Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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S p e c i f i c a t i o n
A Reinforced Concrete Load-Bearing Pile with
Multi-branches and Enlarged Footings and
Means for Forming the Pile
This invention relates to a reinforced concrete load-
bearing pile, especially used for consolidating
foundations of buildings and bridges or other
foundations, and means and method for forming the pile.
Background of the Invention
Present foundations like driving piles, cast-in-place
piles, tree root-like piles, explosion piles and
caissons, have disadvantages such as weak load-
supporting capability, low stability, waste of material,
labor, investment and energy, etc. Especially in case
of complicated soft ground, the foundation tends to
settle wholly or unevenly due to the low load capacity
of the piles. That brings technical difficulty to both
design and construction.
obiect of the Invention
An object of an aspect of the invention is to provide a
reinforced concrete load-beaning pile with multi-
branches and enlarged footings for consolidating
foundations and means and method for forming such a
pile, to overcome the disadvantages in the prevailing
technique.
Summary of the Invention
A reinforced concrete load-bearing pile according to an
aspect of the present invention comprises a pile body,
at least one branch and enlarged footing which are
integrated with the pile body.
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Means for forming the load-bearing pile comprising a
pile cavity drilling/pressing device, a branch cavity
pressing device and an enlarged footing cavity pressing
device.
In forming a pile cavity for a load-bearing pile
according to an aspect of the invention, the pile cavity
drilling/pressing device is firstly used to form a main
pile cavity; the branch cavity pressing device and the
enlarged footing cavity pressing device are successively
used to form at least one branch cavity and enlarged
footing cavity; after the whole pile cavity is
completed, reinforcing steel bars may be placed into the
cavity and casting is carried out.
Other aspects of this invention are as follows:
A branch cavity pressing device for use in forming
cavities in a reinforced concrete load bearing pile,
comprising a base portion, a support means connected to
the base portion, and a means for consolidating earth
capable of being moved with respect to the support
means, the support having a guiding surface along which
the means for consolidating earth can move, for guiding
the means for consolidating earth into surrounding earth
to carry out consolidation.
A branch cavity pressing device for use in forming
branch cavities in a reinforced concrete load-bearing
pile, comprising a first and second arms, each arm
comprising a chisel holder having a bottom portion and a
cavity; a guide connected to the bottom portion, the
guide having a surface directed outward and away from
the chisel holder; a chisel end, power transmitting
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means and a chisel head flexibly connected to and
against one another and being capable of being moved
through the cavity of the chisel holder such that
movement of the chisel end causes movement of the chisel
head along the surface of the guide.
A method for forming a load-bearing pile comprising the
steps of: forming a cavity for a main body of the pile;
forming at least one branch cavity connected with the
cavity for the main body; forming an enlarged footing
connected with the cavity of the main body;
consolidating the surroundings and the bases of the
branch cavity and the enlarged footing cavity; and then
pouring in concrete to cast the pile.
A method for forming a load-bearing pile in soft
foundations comprising the steps of forming a cavity for
the main body of the pile; inserting a concrete pipe
into the cavity, said concrete pipe having at least one
branch opening thereon; forming at least one branch
cavity connected with the cavity for the main body
through the opening in the concrete pipe; forming an
enlarged footing cavity at the end of the concrete pipe;
adding filling material into the cavities; consolidating
the surroundings and the bases of the branch cavity and
the enlarged footing cavity to make them compact; and
then pouring in concrete to cast the pile.
The present invention will be more fully understood from
the following detailed description in connection with
the illustrated embodiment in the accompanying drawings.
Brief DescriPtion of the Drawinqs
Fig. 1 is a sketch of a load-bearing pile with multi-
branches
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and enlarged footings according to the invention.
Fig. 2 is a sketch of a pile cavity drilling/pressing devlce.
Fig. 3. is a sketch of a modified pile cavity drilling/
pressing device.
Fig. 4 is a sketch of a branch cavity pressing device.
Fig. 5 is a sketch of an enlarged footing cavity pressing
device.
Detailed Description of the Invention
A reinforced concrete load-bearing pile according to the present
invention comprises a pile body, at least one branch and
enlarged footing which are integrated with the pile body.
The branches can be connected to any part of the pile body,
preferably arranged in groups along the axis of the pile body.
The branches of each group are preferably staggered with those
of adjacent groups. The numbers of groups and branches in
each group are determined according to the condition of ground,
building, etc. The pile body may consist of a concrete pipe
with correspondingly arranged openings for forming branches,
and a core. The enlarged footings can be connected with the
pile body, e.g., at the bottom end of the pile body. The
enlarged footing, together with all the branches provides
a larger supporting area, thus ensuring higher load-bearing
capability of the pile.
The load-bearing pile according to the present invention can
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be wholly or partly casted-in-place after a corresponding
cavity is formed. Means for forming the pile comprises a pile
cavity drilling/pressing device, a branch cavity pressing
device and an enlarged footing cavity pressing device.
The pile cavity drilling/pressing device can be used to form
a cavity for the pile body. It consists of a pipe body with
a blade portion provided at one end and strengthening portion
at the end part of the blade portion. There can be at least
one opening provided on the pipe body used for forming branch
cavities. In order to remove soil inside the pipe body to
form the pile cavity, means such as an earth auger with screw
blades can be provided. In case of soft ground, a movable
conical head is provided at the beginning end of the pipe
body forming the pile cavity without removing any soil. A
modified structure of the device may have a spiral cutting
blade connected to the outside of the pipe body.
The branch cavity pressing device can be either single-armed
or multi-armed. Each arm has a chisel bearing, a support connected
to the bearing bottom and a chisel which is arranged inside
the bearing and composed of flexibly connected a chisel end,
power transmitting parts and a chisel head. As for a multi-
armed branch cavity pressing device, a movable support can
be futher provided at the bottoms of the supports for positioning
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and supporting, and the chisel bearings can be connected or
integrated. The said support of the device guides the direction
of the chisel head. The transmilting parts can be balls
preferably.
The enlarged footing cavity pressing device comprises a column
with a collar fixed at one end and two collars slidably mounted
thereon, pairs of pivoted arms pivots with the collars at
the same side of the column, a sleeve is slidably provided
on the other end of the column. Preferably two pairs of pivoted
arms are arranged symmetrically.
This invention has the following advantages:
1. A load-bearing pile according to the invention has
substantially higher load-carrying capability and foundation
stability than those of ordinary load-bearing piles,
overcoming at the same time residual settlement problems of
foundations and rendering possible realization of a more solid
and stable foundation.
2. With this kind of piles, more than 50% of the construction
material may be saved compared with those of all other sorts
of prevailing foundations. Also there may be economy in manpower,
energy and investment, shortening construction period and
lowering cost.
3. The formation means of a pile of the invention has the
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advantages of simple construction and easy maintenance, overcoming
the difficulty of making branch cavities in particular, rendering
possible embodiment and application of the techniques of a
load-bearing pile according to the invention.
Referring to Fig. 1, branches 2 are obliquely integrated with
a pile body 1, which comprises a concrete pipe 4 and a core
5. The concrete pipe 4 may be embeded reinforcing steel. The
branches 2 are arranged in pairs along the pile body 1. The
two branches 2 in each pair are symmetrically arranged and
staggered with those in adjacent pairs. An enlarged footing
3 connects to the bottom end of the pile body 1.
Fig. 2 shows a pile cavity drilling/pressing device which
is in the form of a pipe. A blade portion 11 is provided at
one end of the pipe body 14. The thickness of the pipe wall
increases from the blade end. At the end part of the blade
portion 11, a strengthening portion, which is in the form
of a round collar 12, is provided. At least one opening 13
can be provided on the pipe body 14 for forming branch cavities.
The device can be used for either soft ground or stiff ground,
preferably for firm ground. It can be driven into ground by
pressing.
Fig. 3 shows a modified pile cavity drilling/pressing device,
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which is preferred for soft ground. This device is further
provided with a spiral cutting blade 23 connected to the outside
of the pipe body. Means for removing soil such as an earth
auger or a pump (not shown) is provided, or a movable conical
head 25 is provided at the blade end of the pipe body to form
a pile cavity without removal of any soil. This device can
be driven into ground by rotating.
Fig. 4 shows a preferred embodiment of a branch cavity pressing
device which is symmetrically twin-armed. Each of the arm
has a chisel bearing 30, a support 31 connected to the bearing
bottom, and a chisel arranged in the cavity of the chisel
bearing 30 and composed of flexibly connected a chisel end
32, power transmitting balls 33 and a chisel head 34. A movable
support 35 is provided at the bottoms of the supports 31.
The supports 31 are obliquely arranged and can be used as
guides.
Fig. 5 shows a preferred enlarged footing cavity pressing
device. A fixed collar 42 is provided at one end of a column
37. Two collars 39 slidably mounted on the column 37. A pair
of pivoted arms 40 pivot with the movable collars 39 at the
same side of the column 37, and another pair of arms 40 at
the other side. The said two pairs of arms are symmetricaly
arranged. A sleeve 38 is slidably mounted at the other end
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of the column 37. As the sleeve 38 moves downwardly, the pivoted
arms 40 are folded. Thus, the radial dimension of the device
is increased.
In forming a reinforced concrete load-bearing pile according
to the invention, a pile cavity is firstly formed. Then branch
cavities and enlarged footing cavities are to be formed. As
a cavity of the pile is completed, reinforcing steel can be
put in and casting-in-place can be carried out.
The pile cavity drilling/pressing device can be used to form
the pile cavity. Either a pipe type device or a screw type
device can be used according to the degree of compactness
of the soil. The device can be driven into the qround either
vertically or at an angle of inclination. An earth auger 24
is used to take out the soil (or a mud pump can be used to
pump out the-mud). If a movable conical head 25 is mounted
at the beginning part of the device, a pile cavity may be
formed without taking out the soil. If the ground is stiff,
the pile drilling/pressing device can be taken out when the
cavity is made. As the device is being withdrawn, the branch
cavities can be made through the openings on the pipe body,
and the enlarged footing cavities can also be made at the
end of the pipe body. In case of the soil layer which is easy
to collapse, the pile drilling/pressing device may be withdrawn
first, and a precast concrete tube 4 is put in instead. Then
the branch cavities and the enlarged footing cavities are
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made. In forming branch cavities, the chisel head 34 of the
branch cavity pressing device is directed to either the openings
13 on the pipe body 14 of the drilling/pressing device (there
may be a pair of openings at one level and another pair of
openings at different positions of a different level), or
to the openings provided on the precast concrete pipe 4. Pressure
is applied at the chisel end 32. Since the chisel end 32,
the power transmitting balls 33 and the chisel head 34 are
connected by a steel cable, the chisel head 34 can be taken
out at any time for filling consolidating material (soilid
waste, backfill, etc), so that the surroundings and base of
the branch cavities can be consolidated. In forming the cavities
for enlarged footings,the enlarged footing cavity pressing
device is introduced into the pile cavity to a predetermined
depth (there can be more than one enlarged footing for one
pile), then,the pressing sleeve 38 is pressed continually
while the device is rotated. The pivoted arms 40 may form
a cavity for the enlarged footing after the device being rotated
180~. Enlarged footing may also be made with the branch cavity
pressing device by turning the chisel bearing 30 while pressing
the chisel end 32, getting the same effect as using the enlarged
footing cavity pressing device. In forming cavities for enlarged
footings, while the cavities are being pressed, filling materials
may be added, and the base may be compacted by means of rammers
so as to increase the degree of compactness of the soil layer.
After forming the pile cavity, the branches and enlarged foot-
ing cavities, reinforcing steel bars may be placed into the
cavity and concrete may be cast. Thus the entire process of
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making the reinforced concrete load-bearing pile with multi-
branches and enlarged footings is completed. Branches may
be precasted. h~hen the branch cavities are made, the precasted
branches may be put into place by means of the branch cavity
pressing device. The pile can finally be casted.
Thus, while the invention has been described in relation to
a particular embodiment, those having skill in the art will
recognize modifications of materials, structure and the like
which will still fall within the scope of the present invention.
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