US2332168A - Concrete pile and method of sinking it - Google Patents

Description

0a. 19, 1943. I H, G, G, G, RICHES 2,332,168

CONCRETE PILES- AND METHOD OF SINKING THEM Original Filed Nov. 17. 1959 ZSheets-Sheet 1 Oct. 19, 1943. c s

CONCRETE PILEs AND METHOD 0E SINKING THEM Original Filed Nov. 17. 1939 2 Sheets-Sheet 2 Fig. 5.

Pat ented oct. 19, 1943 CONCRETE PILE AND METHon F SINKINGIT HarryQGorklonYGeor -e Greatorex Riches, Singafpore, Straits Settlements, assignor to Shaw 'Darbyaz Company Limited Original application November 17, 1939, Serial No. 305,034. Divided and thisapp ication May 16,

1941, Serial No. 393,8 .vember 22, 1938 In Great BritainNoF 6 Claims. (01, 61-56) 1 t This invention relates 'to concrete piles and to I methods. of sinking them andis'a division of my co-pending application Serial No. 305,034, filed November 17, 1939.

, There are two methods of sinkingconcrete piles in commonuse at present, namely driving precast piles by impact and casting the piles in situ. Eachpossesses"disadvantages. Another known method, not in CQIIlIIlOHI-USB, comprises using a tube which is driven into the ground, so as to form a socket for a precast pilegw hi'ch is lowered into the tube, the tube being..subsequently removed, The end of the tube may'be'clcsed bya loose shoe during the driving. An'iniportant .ob-, ject of theinvention .is to provide such improvements-in this last method as .to render it superior to ,eitherfof themethods in common use. Another object of thisfinventi'on to provide an improved method ofand means for centering a pile in a tube or other preformed Icavity;

Yet another object is to improve the resistance of concrete piles to corrosion.

Other objects of the invention will appear as the description proceeds, reference being made to the accompanying drawings, inwhich:

Figure 1 shows the upper part of a pile during the sinking process;

Figure 2 shows a wedge member used in the process;

Figure 3 illustrates a method of supporting the upper part of another pile during the sinking process;

Figure 4 is a cross-section on the line IVIV in Figure 3; I

Figure 5 shows the pile of Figure Batthe end of the sinking process; and

Figure 6 shows another pile during the sinking process.

When precast piles are being lowered, there is a considerable risk of the pile being displaced out of the vertical or correct position while grout poured around it is setting. There is also a tendency for partof this grout to be forced out of the annular space around the. pile owing to the ground closing in on the pile. To avoid this,

according to one feature of this invention a rigid grout 33. The inner surface of the ring need not fit thepile exactly, Forlexample, as shown, the ring may be a .trueirustum ofja cone, as shown in Figure 2, and thefpile maybe polygonal. .It isto-be understood that the ring may be polygonal-and that the word ring includes any shape that is essentially annular; l I

In certain circumstances" it may be "desirable to use more thanlone ring, these being driven in ontopfof each other, for the purpose of increasing. theirictio'nal value of-the pile by successive ramming and consolidation of the wet concrete,

or ,for the purpose of building up'a greater bearing surface at the head of the pile, or to reinforce each joint. j 1 I ,A ringmay be usedwith advantage in' soft or swampy ground, where the cement grout greatly increases'the frictional resistance between the pile and'the ground and increases itsbearing ca pacity. .Insuch ground, however, 'thegrout would be largely forced out of the space if it were not for'the provision of the ring, This ispa'rtly' due to the natural pressure of the earth which tends to return to its previous position, but when a number of piles are driven simultaneously or at short intervals of time a more important factor comes into play. The impacts set up by the driving of neighbouring piles build up pressure waves which are transmitted to a very considerable distance. When a pile is being driven within this distance of a pile which is surrounded by unset grout, the latter is forced upwards and would be almost completely ejected from the space were it not for the presence of the ring, which in effect seals the space. Th ring also serves the purpose of fixing the positionof the head of the pile in the soft ground and ensuring that the pile remains vertical and in its correct position. I

It is, of coursedesirable to center the pile accurately in the tube while it is being lowered,'and for this purpose the pile may be provided along its length with resilient projecting members which engage the inner walls of the tube and hold the pile centrally in the tube. These members may consist of short lengths of spring metal which project from and are partly embedded in the concrete of the precast pile. By using such members, it is possible to guarantee that the pile will be vertical.

.Figures 3 to 5 illustrate the use of such projecting members. Figure 3 shows the upper part of the pile I being lowered into a tube 15, which has first been sunk, the bottom of the tube being closedby a loose shoe not shown. Springy steel members 3| are embedded in the pile and project outwards from it, and as the pile is lowered these members engage the tube and become bent upwards.

After lowering the pile, cement grout is poured down into the space between the pile and the tube, after which the tube is extracted, the shoe being left behind. More grout may then be added to fill the space vacated by the tube. Fig-e ure 5 shows the pile after these operations have been performed. The members 3 have sprung out into their original positions relative to the pile, and so serve to bond the shell of grout firmly to the pile. The irregular surface formed on the shell of grout offers very great frictional resistance with the ground, so that the resulting friction between the pile and the ground is correspondingly improved.

If desired, the methods of Figures 1 and 2 on the one hand and Figures 3 to 5 on the other hand may be combined. To allow a wedgeshaped ring to be driven down easily, the springy projecting members may be omitted at the top of the pile, as shown in Figure 6. 'This figure shows the stage after the tube has been withdrawn; a wedge-shaped ring 30 is being driven aroundthe top'of the pile.

. Certain soils have a Very corrosive action on ordinary concrete or cement; this may be due to the presence of acid in the soil or of chemical waste. When concrete piles are driven in this type of soil there is danger of the buried pile .being attacked and disintegrated; this is espeshown at 32 in Figures 3 to 5. When the pile is lowered into the tube, there is no danger of the anti-corrosive layer being removed or damaged in the process, as in the case with impact-driven piles. The continuous anti-corrosive coating 32 protects the main pile, even if any outer shell formed by grout should be corroded in parts.

The piles used in the invention may be hollow, although they are preferably solid as shown.

. I claim:

1. In a method of sinking a concrete pile, the

steps which comprise lowering a precast pile into a preformed cavity, pouring grout into the space around the pile in the cavity, and driving a liquid sealing and centering ring downwards around the pile into permanent embeclment in said grout. 2. In a method as claimed in claim 1, the use of a ring wedge-shaped in cross-section.

3. In a method of sinking a concrete pile by sinking a tube in the ground, lowering a precast pile intosald tube, and subsequently withdrawing said tube, the steps which comprise pouring grout around the lowered pile and driving a rigid sealing and centering ring downwards around the pile into permanent embedment in said grout.

5. A precast concrete pile provided with a plurality of resilient projecting members adapted to center said pile in a tube, said parts being constructed and arranged so as to be under compression in the tube.

5. A precast pile as claimed in claim 4, having an anti-corrosive coating through which and beyond which said projecting m'embers pass.

6. A precast pile having a plurality of short lengths of resilient metal partly embedded init and projecting from it to act as centering means on said pile being lowered into a tube, said parts being constructed and arranged so as to be under compressionin the tube.

' H. G. G. G. RICHES.

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