US2924948A - Pile - Google Patents

Description

L. MUELLER Feb. 16, 1960 PILE 5 Sheets-Sheet 2 Filed July l2. 1955 L. MUELLER Feb. 16, 1960 PILE 5 Sheets-Sheet 3 Filed July 12, 1955 L. MUELLER Feb. 16, 1960 PILE Filed July 12. 1955 5 Sheets-Sheet 4 L. MUELLER Feb. 16, 1960 PILE 5 Sheets-Sheet 5 Filed July 12, 1955 2,924,948 Eatented `.Feb-16s. .1960

r"ice United States Patent@ tions rip open the outer wall'of thehollow space at various points, `thuscausing an irregular formation of bulges in the concrete jacket, by which the` loading capacityI of f the pilel is increased to` aconsiderable extent.

The invention will be described further, by way ofexample, with reference tothe accompanying drawings, in which:

y Fig.l. is a. secti onal elevation of a pile constructed in accordance with the invention, driven into the ground and `enclosed up to the topwith concrete,

Fig.. 2,is' a. front,elevationf of the pile, to an enlarged scale,

Fig. 3` is a longitudinal section through the pile, Fig. 4 is a,plan..view of the pile,

Fig..5 isa Across-section taken ontthe line 5 of Fig. 3,

Fig. 6 is a cross-section taken on the line6-6 of Fig. 3, '.FigA `7../,is a cross-,section Vtaken on the.line 7-7 of Fig. 3,

Figs. 8.and` 9 are a vertical longitudinal section and a plan viewwrespectively of a furtherembodiment of the invention,

, Fig..10 is afragrnentary .longitudinal section` of afurther -form,of pilefhavingan inserted ramming shaft,

Y, Eig. 11.isacross-section.through the pile head taken on the line 11-11 of Fig. 10,

Fig. `12. is .af'cross-sectionthrought the pile shaft at the s, PILE 5 Ludwig MuelleriMarbfurg (Lahn), Germany fg `Application July 12,-- 195,5;4 Serial, .cNQ y521,571 lclaims' priority, applicatimg Germany July'17g19s4 s mcnims. renal-57) 'Ifhis invention concerns'gpiles.

y Piles for building foundations areknown,` in` which the lowenend of theY pile shaft isfittelw .itl 1,.,a pile foot whose supper cross-sectional surfaceisgreaten than `the cross-seciqtion of Vthefhollow pile,shaft. VWhenwdrivingthe pile in, there is created .between theipile shaft ,and.:thesoil dis- ,.fplacedby the pilevfoot, a ho11ow.space y,which `simulta- A ,neously with the driving in of thepile is lfilled fromiabove with a ller such as gravel,- orI concrete, in, order to in- -crease the friction between Vthepileand they soil.

. lt-is-anobject of thejnventionto .provideapilesuitable for foundation purposes andL for. securing building yunits,

Vwhich pile ,may `also be driven without. .diiculty linto.the ground of afsite which is..interspersed with `largestones i orptherlargepbstructions to-the driving.,operation,.and ,whoselouter casing of.and: internal` llingnwithconcrete may be producedquickly, cheaply and reliably yinthe ,soil ofthe site immediatelyafterthe drvingoperation by i using:s i,rnple apparatus :foninjectingconcrete ,under-pres` ,sure.

. According to thepresentfinvention a pilefcomprises a hollow shaft,..and. a.wedges hapedfoo`t secured to @the lowerend of the4 shaft, the-,pppercross-sectionalarea of ggthe footl beinggreater thanthegcross-section 4ofthe hollow ,.shaftandi said foot-,being formed with outlet openings at i V-itstl tippen-,einds .whereby i concrete` mayifbe f forced 1 under from said outletspenings-fto. enter fromfbelow-intov1the .holiowzspacei which is produced-rareundthe pile shaft bei ,Y tweenthe latter` and the .compressedrsoil when thefpile is d1' iven i n,saidconeretefrisingfin saidfhollow space' around y thetpile shaft, whereby `owingto--tthe, high pressure of the .concreteftheisoilsnrrounding:the `hollow space is4 further compressede;` andV .the @hollow space is unevenlyf enlarged @corresponding to the -varying resistance ofY the: soilzstrata rth-rloughfwhich thefpile passes.

v The invention resultsl'in la,lsubstantialincreasef ofthe loading capacity'fofthepile, becausedthe concretevj'acket i, ,concrete jacket considerably` increases the bearing surface t thereof relative to the soil,'and on theother hand because owingwto the7 extensive compression" of the soill there is "created an increasedladhesivefriction between the soil and V f thegconcrete jacket.

j-According to ope convenient embodimentof the invention, wedgefshaped clearing projections are formed at spa-cedintervals on the outer walljsurfa'ce' of the pile shaft, by means of'which the hollow space formed around the 'shaft when driving in the pile is continually cleared of 'fsoil and Vstones entering-therein.' "Moreover, the projeclevel of` ardistancepieeand a pair ofV clearingprojections taken on the..l ine..12-12sof Fig. 10.

.-Fig..1.3 isla crosssection through the pile shaft directly aboverthe d isplacingpile foot, taken -on the line.13-.13 of Pig. .10.

, Fig. -14 is `alongitudinal section through the pilenfoot and parallel Vtothespileshoe,

`struction ofrrammingtshaft.

vAt the-l0we1-endl of-the hollowpile shaftl` of Figs .1

f: to 7:;` made. of steelfsectio'n, the-length ofwhich ischosen i to rcorrespond -with-the depth to which thepile isvto be ldriven andwhose cross-section is dimensionedto correspondewith the proposed-static stress which the pilevis inl5` or-rigidlyfconnected therewith=by `other means; a-.fpile tendedtokundergofthereis axially welded tothe pile shaft -ifoot 3. Y A7I?he.-.pile;-shaft la-maypconsist of a 4plurality of -steel` sections omonly'yofvan l integrally formed hollow '--steeh section.

A pileishoe Zisxedr in the pile-foot 3` axially of the @shaft 1 (weldedftherein), infsuchafnam-ien that` its obtuse npperl en d ahnteagainst the -.pile shaft 1, and itslower L. sharp. ed ge Jprojects-.freely downwards; from thepile-foot 3. .i By'formingthepilefoot in `this manner it is possible for .the pile,f.,while. beingdriven `intor split large stones vagainst which it. might-strike.

. The pilewfoot 3 -is ,composedeither of suitablyshaped t i steel flats or steel plates welded together as, in Figs. 2, 3

. the form of acasting'of a special steel.

and?, or, if alargenumberfof steelpiles are required for a foundation, it mayl alternatively be constructed in ,"Thepile footv sfof a hollow formation and wedgeshaped ins'uch a mannerthat'atleasttwq opposite faces Aof the foot project laterallybeyolnd;.thecross-section of the pile;` on either side to suchan' extent that between the pileshaft 1 rand,the""tW:olateral 'faces there are'ecreated several free cross=sectionalareasiQlfand Q2 `s iliicintly large to `allow, c'oncrete forced into" the fipile` topass i throught In the lateral faces there are'jalsoV conveniently i provided bores 'x1 throughjwhicli the concrete may' also pass from the pile foot 3 in a downwardl direction.

The maximum width y of the pile foot is determined by a general consideration of the type of soil in the stratas, taken singly and in combination, of the ground through which the pile has to penetrate when being driven At the upper end of the pile shaft 1, the pile head or hoop 6 of steel is welded on to the pile shaft 1. The pile head is bored in a longitudinal direction relative to the pile shaft -1, so that an inlet pipe for the com pressed concrete may be inserted therethrough and into the shaft 1.

Welded at spaced intervals into the hollow pile shaft '1 are distance pieces 4.4 These distance pieces 4 are also bored longitudinally relative to the pile shaft, so that the inlet pipe 5 for the compressed concrete may also be passed therethrough. Through the pile shaft 1 and the distance pieces 4 there are provided vertically of or.

inclined relative to the longitudinal axis of the pile shaft, bores Z1 and offset relative thereto, further bores Z2, through which the concrete may enter from the pile shaft 1 into the hollow space, between the shaft and the surrounding soil, caused by the displacement of the latter by the pile foot 3 when the pile is driven in.

Towards the upper end there is welded around the pile shaft 1 on the outsidethereof, a sealing gland or collar 9, the width and position of which below the upper edge of the pile also depends on the building foundation and the nature of the soil layers (stratification) through which the pile is driven.

The -compressed concrete inlet pipe 5 extends through the pile head 6 right down into the pile shaft 1 and may be rotated therein about the longitudinal axis common to both. Welded to the upper end of the inlet pipe 5 there is a pipe head 7, and provided between the latter and the pile head 6 is the annular packing ring 8. The inlet pipe 5 for the compressed concrete is interchangeable, i.e., it is not made individually for each pile, but for use with a number of piles of identical length and cross-section.

The mode of operation and the purpose of the present invention are as follows:

First of all, the steel pile, with the inlet pipe 5 for theA compressed concrete removed, is driven into the ground. When sinking the pile into the ground, the wider displacing pile foot 3 compresses the soil around the pile shaft 1, and by displacing the soil around the pile o1'- around the shaft thereof, it creates a more or less large hollow space. The latter generally has a cross-section which tapers towards the top, and experiments have proved that a pile foot 3 which is wedge-shaped on two vsides only, as illustrated in the drawing, clears an approximately equally wide hollow space around the pile shaft, although theoretically it would only be possible for a hollow space to be created over the wide faces of the wedge-shaped pile foot by displacement of the soil. Thus, in most cases it is sufficient for the pile foot 3 to be wedge-shaped on two sides only and not on four sides. Shortly before completing the driving operation at the last downstroke of the pile, the packing gland or collar 9 provided at the upper end also becomes effective to carry the soil from the upper edge of the hole made by the pile, which collapses when driving the pile in, along with it for a short distance, and thus compresses it to such an extent that a plug of soil is formed in the uppermost section of the hole, which plug seals towards the top the hollow space cleared by the foot 3 around the shaft 1 during the driving operation.

After driving in the steel pile, the inlet pipe 5 for the compressed concrete is introduced in the pile shaft 1 through the head 6, and with its pipe head 7 is urged against the head 6 by the interposition of a packing ring 8. Concrete is then forced into the pile through the inlet pipe 5 by means of known concrete injecting apparatus,fviz. at first only into the lower part ofthe pile.

Thus, the concrete fills the lower part of the pile shaft 1 and the pile foot 3 and is discharged from these through the areas Q1 and Q2, and also through the bores x from the pile foot 3 into the surrounding soil. The concrete thus forms a bulge as shown in Fig. 1, around the pile foot and the lower part of the pile shaft and then rises also with increasing resistance in the hollow space around vthe pile shaft 1. With the increase in pressure which Occurs, the inlet pipefor the concrete is turned through about 60, whereby the bores Z1 in the lower part of the pile shaft 1 are uncovered to allow the concrete to emerge from the pile shaft into the soil. If the operational pressure increases again, then the inlet pipe 5 is again turned through a certain angle. The concrete then emerges from the pile shaft through the bores Z2 and rises in the hollow space around the pile shaft up to the sealing gland or collar 9. With the supply pressure of the concrete at a low value, the inlet pipe 5 is slowly drawn out of the pile head 6, and the pile 1 itself is thus also filled internally. with concrete. The pile is now surrounded externally as well as internally by concrete, thus rendering corrosion of the steel impossible. At the same time, however, the concrete jacket around the steel pile considerably increases the loading capacity of the pile owing to the substantial increase of the rpile cross-section and the extensive wall friction which arises between the concrete jacket and the soil.

The step-by-step filling of the hollow space around the pile shaft 1 by means of the concrete injected through the bores Z1 and Z2 or additional bores not only ensures a complete encasing of the pile shaft 1 with concrete, but also promotes the formation of bulges in this 4concrete jacket, by means of which the loading capacity of the steel pile may in turn be increased to a not inconsiderable extent.

Only one inlet pipe 5 for the concrete is required for driving a plurality of piles of identical dimensions. It is not a component part of the steel piles themselves, but serves merelyto control the step by step injecting of the concrete into the steel pile and round same.

When driving steel piles of the type described herein into very compact and tenacious sticky soils such as fatty loam, clay and the like, for promoting the uniform formation of a hollow space around the pile shaft 1 (by the pile foot 3) smaller wedge-shaped displacing shoes are also on the narrow faces of the pile foot 3.

In theembodiment of Figs. 8 and 9 wedge-shaped clearing lugs 12 are mounted on the outer wall surfaces of the pile shaft at spaced intervals. These lugs 12 are located, in the embodiment shown in the drawing,` at those points where transverse openings of the pile shaft are provided. The lugs have an angular cross-section such that they cover the transverse openings in the manner of a roof. They prevent the entry of soil into the internal space of the pile, While the concrete forced in through the pipe 5 may emerge through the lugs which are open at the side.

On the upper part of the pile shaft 1 there is adjustably and detachably arranged a sealing member 14. The sealing member 14 is composed of two halves and carries a collar 15, which is clamped to the pile shaft by means of the connecting screws by which the two halves ofthe sealing member are connected.

The pile shaft of the embodiment according to Figs. l0 to 16 is formed from four steel angle bars 1a, which are interconnected by means of intermediate members Z4 acting as spacers. The uppermost intermediate member at the top end'ofk the pile shaft is formed substantially longer than the other intermediate members, for allowing a sealing member, e.g. the sealing member 14 described above with reference to Figs. 8 and 9 which is split longitudinally, to be fixed to said uppermost intermediate member. For forming a pile head there is welded to the upper end of the uppermost intermediate mem-ber 24 a reinforcing ring or hoop 6. 1n the loweraimaient most intermediate "niibr' "24," which extends -Linto '.-th pile foot-Sjther 'is"w`elded`a tliii'lst nieiber 17, onlwh'i'c'h 1s mounted `a hollow ramming "shaft" 18 inserted l'ir ltlie pile shaft when driving ithe'pile. Formed oneabove the other onthe pil`e"shft"tlere are Wedge-shaped clearmglugslZarran'ged in spaced relationship and staggered relative to one anotherf' 'Attachedtothe?` wedge-shaped plates forming the foot`3 `are"cl'eari'rig"lugs 19,"whicli prevent the soil from,entering-lthrbugh-'the lateral concrete outlet bores of the pile foot. The hollow foot 3 isl covered at" the top by measbftyl fsteel angle? members 20, so that soil simila`rly`4-cant `enter "the pile foot from above during the driving operation.

When driving in the pile, the pile driver strikes the ramming shaft 18 projecting from the pile head 6 and the former transmits the driving force to the pile shoe 2 and the pile foot 3 by way of the thrust member 17. The pile shaft formed by the four steel angle bars 1a and the intermediate members 24 are thus not subjected to a direct thrust, but drawn into the ground by means of the pile foot in the hollow space cleared in the soil by said foot and are consequently only subjected to tractive stresses.

When the pile has been driven in, concrete is forced under high pressure through the hollow ramming shaft 18, first of all into the hollow pile foot, and subsequently while withdrawing the ramming shaft 18 from the pile shaft in easy stages, into the latter and into the hollow space created in the soil.

In place of the annular intermediate members 24 provided on the pile shaft at spaced intervals, it is also possible to utilise a spiral reinforcement extending over the whole length of the pile shaft of round or flat or strip steel, which is electrically welded or connected in any other suitable manner with the section or round steel bars forming the pile shaft.

It is also possible to t on the upper end of the ramming shaft 18 which projects from the pile head, a tensioning device by means of which the pile shaft formed from light steel round sections may be stretched or pre-stressed after the driving operation has been completed. Again, thin steel round sections or steel wires may also be employed to form the pile'shaft, thus producing a kind of prestressed concrete in the pile when moulded with concrete.

The ramming shaft to be inserted in the pile shaft may also be produced from a solid section, e.g. a wide flange girder, as shown in Fig. 17. It is possible over the whole length of such a solid section ramming shaft to connect one or more concrete supply pipes 26, through which the concrete is supplied under pressure to the pile foot and the pile shaft.

I claim:

1. A pile adapted to be driven into the soil for permanent anchorage therein, said pile comprising a hollow shaft having an open trailing end for feeding concrete under pressure into said shaft, a hollow pile foot se cured to the leading end of the shaft, said end being the end to be driven into the soil, said pile foot having a peripheral outline larger in transverse cross-sectional area than the transverse cross-sectional area of said hollow shaft whereby a hollow space is progressively formed around the shaft as the same is driven into the soil, the trailing upper surface of said pile foot including an opening for the discharge of concrete from the pile foot into said hollow space, said hollow shaft having longitudinally spaced outlet openings for the discharge l of concrete from the shaft, and a sealing collar of larger transverse cross-sectional area than the transverse cross-sectional area of said shaft secured to the trailing end of the shaft encompassing said end, said collar being adapted to abut against the soil surrounding the shaft as the pile is driven to define a hollow enclosed space surrounding the pile shaft between said collar and said foot to cause intrusion of concrete into th" sen'surrunaingrrn @snffadiaeentto saines-einser space and to confine the concrete within theen'clbsed'? space aroundrthefpile shaft.. y p

2. The pile iaccordingmtc'claim'- `1 "wherein"`sid collar is displaceablet'along",and`detachablerfromsaid shaft.

3.. The pile according to claim l2 wherein said collar hasia circular'priphl "outline "and is comprised of two partsf each of" said"'prts "having elements coacting with"eachotli 'forsec'uring' the collar to the shaft'.

4. A pile ladaptedto"be driven into the soil for lpermanent 4anchorage therein', saidpilecomprising a hollow shaft' havinghn'hpe "trailing end, 'a hollow pile "foot secured to the leading end of the shaft, said end being the end to be driven into the soil, said pile foot having a peripheral outline larger in cross-sectional area than the transverse cross-sectional area of said hollow shaft whereby a hollow space is progressively formed around the shaft as the same is driven into the soil, the trailing upper surface of the pile foot including `an opening for the discharge of concrete from the pile foot into said hollow space, said hollow shaft having longitudinally spaced outlet openings for the discharge of concrete from the shaft into said space, said outlet openings being angularly displaced with relation to each other, a removable supply pipe for injecting concrete under pressure into the hollow shaft from the trailing end thereof, and a sealing collar of larger transverse crosssectional area than the transverse cross-sectional area of said shaft secured to the trailing end of the shaft encompassing said end, said collar being adapted to abut against the soil surrounding the shaft as the pile is driven to define a hollow enclosed space surrounding the shaft between said collar and said pile foot to cause intrusion of concrete into the soil surrounding the shaft adjacent to said enclosed space and confine the concrete within the enclosed space surrounding the pile shaft.

5. A pile adapted to be driven into the soil for permanent anchorage therein, said pile comprising a hollow shaft having an open trailing end for feeding concrete under pressure into said shaft, a hollow pile foot secured to the leading end of the shaft, said end being the end to be driven into the soil, said pile foot having a peripheral outline larger in transverse cross-sectional area than the transverse cross-sectional area of said hollow shaft whereby a hollow space is progressively formed around the shaft as the same is driven into the soil, the trailing upper surface of said pile foot including an opening for the discharge of concrete from the pile foot into said hollow space, said hollow shaft having longitudinally spaced outlet openings for the discharge of concrete from the shaft, wedge-shaped lugs of angular cross-section lengthwise of the shaft secured to the outside of the shaft opposite said outlet openings, said lugs forming roofs over said openings and having lateral apertures for permitting the discharge of concrete through the outlet openings, a sealing collar of larger transverse crosssectional area than the transverse cross-sectional area of said shaft secured to the trailing end of said shaft encompassing said end, said collar being adapted to abut against the soil surrounding the shaft as the pile is driven to define a hollow enclosed space surrounding the pile shaft between said collar and said foot to cause intrusion of concrete into the soil surrounding the shaft adjacent to said enclosed space and to confine the concrete within the enclosed space surrounding the pile shaft.

6. A pile according -to claim l and further comprising a shoe secured within said foot, said shoe terminating in a wedge-shaped cutting portion protruding beyond the shaft and the foot.

7. A pile according to claim 6 whereinsaid foot is taperedlengthwise of the longitudinal axis of the shaft, said cutting portion of the shoe protruding from the narrow ,end of the foot, the side walls of the f oot and References Cited in the le of this patent UNITED STATESIPATENTS 468,343 Holland Peb. 9, 1892 999,431 Beall Aug. 1, 1911 1,210,160 VFrankignoul Dec. 26, 1916 1,661,270 Ryder et al. Mar. 6, 1928 1,830,651 Frankignoul Nov. 3, 1931 1,983,428 Zeidler Dec. 4, 1934 8 Watrt .v. Nov. 16, 1937 Ranney Aug. 9, 1938 Newman Feb. 7, 1939 Gilstrap Aug. 8, 1939 Hood Dec. 25, 1945 Dresser July 9, 1946 Montague June 5, 1951 Taylor Aug. 19, 1952 FOREIGN PATENTS France Mar. 19, 1952 Switzerland May 1, 1954

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