U.S. patent application number 12/615668 was filed with the patent office on 2010-03-04 for method and apparatus for creating soil or rock subsurface support.
Invention is credited to Colby BARRETT, Robert K. BARRETT, Albert C. RUCKMAN.
Application Number | 20100054866 12/615668 |
Document ID | / |
Family ID | 46327622 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100054866 |
Kind Code |
A1 |
BARRETT; Robert K. ; et
al. |
March 4, 2010 |
METHOD AND APPARATUS FOR CREATING SOIL OR ROCK SUBSURFACE
SUPPORT
Abstract
A subsurface support is provided in the form of a soil nail. The
soil nail has asperities formed on the outer surface thereof to
improve the pullout capacity of the soil nail. The asperities can
take a number of forms to include indentations, deformations and
threads formed on the outer surface of the soil nail. Optionally, a
stinger may be attached to a distal end of the soil nail to further
enhance the pullout capacity of the soil nail.
Inventors: |
BARRETT; Robert K.; (Grand
Junction, CO) ; RUCKMAN; Albert C.; (Palisade,
CO) ; BARRETT; Colby; (Fruita, CO) |
Correspondence
Address: |
SHERIDAN ROSS PC
1560 BROADWAY, SUITE 1200
DENVER
CO
80202
US
|
Family ID: |
46327622 |
Appl. No.: |
12/615668 |
Filed: |
November 10, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11693584 |
Mar 29, 2007 |
|
|
|
12615668 |
|
|
|
|
11460317 |
Jul 27, 2006 |
7338233 |
|
|
11693584 |
|
|
|
|
10741951 |
Dec 18, 2003 |
7226247 |
|
|
11460317 |
|
|
|
|
Current U.S.
Class: |
405/259.1 |
Current CPC
Class: |
E02D 5/808 20130101;
E02D 5/80 20130101; E02D 3/12 20130101 |
Class at
Publication: |
405/259.1 |
International
Class: |
E21D 21/00 20060101
E21D021/00 |
Claims
1-11. (canceled)
12. A method of installing a subsurface support in the form of a
soil nail, comprising: providing a tubular body having a uniform
diameter extending along the length of the body, and having a
plurality of asperities formed thereon, said asperities including
at least two of (i) indentations formed on an outer surface of the
tubular body, said indentations extending into the body, but not
penetrating a wall of the soil nail, (ii) threaded sections, (iii)
deformations changing a cross-sectional shape of the tubular body,
and (iv) protrusions; and placing the subsurface support by at
least one of excavating the ground and inserting the tubular body,
or launching the tubular body from a launching device.
13. A method as claimed in claim 12, wherein: said subsurface
support further includes a stinger secured to the distal end of the
soil nail.
14. A method as claimed in claim 12, wherein: said tubular body
further includes a second set of indentation formed on opposite
sides of the soil nail, and said indentations of said first and
second sets extending substantially along a length of the soil nail
from a proximal end to the distal end thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of
co-pending U.S. application Ser. No. 11/460,317, filed on Jul. 27,
2006, entitled "METHOD AND APPARATUS FOR CREATING SOIL OR ROCK
SUBSURFACE SUPPORT", which is a continuation-in-part of copending
U.S. application Ser. No. 10/741,951, filed on Dec. 18, 2003,
entitled "METHOD AND APPARATUS FOR CREATING SOIL OR ROCK SUBSURFACE
SUPPORT", the disclosures of these applications being hereby
incorporated by reference herein in their entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to subsurface
supports placed in the ground, and more particularly, to a method
and apparatus for creating a soil or rock subsurface support that
can be used in multiple ways to include support for excavations as
a passive soil nail in tension, bending and/or shear, support to
stabilize sloping terrain as a tieback in tension, support for an
above ground structure as a micropile in compression and/or shear,
or support for an above ground structure as an anchor in
tension.
BACKGROUND OF THE INVENTION
[0003] In the construction of buildings, bridges, and other
man-made structures, it is well known to place passive supports
such as footers, piles, and other subsurface supports for
supporting such man-made structures. These types of supports are
passive because the earth around the subsurface support must first
shift or move to mobilize the available tensile, bending, or shear
capacities.
[0004] One particular problem associated with subsurface supports
which may be made of iron, steel, or other metals is that over
time, corrosion takes place which ultimately degrades the ability
of the support to provide designed support for an overlying
structure.
[0005] In addition to providing the above-mentioned subsurface
supports, it is also known to provide ground strengthening by
driving elongate reinforcing members, referred to as soil nails,
into the ground, in an array thus improving the bulk properties of
the ground. The soil nails themselves are not used for direct
support of an overlying structure; rather, the soil nails are
simply used to prevent shifting or other undesirable properties or
characteristics of a particular geological formation that is built
upon.
[0006] In some cases, the earth surrounding or near a man made
structure becomes unstable and requires active support, such as by
a tieback. Tiebacks are pre-tensioned subsurface supports that are
used to restrain any movement of surrounding soil and rock.
Tiebacks are similar to passive soil nails in construction, and can
be emplaced in a similar fashion as a soil nail. More recently,
soil nails and tiebacks have also been used to provide temporary
and permanent excavation support and slope stabilization.
[0007] The U.S. Pat. No. 5,044,831 discloses a method of soil
nailing wherein a soil nail is placed in the ground by being fired
from a barrel of a launcher. The soil nail is loaded into the
barrel, and pressurized gas emitted from the barrel forces the soil
nail into the ground to a desired depth. One advantage of using a
soil nail launcher, is that the soil nails can be emplaced with a
minimum amount of labor and equipment thereby minimizing
environmental impacts as well as providing a simple and economical
means of strengthening the ground. Drilling is the traditional way
to install soil nails, tiebacks, and anchors.
[0008] Although there are a multitude of subsurface supports and
methods by which subsurface supports can be emplaced, there is
still a need for simple and effective subsurface supports and an
environmentally friendly manner in which subsurface supports are
emplaced.
SUMMARY OF THE INVENTION
[0009] In accordance with the present invention, a method and
apparatus are provided to create a subsurface support device that
is placed in the ground. In a first embodiment of the invention,
the support device of the present invention has many potential
uses. In one use, this support device can be used as a passive soil
nail. In another use, this support device of the present invention
can be used as an active tieback in tension. More generally, for
use as a tieback, this support device can also be referred to as a
soil or rock inclusion. The term inclusion refers to the ability of
the support device to increase the tensile capacity of the rock and
soil. In yet another use, this support device can be used as a
micropile in compression, bending and shear. This support device,
when acting as a micropile, can be physically connected to an
overlying structure. In yet another use, this support device can be
used as an anchor in tension. For example, this support may be
tensioned as by a cable that interconnects the support to a man
made structure.
[0010] Once emplaced, this support device includes a protective
outer member or tube, an inner support member, and a stabilizing
mixture, preferably in the form of grout, cement, resin, or
combinations thereof which fixes the inner support member within
the outer protective member. The stabilizing mixture may also be
referred to as a cementious mixture. The outer protective member
supports the opening into the native rock and soil, and acts as a
housing for the cementious mixture. As discussed further below, the
outer member may be perforated thereby allowing the cementious
material to exit the perforations and increase the overall tensile
and compressive contribution of the support device. The outer
protective member also provides a barrier to prevent water or other
corrosive materials from contacting the inner support member. The
inner support member provides the design tensile and compressive
strength of the support. The inner support member may protrude a
desired distance above the outer member to connect to an overlying
structure to provide support in any desired manner to include
bearing/compression, tension, and/or shear. The diameter and length
of the outer member and inner member can be selected to provide the
necessary support. The outer member and stabilizing mixture provide
strengthening support to the inner member. For example, in
compression, the forces are transmitted from the inner support
member directly to the stabilizing mixture and the outer member. In
tension, forces are also transmitted to the stabilizing mixture and
the outer member thereby greatly increasing the force necessary to
dislodge or pull out the inner member. The method by which the
outer member of the subsurface support is emplaced in the ground is
preferably by a launching mechanism, such as that disclosed in the
U.S. Pat. No. 5,044,831.
[0011] In another embodiment of the present invention, the support
device is in the form of an improved soil nail including a
fiberglass body and a metal tip. The metal tip is preferably made
from a single piece of metal, such as a machined ingot of hardened
steel. The tip comprises a contacting portion or stinger that makes
contact with the ground when emplaced, and a proximal base portion
that is received within an opening in the distal end of the
fiberglass body thus allowing the tip to be attached to the
fiberglass body. The base portion may be attached by a compression
fit within the opening of the body and/or may be secured by an
appropriate bonding agent, such urethane glue. The size and
dimensions of the soil nail can be modified for the intended
purpose of use. One common size acceptable for use in many soil
stabilization efforts includes a fiberglass body of twenty feet in
length and a contacting portion of the metal tip extending
approximately six inches in length from the distal end of the
fiberglass body. For those applications in which a shorter body is
required, the same tip construction can be used, and the length of
the body can simply be shortened. Unlike most prior art soil nails,
the soil nail of the present invention has a tubular shaped body
without projections which allows the soil nail to be emplaced by
the soil nail launcher disclosed in the U.S. Pat. No. 5,044,831.
The use of a soil nail with a fiberglass body in conjunction with a
metal tip provides many advantages. The fiberglass body provides a
more cost effective solution than traditional soil nails that are
just made of metal. The fiberglass body also is highly resistant to
corrosion, even more so than many metal soil nails within corrosion
treated surfaces. The weight of the soil nail of the present
invention is also less than a metal soil nail, allowing it to
achieve greater velocity when emplaced by a soil nail launcher,
thus enhancing its ability to penetrate the ground. The strength of
the soil nail is not compromised because the fiberglass has
adequate strength, and has a greater elastic limit as compared to
many metal soil nails enabling the nail to handle even greater
tensile and shear loads. Although the soil nail has a relatively
smooth outer surface allowing it to be emplaced by a launcher, the
surface characteristics of the fiberglass provide excellent
adhesion with soil. Additionally, the stinger can be especially
designed to handle particular soil or rock formations without
having to modify the body of the soil nail. For example, in more
dense soil or rock formations, the stinger shape can be modified
prior to assembly with the body thus making the soil nail more
adaptable for many uses.
[0012] Other features and advantages of the present invention will
become apparent by a review of the following figures, taken in
conjunction with the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a cross-section of the subsurface support of the
present invention in a first embodiment, the support device being
emplaced in the ground and providing tensioning support to an
overlying above ground structure;
[0014] FIG. 2 is a cross-section illustrating an example launcher
that may be used to emplace the outer member of the support
device;
[0015] FIG. 3 is a partial cross-section illustrating a second
embodiment of the support device emplaced in the ground and
providing compression or bearing support to an overlying
structure;
[0016] FIG. 3A is an enlarged section of FIG. 3 illustrating one
way in which to provide holes or perforations in the subsurface
support;
[0017] FIG. 4 is a simplified elevation of a plurality of support
devices that may be used as passive soil nails or as tiebacks to
stabilize a sloping surface, the supports being emplaced in a
horizontal orientation;
[0018] FIG. 5 is an exploded fragmentary perspective view of a
third embodiment of the present invention in the form of an
improved soil nail;
[0019] FIG. 6 is a fragmentary side view of the soil nail of FIG.
5;
[0020] FIG. 7 is a cross section similar to FIG. 2 illustrating the
soil of the third embodiment being loaded in the launcher;
[0021] FIG. 8 shows an example installation of the soil nail of the
third embodiment to reinforce soil near a river or streambed
against scouring.
[0022] FIG. 9 illustrates yet another embodiment of a subsurface
support of the present invention in the form of a soil nail;
[0023] FIG. 10 is a cross-section taken along line 10-10 of FIG.
9;
[0024] FIG. 11 is a perspective view of a modification of the
embodiment of FIG. 9;
[0025] FIG. 12 is a perspective view of yet a further modification
of the embodiment of FIG. 9; and
[0026] FIG. 13 is a schematic diagram illustrating a method of
manufacturing the embodiment of FIG. 9; and
[0027] FIG. 14 is a perspective view of yet another embodiment of
the present invention showing a soil nail with protruding
asperities.
DETAILED DESCRIPTION
[0028] Referring to FIG. 1, the subsurface support 10 in a first
embodiment of the present invention is shown installed in the
ground G. The support device includes an outer member, preferably
in the form of a steel or iron tube 12 having a selected length and
diameter, and having an integral pointed tip 14. The tip 14 can be
conical in shape that facilitates emplacement of the outer tube as
by a launcher, as discussed below. After the outer tube is
emplaced, the stabilizing mixture is placed in the interior chamber
of the outer tube. Then, an inner support member that can be in the
form of an epoxy coated steel rod or bar is then placed within the
stabilizing mixture prior to hardening of the mixture. When the
stabilizing mixture cures, the inner support member 16 can provide
support to an overlying structure in compression, tension, and/or
shear. Depending upon the design requirements of the particular
structure to be built, a plurality of subsurface supports may be
emplaced at desired locations at the construction site, and each of
the support devices can be sized to provide the necessary
support.
[0029] FIG. 1 also illustrates one example of the manner in which
the support device 10 provides support. This one example
illustrates use of the subsurface support as an anchor in tension.
The subsurface support 10 includes a head or cap 20 that is
connected to the exposed upper end of the inner support member 16.
This head or cap can be attached by an integral threaded member 21
that is placed into a threaded well formed in the upper end of the
inner support member 16. The cap or head 20 then can be used for
attachment to the overlying structure. In the example of FIG. 1, a
ring 22 attaches to the cap 20, and a cable 24 connects to the
above ground structure (not shown). Thus, in FIG. 1, the support
device is used for providing tensioning support to the manmade
structure. If the device 10 was needed to provide support in
compression, the inner support member 16 could be directly
connected to the foundation or other base support of the overlying
manmade structure, as further discussed below with respect to FIG.
3.
[0030] Referring now to FIG. 2, a launching device 40 is shown as a
preferred method in which to emplace the outer member of the device
10. The launcher 40 illustrated in FIG. 2 corresponds to the
launcher illustrated in the U.S. Pat. No. 5,044,831, this reference
being incorporated herein in its entirety. The launcher 40 is shown
in its loaded condition with an outer member/tube 12 loaded in the
launcher and ready for firing. The outer tube 12 with the pointed
end 14 is capable of penetrating the ground upon sufficient impact
force. The launcher 40 comprises a barrel 42 communicating with a
breach 44. The breach 44 defines an upper chamber 45. The distal or
forward end of the outer tube 12 is received within an annular
shaped sabot 46, preferably made of a plastics material, which is
slidably received within the barrel 42 adjacent the chamber 45. The
trailing or proximal end of the outer tube 12 extends through the
chamber 44 and projects rearwards from the launcher 40 through an
aperture formed in the cap or upper surface 50 of the breach 44. An
annual shaped breach seal 52 seals the outer tube 12 with respect
to the upper surface 50. A gas inlet tube 54 communicates with the
chamber 45 for the admission of compressed gas. A baffle 56 of a
larger diameter than the barrel 40 forms an axial projection of the
barrel extending into contact with the surface of the ground G. On
firing the launcher, compressed gas is forced into the chamber 45
that causes outer tube 12 to be fired into the ground. The baffle
56 includes a locating ring 58 that forms a snug fit around the
sabot 46 such that the launcher remains in alignment with the outer
tube that is emplaced in the ground. Accordingly, the outer tube
when emplaced, remains in coaxial alignment with the barrel 42. As
also shown in FIG. 2, the breach seal 52 and sabot 46 may be held
in position prior to firing by a plurality of resilient members 60
which exert a separating force between the seal and the sabot.
[0031] Although a launcher of a particular construction is
illustrated in FIG. 2, it shall be understood that other launcher
types and methods can be used to emplace the outer tube within the
ground. For example, a launcher that makes use of an explosive
charge may be used. Alternatively, a vibratory means may also be
used along with some force that helps to ease the outer tube into
the ground. As stated above, it is preferable to avoid excavation
for emplacement of the outer tube as such excavation is equipment
and manpower intensive, and environmentally unfriendly.
[0032] FIG. 3 illustrates a second embodiment 10' of the present
invention. The support device 10' is the same as shown with respect
to the subsurface support of the first embodiment, with the
exception of a plurality of perforations/openings 30 which may be
formed in the outer tube 12. FIG. 3 also illustrates the device 10'
used to support an overlying structure S in compression. More
specifically, the device 10' has its upper end 28 embedded within a
concrete foundation F of a structure S. The foundation is shown as
extending a distance below ground level G. As also shown in FIG. 3,
the plurality of perforations/openings 30 which may be formed in
the outer tube allow the stabilizing material 18 to flow out from
the openings 30, thus forming external stabilizing structures 32.
In compression or tension, these external stabilizing features 32
help to strengthen the connection of the device 10' to the
surrounding soil. When filling the interior chamber of the outer
tube with the stabilizing mixture 18, such filling may take place
under pressure so that a desired quantity of the stabilizing
mixture 18 exits the perforation/openings 30, thereby forming the
external stabilizing features 32. In order to completely fill the
interior chamber of the outer tube, it may be preferable to
commence filling of the chamber from the lower most portion of the
chamber. A line (not shown) carrying the stabilizing mixture under
pressure can be inserted in the chamber and extend to the lower
most end of the support device, and then as the stabilizing mixture
fills the chamber, the line may be raised as necessary. Those
skilled in the art can envision other ways in which the stabilizing
mixture can fill the chamber of the outer tube.
[0033] Now referring to FIG. 3A, an enlarged section of the support
device 10' is shown specifically illustrating one manner in which
holes or perforations may be made in the outer tube 12. In FIG. 3A,
the openings 30 are formed by creating moon shaped cutouts thereby
leaving a chad or tab 34. The chad or tab 34 would be pushed away
from the exterior surface of the outer tube 12 as the pressurized
stabilizing mixture exited the interior chamber of the outer tube.
Alternatively, holes could be drilled or punched in the outer tube
12 in order to create an opening by which the stabilizing mixture
could flow through. Those skilled in the art can envision other
ways in which openings may be formed through the outer tube 12 in
order to facilitate flow of stabilizing mixture therethrough to
create the external stabilizing features 32.
[0034] FIG. 4 illustrates use of the subsurface support of the
invention to stabilize a sloping surface. In the figure, three
support devices 10 are illustrated and are spaced from one another
in a desired arrangement to best support the sloping surface. The
support devices are disposed in a horizontal orientation, but it
shall be understood that the support devices may be placed at any
angle or orientation depending upon the surrounding terrain. The
support devices in FIG. 4 would be representative of use of the
supports as either passive soil nails or tiebacks.
[0035] Additionally, the subsurface support of the present
invention can be used in combination at a particular jobsite to
support an overlying structure and to stabilize surrounding soil.
In this case, one or more support devices can be structurally
connected to an overlying structure such as shown in the figures,
and one or more additional support devices can be used as soil
nails to stabilize the surrounding soil or rock formation. Even in
tunnel construction, the support device of the present invention
can be used to stabilize the soil or rock formation surrounding the
tunnel. In a tunnel, a support device can be emplaced in any
orientation to include stabilizing the ceiling/upper surface of the
tunnel.
[0036] FIGS. 5 and 6 illustrate yet another preferred embodiment of
the present invention, namely, an improved soil nail 70 of dual
material construction. As shown, the nail 70 includes a contacting
portion or stinger 72 that attaches to a fiberglass body 74. The
soil nail extends symmetrically along a longitudinal axis A-A. The
stinger 72 comprises a conical distal tip 76, and a plurality of
axially aligned flanges 78 that extend proximally from the tip 76.
Spaced between the flanges 78 are neck sections 80 defining
portions of the stinger with smaller diameters. A transition flange
82 interconnects the most proximally located neck section 80 to an
intermediate extension 84. A shoulder 86 defines the interface with
the distal end of the body 74. A base portion 88 extends from the
shoulder 86, and is inserted within the opening 90 formed in the
distal end of the body 74. Preferably, the distal end 92 of the
body 74 has a flat surface thus providing a complementary flat
mating surface with the contacting face 94 of the shoulder 86. As
shown, the stinger components are generally smaller in diameter
than the diameter of the body 74. Further, the flanges 78 generally
have a similar diameter as compared to the large end of the conical
distal tip 76. The conical tip 76 and flanges 78 may further
include peripheral edges 79 that extend generally parallel to the
longitudinal axis A-A of the soil nail. The base portion 88
preferably extends approximately one foot within the opening 90 if
the exposed part of the stinger has a length of approximately six
inches. If a longer stinger is used, then preferably the base
portion extends further into the opening 90 in order to provide
adequate support. The base portion may be secured by a compression
fitting in opening 90 and/or an appropriate bonding agent can be
used.
[0037] Referring to FIG. 7, the soil nail 70 is shown as mounted
within the soil nail launcher 40 of FIG. 2. The soil nail 70 is
emplaced in the same manner as the outer tube 12 described in the
first embodiment; however, it being understood that the soil nail
70 is a subsurface support that can also be completely buried
within the soil without exposing an upper end thereof.
[0038] FIG. 8 shows an example use of the soil nails 70. This
figure specifically shows a number of soil nails 70 installed in
and around the bed of a body of water, such as a stream or river R
to thereby stabilize the soil around the bed. The soil nails 70
have been placed adjacent some abutments A that may be used to
stabilize an overhead structure such as a bridge (not shown).
Scouring and other types of erosion can be remedied with use of
soil nails in this manner. It shall be understood that the soil
nail of the present invention can be used in many other
applications, and FIG. 8 is simply one example.
[0039] FIG. 9 illustrates yet another soil nail embodiment of the
present invention. The soil nail 100 of FIG. 9 includes a plurality
of surface asperities that improve the pull out capacity of the
soil nail. Once a soil nail is in place, it is advantageous for the
soil nail to remain in place without slippage or pull out. With
respect to the embodiment shown in FIG. 3, pull out capacity is
improved after the cementious material exits the location of the
external stabilizing features. However, there is also a need to
provide a soil nail with improved pull out capacity wherein such
features are not activated in a later processing step, but rather,
are formed integrally with the soil nail prior to placement. In the
embodiment of FIG. 9, the body 102 of the soil nail 100 includes a
plurality of dimples or indentations 110 formed in a linear
pattern. Referring also to FIG. 10, these indentations 110
preferably do not pass through the entire thickness of the wall of
the soil nail thereby maintaining better structural integrity of
the soil nail whereas a plurality of holes made in the same linear
fashion might otherwise decrease the overall strength of the soil
nail such that it may break apart upon being fired from a launcher
into the ground, or may prematurely deteriorate in the soil. The
surface asperities caused by the indentations enhance the pullout
capacity of the soil nail without materially weakening the
construction of the soil nail. FIG. 9 also illustrates an optional
stinger 104 attached to the distal end 106 of the soil nail.
Therefore, as discussed above with respect to the embodiment shown
in FIGS. 5 and 6, the stinger may be used to further improve the
pullout capacity of the soil nail.
[0040] Although the indentations 110 are shown as extending
uninterrupted between the proximal end 108 and the distal end 106,
it is also contemplated that the indentations could be provided in
a discontinuous pattern, a continuous pattern, or combinations
thereof. Additionally, while the indentations are shown as being
provided in a linear orientation, it is also contemplated that the
indentations could be provided in a non-linear or random
fashion.
[0041] FIG. 11 illustrates a modification to the embodiment of FIG.
9 wherein a combination of surface asperities or features are
provided to improve the pull out capacity of the soil nail. In FIG.
11, the soil nail 120 has at least one linear set of indentations
124, as well as being deformed along a linear line L following the
path of the indentations 124. The deformed shape of the bar, as
well as the indentations each improve the pull out capacity of the
soil nail.
[0042] FIG. 12 shows yet another modification to the embodiment of
FIG. 9. This soil nail is also deformed along a linear line
following a path of the indentations 124, but further includes a
plurality of threaded portions 126 spaced along the length of the
soil nail. The threads also increase the pull out capacity of the
soil nail, and are features that can be formed prior to a placement
of the soil nail.
[0043] FIG. 13 illustrates a method by which a linear set of
indentations may be formed on opposite sides of the soil nail 100
in accordance with the embodiment of FIG. 9. As shown, an upper
sprocket 112 has a plurality of teeth 114 formed on the outer
surface thereof, similar to a sprocket for a bicycle. A lower
sprocket 116 with teeth 118 are also provided, and disposed on an
opposite side of the soil nail. In order to form the indentations,
the bar is orientated so that it passes between the sprockets, and
the sprockets then rotate about their respective central axes to
form the indentations on the outer surface of the soil nail.
[0044] With respect to a method of making the soil nail shown in
FIG. 12, a first step may include creating the various sets of
threads 126 on the outer surface of the soil nail. In the next
step, the indentations 124 can be formed in the manner shown in
FIG. 13. Additionally, it is contemplated that the amount of force
or pressure provided by one or both of the sprockets 112 and 116
could be increased such that the body of the soil nail is deformed
along the path of the indentations.
[0045] FIG. 14 illustrates yet another embodiment of the present
invention. In this embodiment, the soil nail 130 has a plurality of
small asperities formed on the outer surface of the nail. The
asperities in this preferred embodiment are shown as small
protrusions 132. The protrusions are relatively small in comparison
to the tabs 34 shown in the embodiment of FIG. 3A. The protrusions
132 help in increasing the pullout capacity of the soil nail. One
method to create the protrusions 132 is to weld small pieces of
material to the soil nail. The protrusions 132 can be used with a
soil nail that is launched from launcher 40 without concern that
the protrusions will create excessive interference which otherwise
might deform or break the nail upon being launched. The protrusions
can be provided in a geometrically spaced pattern or randomly on
the outer surface of the soil nail. One acceptable general size for
the protrusions may include those that protrude approximately
one-eighth to one-half inch away from the outer surface of the soil
nail. Spacing between each of the protrusions may be approximately
4-6 inches.
[0046] It is also contemplated that the protrusions 132 could also
be combined with the other asperities shown in FIGS. 9-12. Thus, a
composite group of asperities could be provided on a soil nail to
optimize pull out capacity. A desired combination of the asperities
can be tailored to match optimum pullout capacity based on the type
of soil and rock formations present.
[0047] With respect to launching the soil nails illustrated in
FIGS. 9-12 and 14, the launcher 40 illustrated in FIG. 2 can be
used without requiring modification.
[0048] With the method and apparatus of the present invention, a
subsurface support is provided which can be emplaced with a minimum
of effort. In one advantage of the present invention, the
subsurface support provides an alternative to other anchoring means
because the outer tube provides protection to the inner support
member from corrosion or other undesirable environmental factors.
Depending upon the geological conditions, the outer tube can be
emplaced with a launching device that is adapted to account for
varying geological formations. For example, ground formations with
little rock allows emplacement of the outer tube with a minimum of
force while placement of the outer tube into an actual rock
formation would require a greater force provided by the launching
mechanism. In any case, the particular launching device chosen may
have the capability of emplacing the outer tube to the appropriate
depth and through various rock and soil conditions. In another
advantage of the present invention, an improved soil nail is
provided in a two-piece construction. This construction is cost
effective yet provides at least the same performance as compared to
a soil nail made of a single piece of material.
[0049] While the method and the apparatus of the present invention
have been provided in various preferred embodiments, it shall be
understood that various other changes and modifications may be made
within the spirit and scope of the present invention.
* * * * *