Composite Earth Drilling Auger and Method of Installing Same in Situ

In the past, for the purpose of installing load-bearing concrete piles in situ, it has been regular practice in the trade to rotate a hollow shafted, spiral-flighted auger into an earth situs to predetermined depth and then to inject fluid cement mortar through the auger shaft while withdrawing the auger, thereby to fill the drilled cavity, after which the cement mortar was allowed to harden as a solid pile column within the drilled cavity. Such prior methods, however, required use of a substantial amount of heavy, pile drilling equipment for handling large augers, and for pumping cement mortar into the augered cavities in the situs. A major problem with use of the prior pile forming methods in general resided in the fact that each pile cavity of a plurality thereof had to be separately drilled in the situs with use of a continuous flight auger, through which fluid cementitious material was pumped into each respective cavity with progressive withdrawal of the auger. Consequently, the usual cement supply trucks were often required to stand idle while the cavities were being drilled, and quite often the drilling work was seriously hampered by delays in arrival of such supply trucks.

The method and means of the present invention utilizes a novel one use auger-type device to drill a pile cavity in an earth situs, or to drill into a predrilled cavity, the auger device being retained in the cavity as a load-supporting pile body which is, in effect, more than usually anchored within the situs by retention of compressed earth packed along the flighting of the device.

The improved auger type device is adapted for economical use of a tubular or cylindrical shell, comprised of mating half shells of given length, which can be economically formed by known metal stamping methods. The mating shell halves are adapted to be formed with hollow impressions defining external spiral flighting protrusions, which makes it possible to stack or cup like shell halves one within the other, as for convenient storage and shipping purposes. Accordingly, pairs of such mating shell halves can be assembled and secured together, at an earth situs for example, to form a generally tubular auger shaft of required length, and provided with continuous spiral flighting along the same.

Upon assembly and attachment of two such mating shell halves of predetermined length to form a hollow auger shaft, the ends of the shaft may be closed, as by attachment of suitable closure means such as end plates thereto, whereby fluid self-hardenable material may be pumped or fed into the closed shell to fill the hollow of the same, including the hollow portions of the helical flighting of the resultantly formed auger. In this regard, it should be noted that any given number of assembled auger shells of predetermined lengths can be filled with fluid, hydraulic cement mortar, or other self-hardenable cementitious material in quick succession at the situs, for future use with consequent savings in labor and reduction of the usual wasteful presence of idle pile drilling and pumping equipment. In any event, each of the resultantly formed operable augers, with the filler material hardened or hardening therein, is then adapted to be drilled into the earth to the predetermined depth, in rapid succession, and to be retained in the situs as a finished load bearing pile or column.

A particular object of the invention is to provide a new method and means for installing substantially any number of such concrete piles in an earth situs without being subject to delays, heretofore commonly caused by unavailability of fluid cement mortar at the situs about the time workmen are ready to start drilling.

Another object of the invention is to provide a pile-forming auger shell in preformed shell sections which, prior to assembly to form a workable auger, can be compactly nested one within another for economical storage and/or shipping purposes.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

In the annexed drawings:

FIG. 1 is a composite side elevation, partly broken away, illustrating an assembled auger shell of the invention including mating half parts secured together, as by wire loops, to form a hollow spiral flighted auger shaft in accordance with the invention.

FIG. 2 is a top plan view, on an enlarged scale, of the assembled auger shell unit shown in FIG. 1, further illustrating one way that the mating shell halves can be complementally joined and secured together to form an auger shell of predetermined length.

FIG. 3 is a view, on a reduced scale, illustrating the assembled auger shell of FIG. 1 with the ends thereof capped, but with the capped shell prefilled with self-hardenable cementitious material, and thereby to serve as an earth-drilling auger which has been drilled into the earth situs to be retained therein as a load-bearing pile.

FIG. 4 is an enlarged cross-section of the combination auger and load-bearing pile, taken on the line 4--4 of FIG. 3.

FIG. 5 is a view corresponding to the lower portion of FIG. 3, but illustrating use of a modified form of drill bit affixed to the lower end of the pile forming shell.

FIG. 6 is a view corresponding to a lower extent of the pile forming shell of FIG. 3, but illustrating use of at least two assembled auger shell sections affixed end-to-end, and ready for being filled with the self-hardenable cementitious material, and also illustrating use of a modified, one-piece end cap and drill bit.

FIG. 7 is a view corresponding to FIG. 6, illustrating the assembled auger shell thereof filled with hardenable cementitious material, and subsequently being augered into the earth of a situs to serve as a load-bearing pile or column.

Referring to FIGS. 1 to 4 in general, and to FIGS. 1 and 2 in particular, FIG. 1 illustrates an elongated tubular auger shell or shaft 10, initially formed in two complemental shell halves 10a and 10b, of given axial shell length, as by means of known metal stamping equipment (not shown), thereby to have oppositely angled, mating hollow protrusions 11, 11, adapted complementally to connect and overlap along diametrically opposite edge portions 12, 12 of the assembled shell 10, and to form hollow spiral protrusions 11 as best shown in FIGS. 1 and 2. The assembled shell 10 can be of any given unit length and other dimensions, with the connecting protrusions 11 of the mated shell halves 10a and 10b defining continuous spiral flighting 15. In other words, the shell halves 10a and 10b may be secured together, in mating relationship as described, to form a spiral-flighted auger shell 10 of given unit length and other dimensions, as by means of looped wires or bands 16, 16 (See FIG. 1), or by other suitable means such as welding. Each end of the assembled shell unit 10 may have a closure plate or disc 17 suitably affixed thereto, as by crimping edges of the respective plates around integral lugs 18, 18 of the end edges of the tubular shell halves 10a and 10b, as shown in FIGS. 3 and 5.

The opposite end disc plates 17 of the shell units 10 may be of suitable types formed, as best shown in FIG. 3, with integral outwardly and inwardly extending collars 20 or 21, of squared cross-section, so proportioned and shaped that they can be non-rotatably connected with various driving or driven means, to be described later. FIG. 5, for example, illustrates how the hollow collar 21 of the inner plate 17 may be used to attach a drill bit 29 to an auger shell unit 10 of FIGS. 1 and 2. Moreover, a protruding squared collar 20 at the outer end of the auger unit 10 may be adapted for reception in a socket 22 on a power-driven shaft 23, for rotation of the completed auger shell unit, for drilling purposes, in a manner to be described later (see FIG. 3).

When only a single auger shell unit 10 is required, as for installing a pile column in an earth situs, the two end plates 17 may first have elongated reinforcing rods or elements 24, 24 affixed thereto, as by welding means, rigidly to extend within the hollow shell, between the end plates, as shown in FIGS. 3 and 4. If two or more such shell units 10 are required to be fixedly connected together, as shown in FIGS. 6 and 7, in conjunction with FIGS. 3 and 4, rods 24, 24 may be welded to inner and outer end plates 17. The rods 24 may be individually installed as described, or connected by wire or other means in the form of a cage-like reinforcing or post-tensioning structure.

The hollow auger unit 10 in FIGS. 1 and 2, so provided with tension rods 24 affixed therein between end plates 17, may while resting lengthwise on the ground, for example, have self-hardening, cement mortar supplied through one or other of the collars 20 and 21 at the exposed ends of the hollow auger shell 10, until the entire auger shell is solidly filled with pressurized cement mortar from end to end. For this purpose the capped shell 10 may be suitably backed or clamped between fixed backing means 17a, 17a indicated by chain-dotted lines in FIG. 1, while the cement mortar is pumped into the shell in a manner calculated to post-tension the rods 24. Upon eventual hardening of the cement mortar the resultantly post-tensioned reinforcing rods 24 will be solidly embedded therein.

If required, or necessary, a jetting fluid or like conduit 26 may be positioned through the auger shell, prior to pumping in the cement mortar as described, as shown in FIGS. 3 and 4, as for supplying jetting water or other fluid material through the auger for known purposes. For this use the conduit 26 also may be suitably affixed to a hollow tapered head 28 on the inner end of the auger unit 10, as shown in FIG. 3, or to a suitable drill bit 29 as shown in FIG. 5.

FIG. 7 illustrates a combination auger and pile body installed in the earth situs E. The installed pile body of FIG. 7 is of substantially the same construction as the pile body 10 of FIG. 3, except that the shell 10 consists of two or more longitudinal shell sections, telescoped one within the other to a short extent, as indicated at 10t in FIGS. 6 and 7, and affixed to each other by suitable means, such as a wire band 16, or by welding. FIG. 6 illustrates the sectional shell 10 of FIG. 7, as initially assembled, ready for filling the same with self-hardening, hydraulic cement mortar of like cementitious material as described above.

In the FIGS. 6 and 7 construction, the auger and pile forming shell is illustrated as utilizing a modified form of driving bit 30 which includes a disc-like closure plate 31, adapted to be readily secured within the inner end of the tubular shell, as by use of screws 34, 34, and may have an integral axially protruding V-shaped plate 32 extended crosswise of the end of the shell to serve as a drilling point and stop member. The jetting pipe 26 may be threaded to the plate 31 for passage of jetting fluid through an opening 33 in the plate to the exterior of the driving bit.

Practice of the method of the present invention, for certain purposes, presupposes assembling or otherwise furnishing at the situs, in advance, one or more hollow auger shell units 10, as shown in FIGS. 1 and 2, and of predetermined lengths as required, with driving heads and drill bits incorporated therein as described above, and otherwise as needed for variable uses. For most economical use of the novel method of the invention any required number of such hollow auger shell units 10, as shown in FIGS. 1 and 2, for example, may be laid lengthwise on the ground conveniently adjacent to an area in which the piles are to be installed, and then separately pumped full of fluid, self-hardenable cementitious material, as previously described (See FIG. 6, for example). This makes for economical and efficient use of both material and equipment since all of a very substantial number of hollow auger assemblies can be so filled with concrete and made ready for drilling the same into an earth situs, one after the other and without costly delays previously encountered, for example, when concrete supply trucks were not readily available when needed.

With a predetermined number of the assembled shell units 10 of FIG. 1, duly capped and filled with cementitious material, the same may be successively connected to the leads of a drilling rig supporting an auger drive socket 22 of the power driven shaft 23, as shown in FIG. 3. With rotation of the shaft 23 each said filled auger shell may be drilled into the earth situs E to required depth, as shown in either of FIGS. 3 or 7. If necessary, as for drilling into relatively hard soil, concrete filled shells may be drilled into predrilled auger cavities of diameter equal to or smaller than the tubular auger shell. If necessary or desirable jetting fluid, such as water under pressure, may be supplied from a suitable source, not shown, through the central pipe 26 while the auger is rotated into the earth. Moreover, the pipe 26 subsequently may be filled with self-hardenable fluid cementitious material further to increase the load-carrying strength of the finished pile or piles, as shown in FIG. 4. In any event it is desirable that the auger-pile flighting 11, when drilled to predetermined full axial depth, shall be firmly and anchoringly embedded or packed radially into the earth of the situs E, as shown in FIGS. 3, 5 and 7, thereby to increase or at least materially enhance the load-bearing capacity of each respective installed auger-pile.

It is readily apparent that, by use of the above-described novel method and means of present invention, substantially any number of preformed concrete piles made ready at the situs E, in advance as described above, can be drilled into the situs one next to another in continuous succession, for example, and without the long, frequent delays usually experienced in use of prior methods in which the concrete was pumped into augered cavities simultaneously with withdrawal of a cavity forming auger. Moreover, the simple nature of sectional auger-shell 10, as best illustrated in FIGS. 1 and 2, makes possible the economical use of lightweight shell metal, on the order of 22 gauge steel, for stamping out the shell sections. The assembled metal shell 10, however, should be self-supportingly rigid in order to retain its given operative shape upon being filled with fluid cement mortar, as described above.

Among the many advantages of the above-described pile forming method and means, it is important to note that the improved auger, including the assembled shell 10 filled with hardened concrete can be drilled directly into exceptionally soft earth or so-called no-blow count materials of a situs, thereby to avoid the usual procedure of driving a tubular casing through such soft earth and then augering through the soft earth thereby contained within the driven casing.

Modifications of the invention may be resorted to without departing from the spirit thereof or the scope of the appended claims.