Method and Apparatus for Creating Soil or Rock Subsurface Support
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.
This application is a continuation-in-part 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 FIELDThe 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 INVENTIONIn 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.
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.
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.
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.
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.
Although there 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 INVENTIONIn 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.
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.
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 top 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.
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
Referring to
Referring now to
Although a launcher of a particular construction is illustrated in
Now referring to
Additionally, the subsurface support of the present invention can be used in combination at a particular job site to support an overlying structure and to stabilize surround 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 surround the tunnel. In a tunnel, a support device can be emplaced in any orientation to include stabilizing the ceiling/upper surface of the tunnel.
Referring to
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.
With respect to a method of making the soil nail shown in
It is also contemplated that the protrusions 132 could also be combined with the other asperities shown in
With respect to launching the soil nails illustrated in
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.
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.
Claims
1. A soil nail comprising:
- a tubular body having at least one linear set of indentations formed thereon, said indentations extending into an outer surface of said soil nail, but not penetrating a wall of the soil nail.
2. A soil nail, as claimed in claim 1, further including:
- a plurality of threaded sections formed on an outer surface of said soil nail and spaced along a length of the soil nail.
3. A soil nail, as claimed in claim 1, further including:
- a second set of indentations formed on an opposite side of said soil nail from said at least one set of indentations, said indentations of said first and second sets extending substantially along a length of said soil nail from a proximal end to a distal end thereof.
4. A soil nail, as claimed in claim 1, wherein:
- at least one deformation is formed along substantially a length of said soil nail, and said deformation extending linearly with said at least one set of indentations.
5. A soil nail, as claimed in claim 1, wherein:
- said indentations are formed by a sprocket having a plurality of teeth that contact an outer surface of said soil nail, and said sprocket traversing substantially along a length of said soil nail to create said indentations.
6. A soil nail, as claimed in claim 4, wherein:
- said deformation is formed by applying a force to an outer surface of said soil nail thereby crushing said soil nail along a selected length thereof.
7. A soil nail, as claimed in claim 1, further including:
- a stinger secured to the distal end of a soil nail.
8. A method, installing a subsurface support comprising the steps of:
- providing a tubular body having a plurality of asperities formed thereon, said asperities being selected from the group consisting of (i) indentations formed thereon, said indentations extending into an outer surface of said soil nail, but not penetrating a wall of the soil nail, (ii) threaded sections, (iii) deformations of a cross-sectional shape of the tubular body, and (iv protrusions;
- providing a launching device including a chamber and a barrel;
- loading the subsurfaces support in said launching device;
- supporting a barrel of the launching device so that it is spaced from the surface of the ground;
- emitting pressurized gas to a chamber of the launching device; and
- launching the subsurface support into the ground in response to increasing pressure in the chamber.
9. A soil nail comprising:
- a tubular body having at plurality of asperities formed on the outer surface thereof, said asperities including a plurality of protrusions attached to an outer surface of the tubular body.
10. A soil nail comprising:
- a tubular body having at plurality of asperities formed on the outer surface thereof, said asperities including at least two asperities selected from the group consisting of (i) indentations, (ii) threaded sections, (iii) deformation of a cross-sectional shape of said tubular body, and (iv) protrusions.
11. A soil nail, as claimed in claim 10, further including:
- a stinger secured to the distal end of the soil nail.
Type: Application
Filed: Mar 29, 2007
Publication Date: Jul 26, 2007
Inventors: Robert Barrett (Grand Junction, CO), Albert Ruckman (Palisade, CA), Colby Barrett (Fruita, CO)
Application Number: 11/693,584
International Classification: E21D 21/00 (20060101);