Canadian Patents Database / Patent 2809673 Summary

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(12) Patent: (11) CA 2809673
(54) English Title: METHOD AND APPARATUS FOR MAKING AN EXPANDED BASE PIER
(54) French Title: PROCEDE ET APPAREIL DE FABRICATION DE PILIER A BASE ELARGIE
(51) International Patent Classification (IPC):
  • E02D 3/12 (2006.01)
  • E21D 9/04 (2006.01)
  • E21D 9/06 (2006.01)
(72) Inventors :
  • WISSMANN, KORD J. (United States of America)
(73) Owners :
  • GEOPIER FOUNDATION COMPANY, INC. (United States of America)
(71) Applicants :
  • GEOPIER FOUNDATION COMPANY, INC. (United States of America)
(74) Agent: OSLER, HOSKIN & HARCOURT LLP
(74) Associate agent:
(45) Issued: 2018-08-07
(86) PCT Filing Date: 2011-09-01
(87) Open to Public Inspection: 2012-03-08
Examination requested: 2016-05-12
(30) Availability of licence: N/A
(30) Language of filing: English

(30) Application Priority Data:
Application No. Country/Territory Date
12/875,986 United States of America 2010-09-03

English Abstract

A system for constructing a support column includes a mandrel with an upper portion and a tamper head. A feed tube extends through the mandrel for feeding flowable material to the head. The tamper head includes a lower enlarged chamber with a reducing surface at an upper portion for compacting material and restricting upward flow of aggregate. The tamper head is of a size providing an enclosed region for allowing cementitious materials to be placed therein. The system allows a support column including a cementitious inclusion on top of an expanded base to be built.


French Abstract

L'invention porte sur un système de construction d'une colonne de support qui comprend un mandrin ayant une partie supérieure et une tête de dameuse. Un tube d'alimentation s'étend à travers le mandrin pour distribuer un matériau pouvant être fluidifié à la tête. La tête de dameuse comprend une chambre élargie inférieure qui présente une surface de réduction à une partie supérieure pour compacter le matériau et limiter un écoulement d'agrégat vers le haut. La tête de dameuse est d'une dimension fournissant une région fermée pour permettre à des matériaux cimentaires d'être placés dans celle-ci. Le système permet à une colonne de support comprenant une inclusion cimentaire sur le dessus d'une base élargie d'être construite.


Note: Claims are shown in the official language in which they were submitted.

The embodiments of the present invention for which an exclusive property or
privilege is claimed are
defined as follows:
1. A system for constructing a support column, comprising:
(a) a mandrel having an upper portion and a tamper head, and a feed tube
extending
therethrough for feeding aggregate, concrete, grout, or other flowable
materials through
the mandrel to the tamper head, the mandrel further comprising a closure cap
on an end of
the feed tube opposite the tamper head and a concrete supply tube connected to
the feed
tube; and
(b) the tamper head defining a lower enlarged chamber having a reducing
surface at an upper
portion thereof for compacting aggregate or concrete and for restricting
upward flow of
aggregate or concrete into the mandrel during compacting and the tamper head
being of
sufficient size for providing an enclosed region for allowing cementitious
material to be
placed therein.
2. The system of claim 1, further comprising a valve mechanism movable
between an open position
and a closed position for closing off the feed tube from communication with
the tamper head during
tamping operations.
3. The system of claim 1 or 2, further comprising stiffening members
secured between the reducing
surface and the mandrel for providing load support during tamping operations.
4. The system of any one of claims 1 to 3, further comprising chains
attached within the interior of
the tamper head for restricting upward flow of material into the feed tube
during downward
movement of the mandrel.
5. The system of any one of claims 1 to 3, further comprising notches
within the interior of the tamper
head for restricting upward flow of material into the feed tube during
downward movement of the
mandrel.
6. The system of any one of claims 1 to 5, further comprising a second tube
extending through the
mandrel on the side of the feed tube for allowing cementitious material to
flow upward through the
second tube for inspection of the cementitious material during pumping.

13

7. The system of any one of claims 1 to 5, further comprising a hopper
located at the top of the mandrel
for feeding aggregate into the feed tube of the mandrel.
8. The system of any one of claims 1 to 5, further comprising an air
pressure source connected to the
feed tube for evacuating concrete from the feed tube through air pressure
supplied thereto.
9. A method of constructing a support column comprising use of a mandrel
assembly having a feed
tube connected to a tamper head at an opening thereof for allowing aggregate,
concrete, grout, or
other flowable material to flow into the tamper head, the method comprising:
(a) providing the tamper head of a shape with a defined lower enlarged
chamber having a
reducing surface at an upper portion thereof for compaction and for
restricting upward flow
of material into the feed tube during tamping, the tamper head further sized
to provide an
enclosed region for allowing cementitious material to be placed therein;
(b) providing a closure cap on an end of the feed tube opposite the tamper
head and a concrete
supply tube connected to the feed tube;
(c) driving the mandrel assembly into a ground surface to a given depth
thereby forming a
cavity;
(d) lifting the mandrel assembly to release an initial charge of aggregate
or concrete from the
tamper head into a bottom of the cavity;
(e) re-driving the mandrel assembly to compact the aggregate or concrete at
a bottom of the
cavity and to form an expanded base, the expanded base having a width greater
than the
tamper head; and
(f) withdrawing the mandrel assembly while continuously feeding
cementitious material or
aggregate to be subsequently fully or partially treated with grout through the
feed tube,
thereby forming a cementitious inclusion at least partially within the cavity,
the
cementitious inclusion having a width of the cavity and being formed on top of
the
expanded base.
10. The method of claim 9, wherein the tamper head is filled with the
initial charge of aggregate or
concrete before driving.
11. The method of claim 9 or 10, wherein the cementitious material is one
selected from the group
consisting of concrete, grout, or aggregate that is subsequently fully or
partially treated with grout.

14

12. The method of any one of claims 9 to 11, further comprising providing a
valve mechanism movable
between an open position and a closed position at the opening between the feed
tube and the tamper
head, for restricting the passage from flow into the tamper head, and moving
the closure member
to an open position for introducing cementitious material into the tamper
head, and into a closed
position during downward compaction.
13. The method of any one of claims 9 to 12, further comprising introducing
cementitious material into
the enclosed region.
14. The method of claim 9, further comprising introducing a pipe through
the feed tube and tamper
head after formation of the expanded base, placing aggregate during the
withdrawing step to
partially surround the pipe, and introducing cementitious material into the
pipe following aggregate
placement to treat the aggregate.
15. The method of any one of claims 9 to 14, further comprising chains
attached within the interior of
the tamper head for restricting upward flow of material into the feed tube
during downward
movement of the mandrel.
16. The method of any one of claims 9 to 14, further comprising notches
within the interior of the
tamper head for restricting upward flow of material into the feed tube during
downward movement
of the mandrel.
17. The method of any one of claims 9 to 16, further comprising providing
the mandrel with a second
tube adjacent the feed tube to allow for the inspection of cementitious
material during pumping.
18. The method of any one of claims 9 to 17, further comprising a hopper
located at the top of the
mandrel for feeding aggregate into the feed tube of the mandrel.
19. The method of any one of claims 9 to 18, further comprising an air
pressure source connected to
the feed tube for evacuating concrete from the feed tube through air pressure
supplied thereto.

20. A system for constructing a support column, comprising:
(a) a mandrel having an upper portion and a tamper head, and a feed tube
extending
therethrough for feeding aggregate, concrete, grout, or other flowable
materials through
the mandrel to the tamper head; and
(b) the tamper head defining a lower enlarged chamber having a reducing
surface at an upper
portion thereof for compacting aggregate or concrete and for restricting
upward flow of
aggregate or concrete into the mandrel during compacting and the tamper head
being of
sufficient size for providing an enclosed region for allowing cementitious
material to be
placed therein, the tamper head further comprising a valve mechanism movable
between
an open position and a closed position for closing off the feed tube from
communication
with the tamper head during tamping operations.
21. A method of constructing a support column comprising use of a mandrel
assembly having a feed
tube connected to a tamper head at an opening thereof for allowing aggregate,
concrete, grout, or
other flowable material to flow into the tamper head, the method comprising:
(a) providing the tamper head of a shape with a defined lower enlarged
chamber having a
reducing surface at an upper portion thereof for compaction and for
restricting upward flow
of material into the feed tube during tamping, the tamper head further sized
to provide an
enclosed region for allowing cementitious material to be placed therein, the
tamper head
further comprising providing a valve mechanism movable between an open
position and a
closed position at the opening between the feed tube and the tamper head, for
restricting
the passage from flow into the tamper head, and moving the closure member to
an open
position for introducing cementitious material into the tamper head, and into
a closed
position during downward compaction;
(b) driving the mandrel assembly into a ground surface to a given depth
thereby forming a
cavity;
(c) lifting the mandrel assembly to release an initial charge of aggregate
or concrete from the
tamper head into a bottom of the cavity;
(d) re-driving the mandrel assembly to compact the aggregate or concrete at
a bottom of the
cavity and to form an expanded base, the expanded base having a width greater
than the
tamper head; and

16

(e) withdrawing
the mandrel assembly while continuously feeding cementitious material or
aggregate to be subsequently fully or partially treated with grout through the
feed tube,
thereby forming a cementitious inclusion at least partially within the cavity,
the
cementitious inclusion having a width of the cavity and being formed on top of
the
expanded base.
17

Note: Descriptions are shown in the official language in which they were submitted.

METHOD AND APPARATUS FOR MAKING AN EXPANDED BASE PIER
FIELD OF THE INVENTION
[0001] The present invention relates to construction of a structural
support
column.
[0002] More specifically, the present invention relates to a method
and apparatus
for building an expanded base pier to bypass weak soils and transfer
structural loads to
underlying strong soils.
BACKGROUND OF INVENTION
[0003] Heavy or settlement-sensitive facilities that are located in
areas
containing soft or weak soils are often supported on deep foundations,
consisting of driven
piles or drilled concrete columns. The deep foundations are designed to
transfer the structure
loads through the soft soils to more competent soil strata.
[0004] In recent years, aggregate columns have been increasingly
used to
support structures located in areas containing soft soils. The columns are
designed to
reinforce and strengthen the soft layer and minimize resulting settlements.
The columns are
constructed using a variety of methods including the drilling and tamping
method described
in U.S. Patent Nos. 5,249,892 and 6,354,766; the driven mandrel method
described in U.S.
Patent No. 6,425,713; the tamper head driven mandrel method described in U.S.
Patent No.
7,226,246; and the driven tapered mandrel method described in U.S. Patent No.
7,326,004.
[0005] The short aggregate column method (U.S. Patent Nos. 5,249,892
and
6,354,766), which includes drilling or excavating a cavity, is an effective
foundation solution
when installed in cohesive soils where the sidewall stability of the hole is
easily maintained.
The method generally consists of: a) drilling a generally cylindrical cavity
or hole in the
foundation soil (typically around 30 inches); b) compacting the soil at the
bottom of the
cavity; c) installing a relatively thin lift of aggregate into the cavity
(typically around 12-18
inches); d) tamping the aggregate lift with a specially designed beveled
tamper head; and e)
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repeating the process to form an aggregate column generally extending to the
ground surface.
Fundamental to the process is the application of sufficient energy to the
beveled tamper head
such that the process builds up lateral stresses within the matrix soil up
along the sides of the
cavity during the sequential tamping. This lateral stress build up is
important because it
decreases the compressibility of the matrix soils and allows applied loads to
be efficiently
transferred to the matrix soils during column loading.
[0006] The tamper
head driven mandrel method (U.S. Patent No. 7,226,246) is
a displacement form of the short aggregate column method. This method
generally consists
of driving a hollow pipe (mandrel) into the ground without the need for
drilling. The pipe is
fitted with a tamper head at the bottom which has a greater diameter than the
pipe and which
has a flat bottom and beveled sides. The mandrel is driven to the design
bottom of column
elevation, filled with aggregate and then lifted, allowing the aggregate to
flow out of the pipe
and into the cavity created by withdrawing the mandrel. The tamper head is
then driven back
down into the aggregate to compact the aggregate. The flat bottom shape of the
tamper head
compacts the aggregate; the beveled sides force the aggregate into the
sidewalls of the hole
thereby increasing the lateral stresses in the surrounding ground.
[0007] The driven
tapered mandrel method (U.S. Patent No. 7,326,004) is
another means of creating an aggregate column with a displacement mandrel. In
this case,
the shape of the mandrel is a truncated cone, larger at the top than at the
bottom, with a taper
angle of about 1 to about 5 degrees from vertical. The mandrel is driven into
the ground,
causing the matrix soil to displace downwardly and laterally during driving.
After reaching
the design bottom of the column elevation, the mandrel is withdrawn, leaving a
cone shaped
cavity in the ground. The conical shape of the mandrel allows for temporarily
stabilizing of
the sidewalls of the hole such that aggregate may be introduced into the
cavity from the
ground surface. After placing a lift of aggregate, the mandrel is re-driven
downward into the
aggregate to compact the aggregate and force it sideways into the sidewalls of
the hole.
Sometimes, a larger mandrel is used to compact the aggregate near the top of
the column.
[0008] U.S. Patent
No. 7,604,437 is related to a mandrel for making aggregate
support columns wherein flow restrictors are provided to prevent upward
movement of
aggregate through the mandrel during driving of the mandrel. The mandrel
contemplated in
this art relates to formation of an aggregate support column such as described
in U.S. Patent
Nos. 6,425,713 and 7,226,246 discussed above.
[0009] U.S. Patent
Nos. 4,992,002 and 6,773,208 relate to methods for casting
a partially reinforced concrete pier in the ground. One method involves the
use of an
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elongate mandrel with a cupped foot having a larger cross-sectional area than
the mandrel,
wherein flowable grout that is placed in the mandrel flows through openings
located near the
bottom of the mandrel into the space between the mandrel and the foot. The
other method
involves the installation of an elongate hollow tubular casing that is then
filled with fluid
concrete that is allowed to set while the casing remains in the ground. Each
of these
references is merely to concrete hardened inclusions and does not allow for
the additional
stability and strength provided by a pier that has an expanded base.
[0010] In the area
of soil improvement, it is often desirable to install a stiff
inclusion into the ground to transfer loads through a soft or weak soil layer.
Although these
soil layers may also be treated by non-cementitious aggregate columns, non-
cementitious
columns are typically confining-stress dependent (i.e., they rely on the
strength of the
sidewall soils to prevent bulging). Occasionally, it is desirable to utilize
cementitious
inclusions to bypass weak soils and transfer loads to underlying strong soils.
The object of
the present invention is to efficiently form a strong and stiff expanded base
(either
cementitious or non-cementitious) at the bottom of the column and to provide
an efficient
means for the introduction of grout, concrete. post-grouted aggregate, or
other cementitious
material through the upper portions of the column to form a cementitious
inclusion.
BRIEF DESCRIPTION OF INVENTION
[0011] The present
invention relates to a system for constructing a support
column. A mandrel has an upper portion and a tamper head. A feed tube extends
through the
mandrel for feeding aggregate, concrete, grout, or other flowable materials to
the tamper
head. The tamper head includes a lower enlarged chamber with a reducing
surface at an
upper portion thereof for compacting aggregate or concrete and restricting
upward flow of
aggregate or concrete during compaction. The tamper head is of a size
providing an enclosed
region for allowing cementitious materials to be placed therein.
[0012] rlhe
invention may comprise a valve mechanism movable between an
open position and a closed position for closing off the feed tube from
communication with
the tamper head during tamping operations and may comprising stiffening
members secured
between the reducing surface and the mandrel for providing load support during
tamping
operations. The invention may further comprise chains attached or notches
within the interior
of the tamper head for restricting upward flow of material into the feed tube
during
downward movement of the mandrel. A second tube may extend through the mandrel
on the
side of the feed tube for allowing cementitious material to flow upward
through the second
3

tube for inspection of the cementitious material during pumping. A hopper may
be located at the
top of the mandrel for feeding aggregate into the feed tube of the mandrel. A
closure cap may be
on an end of the feed tube opposite the tamper head and a concrete supply tube
may be connected
to the feed tube, and an air pressure source may be connected to the feed tube
for evacuating
concrete from the feed tube through air pressure supplied thereto.
[0013] A method of constructing such support columns with the system
is also
disclosed and may include providing the tamper head of a shape with a defined
lower enlarged
chamber having a reducing surface at an upper portion thereof for compaction
and for restricting
upward flow of material into the feed tube during tamping, the tamper head
further sized to provide
an enclosed region for allowing cementitious material to be placed therein;
driving the mandrel
assembly into a ground surface to a given depth thereby forming a cavity;
lifting the mandrel
assembly to release an initial charge of aggregate or concrete from the tamper
head into a bottom
of the cavity; re-driving the mandrel assembly to compact the aggregate or
concrete at a bottom of
the cavity and to form an expanded base, the expanded base having a width
greater than the tamper
head; and withdrawing the mandrel assembly while continuously feeding
cementitious material or
aggregate to be subsequently fully or partially treated with grout through the
feed tube, thereby
forming a cementitious inclusion at least partially within the cavity, the
cementitious inclusion
having a width of the cavity and being formed on top of the expanded base.
[0013a] Another embodiment of the present invention provides a system
for
constructing a support column, comprising: (a) a mandrel having an upper
portion and a tamper
head, and a feed tube extending therethrough for feeding aggregate, concrete,
grout, or other
flowable materials through the mandrel to the tamper head; and (b) the tamper
head defining a
lower enlarged chamber having a reducing surface at an upper portion thereof
for compacting
aggregate or concrete and for restricting upward flow of aggregate or concrete
into the mandrel
during compacting and the tamper head being of sufficient size for providing
an enclosed region
for allowing cementitious material to be placed therein, the tamper head
further comprising a valve
mechanism movable between an open position and a closed position for closing
off the feed tube
from communication with the tamper head during tamping operations.
4
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[0013b] A further embodiment provides a method of constructing a support
column
comprising use of a mandrel assembly having a feed tube connected to a tamper
head at an opening
thereof for allowing aggregate, concrete, grout, or other flowable material to
flow into the tamper
head, the method comprising: (a) providing the tamper head of a shape with a
defined lower
enlarged chamber having a reducing surface at an upper portion thereof for
compaction and for
restricting upward flow of material into the feed tube during tamping, the
tamper head further sized
to provide an enclosed region for allowing cementitious material to be placed
therein, the tamper
head further comprising providing a valve mechanism movable between an open
position and a
closed position at the opening between the feed tube and the tamper head, for
restricting the passage
from flow into the tamper head, and moving the closure member to an open
position for introducing
cementitious material into the tamper head, and into a closed position during
downward
compaction; (b) driving the mandrel assembly into a ground surface to a given
depth thereby
forming a cavity; (c) lifting the mandrel assembly to release an initial
charge of aggregate or
concrete from the tamper head into a bottom of the cavity; (d) re-driving the
mandrel assembly to
compact the aggregate or concrete at a bottom of the cavity and to form an
expanded base, the
expanded base having a width greater than the tamper head; and (e) withdrawing
the mandrel
assembly while "continuously feeding cementitious material or aggregate to be
subsequently fully
or partially treated with grout through the feed tube, thereby forming a
cementitious inclusion at
least partially within the cavity, the cementitious inclusion having a width
of the cavity and being
formed on top of the expanded base.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention will be better understood from the following
detailed
description made with reference to the drawings, wherein:
[0016] Figure 1 is a side cross-section view of a first embodiment of
a mandrel;
[0017] Figure 2 is a side cross-section view of a second embodiment
of the
mandrel with a valve;
[0018] Figure 3 is a side cross-section view of a third embodiment of
the mandrel
with internal upward flow restrictors;
[0019] Figure 4 is a side cross-section view of a fourth embodiment
of the
mandrel with a grout return pipe;
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[0020] Figures 5A-
5E illustrate a method of constructing a pier with the
mandrel of Figure 1;
[0021] Figures 6A-
6F illustrate an alternate method of constructing a pier with
one embodiment of the mandrel of the invention;
[0022] Figure 7 is
a side cross-section view of an alternative embodiment of
the mandrel using a closed top system to allow air pressure to build;
[0023] Figure 8 is
a more detailed view of the operation of a closed top system
including use of an external air source;
[0024] Figure 9 is
a graph showing results of load tests performed on columns
made according to Example I as compared to reference piers; and
[0025] Figures 10
and 11 are graphs showing results of load tests performed on
columns made according to Example III.
DETAILED DESCRIPTION OF THE INVENTION
[0026] With
reference to the attached figures, various embodiments of a new
and novel mandrel for forming an expanded base pier, as part of a hardened
inclusion, is
provided.
[0027] Figure 1
illustrates an embodiment of a base mandrel assembly (1)
contemplated herein. In this embodiment, a tamper head (2) is formed as a
unitary structure
attached to one end of a feed tube or pipe (4) to form the mandrel assembly
(1). The feed
pipe (4) can typically be 4" to 12" in diameter and has an upper end (not
shown) opposite the
tamper head (2) in which aggregate, concrete, grout, and other flowable
material can be fed.
The tamper head (2) typically comprises an enlarged lower chamber (3),
typically 10" to 24"
in diameter. The reducing surface (5) from the lower chamber walls to the feed
pipe walls
serves the function as a compaction plate for compacting aggregate or concrete
as described
hereinbelow, as well as serving as an upward flow restrictor while the initial
aggregate is
being driven such that the aggregate or concrete forms a "plug" within the
chamber (3) and
does not flow back up into the feed pipe (4). The reducing surface (5) may be
angled as
shown in Figure 2. The lower chamber (3) at the bottom of the head allows for
formation of
a densified bottom expanded base and provides an enclosed area for the
placement of grout or
concrete. Stiffeners (6) can also be placed between the feed pipe (4) and
lower chamber (3)
to assist in load transfer during driving.
[0028] Figure 2
illustrates an embodiment of a base mandrel similar to Figure
1, but includes a special valve mechanism (7) that may be used to further
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aggregate or concrete from the lower chamber (3) into the feed pipe (4). The
valve
mechanism (7) seats against the reducing surface (5) of the feed pipe (4) and
physically
restricts the flow of aggregate, or concrete, back up into the feed pipe
during downward
driving (as opposed to the "plug" formed as described above with reference to
Figure 1).
When the feed pipe (4) is lifted, the valve mechanism (7) opens to allow the
downward flow
of grout, concrete, or other flowable material through the feed pipe (4) and
into the lower
chamber (3). The valve mechanism (7) may be manipulated by a pipe extending to
the top of
the mandrel or by a mechanism that pins the valve mechanism (7) to the
sidewalls of the feed
pipe (4).
[0029] The purpose
of the valve mechanism (7) envisioned with reference to
Figure 2 is to allow subsequent compaction of the bottom aggregate or concrete
expanded
base initially placed and formed. For instance, the mandrel would first be
driven in the
ground with the lower chamber (3) charged with aggregate or concrete. The feed
pipe (4)
would then be lifted, and the valve mechanism (7) would open. Grout or
concrete would then
be added through the feed pipe (4). The mandrel assembly (1) would then be
driven back
down, thereby allowing for further compaction of the aggregate or concrete at
the bottom to
form an expanded base.
[0030] Figure 3
illustrates another variation of the embodiment of Figure 1.
More specifically, chain links (8) are attached within the tamper head (2) so
that upon
tamping, the chain links (8) move inward to constrict the aggregate or
concrete in the lower
chamber (3) and restrict aggregate or concrete from flowing upward into the
feed tube (4). It
is also envisioned that internal notches may be provided in lieu of chains in
order to provide
non-mechanical (or passive) upward flow restriction.
[0031] Figure 4
illustrates a further embodiment of a mandrel similar to that
shown in Figure 1 but which includes a special provision for ensuring grout
placement.
Instead of having only a single chute feed pipe or tube (4) as shown in Figure
1, the
embodiment contemplated with reference to Figure 4 has a feed pipe including a
primary feed
pipe (4) and a grout return pipe (9) that is used to ensure that a continuous
column of grout is
installed. Positive flow of grout from the top of the grout return pipe (9)
demonstrates that
the mandrel is full of grout before or during mandrel extraction (lifting)
operations.
[0032] A method of
use is shown with reference to Figures 5A-5E, which
shows an installation sequence with the base mandrel depicted in Figure 1.
Step A (Figure
5A) shows placing a mound (10) of the aggregate on the ground surface. Step B
(Figure 5B)
shows driving the mandrel assembly (1) through the mound (10) of aggregate (to
form an
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initial charge of aggregate) and to the final driving elevation. During the
driving process, the
aggregate in the lower chamber (3) forms a plug (11) in the neck of the feed
pipe (4) at the
bottom of the tamper head (2). The valve mechanism (7) shown in Figure 2 or
the chain
links (8) shown in Figure 3 may be used within the tamper head (2) to
facilitate plugging.
Step C (Figure 5C) shows lifting of the mandrel assembly (1) wherein the
aggregate plug (11)
or initial charge remains in place at the bottom of the hole (it is understood
that the initial
charge may also be added after driving of a closed tamper head, such as with a
sacrificial cap
covering the bottom opening of the tamper head). Step D (Figure 5D) shows re-
driving the
mandrel assembly (1) one or more times to compact the aggregate at the bottom
of the hole
and to form an expanded base (12). Grout or concrete (13) may then be pumped
through the
feed pipe as shown. Step E (Figure 5E) shows placing grout or concrete (13)
from the
element up from the bottom while removing the mandrel. When the grout return
pipe (9) as
shown in Figure 4 is used in conjunction with Step E of the construction
process, grout
continuity within the mandrel shaft is determined if grout continues to flow
out of the grout
return pipe (9) during extraction. The finished support column comprises an
expanded base
with a cementitious inclusion located thereon.
[0033] An
alternative method of use can also be used with reference to
Figures 5A-5E. Step A consists of filling the lower chamber (3) of the tamper
head (2) with
concrete. This may be achieved by driving the tamper head (2) through a mound
(10) of
concrete as shown in Figure 5A or by pumping concrete through the feed tube
(4) while the
tamper head (2) is resting on the ground surface. In this case, the ground
surface seals the
concrete from flowing out of the bottom of the lower chamber (3). As shown in
Figure 5B,
the tamper head (2) is then driven to design elevation with the concrete at
the bottom of the
tamper head (2) forming a plug (11) at the bottom of the assembly mandrel (1).
The
valve mechanism (7) shown in Figure 2 or the chain links (8) shown in Figure 3
may be used
within the tamper head (2) to facilitate plugging. Step C shows the retraction
(lifting) of the
assembly (2) to allow the concrete to flow out of the bottom of the tamper
head (2). Step D
shows the placement of additional concrete (13) through the feed pipe (4) and
the subsequent
or simultaneous lowering of the mandrel assembly (1) onto the previously
placed concrete to
force the concrete outward thus forming an expanded base (12). Step E shows
the
simultaneous placement of grout or concrete (13) through the feed tube (4)
while extracting
the mandrel assembly (1) to the ground surface. This technique forms an
expanded base pier
comprised of concrete at the expanded base (12) and concrete within the pier
shaft (or
inclusion) on top of the expanded base (12).
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1100341 The benefits
of the system contemplated herein are the efficient
formation of an expanded base (12) that allows load to be transferred to the
bottom of the pier
and the very quick and efficient formation of the grouted inclusion by rapidly
raising the
mandrel while placing grout or concrete (13). While the method sequence of
Figures 5A-5E
depicts the use of the base mandrel shown in Figure 1, it is envisioned that
the method could
principally be used with any of the mandrels shown in Figures 1 - 4.
[0035] Figures 6A-
6F shows an alternative construction sequence where Steps
A through C (Figures 6A-6C) are generally as described above with reference to
the initial
charge of aggregate being in the lower chamber (see Figures 5A-5C). In Step D
(Figure 6D)
of this sequence, the mandrel assembly (1) is lowered to compact the aggregate
and a
secondary disposable pipe (14) is inserted into the mandrel assembly (1) to
rest on the
expanded base (12). In Step E (Figure 6E) the mandrel assembly (1) is raised
and additional
aggregate (15) is allowed to fill the annular space between the disposable
pipe (14) and the
sidewall of the cavity (16). A hopper (17) can be used to place the aggregate
(15) within the
feed pipe (4). The aggregate (15) placed in this step is not compacted. In
Step F (Figure 6F)
the disposable pipe (14) is then used as a conduit to place grout into the
inclusion by filling
the voids in the loose aggregate (15) around the disposable pipe (14).
Typically, the
disposable pipe (14) is not removed but can be cut at ground level or just
below ground level
and made part of the peimanent inclusion. Additionally, while Figures 6D-6F
depict
representative grout ports at the bottom end of disposable pipe (14), it is
understood that such
ports or other openings can be located partially or fully along the length of
disposable pipe
(14).
[0036] Figure 7
illustrates a further embodiment of a mandrel similar to that
shown in Figure 1 but which includes a closed system for the placement of
concrete, grout, or
other flowable materials. The mandrel of this embodiment includes an external
feed tube
(18) that enters the mandrel feed tube (4) near the top of the mandrel to
allow for the passage
of a flowable material (19). The external feed tube (18) is used to pump
concrete, grout, or
other flowable materials into the primary feed tube (4). The top of the
mandrel is sealed with
a top plate (21) making this a closed system. An air pressure gage (20) may
optionally be
installed to measure the internal air pressure within the mandrel and allow
for the use of a
pressure release valve (22) to facilitate removal of excess internal pressure
during pumping.
The mandrel system of Figure 7 may be used in conjunction with the
construction sequences
shown in Figures 5A-5E.
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[0037] Figure 8
illustrates yet another embodiment of the mandrel similar to
that shown in Figure 7. In this embodiment, an air source, such as compressor
(24), may
optionally be used to apply elevated air pressure to trapped air (23) within
the mandrel feed
pipe (4) to evacuate concrete (13) from the mandrel.
[0038] The following examples illustrate further aspects of the
invention.
Example I
[0039] As an
example, an embodiment of the system of the present invention
was used to install a support column, also described herein as an expanded
base pier ("EBP"),
at a test site in Iowa. The test site was characterized by 4 feet of sandy
lean clay underlain by
sand. This testing
program was designed to compare the load versus deflection
characteristics of this embodiment of the EBP to reference piers constructed
in successive
lifts, such as a pier constructed by the tamper head driven mandrel method.
The reference
piers of this example had a nominal diameter of 20 inches and an installed
length of 23 feet.
One reference pier was constructed of aggregate only to a diameter of 20
inches. Another
reference pier was constructed with a grout additive, commonly refeffed to as
grouted pier, to
a diameter of 14 inches.
[0040] In this
embodiment of the invention, the EBP was formed by filling the
extractable mandrel (Figure 1) with a combination of open graded aggregate and
fluid grout.
The mandrel had a lower chamber (3) outside diameter of 14 inches and a feed
pipe (4)
outside diameter of 12 inches. The mandrel of this embodiment was connected at
its open
end (opposite the tamper head) to an open hopper for filling and was attached
to a high
frequency hammer which is often associated with driving sheet piles. The
hammer is capable
of providing both downward force and vibratory energy. The full mandrel was
advanced to a
depth of 23 feet below the ground surface. The mandrel assembly was then
raised 3 feet and
lowered 3 feet a total of 3 times to form a bottom expanded base. Each raising
and lowering
of the mandrel is referred to as a "stroke." The mandrel was then raised 3
feet. lowered 2
feet, and then slowly extracted to the ground surface allowing a column of
grout and
aggregate to be placed in the cavity created during mandrel installation. The
EBP was
constructed with a base diameter of 20 inches, and a shaft diameter of 14
inches. Once the
mandrel was fully extracted, a 1 inch diameter reinforcing steel rod was
inserted the full
length of the EBP. A concrete cap was then poured above the EBP to facilitate
load testing.
[0041] The
reference piers and the EBP were load tested using a hydraulic jack
pushing against a test frame. Figure 9 shows the results of the load test of
the EBP compared
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with the reference piers. At a top of pier deflection of 0.5 inches, the
reference pier with
aggregate supported a load of about 23,300 pounds, the reference pier with
grout supported a
load of about 50,000 pounds, and the EBP supported a load of about 70,300
pounds. At a top
of pier deflection of I inch, the reference pier with aggregate supported a
load of about
38,800 pounds, the reference pier with grout supported a load of about 62,700
pounds, and
the EBP supported a load of about 97,000 pounds. The load carrying capacity of
the pier
constructed in accordance with this embodiment of the present invention showed
a 2.5 to 3
fold improvement when compared to a reference pier with aggregate, and a 1.4
to 1.5 fold
improvement when compared to a reference pier with grout. The difference in
the behavior
relative to the grouted pier is caused by the formation of the bottom expanded
base during the
construction of the EBP according to the invention.
Example II
[0042] As another
example, the system of another embodiment of the present
invention was used to install five EBP elements at a test site in Virginia.
The test site was
characterized by hard clay. Prior to installation of the EBP, 30 inch diameter
drill holes were
excavated to a depth of 8 feet below the ground surface. The voids were then
loosely
backfilled with sand. The EBP elements of this example were formed within the
backfilled
holes.
[0043] In this
embodiment of the invention, the EBP was formed by filling the
mandrel described in Figure 7 with concrete. The mandrel of this embodiment
featured a
"closed top" as opposed to the "open hopper" configuration as described with
reference to
Example I. The mandrel in this embodiment was attached to a similar hammer as
in the
embodiment of Example I. The full mandrel was advanced to a depth of 8 feet
below the
ground surface. The mandrel was then raised 3 feet, and then lowered 2 feet
for three
repetitions to create the expanded base. A process of raising the mandrel 3
feet, and then
lowering 1 foot was then used to complete the full length of the pier. Once
the concrete had
cured, each of the piers was excavated and the pier base and shaft diameters
were measured.
[0044] The lower
chamber in this embodiment had a nominal 12 inch diameter
outer dimension. The excavated and measured piers had an average nominal
diameter of 18
inches. Expanded bases at the bottoms of the piers exceeded 24 inches
demonstrating the
effectiveness of this construction technique.

CA 02809673 2013-02-26
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Example III
[0045] As yet
another example, the embodiment of the present invention from
Example II was used on a site in Washington, D.C. The site was characterized
by 20 to 30
feet of soft clay and clayey sand underlain by dense sand or hard clay. The
embodiment of
the present invention at the site was used to support mechanically stabilized
earth (MSE)
walls and embankments. The mandrel used for this project was similar to that
used in
Example II. The lower chamber in this embodiment had a nominal 18 inch
diameter outer
dimension. In this example, two fully concrete EBP were constructed and
subsequently load
tested. In this example of the embodiment, the EBP were constructed with a 24
inch diameter
expanded base, and an 18 inch diameter shaft.
[0046] In this
embodiment of the invention, the EBP was formed by filling the
mandrel (such as in Figures 7 or 8) with concrete. The full mandrel was then
advanced to a
depth of 26 feet below the ground surface for Test Pier 1 and to a depth of
36.5 feet below the
ground surface for Test Pier 2. The mandrel was then raised 4 feet, and then
lowered 3 feet.
The process of raising the mandrel 4 feet, and then lowering 3 feet was
completed for a total
of 4 cycles at the test piers to create an expanded base. After the expanded
base was created,
the mandrel was extracted at a constant rate while pumping concrete into the
mandrel. Once
the concrete had cured, each of the piers was load tested.
[0047] The load
tests were performed using Statnamic load test methods.
Figure 10 shows the results of the load test on Test Pier 1 (26 feet below
ground surface) and
Figure 11 shows the results of the load test on Test Pier 2 (36.5 feet below
the ground surface
- two test load cycles on this test pier). Both Test Pier 1 and Test Pier 2
supported a test load
of approximately 425 kips at 1 inch of top of pier deflection, with a maximum
supported load
of approximately 575 kips.
[0048] The
foregoing detailed description of embodiments refers to the
accompanying drawings, which illustrate specific embodiments of the invention.
Other
embodiments having different structures and operations do not depart from the
scope of the
invention. The term "the invention" or the like is used with reference to
certain specific
examples of the many alternative aspects or embodiments of the applicant's
invention set
forth in this specification, and neither its use nor its absence is intended
to limit the scope of
the applicant's invention or the scope of the claims. This specification is
divided into
sections for the convenience of the reader only. Headings should not be
construed as limiting
of the scope of the invention. The definitions are intended as a part of the
description of the
invention. It will be understood that various details of the invention may be
changed without
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departing from the scope of the invention. Furthermore, the foregoing
description is for the
purpose of illustration only, and not for the purpose of limitation.

A single figure which represents the drawing illustrating the invention.

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Admin Status

Title Date
Forecasted Issue Date 2018-08-07
(86) PCT Filing Date 2011-09-01
(87) PCT Publication Date 2012-03-08
(85) National Entry 2013-02-26
Examination Requested 2016-05-12
(45) Issued 2018-08-07

Abandonment History

There is no abandonment history.

Maintenance Fee

Last Payment of $200.00 was received on 2020-09-02


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Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $400.00 2013-02-26
Maintenance Fee - Application - New Act 2 2013-09-03 $100.00 2013-06-12
Maintenance Fee - Application - New Act 3 2014-09-02 $100.00 2014-09-02
Maintenance Fee - Application - New Act 4 2015-09-01 $100.00 2015-08-10
Request for Examination $800.00 2016-05-12
Maintenance Fee - Application - New Act 5 2016-09-01 $200.00 2016-08-15
Maintenance Fee - Application - New Act 6 2017-09-01 $200.00 2017-08-21
Final Fee $300.00 2018-06-21
Maintenance Fee - Patent - New Act 7 2018-09-04 $200.00 2018-09-04
Maintenance Fee - Patent - New Act 8 2019-09-03 $200.00 2019-08-28
Maintenance Fee - Patent - New Act 9 2020-09-01 $200.00 2020-09-02
Late Fee for failure to pay new-style Patent Maintenance Fee 2020-09-02 $150.00 2020-09-02
Current owners on record shown in alphabetical order.
Current Owners on Record
GEOPIER FOUNDATION COMPANY, INC.
Past owners on record shown in alphabetical order.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Document
Description
Date
(yyyy-mm-dd)
Number of pages Size of Image (KB)
Abstract 2013-02-26 2 65
Claims 2013-02-26 4 128
Drawings 2013-02-26 9 144
Description 2013-02-26 12 635
Representative Drawing 2013-04-02 1 7
Cover Page 2013-04-29 2 42
Correspondence 2013-04-12 2 90
PCT 2013-02-26 8 345
Assignment 2013-02-26 2 101
PCT 2013-04-12 1 47
Fees 2013-06-12 1 48
Correspondence 2013-08-22 1 58
Correspondence 2013-10-18 1 12
Fees 2014-09-02 1 45
Prosecution-Amendment 2016-05-12 1 41
Fees 2016-08-15 1 43
Prosecution-Amendment 2017-05-23 3 205
Prosecution-Amendment 2017-05-23 3 205
Prosecution-Amendment 2017-10-30 17 647
Description 2017-10-30 13 631
Claims 2017-10-30 5 170
Correspondence 2018-06-21 1 43
Representative Drawing 2018-07-10 1 5
Cover Page 2018-07-10 1 36
Fees 2019-08-28 2 40
Fees 2020-09-02 1 33