US3423944A - Method for forming end bearing concrete piles - Google Patents

Description

Jan 28, 1969 w. B. GOODMAN METHOD FOR FORMING END BEARING CONCRETE PILES Filed Aug. 28, 1967 FIG. 2

FIG. I

FIG. 4

Flefa INVENTOR:

w.B.eooDMAN en? 73M Hls ATT RNEY United States Patent O .4 Claims ABSTRACT OF THE DISCLOSURE An elongated borehole forming tubular member, having a cheek valve intermediate its ends, is sonically driven into an earth formation to a predetermined depth to form a borehole, then withdrawn a short distance from the bottom of the hole as a slurry of concrete or cement is pumped through the tubular member and through the check valve into the hole. The tubular member is again sonically driven downward with the valve closed forcing the cement outward into an enlarged bulbular shape in the formation. The tubular member is then withdrawn from the hole as it is being sonically vibrated and cement is pumped through the tubular member into the hole to form the body of the pile.

BACKGROUND OF THE INVENTION Field of the invention y In the construction of buildings, bridges, piers, drilling platforms and other similar structures, it is essential that a solid, stable foundation be established on which to rest the structures. Such foundations are generally established by sinking a number of piles into the earth on which t rest the structure. The load capacity of these piles depends upon such factors as soil conditions and size, shape and length of the pilings. The resistance of a pile to displacement in an earth formation is provided by friction along the length of the pile and on tip resistance or resistance by the soil to displacement by the end or tip of the pile. In some soils very little shaft resistance is encountered, in which case, tip `or end resistance must carry the entire load.

The type of soil into which the pile is driven has an important bearing upon its load carrying capacity. For example, piles which are sunk into clay type soils carry most of the applied load by soil friction 'along their shaft length. Very little resistance is supplied by the tip. On the other hand, piles which are placed into a sandy type of formation carry most of the applied load by tip resistance when the load acts downward, and very little of the load is carried by soil friction along the shaft.

It has been found that an ideal shape for an end or tip bearing pile would be one having a large or bulbous base or foot, and a normal or regular sized sh-aft. Such a shape for such piles would offer' great savings in materials in that the length and diameter of the shaft of such a pile would be much less than for a pile of constant diameter having the same load carrying capacity'.

The present invention relates to the construction in place of concrete piles and pertains more particularly t0 a method for the forming in place of end bearing piles having a large bulbular base or foot and therefore a high load capacity.

Description of prior art Various methods are known for constructing bulbular or large based piles. One method is known as the Franki method. In accordance with this method a specially constructed rig is moved to the construction site. A casing or heavy gauge, high-tensile alloy steel is raised in place. A portion of very dry concrete is then placed in the bottom of the casing to form a driving plug. Next, a heavy, solid rarn weighing from two to four tons is lowered into the casing and raised in front to drive the plug into the ground which pulls or carries the casing with it by means of friction between it and the casing. At the desired level the casing is then anchored to the rig and the plug driven out the bottom of the casing. More concrete is then dumped into the casing and rammed out the bottom of the casing to form the bulb. The casing is then raised small increments as more concrete is dumped into the casing and rammed out the bottom to form the rest of the pile.

Among the disadvantages of the prior known methods of constructing such bulbular base piles is that the steps are long and slow. Such methods, being time consuming, are therefore expensive.

Furthermore, the apparatus used in such prior known methods is heavy, complicated and cumbersome. This also adds to the cost of constructing such piles.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome the above and other disadvantages of such prior methods and apparatus by providing a method and apparatus that is rapid and efficient for the construction in place of high load capacity piles.

It is a further object of the present invention to provide a method that is simple, easy to use and rapid in the formation in place of high load capacity piles.

Still another object of the present invention is to provide a method of forming bulbular base piles that utilizes a sonic vibratory driving head Ias power means for forming the bulbular base.

A further object of the present invention is to provide a method of forming bulbular base piles that takes advantage of the power and eiciency of a sonic driving head to form the borehole and the bulbular base for the pile.

Still -a further object of the present invention is to provide a method of forming a bulbular base pile that takes maximum advantage of the various load carrying capacities of the various strata in an earth formation.

In accordance with the invention, an elongated borehole forming tubular member having a check valve in the bore intermediate the ends thereof is provided with a driving tip and sonically driven to a predetermined depth. The tubular member is then wtihdrrawn a predetermined amount as a slurry of solidiable material such as cement is pumped through the tubular member and through the valve filling the borehole and the bore of the tubular member with a column of solidiable material. The tubular member is then sonically driven downward with the valve closed, forcing the column of material downward and the lower portion thereof outward into the formation forming an enlarged bulbous base. The tubular member is sonically vibrated as it is withdrawn and as more of the material is simultaneously injected into the borehole to form the body of the pile.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects and advantages will become apparent from the following description used to illustrate a preferred embodiment of the invention when read in connection with the accompanying drawings in which:

FIGURE 1 is a diagrammatic View, partially in section, of apparatus used in carrying out the present invention driven to the desired depth in an earth formation.

FIGURE 2 is a diagrammatic View, partially in section, through the borehole showing the tool member partially withdrawn from the bottom of the borehole.

FIGURE 3 is a diagrammatic view, partially in section, through the borehole and partially in section through the tool, showing the base of the pile after it has been formed.

FIGURE 4 is a diagrammatic view, partially in section through the borehole showing the base of the pile and a portion of the shaft as completed and the tool being withdrawn.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a preferred embodiment of an apparatus for carrying out the present invention is illustrated. In FIGURES 1-4 a :bore-forming tool 11 is connected in any suitable 'manner such as by a clamp or flange 12 to a sonic driving head 13, which is supported by means of a cable or ilexible member 14 from any suitable derrick or crane-like structure, not shown. The bore-forming tool 11 generally comprises an elongated elastic tubular member 14 having a check valve 16, intermediate the ends thereof at a predetermined point above the lower end to close off the bore thereof. A cap or driving plug 17 is generally provided to close the lower or driven end of the tubular member. A conduit 18 located above the check valve 16 leads from a suitable source, not shown, of solidiiiable material, such as cement or concrete, which is to be pumped through the bore of the tool member and into the formation.

The sonic method of driving piles and the underlying theory is disclosed in U.S. Patent No. 2,975,846, issued to A. G. Bodine. Reference is made to the aforesaid patent for suitable sonic generators as well as a detailed explanation of the sonic pile driving method. Briey, this method comprises acoustically coupling a sonic generator to the upper end of a pile and operating the sonic generator so as to set up longitudinal standing waves in the pile with the lower end of the pile in tight engagement with the earth. The pile then :buries itself by sonic standing wave action.

OPERATION In operation, the pile forming tool 11 is hoisted into place with cap 17 in place on the lower end thereof. The sonic driving head 13 is started up and the tool driven to a predetermined depth as shown in FIGURE l. The tool is then withdrawn a distance from the bottom of the bore hole as shown in FIGURE 2 and a slurry of solidifiable fiuid material such as cement or concrete is pumped through the bore of the tool into the bottom of the borehole. The sonic driver 13 is then started up and the tool 11 sonically driven downward. The increased pressure on the column of material 19 from driving the tool downward closes check valve 16, trapping the column of material and forcing a portion of it downward and the exposed walls of the borehole outward into the formation, thus forming an enlarged base or footing 20 for the pile as seen in FIGURE 3. This process of trapping and driving a column of the material downward is repeated if necessary until a sufficient volume of the material is displaced into the formation to form a suitable sized base 20 for the pile. After a suitable base has been formed, the tool is withdrawn from the formation while being sonically vibrated and a slurry of the solidifiable material is continuously fed into the bore to form the column of the pile as shown in FIGURE 4.

It can also be appreciated that the lower or driven end of tube 15 may also be closed off without the use of plug 17. This may be accomplished by placing the open end of the tubular member 15 against the earth formation and then lling the tube or bore thereof with the solidifiable material. The column of material thus trapped will act as a plug to prevent the entrance of earth material into the bore of the tubular member.

It may also be appreciated that the present invention is not limited to the yforming of piles vertically in an earth formation, but may be used for forming piles that may be set at various angles to the vertical. For example, horizon tal pilings may be formed in place by the method of the present invention.

I claim as my invention:

1. A method of forming a bulbular based pile comprising the steps of:

providing an elongated pile forming member with an axial bore therein and valve means yfor closing said bore at a predetermined point above the lower end thereof;

temporarily closing said lower end of said member;

sonically forcing said one end of said elongated 'member into an earth formation to a predetermined depth, to thereby form a material-receiving borehole in said formation;

withdrawing said elongated member a predetermined distance from the bottom of said material-receiving borehole, to thereby expose a portion of the wall of said borehole;

substantially filling said material-receiving horehole and said bore of said elongated member below said valve means with a slurry of solidiable material, to thereby form a column of said material;

closing said valve means to confine said material in said bore', and

sonically forcing at least a portion of said column of material downward, and at least a portion of the exposed walls of said earth borehole outward to form an area of said material of enlarged diameter.

2. The method of claim 1 further including the steps of:

withdrawing said elongated member while sonically vibrating said member; and

feeding additional solidiable material through the valve means and bore of said member and into said material-receiving borehole.

3. The method of claim 1 wherein the step of closing said one end of said member includes:

placing a removable cap over said one end.

4. A 'method of forming a bulbular based pile comprising the steps of:

providing an elongated pile forming member with an axial bore therein and valve means for closing said bore at a predetermined point above the lower end thereof;

temporarily closing said lower end of said member by placing said end of said member into contact with said earth formation;

filling said bore of said member at least up to said valve means with a slurry of solidifable material under pressure;

sonically forcing said one end of said elongated member into an earth formation to a predetermined depth, to thereby form a material-receiving borehole in said formation;

withdrawing said elongated member a predetermined distance from the bottom of said material-receiving borehole, to thereby expose a portion of the wall of said borehole;

6 substantially filling said material-receiving borehole and References Cited said bore of said elongated lmember below said valve UNITED STATES PATENTS means with a slurry of solidiable material, to thereby form a column of said material; 1g; vegton "EIMS-3235? closing said valve means to confine said material in e, er

said bore; and 5 I 3,187,513 6/1965 Gund 61 53.5

sonically [forcing at least a portion of said column of JACOB SHAPIRO Primary Examiner material downward, and at least a portion of the exposed walls of said earth borehole outward to U S` C1, X,R, form an area of said material of enlarged diameter. 10 6l-53.66

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