US2036355A - Method and apparatus for driving piles - Google Patents

Description

C. A. ORR El' AL METHOD AND APPARATUS FOR DRIVING PILES Filed March l, 1934 2 Sheets-Sheet l sx IIIIII/// April 75 36f, c. A. @RR Er AL 035,355

METHOD AND 'APPARATUS FOR DRIVING PILES Filed March l, 1934 2 Sheets-Sheet 2 PATENT OFFICE accents im AND APPARATUS FOR DG PILES f Chester A. Orr and Edmund W. Riemenschneider, Canton, Ohio, assignors to The Union Metal Manufacturing Company, Canton, Ohio, a cor- Application March l, 1934, Serial No. 713,535 18 malins. (Cl. 157) The invention relates to piles and more parly transmitted to the shell throughout the enticularly to the driving and setting of piles in tire length of the shell, to drive the shell into which a tapered, tubular, metal shell is sunk into the ground. the ground by utilizing a tapered, substantially Thus, the diiculties which are encountered in rigid, driving mandrel or core for driving the utilizing a radially non-expansible shell, due to 6 shell into the ground, after which the core is'rethe shell and mandrel being oil-taper with removed and the shell may be filled with suitable spect to one another, due to the mandrel being bearing material, preferably concrete, to form the worn, due to the shell or mandrel being out of pile; and the present invention is a continuation round, or due to the shell or mandrel being unlo in part of the common subject matter of our dersize or oversize, are avoided; and these difcopending application Yfor Piles and methods and culties, if not avoided, might result in a tearapparatus for setting the same, illed October 12, ing or splitting of the shell, or in a tearing out 1932, Serial No. 637,454. of the nose thereof, or in an ineicient utiliza- A tapered, tubular, metal shell of almost any tion of the driving force imparted to the mandrel.

l5 length, preferably provided with a nose integral It is therefore a further object of the present 16 with the small lower end thereof, may be sunk invention to provide for the driving of pile shells to almost any depth into the ground by utilizing into the ground by utilizing a longitudinally .a tapered, substantiallyY rigid, longitudinally conribbed, corrugated or iluted, tapered. tubular. tinuous, driving mandrel, by providing the shell metal shell, by utilizing a tapered, substantially 2@ with longitudinal ribscorrugations or flutes, by rigid, driving mandrel, by telescoping and wedg- 20 telescoping the mandrelwithin the shell and ening the mandrel 121130 the Shell and radially eX- gaging the mandrel Iv vith the shell flutes and pending the shell throughout its entire length nose, and by then driving .the mandrel to drive until the lowerend of the mandrel engages the Vthe shell into the ground. The mandrel may shell nose and/or until contact is established be' then bereadily removed from the shell. and the tween the mandrel and all of the shell yflutes 25 tapered shell which is preferably, but not necesthroughout their en tire length, by then driving sarily, formed of very thin sheet metal, provides the shell and mandrel into the ground. and by a form which may beillled with a core of suitthen removing the mandrel from the shell. able material, such as concrete, to form a pile. Furthermore, we have discovered that the driv- 30 It is therefore the principal object of the presing of a tapered pile shell with a tapered mandrel 30 ent invention to provides tapered, tubular', metal by initially radially expanding the shell and shell having a cap or -nose on its small end, to thereafter driving the Shell into the ground may provide a tapered, substantially rigid, longitubestbeaccomplished when alongitudinallyribbed, dinally continuous, driving mandrel,l to provide corrugated or iluted, tapered, tubular metal Shen the shell with longitudinal ribs, corrugations or is utilized. However, if a tapered shell is to be 35 flutes, to telescope the mandrel within the shell so driven, care must be taken to avoid the usual in line contact with the ribs, corrugations or flutes dimculty of removing the mandrel from the shell, and in engagement with the shell nose, to drive which is experienced in drivingl tapered pile the mandrel and shell into the ground to the shells, because of a tendency of the shell to come 4@ desired depths, to then remove the mandrel, and up with the mandrel. 40 to then preferably nil the shell with a core ci A number of prior methods or constructions suitable' material, such as concrete, to form a have been proposed for overcoming the tendency pile, of a pile shell to come up with the mandrel which We have discovered, that if a longitudinally has been used to drive the shell into the ground,

ribbed, corrugated or iluted. tapered, tubular which include among others, the utilization of 45 metal shell is driven into the ground by a slightly collapsible and longitudinally sectional mandrel f larger tapered, substantially rigid', driving manconstructions. However, such mandrel construcdrel, that initially the mandrel is telescopically. tions which have heretofore been used are obwedged into the shell .and radially expands the Jectionable because of the initial high cost of the o0 shell substantially throughout its length until the same, because of the injury or wear to which the 50 lower end of the mandrel engages 'the shell nose, numerous interconnected parts are subjected by thereby establishing contact by the mandrel with the blows of the pile driving hammer, and bey all oithe shell flutes throughout their entire cause oi time lost inmaking repairsto suchvconlength; with the result that the driving force structions. Stillanother mandrel construction thereafter imparted to the mandrel is uniformavoids some ot these diiliculties, but frequently lo causes pulling out or failure of the shell nose when the mandrel is being stripped from the shell.

' We have discovered that if a substantially rigid, preferably longitudinally continuous, tapered, driving mandrel having a radially expansible and contractable,` preferably 'longitudinally continuous, shell engaging member is utilized for driving .a tapered, tubular, metal pile shell into the ground, an initial radial expansion of a shell whether or not it is longitudinally ribbed, corrugated or iluted, together with the attendant advantage-s thereof, may be obtained; and/or the mandrel may be readily removed from any type of tapered tubular pile shell driven by such a mandrel without in any manner dislodging the pile shell from its driven position in the ground, thereby overcoming the difficulties heretofore experienced in the use of prior mandrel constructions.

It is therefore a further object of the present invention to provide a tapered, substantially rigid, driving mandrel having an expansible and contractable shell engaging member for driving a tapered, tubular, metal pile shell into the ground, or for driving a tapered, longitudinally ribbed, corrugated or fluted, tubular, metal pile shell into theground. l

These and other objects may be obtained by the elements, combinations, structures, methods and apparatus, lpreferred embodiments or steps of which are hereinafter claimed, and described in detail, and are likewise shown in the drawings, in whichz Figure 1- is a diagrammatic view, partly-in section, showing the improved pile driving apparatus withA the improved mandrel inserted in a longitudinally fiuted, tapered pile shell, ready to radially expand the pile shell;

Fig. 2 is a view similar to Fig. 1, showing the pile shell driven to the desired position in the ground;

Fig. 3 is a. view similar to Figs. 1 and 2 showing the position of the members of the improved mandrel after the mandrel driving member has been partially withdrawn from the mandrel sleeve member to permit contraction of the sleeve member;

Fig. 4 is a sectional view through the mandrel and shell taken on the line 4-4, Fig. 1;

Fig. 5 is a sectional view similar to Fig. 4, taken on the line 5-5, Fig. 2;

Fig. 6 is a sectional view similar to Figs. 4 and 5, taken on the line 6 6, Fig. 3;

Fig. 7 is an enlarged fragmentary view of certain of the parts shown in Fig. 4, also showing in dot-dash lines the position of the same parts as shown in Fig'. 5;

Fig. 8 is a'. longitudinal sectional view of the pile shell shownvin Figs. 1 to 7, after it has been driven into the ground;

Fig. 9 is a longitudinal sectional view of the pile shell shown in Fig. 8 filled with concrete to form a pile;

Fig. 10 is a view similar to Fig. 4, but showing a slightly modified form of mandrel inwhich a solid driving member is utilized;

Fig. 11 is a view similar to Fig. 10, but showing the parts after the shell has been radially expanded;

Fig. 12 is a view similar to Fig. 4, but showing a modiiled form of shell in which inturned shell flutes are utilized;

Fig. 13 is a view of the parts shown in Fig. 12 after the shell has been radially expanded;

Fig. 14 is a view similar to Fig. 4, but showing another modified form of longitudinally corrugated pile shell;

Fig. 15 is a view of the parts shown in Fig. 14 after the corrugated shell has been radially expanded;

Fig. 16 is a view similar to Fig. 4 showing a still further modified form of longitudinally ribbed shell;

Fig. 17 is a view of the parts of Fig. 16 after the longitudinally ribbed shell has been radially expanded;

Fig. 18 is a view similar to Fig. 4, showing another modied form of shell;

Fig. 19 is a view similar to Fig. 4, showing still another modied form of shell; and

Fig. 20 is a view similar to Fig. 4, showing the improved mandrel used for driving a plain shell.

Similar numerals refer to similar parts thoughout the drawings.

Referring to Figs. 1 and 4, a tapered, tubular pile shell is generally indicated at I8, and is preferably, but not necessarily, formed of light gauge sheet or strip metal, to provide, when driven into the ground, a form which may be filled with a core of suitable material, such as concrete, to form a pile. The shell I8 is preferably provided, on its lower end, with a nose boot I8 and a nose cap 20; and the shell I8 is also preferably provided with longitudinally continuous, preferably outturned reinforcing flutes 2 I. The shell I8 may be any desired length, and because of its taper,it readily penetrates the ground and may therefore be readily driven to the necessary depth.

A usual pile driver may be utilized for driving the shell into the ground, and the same may include the tower frame 22, a frame 23 slidably mounted in the tower frame and a hammer unit. The hammer unit comprises a steam cylinder 24 sldably mounted in the frame 23, a hammer base or core 25 suspended from the cylinder by the rods 26, and a reciprocable hammer plunger 21 guided for recprocation on the rods 26 and connected with a piston in the cylinder 24 by a piston rod 28.

The improved driving mandrel includes an inner, one-piece, tapered, substantially rigid, longitudinally continuous, preferably tubular, driving member 28, provided with a nose and connected with the hammer base 25 by a suitable sling 3|; and the improved mandrel also includes an outer one-piece tapered, split-sleeve, resiliently expansible and contractable, longitudinally continuous, shell-contacting member 32 telescopically mounted for longitudinal movement on the inner member 29.

The split-sleeve member 32 is preferably provided at its' upper end with a split-reinforcingring 33. Means is provided limiting longitudinal movement of the outer mandrel member 32 on the inner mandrel member 29, as by providing a cross arm 34 which passes through the upper end of the split-sleeve member 32, at 35, and is secured thereto as by a pin 36 and a bolt 31. The cross arm 34 is adapted to be reciprocated through the length of the cross arm slots 38 in the upper end of the inner mandrel member 25.

The cross arm 34 is also adapted to be connected to or to be engaged by the lower end of the frame 23, as at 39, for the purpose of stripping the mandrel from the shell I8, as will be later described.

In the operation of driving a shell I8 in the ground, the frame 23 with its contained hammer ing through the sheaves accepts l unit is raised to the top of the derrlck tower with the improved mandrel projecting therefrom. 'l'he shell I8 is then placed under the mandrel and the mandrel is lowered to the position shown in Fig. l, when the outer split-sleeve mandrel member 32 is telescoped within the shell it, and

. the lower end of the outer mandrel member 32 rests on the shell nose cap ld.

.The driving operation is then commenced by operation of the steam cylinder lill so that the operation or-the hammer 2l drives the inner mandrel drivingmember 29 longitudinally.telescopically into the outer split-sleeve mandrel member 32 until the nose 30 ol the inner mandrel member 29 contacts with the nose cap 20 of the shell I8, and-until the hammer base 25 contacts with the upper ring end 33 of the split-sleeve member 32. vThis driving operation radially expands the split-sleeve member 32 from the position shown in Figs. 1, 4 and 'l'. to the position shown in Fig. and shown in dot-dash lines in Fig. 'l'. Y The radial expansion ol the split-sleeve member 32 causes a widening of the open slot indicated at 140 in Fig. 4, between the adjacent edges of the,,slit in the sleeve member 32 so that the open slot has a width as indicated at t0n in Figs. Zand 5.

Meanwhile, vthe radial expansion oi' thesplit sleeve member 32 causes a radial expansion of the walls of the pile shell I 8 because of the tact that the shell I8 is longitudinally corrugated; with the result that the corrugations 2| become slightly shallcwer as indicated at 2Ia in Fig. 5, and in dot-dash lines in Fig. 7. The radial expansion of the shell IB is accompanied by the establishment of substantially complete contact by the mandrel with all of the shell flutes throughout their entire length, so that driving `force thereafter imparted to the mandrel is uniformly transmitted to the shell throughout the entire length o1' the shell.

The hammer 2lfis then operated to drive the shell I8 and mandrel into the ground to the desired depth, as indicated in Fig. 2. Thereafter, the mandrel is strippedfrom the shell by applying a pulling force to the cable 4l, which, operat- 42 and 43 vapplies an upward pull to the mandrel driving member 29 through the cylinder 24, the rods 26, the hammer base 25, and the slingl; which upward pull reacts against the mandrel sleeve member 32 through the medium of the frame 23 and the cross arm 34. Thus, the upward pull on the cable di causes a relative stripping motion to be imparted to the mandrel members'25 and 32, whereby the inner driving member 29is axially moved relative to and partially withdrawn from the sleeve or shell engaging member 32 until the position 'of the parts shown in Figs. 3 and d is reached, so as to release the expanding pressure oi' the driving member 29 on the shell engaging member 32; whereupon the lower ends of the cross arm slots 38 of the inner mandrel member 29 engage the cross arm 34 and the mandrel members 29 and 32 are removed in unison from the shell i8.

.as the mandrel driving member 285 is being partially withdrawn from the resilient 'splitsleeve member 32, the split-sleeve member 32 may contract radially to the position shown in Figs. 3 and 6 of the'drawings and engagement thereof with the shell lil is thereby releaaed sa that the removal of the mandrel from the shell it does not pull the shell up; but the shell remains in situ in the ground at the place-or to which it was driven.

Thereafter, other pile shells may be driven by the pile driver and mandrel; a pile shell I8 driven to the desired position in the ground being shown in Fig. 8. Subsequently, if desired, the pile shell I8 may be illled with suitable material such as concrete 42 to form a pile indicated at 43 in Fig. 9. It should be understood, however, that the pile shells I8 are not necessarilyiilled with concrete, but are only so iilled incase they are made of thin gauge material. It the material from which the shell .I8 is made, is a heavy gauge material,l such a shell may be driven into the ground in the manner described above; and may thereafter serve directly as a pile, in the manner which may also beillustrated by Fig. 8.

While the improved driving mandrel has been described as preferably comprising a tubular in ner driving member 2s, it is understood that such mandrel innerdrlving member may be a solid member, as shown in Figs. 10 and 11 at 23a; the

location in the position which they assume after the mandrel has been fully telescopically wedged into the shell I8 to radially expand the shell.

Referring to Figs. 12 and i3, the shell Ita to be driven into the ground may be provided with Inturned longitudinal flutes 2i' rather than outturned flutes as shown in Figs.l l to 10 inclusive;

.cally wedged into the shell I8a to radially expand the shell and provide shallower iiutes 2Ia'.

Likewise, referring to Figs. 14 and l5, in certain the mandrel has been fully telescopically wedged into the shell llc to radially expand the shell and form shallower ribs 2Ic'.

Referring to Fig. 18, there is shown therein another form of shell I8d provided with longitudinal panels 2id, which may be readily driven by the improved mandrel having the mandrel driving member 29 and the mandrel split-sleeve member 32; and referring to Fig. 19, there is shown therein another modled form of improved shell I 3e provided with longitudinal panels RIe connected by outturned longitudinal ribs 2Ie', which may also be readily driven by the improved mandrel consisting of the mandrel driving. member 29 and the mandrel split-sleeve member 32.

And iinaily, referring to Fig. 20, mandrel comprising the mandrel driving member 29 and the mandrel split-'sleeve member 32, may

the improved be utilized for driving a plain, tapered pile shell IU. The improved mandrel upon being initially inserted into the shell will accommodate the shell |8f even if the shell is slightly out of round, or slightly off taper. Although there may be no considerable radial expansion of the shell If, excepting to a slight extent as by a stretching of the metal shell walls for accommodating an out of round or an oil' taper shell, or one which otherwise does not match the mandrel; nevertheless, the use of the improved mandrel for driving a plain tapered shell If permits easy removal of the mandrel from the shell after the shell has been driven.

The terms rigid or substantially rigid or solid utilized herein as distinguished from collapsible or longitudinally sectional, refer to mandrels having sufficient rigidity and strength to be driven into the ground and/or removed therefrom without failing under normal working conditions; the terms one-piece or integral utilized herein with reference to mandrels, mandrel members or shells, refer to elements which may be originally made oi' a plurality of pieces` and permanently joined together in any suitable manner so that they may be driven or sunk into the ground as unitary structures; and iinally, the terms ribbed, corrugated, panelled, and iluted are used herein more or less synonymously, it being understood that in referring to a iluted shell, herein and in the claims, the same is intended to include shells which are either ribbed, corrugated, panelled or iluted,l or are otherwise susceptible to being radially expanded.

- We claimzl. A method of setting piles, including the steps of utilizing a tapered, iluted, tubular, metal shell; securing a nose to the small end of the shell; utilizing a substantially rigid, longitudinally continuous, tapered mandrel; pulling the shell into the ground by driving the mandrel against the nose while normally maintaining the mandrel within the shell in contact with the bases only of .the flutes; removing the longitudl` nally continuous mandrel and leaving the shell in situ to form a pile shell; and filling the shell with a core.

2. A method of setting piles, including the steps of utilizinga tapered, tubular, metal shell having outturned longitudinal flutes; utilizing a substantially rigid, longitudinally continuous, tapered mandrel; telescoping the mandrel within the shell and contacting the mandrel with the bases only of the outturned flutes; driving the mandrel and shell into the ground; removing the longitudinally continuous mandrel and leaving the shell in situ to form a pile shell; and filling the shell with a core.

3. A method of setting piles, including the steps of utilizing a tapered, tubular, metal shell having outturned longitudinal flutes; securing a nose to the small end of the shell; utilizing a substantially rigid, longitudinally continuous, tapered mandrel; pulling the shell into the ground by driving the mandrel against the nose while normally maintaining the mandrel within the shell in contact with the bases of the outturned utes; removing the longitudinally continuous mandrel and leaving the shell in situ to form a pile shell; and filling the shell with a core.

4. A method of setting piles, including the steps of utilizing a tapered, tubular, metal shell having inturned longitudinal flutes; securing a nose to the small end of the shell; utilizing a substantially rigid, longitudinally continuous.` tapered mandrel; pulling the shell into the ground by driving the mandrel against the nose while normally maintaining the mandrel within the shell in contact with the apexes of the inturned flutes; v

removing the longitudinally continuous mandrel and leaving the shell in situ to form a pile shell; and filling the shell with a core.

5. A method of driving a pile shell, including the steps of utilizing a tapered, fiuted, tubular, metal shell; utilizing a substantially rigid, tapered, driving mandrel; radially expanding the shell throughout its length by driving and telescopically wedging the mandrel into the shell; then driving the shell and mandrel into the ground; and then removing the mandrel from the shell and leaving the shell in situ in the ground.

6. A method of driving a pile shell, including the steps of utilizing a tapered, iluted, tubular, metal shell; providing a nose on the small end of the shell; utilizing a substantially rigid, tapered, driving mandrel; radially expanding the shell throughout its length by telescoping and Wedging the mandrel into the shell until contact is established between the mandrel and all of the shell flutes throughout their entire length, and until the lower end of the mandrel engages the shell nose; then driving the shell and mandrel into the ground; and then removing the mandrel from the shell and leaving the shell in situ in the ground.

'7. A method of driving a pile shell, including the steps of utilizing a tapered, fluted, tubular, metal shell; utilizing a substantially rigid, tapered, driving mandrel having an expansible and contractable shell engaging member; driving and telescopically wedging the mandrel into the shell to radially expand the shell engaging member into engagement with the shell and to thereafter radially expand the shell throughout its length; then driving the shell and mandrel into the ground; and then removing the mandrel from the shell by ilrst axially moving the driving mandrel relative to the shell engaging member to release the expanding pressure of the driving mandrel on the shell engaging member and thereafter withdrawing the mandrel and its shell-engaging member from the shell to leave the shell in situ in the ground.

8. A method of driving a pile shell, including the steps of utilizing a tapered, fluted, tubular, metal shell; providing a nose on the small end of the shell; utilizing a substantially rigid, tapered, driving mandrel having an expansible and contractable shell engaging member; driving and telescopically wedging the mandrel into the shell to radially expand the shell engaging member into engagement with the shell and to thereafter radially expand the shell throughout its length until the lower end of the mandrel engages the shell nose; then driving the shell and mandrel into the ground; and then removing the mandrel from the shell by iirst axially moving the driving mandrel relative to the shell engaging member to release the expanding pressure of the driving mandrel on the shell engaging member and thereafter withdrawing the mandrel and its shell engaging member from the shell to leave the shell in situ in the ground.

9. A pile vshell driving mandrel. including a tapered, substantially rigid, longitudinally ccntinuous, driving member; a tapered, split-sleeve. shell-contacting member telescoped over said driving member and mounted for longitudinal movement thereon; and means limiting longiabsents tudinai movement of said sleeve member on said driving member.

l0. A pile shell driving mandrel, including a tapered, substantially rigid, longitudinally con-Il tinuous, driving member; and a tapered, longitudinally continuous, expansible and contractable, split-sleeve, resilient, metal, shell-contacting member telescoped over said driving member;

said sleeve and driving members being mounted for limited relative longitudinal movement.

1l. A pile shell driving mandrel, including an inner, tapered, substantially-rigid, driving member; and an outer, tapered, resiliently expansible and contractable, longitudinally continuous, split-sleeve member mounted on the driving member.

l2. A pile shell driving mandrel, including a one-piece, tapered, rigid, driving member; and a one-piece, tapered, resiliently expansible and contractable, split-sleeve member mounted on the driving member.

13. Apparatus for driving pile shells, including a tapered, substantially rigid, driving mandrel adapted to be inserted in a pile shell, said mandrel having an inner, tapered, driving member and having an outer, tapered, resilient, splitsleeve member mounted on the driving member; means for telescoping the driving member within the sleeve member for radially expanding said sleeve member to establish contact throughout the length thereof with the pile shell and for thereafter driving the shell into the ground; and means cooperating with said last mentioned means and the sleeve member and driving mem-- ber for applying oppositely acting stripping forces to said mandrel sleeve member and said driving member and for thereafter removing said mandrel from the shell.

11i. Apparatus for driving pile shells, including a tapered, substantially rigid, driving mandrel adapted to be inserted in a pile shell, said mandrel having an inner, tapered, driving member and having an outer, tapered, resilient, split-sleeve member mounted on the driving member; means engaging the driving member for driving the driving member into the sleeve member to radially expand said sleeve member to establish contact throughout the length thereof with the pile shell; said means thereafter also engaging the sleeve member for driving the shell into the ground; means cooperating with the engaging means and the sleeve member and driving member for applying opposltely acting stripping forces to said mandrel sleeve member and said driving member to release engagement of the mandrel with the shell; and said last mentioned means including means for removing said mandrel from said shell.

oi the shell ilutes; means for driving the shell inte the ground, including driving head initially eontacting with the mandrel driving member to drive the same inte the mandrel sleeve member to expand the sleeve member and the shell, and said driving head thereafter contacting also with said mandrel sleeve member to drive the shell into the ground; and means cooperating with the driving means and the mandrel for removing the mandrel from the shell.

16. Apparatus for setting piles, including a longitudinally fluted, tapered, tubular shell; a ta pered, longitudinally continuous. driving mandrel having an inner, rigid, tapered, driving member and an outer, tapered, expansible and contractable, split-sleeve, shell expanding member in contact with the bases only of the shell flutes; means for driving the mandrel and shell into the ground; means cooperating with the driving means and the mandrel for applying an upward pull on said mandrel driving member reacting against said mandrel sleeve member to partially withdraw the driving member from the sleeve member and permit contraction lof the sleeve member for releasing engagement thereof with the shell; and said last mentioned means including means for removing the mandrel from the shell.

17. Apparatus for setting piles, including a longitudinally fluted, tapered, tubular shell; a tapered, longitudinally continuous, driving mandrei having an inner, rigid, tapered, driving member and an outer, tapered, expansible and contractable, split-sleeve, shell expanding member in contact with the bases only of the shell flutes; means for driving the shell into the ground, including a driving head initially contacting with the mandrel driving member to drive the same into the mandrel sleeve member to expand the sleeve member and the shell, and said driving head thereafter contacting also with said mandrel sleeve member to drivethe shell into the ground; means cooperating with the driving means and the mandrel for applying an upward pull on said mandrel driving member reacting against said mandrel sleeve member to partially Withdraw the driving member from the sleeve member and permit contraction of the sleeve member for releasing engagement thereof with the shell; and said last mentioned means including means for removing the mandrel from the shell.

18. The method of driving a pile shell, including the steps of utilizing a tapered, radially expansible, tubular. metal shell; utilizing s. substantially rigid, tapered, driving mandrel; radially expanding the shell throughout its length by driving and telescopically wedging .the mandrel into the shell; then driving the shell and mandrel into the ground; and then removing the mandrel from the shell and leaving the shell in situ in the ground.

CHESTER A. 0.

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