US1775217A - Method of making piles in place - Google Patents

Description

Sept 9, l930- J. H. THORNLEY 1,775,217

METHOD OF MAKING PILES IH PLACE Filed Nov. 2, 1927 Patented Sept. 9, 1930 UNITED STATES PATENT OFFICE JOSEPH H. THORNLEY, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN FOUNDATION COMPANY, 0F CWICAGO, ILLINOIS, A CORPORATION OF ILLINOIS METHOD OF MAKING PILES IN PLACE Application filed November 2, 1927. Serial No. 230,434.

The present invention pertains to cast-inplace concrete piles and to an improved method of making the same. More specifically, the invention relates to that type of cast-inplace pile having an enlarged lower end or pedestal portion.

One of the objects of the invention is to provide an improved method of expanding or forcing the concrete outwardly at the bottom of the hole in the formation of the enlarged pedestal portion. According to this method of forming the pedestal portion, the expansive pressure is applied to the concrete in such manner that the major portion of the pressure acts laterally and downwardly, so that the reaction pressures of the soil against the pedestal portion will be in the proper direction for giving the maximum load bearing value to the finished pile.

Another object of the invention is to provide an improved method of bonding the column portion of the pile to the expanded pedestal portion. According to this method, the column portion of the pile has a socketed bonding in the pedestal portion of the pile, i. e., in the formation of the pedestal portion a vertical socket is formed therein in which the column portion of the pile is cast. In the preferred construction, the column portion of the pile comprises a corrugated tubular shell which extends down into this socket, whereby the corrugations of the shell establish an interlocking bond between the pedestal portion and column portion of the pile.

Other objects and advantages of the invention will appear in the following description of the preferred manner of carrying out my invention. In the drawing accompanying this description:

Figures 1, 2, 3 and 4 are vertical sectional views through the lower portion of the hole in which the pile is to be cast, illustrating successive steps in the formation of the pile; and

Figure 5 is a similar sectional view showing the lower portion of the completed pile.

The hole in which the pile is to be cast is sunk in any preferred manner such as by driving, jetting or digging, depending upon the character of the soil through which the `core to compact its mass.

operation is carried. The present invention 1s not concerned with the method of sinking the hole, 1t being desirable, however, that a suitable casing line the hole after its completion, such casing either being carried down progressively with the sinking of the hole or being thereafter inserted.

Referring to Figure 1, the hole is indicated at 8, and the casing referred to is indicated at 9. After the hole has been sunk to the desired depth, and with the lower end of the casing 9 sustaining the side walls of the hole against collapse, a charge of concrete 1l is dumped into the lower end of the casing. This charge is sufliciently large to form the main body of the pedestal portion. A ram or core 12 is then lowered into the casing to bring its lower end into contact with the charge of concrete 11. If desired, the charge may be tamped lightly a few times by the i The next step in the operatlon is illustrated in Figure 2, and consists in drawing the casing 9 upwardly to bring its lower edge into proximity to the lower end of the core or ram l2, meanwhile holding the core pressed downwardly against the top of the charge of concrete 11. The weight of the core will ordinarily be suiiicient to hold it down upon the concrete, but if there is any tendency for the core to rise with the casing such is overcome by holding a stationary abutment against the upper end of the core,'in a manner well known. As the casing is pulled upwardly, the concrete will expand outwardly into the space occupied by the casing, the ram 12 following the slight downward recession of the top of the concrete charge as this outward expansion takes place. Aj shown in Figure 3, the upper end of the casing is provided with the usual hoisting collar 13, with which any suitable hoisting tackle may be connected for lifting the casing. It will be evident that by thus lifting the casing and holding the ram in place, the pedestal forming charge of concrete 11 will be stripped out of the casing, remaining in the bottom of the hole 8 and coming into direct contact with the side Walls thereof. The density of the concrete will prevent any possibility of the sides of the hole collapsing inwardly during the lifting of the casing.

The next step in the operation is illustrated in Figure 3, and consists in forcing the core and casing downwardly into the charge of concrete, the core and casing operatingl as a unitary spreading or pressure member. To facilitate concurrent downward movement of the core and casing the upper end of the core is provided with a head 14 which is adapted to bear upon the hoisting collar 13 of the casing when the lower ends of the core and casing are in proximity to each other, as shown. 1n Figures 2 and 3.. By transmitting drivlng blows to the head 14 the core and casing will move downwardly as a unit through the engagement of the head 14 with the collar 13. In such downward movement, the charge of concrete will be crowded outwardly against the side walls of the hole 8, compressing the soil outwardly to enlarge the hole, and resulting in the concrete assuming the enlarged or bulb-shaped formation indicated at 11. 1n Figure 3. The descent of the core and casing is preferably limited so that they will not pass entirely through the concrete, but will leave a considerable thickness thereof at the bottom of the pedestal formation 11. The result of this ramming operation is to expand the concrete outwardly, as above described, and to produce a longitudinal socket 15 in the pedestal formation, which socket extends down axially from the top of the pedestal to a point adjacent to the bottom thereof.

Certain important advantages accrue to l this method of expanding the concrete. Heretofore, the practice most generally followed has been to confine a charge of concrete within the lower portion of the casing, and to force such charge down out of the end of the casing by downward movement of a ram within the casing. Sufficient pressure is exerted downwar-dly on the charge of concrete to compel it to flow out of the casing and to expand outwardly below the end of the casing into pressure contact with the earth walls, the fluid pressure of the concrete compressing the earth walls and enlarging the bottom of the hole sufficiently to produce the enlarged pedestal formation. This prior method is based upon a fluid iiow of the concrete, requiring a comparatively wet mix thereof, such fluid flow resulting in the pressure imparted to the charge being transmitted substantially equally in all directions. Hence a considerable part of the'pressure acts upwardly on the soil superposed over the pedestal formation, and, in consequence, the reaction of this superposed soil is downwardly, which detracts from the load bearing Value of the pile in so far as carrying compression loads is concerned.

Such objection is avoided in the practice of the present method. Owing to the fact that the expansion of'the concrete outwardly results more by virtue of the physical displace mass, there is very little tendency for the concrete to establish upwardly acting pressures against the soil superposed over the pedestal formatlon. The mechanicaldisplacement of the concrete creates outwardly and downwardly acting pressures therein, which establish reaction pressures in the soil acting inwardly and upwardly with respect to the pedestal formation, thereby giving a firm anchorage to the pedestal and giving a, maximum load bearing value to the pile. Moreover, the present method results'in the formation of a long socket in the pedestal, as above remarked, which socket is a desirable feature for anchoring the column portion of the pile, as I shall now describe.

After the core and casing have been driven down into the concrete to the desired depth, the core is withdrawn, leaving the casingwithin the pedestal formation in order to maintain the formation of the socket 15 against the inwardly acting pressure of the concrete. The next step in the operation is illustrated in Figure 4, and comprises lowering a light crete is dumped into the interior of the shell,

preferably to fill the same completely. Such additional concrete is indicated at 17 in Fig.

5. Preparatory to dumping this additional concrete, any suitable reinforcing means may be inserted in the shell, represented, for example, by the relatively heavy bar indicated at 18 in Figure 5.' The outer casing 9 forms no part of the completed pile, and is withdrawn either before the additional concrete 17 is dum ed into the shell 16, or after the shell has een filled with concrete. Where the soil is of such-character that it is possible that the earth pressure might collapse the light shell 16, itis, of course, desirable to retain the casing 9 in the ground as a protecting element until the light shell has been filled with concrete.

The withdrawal ofthe casing allows the concrete in the pedestal portion to move back into direct adhesive contact with the corrugations of the light shell. Thus as soon as the concrete sets the pedestal portion 11 has interlocking engagement with the shoulders 16 formed by the annular corrugations in the shell.v Similarly the concrete 17 within the shell has interlocking engagement with the inner shoulders formed, by the annular corruiso the column portion 17 have bonded engagement through the walls of the shell throughout the entire length of that portion of the shell which is embedded in the pedestal.

' Cementitious bonding will also occur between the lower end of the column portion and the lower stratum extending across the bottom of the pedestal portion. It will be observed that by forming the socketl in the pedestal portion, the reinforcing means 18 can be' extended down into the body of the pedestal portion so that the stresses transmitted to this reinforcing Vmeans will be distributed throughout substantially the entire body portion of the pedestal.

It will be observed that at no stage in the operation of casting the pile is there any opportunity for sub-surface water to enter between the pedestal and the column, or for such water to enter or have contact at any other point where it might deleteriously aii'ect the casting of the pile. The long length of bonded joint between the column portion and pedestal portion gives a high tensile strength to the finished pile, and it will be observed that by extending the shell 16 down into the pedestal portion there is no possibility of upwardly acting earth stresses causing the column portion to separate from the pedestal portion before the concrete has set.

While I prefer to construct the column portion of the pile as a cast-in-place structure consisting of the shell 16 and concrete fillin 17, nevertheless it will be understood tha some of the advantages of the invention lcan be realized by constructin the edestal portion in the manner above escri ed and then seating a pre-cast concrete Eile, or any other type of completed pile wit 'n the socket 15 for bonding with the pedestal portion.

What I claim as my invention and desire to secure by Letters Patent, is

1. The method of forming cast-in-place piles which comprises de siting a charge of concrete in the hole in w 'ch the pile is to be formed in direct contact with the earth walls thereof, and ramming a core and casing down into said charge to expand the latter out wardly and to form a vertical socket within the expanded charge of concrete, which sc cket is retained against collapse by said casing when said core is withdrawn.

2. The method of forming' cast-in-place piles which comprises depositin a charge of concrete in the hole in contact with the earth walls thereof, ramming a core and .casing down into said charge for expandin the latter outwardly to form an enlarged estal portion having a vertical socket therein, withdrawing the core while said casing maintains the form of said socket, and completing the pile with the column portion thereof extendmg down into said socket.

The method of forming castinplace piles which comprises depositing a charge of concrete in the bottom of the holein which the pile is to be formed, ramminga core and casing down into the charge to ex and the latter outwardl around the outer sides of the casing in the orm of an enlarged pedestal portion, withdrawing said core while retaining said casing within said pedestal portion, lowering a shell within said casing to have its lower end extend into said pedestal portion, dumping concrete into said shell, and withdrawing said casing.

4. The method of forming cast-in-place piles which comprises sinking a hole in which` the pile is to be formed, extending a casing down into said hole adjacent to the bottom thereof, depositing a charge ofconcrete within said casing, raising said casing a predetermined distance to allow the concrete to contact directl with the earth walls at the bottom of the hole, driving said casing with a core therein down into said charge of concrete for expanding the latter outwardly andv to line the sides thereof substantially to the l bottom of said hole, dumping a destal forming charge of concrete intosai casing, placing a core within said casing to bear upon said charge of concrete, raisin said casing al predetermined distance whi e said core forces the concrete out of the lower end of said casinlg into direct contact with the earth walls at t e bottom of the hole, driving said core and casing downwardl as a unit into the charge of concrete, there y spreading the charge outwardl against the earth walls for producing an en ar ed pedestal portion and also formin a soc et extending down into said pedesta portion, withdrawing said corewhile retainin said casing its driven walls of said socket, lowering a corrugated shell within said casing to have its lower end extend down approximately to the bottom of said socket, placing reinforcing means within said shell, dumping additional concrete into the same for stantially filling said shell, and withdrawin said casing after said shell has been lowere into said socket.

JOSEPH H. THORNLEY.

substantially in sition for sustaining the side

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