US2050216A - Apparatus for testing the point bearing capacity of a driven pile shell - Google Patents

Description

APPARATUS FOR TESTING THE POINT BEARING CAPACITY OF A DRIVEN FILE SHELL E. D. WATT Aug. 4, 1936.

Original Filed April 5, 1955 2 Sheel'xs-Sheetl l INVENTOR. EZ/Lu/ 0; WQ

/J/f ATTORNEYS.

Aug. 4, 1936. E. D. WATT APPARATUS FOR TESTING THE POINT BEARING CAPACITY OF A DRIVEN PILE SHELL 2 Sheets-l-Sheet 2 Original Filed April 5, 1935 0 m w 4 y h y I .a I II t m I, 7 O 7 A q A a O 4 o 8 3 a 2 9 a 2 M, a 4 3 l u w w `m w \V\\\\\\*\\ \\V g/) \\\\\\\\\\\N\\\\\\\\\\\\ \\\\\W W 0 lNvENToR. Ehh@ Wal/ ATTO EN EY'.

Patented Aug. 4, 1936 pairs!) STT-iras PATE NT LFIIC E APPARATUS Foa TESTING TII-E POINT BEARING oAPAcrTY oF A DRIVEN PILE SHELL @riginal application April 5, 1933,"Seral No.

Divided and this application August 3i, i934, Serial No. '742,457

8 Claims.

This application is a division of my co-pending application, Serial No. 664,517, and pertains to the manufacture of concrete piles in which the thin, comparatively delicate shell used as a permanent mold for the concrete is surrounded and protected during the driving operation by a heavy tubular casing which is subsequently removed.

An object of the present invention is to disclose apparatus for testing the point resistance of the shell after driving, and prior to filling it with concrete.

Further and other objects and advantages Will be apparent from the specification and claims, and from the accompanying drawings Vwhich illustrate what is now considered the preferred embodiment of the invention.

Fig. l shows a shell casing and driving core at conclusion of the driving operation, the v'driving core being provided With a drop hammer within its lower end.

Figs. 2 and 3 show modifications of the lower end of Fig. l.

Fig. 4 is a view similar to Fig. 1, but with a hydraulic plunger in the driving core in place of the drop hammer.

Fig.5 lshows a modification of the lower end of Fig. 4.

Thepile shell, designated 28, is provided at its lovver end with a Welded-on sheet steel boot 22, and the casing is'designated 28. The casing is provided at its upper end with a ring 38 having hooks 82 adapted for engagement by links 34 hanging from the drive head. During the driving operation collar 36 is in Contact with the under surface of the drive head and after the driving is finished, hooks 32 serve as convenient means for engaging the casing to Withdraw it from its position about the shell.

Boot 22 is provided near its top with a circumferential bead 33 and above the bead is an angle ring i6 fitted as shown snugly around the top of the boot. The bottom of casing 28 engages ring 46 as shown and the ring serves during driving to prevent entrance of material between casing and shell. Also, during driving, ring 4i! serves as a plow in advance of the casing.

After the driving operation is iinished, the drive core and casing may be withdrawn, leaving shell 26, boot 22 and ring 46 in place. During withdrawal, any attempt of shell 26 to follow the casing and core is usually prevented by engagement of the surrounding earth with ring 46, which in turn engages bead 38 on the boot.

During the driving of a pile shell by the method described above, two kinds of resistance are encountered, one being the friction of the casing, and thev other being the pointbearing or resistance of theA boot, or bottom of the shell. After the pile isy completed, the carrying capacity represented by the point bearing remainsjbutfthe friction of thefground on the sides of thepile may be largely-lost, due tothe fact-'that the Withdrawal of the casing leaves a void between shell `vand ground, and the void may not completely applying a knovvnforce to the boot/'afterit is1 driven. One method is shown in Figs.-1, 2 and 3, in which a drop hammer; 58'is inserted in the bottom part of the drive Vcore 52, the -.top of the hammer contacting with'shoulde'r 54 ofthe core. After the driving operation is nished, the core is raised possibly two or three feet and the hammer is operated .by means of cabley 56 passing over 'sheave'58 in drive head' 59, the' driving core actingv as a guide for the hammer. If the bearing capacity of the pointbe found insuiiicient, the drop hammerj may be loperated until suitable 'carrying' capacity is obtained. VThe' drop hammer Ymay also be used to'assist in holdingU down the shell during Withdrawal of core and casing. The

Jharn'm'eris"`iinall'y withdrawn' by its cable' 56.

Fig. 1 shows both drop weight and core in contact with boot 22, thus permitting the hammer to contact with a very limited area of the boot.

Fig. 2 shows a modicaion permitting greater contact between hammer and boot. Shell and boot 60 are attached to a step ring 62, and the hammer 64 is so shaped as to bear on the step ring as Well as on the inner surface of boot 60. During the driving operation core 66 is raised to serve as a guide for the hammer.

Fig. 3 shows a modification in which an anvil 68 remains in contact with boot 60 and step ring 62, the anvil being driven by hammer 10. The anvil is connected to the hammer by a pin 12 having a head 14 with which split collar 16 (fast in the hammer) engages when the hammer is raised out of the shell.

Figs. 4 and 5 show the use of a hydraulic plunger to test the point bearing capacity of the pile and also to lift the core and casing by reaction against the point of the shell. During the driving operation the parts are assembled as in Fig. 4, shell 20, boot 22, casing 28, bead 38 and angle ring 40 being the same as before. In this modication, however, the drive core 80 is bored to receive a plunger 82 adapted to be forced downwardly relatively to the core when fluid under pressure is admitted to space 84 between plunger 82 and drive head 86. For convenience, plunger 82 is usualy hollow, and its lower end has a head 88 seating in concrete 90 with which boot 22 is filled (Fig. 4). A modfied arrangement of plunger head is shown in Fig. 5, in which no concrete is used in the boot, Contact being made directly with the boot by a suitably shaped head 92.

After driving, fluid is forced through passage 95 into space 84. This fluid tends to lift the core and casing and to force the shell further into the ground. If the friction between ground and casing, aided by a load placed on drive head 86, is sufficient, the force acting downwardly on the point will be sufficient to impose a satisfactory test load (as measured by a pressure gauge) on the pile point. If the point resistance is below requirements, the shell can be pushed down by the plunger until suicient point resistance is obtained. Core and casing. are finally raised by still further increasing the uid pressure or by removing load from the drive head, or both. This reaction arrangement eliminates all possibility of the shell rising while core and casing are being withdrawn.

The plunger is withdrawn into the core by cable 94 passing between shell 20 and core 88 through a passage in head 88 or 92 and over sheaves 96 in drive head 86.

It is to be understood that the invention is not limited to the specific embodiments herein illustrated and described, but may be used in other ways without departure from its spirit as dened by the following claims.

I claim:-

1. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, means for applying a known downward pressure on said boot, and means for preventing contact of the shell with the surrounding ground while said downward pressure is being applied.

2. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, means for hammering downwardly with known force on the inside of the boot, and means for preventing contact of the shell with the surrounding ground while said hammering is taking place.

3. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, cornprising in combination, a drive core within the shell, a drop hammer in said core, a casing surrounding the shell, and means for dropping said hammer onto the inside of said boot.

4. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, a hammer within the shell, guide means for said hammer, a casing surrounding said shell to prevent contact of the shell with the ground, and means for applying said hammer to the inside of said boot.

5. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, a drop hammer within the shell, a drive core within the shell and serving to guide said hammer, a casing surrounding said shell, and a cable attached to said hammer and passing upwardly through said drive core whereby said hammer is applied to the inside of said boot.

6. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, hydraulic pressure means for pressing downwardly on the inside of said boot, and a casing surrounding the shell to prevent contact of the shell with the ground while the pressing operation is taking place.

'.7. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, a drive core within the shell, a plunger slidable vertically in said core, a casing for keeping the exterior of said shell out of contact with the ground, said plunger being adapted to be pushed by iiuid pressure downwardly against the inside of the boot.

8. Apparatus for testing the point bearing capacity of a driven pile shell having a boot, comprising in combination, a drive core within the shell, a plunger slidable vertically in said core, a casing for keeping the exterior of said shell out of contact with the ground, said plunger being adapted to be pushed by fluid pressure downwardly against the inside of the boot, and cable means for withdrawing said plunger upwardly into said core.

ELIHU D. WATT.

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