US1998643A - Apparatus for constructing concrete piles - Google Patents

Description

April 23, 1935. J. H. THORNLEY APPARATUS FOR CONSTRUCT-ING CONCRETE P ILES Filed Dec. 14, 1932 2 Sheets-Sheet 1 & M.

April 23, 1935.

J. H. THORNLEY 1,998,643

APPARATUS FOR CONSTRUCTING CONCRETE PILES Filed Dec. 14, 1932 2 Sheets-Sheet 2 i? fiWM-m Patented Apr. 23, 1935 PATENT OFFICE APPARATUS FOR CONSTRUCTING CONCRETE PILES Joseph H. Thornley; Evanston, Ill. Application December 14, 1932, Serial No. 647,149

8 Claims.

The present invention pertains to apparatus for constructing concrete piles of the type wherein the concrete is cast in place in a relatively light tapered shell which has been previously driven into the ground by a tapered driving core. This core substantially fills the light'tapered shell and reenforces the same during the driving operation. After the core and shell have been driven down to the desired depth the core is withdrawn from the shell, leaving the latter in the ground. Thereupon, the shell serves as an outer form for excluding water and for retaining the sides of the hole open to receive the concrete, the shell remaining as a permanent part of the finished pile, in the form of a thin metallic sheath encasing the concrete shaft. Since there are as many shells required as there are piles to be cast in place, it follows that it is of extreme importance that these shells be of as low cost as possible, prefera-bly being of relatively light gauge metal.

It has, for many years, been common practice to construct cast in place concrete piles in this particular manner. Such difliculty has been experienced, however, in withdrawing the core from the tapered shell, because of the tendency of the shell to come up with the core. One prior method of freeing the core from the shell has been to make the core of collapsible construction so thatit can be reduced in size within the shell to facilitate its removal therefrom. This collapsible construction is, however, objectionable for several reasons, including the high initial cost, the rapid deterioration under the severe blows oi the pile driving hammer, and the time lost in makin repairs which are so frequently necessitated by the extreme service conditions.

It has also been common practice, for the past twenty years or so, when removing the core from the shell in pile forming apparatus and in steel pipe piles where a heavy shell of steel is used, to attach or anchor the upper end of the shell temporarily to the pile driver leads, as by means of struts or dogs engaging between the upper portion of the shell and the base portions of the leads, or by means of a cable sling wrapped around the upper portion of the shell and anchored to the leads, and thereafter to withdraw the core by taking the hoisting pull of the lifting tackle over the head block in the upper ends of the leads, whereby the reaction of this pulling force is transmitted downwardly through the pile driver leads and through the aforesaid struts, dogs or sling into the upper head portion of the shell,

so as to prevent the possibility of the shell beingv raised with the core. 7

It has not, in the past, been practicable to use this last described method for removing a core from a light gauge shell because these light shells have relatively small strength against compression stresses and hence if the reaction of pulling the core is applied to the head end of such a shell where it is borne solely by the compression strength of the shell, there is the likelihood of the shell buckling or crumpling under this strain.

The present invention aims generally to provide an improved tapered driving core and associated core removing apparatus which avoids the complications and objections residing in the prior collapsible type of driving core, and which hasparticular cooperation with the driving of thin shells or light gauge metal in that the core can be withdrawn in a convenient, expeditious. manner without distorting the light shell or otherwise subjecting it to stresses which it is not able or adapted to withstand. More specifically, it is one of the objects of the invention to pro-. vide apparatus which, in causing separation between the core and shell, will result in the reaction force being borne as a tension stress in the shell. That is to say, the reaction force incident to the upward pulling effort exerted on the core is applied not to the upper end of the shell, but rather to the lower end where it places. the entire shell under tension. For example, in the preferred embodiment of the present apparatus, this downward reaction force is trans-1 mitted through a long bar or push rod constituting the inner portion of the core, which push rod applies the reaction force to theflower closed end of the shell. By thus applying this downward pushing force to the lower portion of the shell, the entire length of the shell is maintained under tension stress during the separating operation, i. e., the reaction force is borne solely as a tension stress in the shell. While these light shells have a relativelyslow load bearing value in compression, they have an extremely high load. bearing value in tension, and hence they are well able to bear all of the reaction of the separating force, incidentto freeing the friction gripof the core therein, when this reaction force is sustained as'a tension in the shell. I

Other objects and advantages of theinvention will appear from the following detail de-, scription of, a preferred embodiment thereof. In the accompanying drawings illustrating such em-i bodiment:-

Figure l is a View of the apparatus as seenfrom the front of the pile driver leads, the light shell and the improved construction of core being fragmentarily illustrated in section;

Figure 2 is a fragmentary vertical sectional view taken approximately on the plane of the line 2-2 of Figure l; and

Figures 3 and 4 are views similar to Figures 1 and 2, illustrating a modified embodiment or application of the invention.

The light metallic shell, Within which the pile is subsequently formed, is indicated at 8. In the case of a relatively long pile, this shell may consist of a plurality of connected sections. The driving core 9, iii which fits within this shell is of two-piece construction, comprising the tapered outer body portion 9 and the reciprocable inner thrusting member iii. The shell 8 and the body portion 9 of the core preferably have substantially the same degree of taper throughout their contacting portions. The lower end of the shell 5 is preferably closed, and may have a rounded or square ended extremity H, as desired. A driving end head or button i2 is suitably secured to the lower end of the inner thrusting member if! for transmitting the driving force to the base end of the shell and also for transmitting thereto the downward pressure of the thrust member ii in the separating operation. The upper end of the shell 8 may, if desired, be reenforced by an external annular flange 53.

The upper end of the core body 9 carries a driving head M. The thrusting element in extends substantially the entire length of the core body 9. Said thrusting element is suitably guided for sliding motion in the core, and can be projected from the lower end i of the core body, substantially as illustrated in Figure l. The core body can be of solid construction, with an appropriate bore therein for the thrust member Iii, or it can be of relatively heavy hollow construction provided with suitable spiders or bearing hubs disposed at longitudinally spaced points in the core body for guiding the rod member In. The latter construction is shown, and the spaced spiders or bearing hubs are indicated at Hi.

In the preferred construction, the thrusting element ill serves as a driving element as well as a separating element. Accordingly, this thrusting element is made of heavy construction, preferably consisting of a heavy pipe. During the driving operation the upper end of this pipe abuts against the lower side of the driving head I4 and the end plug ii of said pipe abuts against the closed bottom of the shell 8. This pipe sustains the major portion of the driving force, and it might be constructed to sustain all of the driving force. Where the core body 9 is to sustain some of the driving force, the end lb of said body abuts against the end plug 52 during the driving operation. The bearing supports it prevent any sidewise buckling or bending of the pipe [0 during the driving and separating operations. The upper portion of the core body is provided with diametrically opposite vertical slots 51 through which passes a cross yoke or bar 58. The latter is adapted to transmit the downward reaction pressure to the thrusting pipe it! during the separating operation; such cross bar having any suitable connection with the pipe, represented, for example, by an eye or apertured loop portion l9 in the center of the cross bar. This eye or loop portion lies horizontally and the thrusting pipe It passes up through the aperture therein. Flanges or collars 21 secured to the pipe engage the top and bottom of the eye or loop portion l9.

After the shell and core have been driven to the desired depth in the ground, the core is released from this driving wedge grip with the shell by applying an upward pulling force on the head l4 and by applying a downward reaction force to the base end of the shell through the thrusting element i B which then serves as a push rod. The apparatus for exerting these separating forces comprises a series of upper sheaves 24 mounted in an upper sheave block 25, and a cooperating series of lower sheaves 26 mounted in a lower sheave block 27. A cable 23 is reeved successivelyv over these upper and lower sheaves, and has its one end operatively connected with a winch'and its other end suitably dead-ended, in a manner which I shall hereinafter describe. The tension transmitted to this cable from the winch exerts an upward pull on the lower sheave block 2? and exerts a downward reaction thrust on the upper sheave block 25. The downward thrust of the upper sheave block 25 is transmitted to the cross bar is through the instrumentality of a frame 3!. The vertical side rails 35' of this frame have suitable sliding engagement with the leads 32 of the pile driver tower. For example, these side rails 3 i may be formed with outwardly facing channel guides for engaging directly over the inner guide surfaces of the leads 32, or they may be formed with other forms of guide suraces for engaging with supplementary guide surfaces on the leads, separate from the inner surfaces of these leads. The upper sheave block is fixedly secured to the upper cross rail 3! of the frame 3!. The lower portions of said side rails 3! have operative connection with the ends of the cross bar 18 in any suitable manner. For example, this attachment may be effected by brackets 33 which are detachably secured to the side rails 3i. The lower portion or" each bracket is formed with a semi-cylindrical socket, and a 31 lower attachment clip 33' is formed with a matching semi-cylindrical socket. The ends of the cross bar are mounted in these sockets and each bottom clip 33' is detachably bolted to its upper bracket portion 33 for holdin the cross bar in place.

The lower sheave block 2'! is operatively connected to transmit an upward pull to the driving head M on the upper end of the core. In the preferred arrangement illustrated, this sheave block is operatively connected with said driving head [4 through the instrumentality of the pile driving hammer, generally indicated at 36, although it will be understood that said sheave block 21 might be attached directly to the head I4, during the operation of separating the core from the shell. The hammer unit 34 is adapted to slide vertically within the frame 38, and comprises the upper steam cylinder 35, the lower hammer base 35 and the reciprocating ram 37. Vertical guide rods 38 extend from the cylinder 35 down to the hammer base 85, and the ram 37 is guided for reciprocation along the rods. The impacting end 3'! of the ram 3? can be arranged to strike the core head It, or to strike the hammer base 35, or a member interposed between said impacting end and the core head. The cylinder 35 has outwardly extending side portions 35' and the hammer base 36 has outwardly extending side portions 35', which side portions 3 3' and 36' may be formed with guide surfaces for sliding contact directly with the inner sides of the frame rails 3!, or which side portions may be connected by a sub-frame slidably mounted within the frame 3|. In the illustrated construction,

l-y within the shell. After the core has beenlift the hammer unit 35 with these guide extensions 35, 36' also forms, in effect, an inner frame member or core releasing member guided for vertical movement within the outer frame structure 3!. Means are provided for transmitting an upward pull from the hammer base 36 to the core head l4, such being illustrated in the form of links or hooks 4! having operative attachment to the hammer base and to the core head. The range of upward movement of the hammer unit 34 within the frame 3! is limited bythe lower ends of the slots ll engaging the under sides of the cross bar arms [8.

In the operation of driving the shell, the frame 3! with its contained hammer unit 3 3 is hoisted into the top of the derrick leads 32, with the core 9 and its container push rod l0 depending therefrom. The shell 8 is then lifted into position between the hammer leads 32; and the core 9, i0 is lowered into the shell. Thereupon, the driving operation is performed by the operation of the steam hammer, the blows of the ram 3? driving the core and shell down into the ground. The tied connection between the core head 54 and hammer base 36 may be relied upon to guide the shell and core, or other supplementary guiding means may bearranged to assist in guiding the core and shell in their downward movement.

After the shell has been driven to the desired depth the core is separated therefrom by exerting a tension on the cable 28. The cable may be reeved in various ways so as to exert different separating forces between the core and shell, and so as to combine therewith, if desired, different lifting pressures on the core assembly. That end of the cable which is being wound around the winch, and which may be termed the pulling end, is designated 23a, and the other end of the cable, which may be termed the dead end, is designated 2817. A proper understanding of the invention will be facilitated by first assuming the cable to be reeved as illustrated in Figures 3 and 4, with the dead end 20b tied to an eye it or otherwise dead-ended either to the frame 3i or to the lower sheave block 21; and with the pulling end 28a extended directly from the top of one of the upper sheaves 24 in a more orless downward direction to the winch ll. Assuming-that the winch exerts a pull of 5000 pounds on the cable, it will be evident that the six strands or spans of cable illustrated as extending between the upper and lower sheaves and between the last lower sheave and the dead end connection will establish a force of approximately 30000 pounds tending to draw the sheave blocks 25 and 2': together. A separat ing force of 30000 pounds is thus effective tending to separate the core from the shell. With the cable reeved in this arrangement, a positive downward pressure will also be exerted on the core and on the shell, of a magnitude depending more or less on the angle which the pulling end 28a of the cable takes, in extending from the end sheave 24 of the top group downwardly to the winch ll. Assuming this strand of the cable to be substantially vertical, it will be evident that the cable will exert a downward force on the shell and on the core of approximately 5000 pounds. However, notwithstanding this downward force on both the shell and core, the strands of cable extending between the multiple sheave blocks are creating a 30000-pound force tending to separate the core from the shell. Assuming that this separating force is amp e to break the static friction of the driving wedge fit between the core and the shell, the core will thereupon move upwarded to a sufficient distance within the shell, where it is exerting no dragging friction on the shell, the hammer unit 34 can be locked in this elevated position within the frame 35 by any suitable locln ingmeans, such as by passing pins 48 (Figure 3) through lugs 59, 09 projecting from the frame rails 3i and from the hammer base 36. A separate tackle line 52, also shown in Figure 3, inde pendent of the cable 28, may now be utilized to lift the frame 3! and core 9, it] up into the hammer leads. This separate line 52 is shown as being dead ended to an eye 53 secured to the top of the slidable frame 3i, and passing over the head block 54- in the top of the tower and thence downwardly to any suitable winch or pulling mechanism #17 (Figure l) on the pile driver platform.

It will be seen that the foregoing arrangement and mode of operation provides means whereby a large separating force is established for breaking the static friction of the driven wedge grip of the core within the shell; also, that it provides means whereby the separating forces introduce no upward pull on the shell, since the reaction of the upward pull on the core is transmitted in a downward direction to the shell through the push rod l0. Entirely aside from the fact that the upward pull on the core is not transmitted as an upward lift on the shell but rather its reaction is transmitted as a downward thrust to the shell, there are other forces involved which transmit a positive downward force to the shell relative to the earth. These are the combined effect of the tension in the pulling end 28a of the cable, plus the weight of the hammer unit 34, frame 3i and core 9, l0. For example, if the downward force in the pulling end 28a of the cable is 5000 pounds and the weight of the hammer unit, frame and core is 10,000 pounds, the combined effect of the through the frame 3 5, cross arm l8 and push rod two, or 15,000 pounds, is acting downwardly through the frame 3 l cross arm l8 and push rod It to the base end of the shell. This operating arrangement is therefore of particular advantage in situations where it is desirable to have a heavy downward force effective on the shell during the core releasing operation, separate from and supplementary to the reaction of the core separating force.

In Figures 1 and 2 I have illustrated another preferred operating arrangement. In this arrangement, the secondary cable 52 is dispensed with, and the main cable 28 is extended from the end sheave of the lower group 26 directly up to the head block 54 at the top end of the tower, and thence downto the winch 41. In this arrangement, the compounded reeving of the cable over the upper and lower sheaves 24 and 2E creates, in the same manner previously described, the relatively large separating force which insures the breaking of the static friction between the core and the shell; The reaction of this separating.

force is, in the same manner, transmitted through the frame 3|, cross-bar l8, and thrust pipe down to the base end of the shell. That is to say, if there is a 5000 pound tension in the cable 23 and if there are five strands effective between the upper and lower sheaves, the separating force will be 25000 pounds if six strands the separating will be 30000 pounds, etc.; and the reaction of each of these forces will be downward on the shell. With reference to the secondary forces active between the shell and the earth, it will be evident that it is onlythe 5000 pound force in the strand of cable passingupwardly over the head block 54 that acts upwardly. But this force, relative to the earth, is opposed by the weight of the hammer unit 34, frame 3| and core 9, III, which, we have arbitrarily assumed for illustration, is 10000 pounds. Hence, there then remains a force of 5000 pounds acting downwardly on the shell relative to the earth.

For simplicity of description, I have shown only a single strand extending up over the head block 54. If the safe limit of tension which can be imposed on this single strand is not equal to the weight of the hammer unit 34, frame 3i and core 9, l0, it will be necessary to extend one or more additional strands between the head end of the tower and the frame or hammer unit to develop the necessary pull to lift the hammer unit, frame and core up into the leads after the static friction of the joint between the core and shell has been broken. According to one practice, the dead end 2% of the cable can be transposed from the eye 45 in the frame 3! to an upper eye 56 in the head end of the tower, after the static friction has been broken and preparatory to raising the apparatus into the tower; and, according to another practice, this dead end 28b may be left permanently connected to the upper eye 56 for both the joint breaking and lifting operations. In the operation of either of arrangements, after the static friction of the wedge fit is broken, permitting the core to move upwardly in the shell, the further winding in of the cable carries the hammer unit 34 upwardly until the bottom ends of the slots ll engage the cross yoke 53 and thereafter the hammer unit, frame and core move upwardly into the upper ends of the leads. It will be evident that by increasing the number of upper and lower sheaves E i and 26, the mechanical advantage of the apparatus can be increased to the point where the tension applied on cable 23 is relatively small, while still exerting a tremendous separating force between the core and shell. This may be utilized to develop extremely large separating forces with a cable or source of power of limited capacity, or may be utilized, during the joint breaking operation, to reduce the lifting tendency of any strand of cable extending up to the head end of the tower.

It will be seen that in each of the preceding embodiments, the reaction force of separating the core from the shell is transmitted through the push rod Hi to the base end of the shell where it establishes a tension in the shell. As previously mentioned, by thus having this reaction force borne in the shell as a tension stress, the shell is better able to withstand this force, even when made of relatively light material, and is better able to withstand the inwardly acting earth pressures, particularly at the instant of separation of the core from the shell. In transmitting said reaction force to the shell it will be noted the rod if! functions in the nature of a stripper or pusher for stripping the shell from the core member 9.

I have described what E regard to be the preferred apparatus and the preferred method for carrying my invention into effect, nevertheless it will be understood that such are merely exemplary and that numerous modifications, rearrangements, and different steps may be adopted without departing from the essence of the invention. For example, the same inherent features of the invention can be embodied in a construction wherein the outer tapered core element 9, instead of being a single solid unit from end to end, can consist of several sections, like the successive frustums of a long cone, with these sections connected together successively by lostmotion means such as chains, slotted links or the like, whereby the upper section is first released, then the next lower section and so on, all while the reaction of the upward pulling force exerted on these sections is transmitted through the push rod I3 to the base end of the shell 8. Within the purview of the invention is also included the use of hydraulic apparatus for breaking the friction wedge grip, represented for example by a hydraulic. cylinder connected between the top or" the cylinder 35 and the top of the frame 3! in lieu of the sheave blocks 25 and 23' and connecting strands of cable.

I claim:-

1. Apparatus of the class described for driving a pile shell into the ground and releasing itself therefrom, comprising a tapered core which is adapted to b inserted into the shell for forcing the same into the ground, said core comprising two parts, namely, pair of coaxial members relatively slidable with respect to each other for releasing the core from the grip of the shell, and means for producing relative sliding motion between said two parts, comprising two frame memthe first frame member being an open paral lel sided frame having its bottom connected to of said parts for transmit "lg thrust, the second fr me member being a sliding guided within J8 first frame member and being conr c-ted to second of said parts for transmitting on ad a cable and pulley connecting said members for drawing them towards each other and thereby sliding said coaxial core members with respect to ea-"h other for loosen the core from the grip of the shell.

2. Apparatus of the class described for driving a pile shell into the ground and releasing itself thei irom, comprising a tapered core which is adapted to be inserted into the shell for forcing the same into the ground, said core comprising two parts, namely, a pair of coaxial members relatively slidable with respect to each other for releasing the core from the grip of the shell, and means for producing relative sliding motion be tween said two parts, comprising two frame members, the first frame member being an open parallel sided frame having its bottom connected to one of said parts for transmitting thrust, the second frame member being a sliding bar guided within the first frame member and being connected to the second of said parts for transmitting tension, a pair of vertical ways in which said first frame member is slidably guided, and a cable and pulley connecting said two frame members for drawing them toward each other and thereby sliding said coaxial core members with respect to each other for loosening the core from the grip of the shell.

3. In apparatus of the class described for driving a tapered pile shell into the ground and releasing itself therefrom, the combination of a tapered core and a stripper adapted to be inserted into the shell for driving the latter into the ground, said stripper extending down into the pile shell to adjacent the lower end thereof and adapted to have contact with said shell, said core and said stripper being capable of relative longitudinal movement, and mechanism for releasing the friction grip between said core and said shell after the driving operation comprising an upper member disposed above said core and having pressure transmitting connection with said stripper, a lower member movable substantially vertically relatively to said upper member and having tension transmitting connection with said core, and block and tackle means connected to said upper and lower members and operative to cause relative converging motion therebetween.

4. In apparatus of the class described for driving a tapered pile shell into the ground. and releasing itself therefrom, the combination of a tapered driving core adapted to be inserted into the pile shell for driving the latter into the ground, a supporting structure comprising two substantially vertical spaced guide members extending upwardly substantially above said core, a sheave block mounted on the upper portion of said supporting structure, two vertically spaced core releasing members disposed below said sheave block, means establishing a pressure transmitting connection between the upper of said two members and said shell, means establishing a tension transmitting connection be tween the lower of said two members and said core, pulleys mounted on said members, and a cable reeved over said sheave block and extending down and reeved around said pulleys, said cable being operative to create tension for caus ing relative converging motion between said members in order to free said core from said shell and being thereafter operativeto raise said core and both of said core releasing members upwardly toward said sheave block.

5. In apparatus of the class described, the combination of a tapered driving core adapted to be inserted into a tapered pile shell for driving the latter into the ground, and mechanism for withdrawing said core from said shell after the driving operation comprising an upper member disposed substantially above said shell, a stripper operatively connected with said upper member and adapted to bear against said shell, said stripper constituting a pressure transmitting connection between said upper member and said shell, a lower member movable substantially vertically relatively to said upper member, means for transmitting tension from said lower member to said core, and rope and pulley means connected to said upper and lower members and operative to cause relative converging motion therebetween.

6. In apparatus of the class described, the combination of a tapered driving core adapted to be inserted into a tapered pile shell for driving the latter into the ground, and mechanism for withdrawing said core from said shell after the driving operation comprising guide means arranged substantially above said core, an upper member guided for substantially vertical movement by said guide means, a stripper operatively connected with said upper member and adapted to bear against said shell, said stripper constituting a pressure transmitting connection between said upper member and said shell, a lower member movable substantially vertically relatively to said upper member, means for transmitting tension from said lower member to said core, and rope and pulley means connected to said upper and lower members and operative to cause relative converging motion therebetween.

'7. In apparatus of the class described, the combination of a driving core adapted to be inserted into a pile shell for driving the latter into the ground, and mechanism for separating said core from said shell after the driving operation comprising an upper member disposed substantially above said shell and having pressure transmitting connection therewith, a lower member movable substantially vertically relatively to said upper member and having tension transmitting connection with said core, and rope and pulley means connected to said upper and lower members and operative to cause converging motion therebetween.

8. In apparatus of the class described, the com bination of a driving core adapted to be inserted into a pile shell for driving the latter into the ground, a frame disposed substantially above said shell and having pressure transmitting connection with said shell, a member movable within said frame and. having tension transmitting connection with said core, and block and tackle means connected with said frame and with said member for causing relative motion therebetween.

JOSEPH I-I. THORNLEY.

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