CA1181603A - Apparatus for constructing cast in place tubular piles and method of constructing such piles by same apparatus - Google Patents

Abstract

Abstract The apparatus includes two tools for forming holes in the subsoil without oxcavating it, which tools being coaxially mounted on a drill column. To the end of the drill column there is attached a hollow tool which is concealed when a skirt is in a lower position and exposed when the skirt is in an upper position. A soil displacing body is mounted on the drill column and above the tool. The soil displacing body is a hollow structure and has an upper opening wherethrough its inner space communicates with a concrete feeding tube and a lower opening closable by the skirt in its upper position. To construct a tubular pile the apparatus is driven into the subsoil whereby a design hole is formed, then the apparatus is withdrawn from the hole with a simultaneous filling of the hole with a concrete mix through the concrete feeding tube, the soil displacing body, and the lower opening provided there-in. A ballasting material is concurrently fed through the drill column, out of the hollow tool, and into the space defined by the skirt, which, as the apparatus is being withdrawn, assumes a lower position to conceal the hollow tool and define a hollow in the concrete that has been laid in the tube.
The invention is useful in constructing cast in place tubular piles in loose and water-saturated soils.

Description

Field of the Inventi.on The present invention relates to apparatus for constructing cast in place tubular piles and to a method of constructing such piles by the same appara-tus.
Description of the Prior ~rt There is known an apparatus including a drill column, a hollow soil displacing tool having a helical ribbon surface and a tip portion, the hollow soil displacing tool being provided with a tubular soil dis-placing body received therein and having projections on its upper portion while the same soil displacing tool being also provided with slots on its inner surface for cooperation with the projections of the tubular soil displacing body, besides the apparatus being provided with a skirt axially movable along the drill column and having an outer helical ribbon surface on its upper portion.
The prior art apparatus suffers from a disad-vantage of an inadequate scope of its application as regards the construction of the cast in place tubular piles because difficulties are involved in lowering the apparatus true to center into a hole previously formed by another tool and filled with a concrete mix.
Known in the art is also a method of construc-ting a cast in place tubular pile, which bears closelyon the

- 2 - ' ~a~ 3 in~ention (USSR Invell-tor~s Certifica-te No. 777,144), where in a ca~ing i9 driven i~to the subsoil~ the casing being compo~ed of a number of concentrically ~paced tubular mem-ber~ previously capped to~ether and havi~g a reinforcement arranged between the tubular member~.
~ he prior art method, however, suffer~ from di~advan-tages as listed below:
1. A low efficiency because of difficultie~ in dri-ving the ca~ing into the sub~oil due to a hi~h resistance from the sub~oilO
2. The .qoil i9 inadequa-taly compacted and over a~ in-sufficient area about the casing to insignific~ntly inc-rea~e bearing capacity of the casing ag~in3t the sub~oil.
30 ~he .Qurface of the ca~ing is not protected against the corrosive action of the subsoil water thereby the ca-sing i~ rapi~y destroyed~
4. The proposed method does not insure that the pile~
will be of acceptable quality becau~e gravel a~ well as the 90il iS likely to get into the spacing between the tu bular member3, since practi.cally the spacing cannot be re-duced to a 3ati~factory amount.
5. A limited length of the cast in place tubul~r pile~ is due to a high soil to casing re~istance, 6. A high power con~umption of the construction~
Th~ invention contemplates the provision of an appa-ratu~ for constructing ca~t in place tubul~r piles and to ~ method of con~tructin~ such piles by the same apparatus, which make it possible to enlarge the area and amount of the ~oil Compaction as well as to make the construction efficiency increased.

Summary of the Invention An object of the invention is to provide an apparatus ~or constructing cast in place tubular piles and a method therefor? which ensure a wider scope of application of a novel apparatus.
A further object of the invention i~ to provide an appar~tu~ for constructing cast in place tubular pile~ and a m~thod therefor, which ensure a larger area and a grea-ter amount o~ the soil compaction a~ well as a higher ef-ficien~-y in the pile construction.
According to the invention the appar~tus is provided with a hollow 80il displacing body co~nected to a concrete feeding tube, arranged a~iall~ with the soil displacing tool~ and having a cylindrical sizing portion, a lower portion defined by an outer helical ribbon surface termi-nating in an opening closable by the skirt, and an upper taped portion, besides, the hollow s~il displacing body i9 immovably mounted on the drill column through a spider.
The outer ~urface of the upper portion is t~pering upward ~hile the ~kirt is mounted on the drill column to transmit torque. The skirt has an a~ial length ~ufficient to con-ce~l ~he ~oil displacing tool together with its tip por-tion when the skirt is in a lower po~ition.
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The invention also re3ideq in the provi~ion of a me-thod of constructing cast in place tubular pile3, wherein a hole is forrned by the apparatus of the inven-tion and as the same apparatus is being withdrawn the hole i9 ~illed wi.th concrete to form a tubular pile wi-th a hollow a~ially e~tending along ~ predetermined length of the pile, the ~tep of filling hole with concrete being carried out ahe3d of the step o~ forming a hollow in the concrete that has been laid in tho hole, and in order to protect the pile against eorrosion an outer shell i3 ~irnultaneously formed by displacing a corrosion resistant material into the hole ~all by the same apparatus, which material being fed into the hole mouth.
~ n alternative way of practiclng the method consists in that a corrosion resi~ting material is fed in-to the hol0 mouth Qimultaneously with the step of withdrawing the apparatus ~rom the hole and di3placed into the side walls of the hole by the same apparatu~ as it is withdra~Nn from the hole.

Brief Description of the Drawings Fig, 1 i~ a general view of -the apparatus;
Fig~ 2 i~ a ~iew ~imilar to that in Fig. 1 but repre-~enting an outer helical ribbon surface of the upper tape-re~ por-tion;
Figo 3 is a longitudinal ~ection throueh the appara-tu9 in the position of formi.ng a hole;

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Fig~ 4 is a sectional view -taken on the line 4-4 of ~ig. 3;
Fig. 5 i~ a sectional view taken on the line 5-5 of Fig, 3;
Fig. ~ is a se~tional view taken on the line 6-6 o:f ~ig~ 3;
~ ig. 7 is a sectional view taken on the line 7-7 of ~ig. 3;.
~ ig. 8 is a ~ectional view takan on the line 8-8 of ~ig7 3;
Fig~ 9 i~3 a longitudinal ~ection through the appara-tu~ in the po~ition of feeding a concrete mix and a balla~ting filler into tne hole;
Fig. 10 is a view of a hole in the process of its ~o r~at i OIl;
Fig. 11 iq the initial ~ta~e of forming a tubular pile in the hole;
Fi~ 12 qhows the proce3s of forming ~ concrete tubu-lar pil~ and filling the pile hollow with a ballasting;
~ig. 13 i9 a view of a completed tubular pile~

. Detailed Description of the Invention Refer~ing to Fig~ 1-3, the apparatus for construc-ting ca~-t in place tubular piles includes a helical tool as~embly mounted-on a drill column 1 and compri~ing a hollow ~kirt 2, a ~qoil displacing tool 3 wherein a tubu-lar soil dis" ~cing body 4 h~ving a tip portior 5 i~ ar-.
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ranged. Above the soil diqplacing tool 3 there iY a hollow~oil di4pl~cing body 6 mounted on the ~ ill column 1 and having cylindrical sizing portion 7, a lower tapered por-tion 8 having an outer helical ribbon surfaGe and termina-ting in an opening, and an upper tapered portion 9 connec-ted to a concrete feeding tube 10 (~ig. 4~ containing the drill column 1 coa~ially arranged within the tube 10. The upper tapered portion may have an outer helical ribbon 3urface, The drill colw~ idly secured to the cy-li~drical portion 7 inside the hollow Yoi1 displacing body 6 with the help of a spider 11 (~igs 4 and 5)0 The hollow soil di3placing body 6 i9 arranged coaxially with the 90il diqplacing tool 3. The skirt 2 at its upper portion where lt is joined with the drill column 1 i~ provided with a hollow cone 12 ~laving inner ~lot3 13 (Fig. 6) coacting with longitudinal ribs 1~ proviùeil on the outer sur-~ace of t~le dlill colul~n 1 for transmitting torque ~nd for axial movement. The tubular soil displacing body 4 i9 as~ociated with the soil displacing tool 3 through radial proJections 15 received in 310ts 16 ~Fi~. 8) provided on the soil di~-placing tool 3 whereby the tubular ~oil displacing body 4 i9 movable along the slots 16. The tubular soil displacing body 4 has an inner diameter equal to that of the drill column 1. The body 4 at. it~ lower portion i5 pro~ided with pouring port~ 17. The slots 16 limit the movement of the body 4 ~nd provide a means for opening and closing the pouring port 3 17 as well a~ prevent rotation of the body 4 ..

~bout the qoil displacing tool 3 during -the formation of the hole. When the ~kirt i~ in it3 upper po~ition (~igo 3 it closes the -through opening 18 in -the lower tapered por tion 8. Rotation o~ the skirt 2 about the longitudinal axis of the apparatu~ i3 precluded by the longitudinal ribs 14 received in the ~lots 13. '~hen the skirt 2 i~ in i-t~ lower po~ition (~`ig. 9) it conceal~ the helical ribbon ~urface o~ the tool 3, the ~kirt 2 being of the length ex-ceeding that of the tool 3 with tha tip portion 5 in an extended position~ When the skirt 2 i~ in it~ lower po~i-tion the through opening 18 is open. The helical ribbon ~urfaces of the tool 3~ the tip portion 5, and the tapered portion~ 8 and 9 of the ~oil di~placing body ~ have col~
lar~ or vaneq 19 providing a means for the apparatu~ to s~re~ it into -the sub~oil during the form~tion of a hole ~0 .
The method of the invention and the novel apparatu~
are put to use a3 follows. The drill column 1 together with the concrete feeding tube 10 both rigidly intercon-nected are rotated with a simultaneou~ axial thru~t, whe-reby the hole 20 (~ig. 10) is being formed, which i~ al~o en~ured by the helical ribbon ~urfaces and the vane3 19 provided on -the tool 3, the tip portion 5, and the lower tapered portion 8 of the qoil displacing body 6. At the time of hole formation the Qkirt 2 is tightly held in it~
upper po~ition (Fig, 3) and rotation thereof about the longitudinal a~i9 i9 checked by the slots ~hich are in .. . .

gear with the longitudinal ribs 14~ With the ~kirt 2 being held in the upper position, the through opening 18 in the body 6 is closed and the soil will not get in-to the body 6~ The lowermost edges of the ~kirt 2 in thi~ posi-tion~oinclde or are in register with the helical ribbon surfaces of the tool 3. The tubular body 4 is retracted and the pouring port~ 17 are closed.
~ ith the hole 20 completed a concrete mi~ 21 i9 ~Up-plied through the tube 10 and into the body 6. Then the apparatu~ i~ raised a predetermined amount (~ig. 11) and the concrete mi~ 21 forces the skirt 2 (gravity forces are also con~idered) into a lower po~ition to let the concrete mix 21 ~low into the hole 20 thus providing a bottom por-tion 22 o~ the tubular pile and further on a~ the appara-tUS i9 withdrawn ~rom the hole the concrete mix 21 flows through the tube 10 while a filler materi~l 23 flows through the drill column 1. The filler material 23 may include dry or water-saturated sand, a mor-tar containing clay and ~eighting additi~es and other 3uitable materials.
The filler 23 ~orces the body 4 to slide along -the slots 1~ into its extended po3ition whereby the pouring por-ts 17 are opened and the filler 23 flows into the hollow of the pileO In this case the skirt serves a~ a molding means which defines the walls 24 of the tubular pile and hold3 the ~iller 23 within the hollow thus formed. ~9 the con-creting proces~ ~nd the placing.of the filler 23 continue the skirt 2 togethor with the apparatus ascends. The skirt 2 holds the concrete mi~ 21 from intermixing with the filler 23 as they are fed into the hole. If it i~ desired to provide protectiYe shells 25 on the outside of the tu-bular pile, a ~uitable material 26 (Figs 12 and ~3) is fed into the hole as the apparatus is wit~;drawn~ Such ma-terial may be bituminou~ concrete, a compound ba~ed on a synthetic binder and the like. In -this case the ~pparatus is raised by rotating the same. The material 26 i3 digpla-ced into the hole walls by tha helical ribbon surfaces of the tapered portion 9 of the body 6~ In order to prevent raising of the material 26 from the hole 20 it3 la~er should be not less than 3 m, although this value can be corrected while constructing the first pile. This correc-tion is necessary in view of various diameters of the pi-les~ the thickness of the walls, the taper of the tool and the characteristics of the materisls used.
The inner diameter of the skirt 2 is found from the formula di = Dp - 2 $, where Dp i8 the diameter of the tubular pile;
d is ~he thickness of the wall 22 of the pile.
Utilizatio~ of the novel apparatus provides for an improv0ment in the ~daptability to the process of the con~truction o~ the cast in place tubular piles in the soil including loose and water-s~turated soils resulting in mud flow~ when the conventionai method of forming holes is utilized. The processes of forming holes and 6~3 con~tructing the pile~ are brought into coincidence ~nd the hollow i~ true to center.
The pile bearing capacity i~ improved because the piles are con~tructed in -the holes having compacted wall~
The apparatus makes it possible to construct tubular piles in protective outer shells such as corrosion resis-tant shells.
The corrosion resi~tant ma-terial~ may be bituminou~
concrete of various grade~ v~riou~ bituminou3 compou~ds based on polymeric materialsO .-C~-t in place tubular piles may have through hollow~.
In this c~se the hollo~ is filled with the ballast mate-rial ~rom the bottom.
~ n increase in the ~rea and the amount of 30il com-paction sround the pile is due to the f~ct that the pile has a cross-sectional area equal to that of the hole and the 90il i~ not excava-ted but di3pl~ced radi~lly of the hole, Al~o, an additional increase in the area and the amount o~ ~oil compaction i9 achieved due to the provision of the outer shell which is produced by di~placing a cor-rosion resistant material into the hole walls.
The ~ervice life of the ca~t in place tubular pile in a corrosive medium i~ extended due to the outer corro-~ion re~istant ~hell.
The efficiency i~ improved due to coincidence of the steps of hole formin~, c~3ting concrete to produce a pile and making &~ outer corro~ion re~i~tant ~hell while the - tl - -

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apparatus i~ in the hole~ The proce~3 of constructing a tubular pile i~ carried ou-t continuo-u~ly~
~ urthermore~ the hollow in the pile is forrned before the concrete sets since the concrete wall will not collap-se because the filler i~ ~ed into the hollow a~ soon as it is form2d.
The efficiency is 40 to 65~ higher than that of the con~entlonal methods.

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Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An apparatus for constructing cast in place tubular piles comprising:
- a drill column;
- a hollow soil displacing body immovably mounted on said drill column and having a cylindrical sizing portion, a lower tapered portion having an outer helical ribbon surface termi-nating in a first opening of a predetermined diameter, and an upper tapered portion terminating in a second opening;
- a concrete feeding tube attached to said upper tapered portion around the second opening of said soil displacing body;
- a hollow tapered soil displacing tool having an outer helical ribbon surface and attached to the end portion of said drill column below said soil displacing body so that the inner space thereof communicates with the inner space of said drill column;
- a tubular soil displacing body having a tip portion and a pouring port wherethrough the inner space thereof communica-tes with the inner space of the hole being formed in the sub-soil and of said drill column and arranged within said soil displacing tool for axial movement between an extended position to open the pouring port and a retracted position to close the pouring port with said soil displacing tool;
- a skirt axially movable along said drill column between a lower position to enclose said soil displacing tool and an upper position to dispose said soil displacing tool and to close the first opening in said hollow soil displacing body.

2. A method of constructing cast in place tubular piles comprising:
driving an apparatus as claimed in Claim 1 into the sub-soil to thereby form a required hole;
withdrawing said apparatus from the hole to simultaneous-ly carry out the following steps:
- filling the hole with concrete, forming the concrete being laid in the hole in a manner to define a hollow;
and - filling the hollow with a ballasting material, the step of filling the hole with concrete being carried out ahead of the step of forming the concrete laid in the hole in a manner to define a hollow.

3. A method as claimed in Claim 2 wherein a corrosion-re-sisting material is fed into the hole mouth simultaneously with the step of withdrawing the apparatus from the hole and diasplaced into the side wells of the hole by the same appara-tus as it is withdrawn from the hole.