Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~040~376
ME~HOD 0~ ~AeING BUTT~--IN--PI~E ~EINFORC~D
CONCR~E PIIES
~ e invention relates to the ma~ufacture o~ structuralmembers, and more particularly, to met~ods of makin~ built-
-i~-place reinforced concrete piles~
~ he invention may be widely used in constructing pile
~oundations, consolidating earth slope~ and the like.
It is widel~ k~own to make built-in~place re~n~orced con-
crete piles by a method wherein a borehole is ~ormed in ~oil
b~ using any appropriate equip~ent, and t~e~ a reinforcement
i8 placed in the bore~ole. ~ubse~ue~tly, the borehole is fil-
led with concrete mix w~ich iB then po~itively compacted b~
means of vibrator~ to obtain a pile.
In making the borehole in soil, the borehole diameter is
Rlways determined by the desired diameter o~ t~e pile. As the
drill~ng oi vertical and inclined boreholes i~ always associa-
ted with the employment o~ cumber~ome equipment, the construc-
tion of large-diameter piles (more than 300 mm) i8 ~ery labour
consumin~ and completely exclude~ any opportunitg of work~n~
in d~fficultly accessible place~ (e-g- when m~king pile founda-
tions i~ expand~ng iactory buildings or on o~her sites occu-
pied by buildin4s, a~ well as in consolidating rail~a~ beds).
In addition, dur~ng the placing o~ concrete in the borehole
and compacti~g of concrete mix, the rein~orcement tends to be
displaced ~rom the design po~ition 80 that the load-carryi~g
capacit~ of the pile i5 con~iderablg reduced.
~k
.
., x,, ..,, ., - .
-
- . ..
` `" 1'~4~376
Ensuring the desired strength of structures to be
built requires the number of piles used to be increased, or the
piles to be made more bulky. -~
The present invention provides a method of making
built-in-place reinforced concrete piles which ensures the pro-
vision of piles having an increased load-carrying capacity and
allows working at any place, including difficulty accessible
sites, with the employment of mobile equipment.
The present invention also provides a method of making
built-in-place reinforced concrete piles having a maximum
possible load-carrying capacity which is especially important
in constructing pile foundations withstanding horizontal loads.
The present invention also provides a method of making
built-in-place reinforced concrete piles having an improved
corrosion resistance and prolonged service life.
According to the present invention there is provided
a method for making built-in-place reinforced concrete piles
J which comprises the following steps: forming a borehole in soil
with a diameter smaller than the diameter of the pile to be ;
built, placing a reinforcement in said borehole, filling the
borehole with concrete mix and subsequently repeatedly passing
_ a pneumatic mole through the borehole filled with the concrete
mix for enlarging the borehole to obtain the desired diameter
`'~
,:
`
_
_, '~ '' '
- 2 -
. : .
. . . .
.: .` : ` . ~ .
. .
,
1~4~)876
.
thereof, whereby the concrete mix and the soil around the
borehole are compacted in the radial direction.
The pile reinforcement preferably comprises a tubular
frame which is deformed in the transverse direction prior to
the installation in the borehole. The pile reinforcement
preferably comprises a reeled metal net.
In a preferred embodiment of the present invention
the internal cavity remaining after the extraction of the
pneumatic mole is filled with a concrete mix.
The invention essentially consists in the following.
Due to the fact that the compaction of the concrete mix in
the borehole is effected by repeatedly passing a pneumatic mole
therethrough, an intensive compaction of the concrete mix takes
place in the radial direction with respect to the borehole to
form a concrete envelope inside the borehole. While being
compacted, the concrete transmits the compacting force to the
soil in the peripheral zone of the borehole thus enlarging it.
This permits making a borehole of a considerably smaller diameter
as compared the design diameter of the pile so that light-weight
portable equipment may be used for that purpose. Thus, after
4 - 5 passes of the pneumatic mole through the borehole filled
with concrete mix having a diameter of 130 mm, a pile having
a diameter from 230 to 250 mm can be built.
1~14~876
Tllis in turll permits building reinforced concrete piles
in diLficultly accessible places.
I'he concrete mix, which is radially displaced during the -
~compaction, entrains the reinforcement, and, as the degree of com-
paction increases, secures it in the clesign position thus providing
for a high load-carrying capacity of the pile.
In certain applications, where pile foundations are to
withstand horizontal loads, the pile is reinforced with a cylindrical
frame. ~ frame may be laced or it may be made of a metal net. The
! ~ frames of such a shape should be deformed in the transverse direc-
tion prior to the installation in the borehole. Thus, laced cylin-
drical frames are simply compressed at the sides, and frames made of
a metal net are reeled. This provides for a more reliable and accu-
rate location of reinforcement in the design position and improves
the load-carrying capacity of piles withstanding horizontal loads.
Where piles are to be built in weak water-saturated soil
or in an aggressive environment, the internal cavity remaining after
the extraction of the pneumatic mole is filled with concrete mix to
seal the pile. This improves the corrosion resistance of the pile
~O and prolonye its service life. '~
The invention will now be described with reference to
s~ecific embodiments thereof illustrated in the accompanying draw- /~
ings, in which:
'~
~ ';
- 4 -
;,. , . :
,, ~,.
i~4lf~f~6
Figure l shows a longitudinal section of a borehole and
a reinforcement frame placed over the borehole;
- Figure 2 shows a longitudinal section of the same bore-
hole with the reinforcement frame deformed in the transverse direc-
tion installed in the borehole;
Figure 3 is a sectional view taken along the line III-III
in Figure 2;
Figure 4 shows a longitudindl section of the same bore-
hole after filling it with concrete mix;
Figure S shows a longitudinal section of the same bore-
hole duriny the coMpaction of the concrete mix; fp
E`igure 6 snows a longitudinal section of finished pile.
The method of making pile consists in the following.
First a borehole 1 (Figs 1 - 6) is formed in soil using
any equipment appropriate for that ~urpose, e.g. a pneumatic mole.
In accordance with the above considerations, the borehole
diameter is selected to be by 20 - 40~ smaller than the design dia- f'~
meter of the pile being built. Then the borehole 1 is filled with f~"
a dry concrete mix having a moisture content of up to 16% by weight, f -
and subsequently the mix is distributed over the borehole walls with
a single pass of a pneumatic mole to form a protective concrete
layer 2 therein. A reinforcement in the form of a tubular frame 3
is installed in the borehole 1 until the protective concrete layer ! .
has the time to set. f.;
The reinforcement frame may also comprise a net reeled
into tube or single rebars.
1~4~876
The frame 3 should preferabl~ have a larger diameter than
the diameter of tl~e initial borehole 1 by 15 - 30~. Prior to the
installation in the borehole 1, the frame is deformed in the trans-
verse direction so that it could pass into the borehole 1. After
the installation of the frame 3, the borehole 1 (Fig. 4) is filled
with concrete mix ~ (Figs 4 - 6) which is in~ediately compacted by
means of a pneumatic mole 5 as shown in Figure 5 wllich also expands
the initial borehole, the pneumatic mole penetrating the concrete
mix along the borellole axis in the space within the frame 3.
During tlle above-described compaction of the concrete mix
and concurrent expansion of the initial borehole, hence of the pile
body, the reinforcement is stretched in the transverse direction
along with the compaction of the concrete mix so that the design
positioning of the reinforcement in the finished pile is ensured.
Furthermore, the soil around the pile walls is compacted, the bore- -
hole walls are strengthened, and the pile body is pressed into soil
so that the cohesion between the outer surface of the pile and the
soil is improved. r . -
After the concrete compaction is completed, the pneumatic
mole 5 is reversed to withdraw it from the pile body. ~`
A cavity 6 (Fig. 5) formed by the pneumatic mole is again
filled with the concrete mix, and the pneumatic mole is passed sev- .
eral times until the design pile wall thickness is ~'~
.~ ~ ` ' '
~;
-- 6
' ,. .
1~4~3876
o~tained. Thus, the manufacture of the reinforced concrete pile is
completed.
The above-described method is used for making hollow piles.
In certain applications, where corrosion resistant piles
are to be ~uilt, the internal space of the pile is filled with con-
crete mix as shown in Figure 6.
`
.. ..
~:
., ': . '. .' ' ' ', . - ,;
