US2323772A

US2323772A - Construction of concrete piles or the like

Info

Publication number: US2323772A
Application number: US460436A
Authority: US
Inventors: Hood Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-08-28
Filing date: 1942-10-01
Publication date: 1943-07-06
Anticipated expiration: 1960-07-06

Description

A. HOOD July 6, w43.

CONSTRUCTION OF CONCRETE PILES `OR THE LIKE Filed Oct. l, 1942 Patented July 6, 1943` CONSTRUCTEON OF CONCRETE PILES OR THE LIKE Jandrew Hood, Carmarthenshire, Wales Application October 1, 1942, Serial No. 460,436

In Great Britain August 28, 1941 7 Claims. Y (Cl. 61-57) This invention is for improvements in or relating to the construction of concrete piles or the like by the method of driving a hollow piling tube fitted with a removable closure member into the ground by percussion means and thereafter lling the tube with a fluid concrete mix and withdrawing the tube from the ground leaving the said closure member at the foot -of the nished pile. The invention is not concerned with screw-piles which are driven into the ground,

after the manner of an auger, by the application of torsion to a hollow piling tube tted with a fixed screwhead at its foot and left in situ as the pile itself or as a part of a nished concrete pile.

According to the present invention there is provided a metal piling tube closed at the foot thereof with a removable closure member e. g a conventional shoe and having rigidly secured thereto, or formed integrally therewith, evenly spaced inclined ribs running spirally round the -f outside of the tube, at least one rib extending along substantially the whole length thereof. Where two ribs are provided it will be appreciated that one may extend along substantially the whole length of the tube whilst the other,

similarly inclined, extends only a short distance from the foot of the tube. The even spacing of the ribs round the tube prevents any lateral wandering of the piling tube whilst it is being driven into the ground.

Preferably the rib is formed by securing a channel section metal strip to the outer surface of the tube to leave a space between it and the tube through which fluid or air can pass.

It will be appreciated that the space between the channel section metal strip and the outer surface of the tube may be used for the introduction of moisture to the foot of the tube while it is being driven through the ground whenever a stratum of the earth is found to be unduly hard or otherwise dicult to penetrate. It will also be appreciated that the said space could, if desired, be used for passing a grouting mixture of cement grout (if desired also containing sand) down to the lowermost edge of the tube while it is being driven into or withdrawn from the ground to eiiect cementation of any particular Astratum of the ground e. g. a porous sandy or gravel stratum When in use, the tube is freely positioned in a collar secured to the base of a piling frame which collar is formed with a groove, shaped to engage with the rib, on the tube to ensure rotation of the tube during its axial movement.

The invention also includes within its scope the construction of concrete piles, utilising a tube constructed as above described.

The present invention provides great improvements in relation to concrete piles as the spiral rib projections running around the pile shaft greatly enhance the frictional Value of the pile and consequently its `load-bearing capacity by developing the maximum frictional value even in the weakest of ground strata. In fact the pile of the present invention is a Combination of the shaft and screw piles and possesses all the advantages of both but with none of their disadvantages. The normal desired diameter of the pile is denitely maintained throughout its whole length whilst the ribs act as load-bearing agents and aord a considerable increase over the normal diameter of the pile. 'f

The invention can'be put into effect in a very simple manner by means of a simple and inexpensive modication of any standard pile-driving equipment, for instance, the spiral ribs can be afxed t0 a standard pile-driving tube whilst at the same time the conventional piling frame can be used with a very slight modification.

and also to the reduction of suction forces Where hollow ribs are used.

The length of the piling tube can be adjusted to suit the circumstances and the piling frame can, by the adoption of standard lengths of piling tube, be standardised to a conveniently manageable height as, for example, 35 to 40 feet.

The following is a description of one embodiment of the invention illustrating the construction of the tube and its method of use in the formation of a concrete pile described with reference to the accompanying drawing in which:

Figure 1 is a side elevation of a piling tube,

Figure 2 shows the piling tube arranged in relation to a piling frame,

Figure 3 shows a View of the concrete pile of the invention in position in the ground,

Figure 4 is a cross section of Figure 1 along the line A-A,

Figure 5 is an enlarged detailed View of the lower part of the tube shown in Figure 1 and Figure 6 is a cross section of the concrete pile on the line B-B of Figure 3.

The tube a, which may be of any convenient diameter depending upon the diameter of the concrete pile which it is desired to form, is a hollow cylindrical member provided at its foot with the ordinary customary circular metal shoe b which is provided with a projection lc which nts within the lowermost end of the tube with the ange P abutting the end of the tube as best seen in Figure 5. Fixed rigidly to the external surface of the tube are two metal rib projections c, d, one of which (c) extends for the full length of the tube in the form of a slow spiral and the other of which (d) extends up for a short distance from the bottom of the tube and is inclined to the axis of the tube at the same angle as the .full-length rib. The short rib is arranged so as to be diametrically opposite the long rib so that during the movement of the tube into the ground, the lateral thrust caused by the long rib is, at the foot, prevented from causing a lateral wandering of the piling tube.

The bottom ends of both ribs are cut at an angle so as to form a cutting edge in order that as the tube is driven into the ground two spiral grooves will be cut in the surrounding ground.

The two ribs are formed by bending a piece of bridge rail into the desired form and securing it to the outer surface of the tube by welding along both its flanges over the whole length thereof; the short rib is of course similarly formed; it will of course be understood, however, that the ribs may be formed in any other convenient manner.

The tube and rib may be in one length L or may be in any desired number of lengths S, Si (so as to permit of convenience in handling the separate lengths) the various lengths being secured together preferably by means of screwed joints.

The rib is preferably of such a pitch as to have :one revolution in a length of tube which is from twenty to twenty-five times its diameter.

The top end of the tube is provided with the conventional driving head and helmet m.

In use, the tube is clamped in an ordinary loose collar r which travels down with the tube and is secured to the leaders of a piling frame with the shoe b penetrating the ground in the selected pile position. At or near to the ground surface the tube is clamped by a heavy guide collar e, secured to the base of the piling frame and formed with an internal groove arranged to engage the rib so as to ensure that the tube rotates, as it is driven into the ground, in such a manner as to cut clean grooves through the ground. The guide collar may be provided with strong springs suitably disposed to take up variations in the drive.

When the shoe has been placed on the ground in a selected position and the tube has been lowered on to it and the guide collar e has been clamped around the tube a, then the tube can be driven into the ground by means of any conventional hammer indicated generally by H. It will be understood that owing to the loose fit between the tube a and the shoe b, the shoe does not itself necessarily revolve and will remain in the bottom of the hole and at the foot of the pile when the tube is withdrawn.

When the tube has been driven a sufficient distance into the gro-und the operation of forming the concrete piie may then commence.

A liquid concrete mixture is poured into the middle of the tube a so as to fill up the space within and the tube is then withdrawn by the conventional method of reversing the action of the driving hammer H so as to drive the tube in an upward direction, or alternatively the tube may be pulled out of the ground; the tube is still in position in the guide-collar and will consequently rotate as it is withdrawn thereby preserving the shape of the grooves in the ground. It will of course be appreciated that where a reinforced pile is required, a steel cage reinforcement f is introduced into the tube preferably so as to rest on the upper surface of the shoe.

It will be understood that as the tube is extracted from the ground the uid concrete mixture within the tube will completely ll the hole, including the groove or grooves formed by the ribs, and consequently the nished concrete pile will be in the form of a concrete core with two spiral ribs, g formed around it along the whole of its length; these spiral ribs have an important effect in providing additional frictional contact with the surrounding ground so as more readily to prevent any movement of the pile by increasing the effective diameter of the pile from Di to D2 as seen in Figure 6 thereby increasing its loadbearing capacity.

It will be appreciated that certain modificatiens may be made to the procedure described above, for instance instead of the tube being progressively withdrawn from the ground it may be gradually withdrawn with an up and down movement which has the effect of tamping the concrete so as to form a closer and more compact pile or it may be vibrated mechanically during its withdrawal to increase the density of the concrete.

It will be appreciated that although the foregoing description has made reference only to a single rib extending along the whole length of the tube, any desired number of ribs c, may be arranged evenly spaced around the periphery of the tube in which case the short length of tube could be dispensed with.

What I claim is:

l. A piling tube adapted to be closed at the foot thereof with a removable closure member and driven into the ground by percussion means for the formation of an in situ concrete pile comprising a metal piling tube provided with a number of evenly spaced inclined ribs running round the outside of the tube, at least one of said ribs extending along substantially the whole length thereof and being hollow and adapted to permit the passage of liquid to the foot of said tube.

2. A piling tube adapted to be closed at the foot thereof with a removable closure member and driven into the ground by percussion means for the formation of an in situ concrete pile comprising a metal piling tube provided with two diametrically opposite inclined ribs running round the outside of the tube, at least one of said ribs extending along substantially the whole length thereof and being hollow and adapted to permit the passage of liquid to the foot of said tube.

3. A piling tube adapted to be closed at the foot thereof with a removable closure member and driven into the ground by percussion means for the formation of an in situ concrete pile comprising a metal piling tube provided with a number of evenly spaced inclined hollow ribs running round the outside of the tube, at least one of said ribs extending along substantially the whole length thereof.

4. A piling tube adapted to be closed at the foot thereof with a removable closure member and driven into the ground by percussion means for the formation of an in situ concrete pile comprising a metal piling tube provided with two diametrically opposite inclined hollow ribs running ber of evenly spaced inclined hollow ribs formed of channel-section metal strip secured to the outside of the tube and running round the outside of the tube, at least one of said ribs extending along substantially the whole length thereof.

6. A piling tube adapted to be closed at the foot thereof with a removal closure member and4 driven into the ground by percussion means for the formation of an in situ concrete pile comprising a metal piling tube provided with two diametrically opposite inclined hollowribs formed of channel-section metal strip secured to the outside of the tube and running round the outside of the tube, at least one of said ribs extending along substantially the whole length thereof.

7. A piling tube adapted to be closed at the foot thereof with a removable closure member and driven into the ground by percussion means for the formation of an in situ concrete pile comprising a metal piling tube provided with a number of evenly spacedinclined ribs'running round the outside of the tube, at least one of said ribs being hollow and extending along substantially the Whole length thereof said ribs being inclined at an angle of from l in 20 to 1 in 25.

ANDREW HOOD.