulder, said shoulder striking said cams when said rod is moved downwardly thereby forcing said spread foot members outwardly after said drive shoe is disengaged therefrom.

12. The assembly according to claim 8 in which said further means includes a cam formed on the inner surface of each of said spread foot members, said plunger rod having a shoulder formed towards the lower end thereof whereby the portion above said shoulder is of a greater diameter than the portion below said shoulder, said shoulder striking said cams when said rod is moved donwwardly thereby forcing said spread foot members outwardly after said drive shoe is disengaged therefrom.

13. The assembly according to claim 9 in which said further means includes a cam formed on the inner surface of each of said spread foot members, said plunger rod having a shoulder formed towards the lower end thereof whereby the portion above said shoulder is of a greater diameter than the portion below said shoulder, said shoulder striking said cams when said rod is moved downwardly thereby forcing said spread foot members outwardly after said drive shoe is disengaged therefrom.

14. The assembly according to claim 10 in which said further means includes a cam formed on the inner surface of each of said spread foot members, said plunger rod having a shoulder formed towards the lower end thereof whereby the portion above said shoulder is of a greater diameter than the portion below said shoulder, said shoulder striking said cams when said rod is moved downwardly thereby forcing said spread foot members outwardly after said drive shoe is disengaged therefrom.

15. A method of installing hollow cored foot piles in which said piles include a base cap on the lower end of said hollow cored pile, a plurality of spread foot members hingedly secured by the upper ends thereof to said base cap and a drive shoe engageable over the lower ends of said spread foot members; said method being characterized by the steps of driving the pile downwardly to the desired location, inserting a plunger member downwardly through said hollow cored pile into engagement with said drive shoe, driving said shoe downwardly by said plunger member until said shoe is clear of said lower ends of said spread foo't members, withdrawing said plunger and then driving said pile deeper whereby said spread feet are driven radially outwardly by engagement of the lower ends of said spread foot members with the upper end of said drive shoe.

Claims

5. The assembly according to claim 3 in which said means to limit the degree of spread of said spread foot members includes a pair of tie rod links pivotally secured together by the inner ends thereof and pivotally secured to adjacent the other end of said spread feet.

6. The assembly according to claim 4 in which said means to limit the degree of spread of said spread foot members includes a pair of tie rod links pivotally secured together by the inner ends thereof and pivotally secured to adjacent the other end of said spread feet.

15. A method of installing hollow cored foot piles in which said piles include a base cap on the lower end of said hollow cored pile, a plurality of spread foot members hingedly secured by the upper ends thereof to said base cap and a drive shoe engageable over the lower ends of said spread foot members; said method being characterized by the steps of driving the pile downwardly to the desired location, inserting a plunger member downwardly through said hollow cored pile into engagement with said drive shoe, driving said shoe downwardly by said plunger member until said shoe is clear of said lower ends of said spread foot members, withdrawing said plunger and then driving said pile deeper whereby said spread feet are driven radially outwardly by engagement of the lower ends of said spread foot members with the upper end of said drive shoe.