Patent Description:
The present disclosure relates in general to pile leads and extensions with soil displacement assemblies for forming composite pile columns.

Piles are often required to be placed into the ground for providing support for foundations or other structures. It is desirable to install such piles quickly and efficiently so as to reduce construction costs. Often it is beneficial to form the piles in place, i.e., at the job site. One conventional method for forming piles at the job site involves inserting a flat disk on a shaft down through the soil by turning a screw at a lower end of a shaft. The disk clears a cylindrical region around the shaft. The cylindrical region is filled with grout to encapsulate the shaft. Another conventional method for forming piles at the job site involves placing a helical pile that appears to have an elongated pipe with a central chamber in the soil. The pipe has a helical blade with an opening in the trailing edge of the blade where grout is extruded. The grout fills the portions of the soil disturbed by the blade. The present disclosure provides a new system to form pile columns at the job site. D1 (<CIT>) discloses a soil displacement pile for forming a composite pile column, the soil displacement pile comprising a lead, wherein the lead comprises: a lead shaft; and at least one lead soil displacement assembly attached at least partially to the lead shaft, the at least one lead soil displacement assembly including: an upper helical plate defining an inner edge portion and an outer edge portion; a lower helical plate having a central opening defining an inner edge portion and an outer edge portion, the lower helical plate being independent of the upper helical plate and spaced a predefined distance from the upper helical plate along a longitudinal axis of the soil displacement assembly; and a curved soil displacement plate having a first edge portion attached to the upper helical plate and a second edge portion attached to the lower helical plate such that a convex surface of the curved soil displacement plate forming a soil contacting surface extends from the inner edge portions of the upper helical plate and the lower helical plate to the outer edge portions of the upper helical plate, and such that the convex surface is oriented to contact soil when the soil displacement assembly is driven into the soil to displace the soil from the inner edge portions of the upper helical plate and the lower helical plate toward the outer edge portions of the upper helical plate and the lower helical plate so as to create a cavity in the soil; and at least one extension comprising an extension shaft.

An aspect of the present invention is provided in the independent claim <NUM>. The present disclosure provides descriptions of soil displacement assemblies that are attached to helical pile leads and/or extensions and used to form composite pile columns at the job site.

The present disclosure also provides descriptions of soil displacement piles having one or more soil displacement assemblies that are used to form composite pile columns at the job site. According to the invention, the soil displacement pile comprises a lead and at least one extension. The lead has a lead shaft, and at least one lead soil displacement assembly attached at least partially to the lead shaft. The at least one extension has an extension shaft, and at least one extension soil displacement assembly attached to the extension shaft. In another exemplary configuration, the soil displacement pile comprises a shaft, and a plurality of soil displacement assemblies secured to the shaft and separated by a longitudinal distance.

The figures depict configurations for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative configurations of the structures illustrated herein may be employed without departing from the principles described herein, wherein:.

The present disclosure provides configurations of pile leads and extensions with soil displacement assemblies that facilitate the formation of grout, concrete or cement based pile columns. The soil displacement assemblies push the soil so as to displace the soil radially outwardly away from a shaft of the soil displacement pile lead and any extensions to form a cavity in which grout, cement or concrete can be poured to at least partially surround the pile leads and any extensions. The cured grout, cement or concrete with the embedded pile form a composite pile column. For ease of description the word "filler" is used when describing the material being poured into the cavity. The filler may include grout, cement, concrete or other suitable material that can be poured into the cavity and hardened to form the composite pile column.

Referring to <FIG>, an exemplary configuration of a soil displacement pile according to the present disclosure is shown. The soil displacement pile <NUM> has a lead <NUM> and possibly one or more extensions <NUM>. The lead <NUM> comprises a square or round shaft or pipe <NUM> and at least one soil displacement assembly <NUM>. The lead shaft <NUM>, which is the bottom most shaft of a soil displacement pile <NUM>, has a lead head portion <NUM> and a lead end portion <NUM>. The lead end portion <NUM> is configured to first penetrate the soil, and terminates at its distal end with a tapered tip <NUM>. Each of the one or more extensions <NUM> comprises a square or round shaft or pipe <NUM> and at least one soil displacement assembly <NUM>. Each extension shaft <NUM> has extension head portion <NUM> and an extension end portion <NUM>. The first extension added to the soil displacement pile <NUM> is secured to the lead <NUM> where the extension end portion <NUM> is mated with the lead head portion <NUM> using one or more nut and bolt. Subsequent extensions may be sequentially joined together where the extension end portion <NUM> of the next in line extension <NUM> is mated with the extension head portion <NUM> of the previous extension <NUM> using one or more nut and bolt. The lead shaft <NUM> and the extension shaft <NUM> can be hollow or solid, and the shafts <NUM> and <NUM> can be made of metal, e.g., steel or galvanized steel, or carbon fiber, or other suitable material known in the art.

As noted, the extensions <NUM> are optional such that the lead <NUM> may comprise the soil displacement pile <NUM> and a pile drive system head is used to rotate the lead <NUM> into the soil. If one or more extensions <NUM> are added to the lead <NUM> then the lead and the one or more extensions form the soil displacement pile <NUM>, and the pile drive system head is used to first rotate the lead <NUM> into the soil and then each extension successively into the soil.

As noted, the lead <NUM> and extensions <NUM> according to the present disclosure include one or more soil displacement assemblies <NUM> secured directly or indirectly to the lead shaft <NUM> and/or the extension shaft <NUM>. Securing the soil displacement assemblies <NUM> directly to the lead shaft <NUM> and/or the extension shaft <NUM> includes a direct connection between the respective shaft and the soil displacement assembly, such as by welding or mechanical fasteners. Securing the soil displacement assemblies <NUM> indirectly to the lead shaft <NUM> and/or the extension shaft <NUM> includes an indirect connection between the respective shaft and the soil displacement assembly, such as by using a coupler to join the respective shaft and the soil displacement assembly and securing the coupler to the shaft, or by mating the soil displacement assembly with a coupling already on the respective shaft. In the configuration of <FIG>, the lead <NUM> has one soil displacement assembly <NUM> and the extension <NUM> has one soil displacement assembly <NUM>. In the configuration of <FIG>, the lead <NUM> has three soil displacement assemblies <NUM> spaced along the length of the shaft with a longitudinal distance "Ls" between each soil displacement assembly. The longitudinal distance "Ls" between the soil displacement assemblies may be in the range from about <NUM> feet to about <NUM> feet. Similarly, in the configuration of <FIG>, the lead <NUM> has three soil displacement assemblies <NUM> spaced along the length of the shaft with a longitudinal distance "Ls" between each soil displacement assembly, and also includes one or more spaced apart load bearing helical plates <NUM> arranged on the lead shaft <NUM>. The load bearing helical plate <NUM> is typically in the lead end portion <NUM> and separated from the lower soil displacement assembly <NUM> a distance "Lt". The spacing "Lt" between the load bearing helical plate <NUM> and the lower soil displacement assembly <NUM> may range from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches). The load bearing helical plate <NUM> is provided to initially penetrate the soil and pull the soil displacement pile <NUM> downward when the lead shaft <NUM> is rotated.

In the configuration of <FIG>, the lead <NUM> has a single load bearing helical plate <NUM>. In the event more than one load bearing helical plates <NUM> are secured to the lead shaft <NUM>, the load bearing helical plates <NUM> may have the same diameter, or the load bearing helical plates <NUM> may have different diameters that are in, for example, a tapered arrangement. To illustrate a tapered arrangement, the smallest diameter load bearing helical plate <NUM> may be positioned closest to the tapered tip <NUM> of the lead shaft <NUM>, and the largest load bearing helical plate <NUM> may be positioned at a distance away from the tapered tip <NUM>. Such load bearing helical plates <NUM> on the lead shaft <NUM> may be spaced apart at a distance sufficient to promote plate load bearing capacity as is known in the art. The diameter of the load bearing helical plates <NUM> may range from between about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) depending upon the load the soil displacement pile <NUM> is to carry. The pitch of the load bearing helical plates is between about <NUM> (<NUM> inches) and about <NUM> (<NUM> inches). For example, the pitch may be about <NUM> (<NUM> inches).

Referring now to <FIG>, exemplary configurations of a soil displacement assemblies <NUM> according to the present disclosure are shown. Referring to <FIG>, the soil displacement assembly <NUM> includes, for example, a pair of helical plates <NUM> and at least one soil displacement plate <NUM>. Each helical plate pair <NUM> comprises an upper helical plate <NUM> and a lower helical plate <NUM>. The upper and lower helical plates <NUM> and <NUM> are separated by a longitudinal distance "Lp" creating a void <NUM> between the upper and lower helical plates. The distance "Lp" is based upon, for example, the helix pitch and diameter. The distance "Lp" can range from between about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches). Preferably, the longitudinal distance between the soil displacement assemblies "Ls" is greater than the longitudinal distance between the helical plate pair "Lp".

Referring to <FIG>, the diameter "D" of the upper and lower helical plates <NUM> and <NUM> may range from between about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) depending upon the size of the cavity to be created by soil displacing assembly <NUM> and thus the size of the pile column created by the cured filler and soil displacement pile <NUM>. The diameter "D" of the upper and lower helical plates <NUM> and <NUM> may be the same, as shown in <FIG>, or they may differ, as shown in <FIG>. More specifically, the upper helical plate <NUM> may have a diameter that is larger than the lower helical plate <NUM>, or the upper helical plate <NUM> may have a diameter that is smaller than the lower helical plate <NUM>. For example, the diameter of the upper helical plate <NUM> may be about <NUM> (<NUM> inches) and the diameter of the lower helical plate <NUM> may be <NUM> (<NUM> inches). As another example, the diameter of the upper helical plate <NUM> may be about <NUM> (<NUM> inches) and the diameter of the lower helical plate <NUM> may be <NUM> (<NUM> inches). The upper and lower helical plates <NUM> and <NUM> have a helical pitch "P" of between about <NUM> (<NUM> inches) and about <NUM> (<NUM> inches). For example, the pitch may be about <NUM> (<NUM> inches). The pitch of the upper and lower helical plates <NUM> and <NUM> creates a gap <NUM> between the leading edge of each plate and the trailing edge of each plate. This gap <NUM> permits filler being poured into the cavity <NUM>, seen in <FIG>, created by the one or more soil displacement assemblies <NUM> to fill the void <NUM> between the upper and lower helical plates <NUM> and <NUM>, and to permit filler to pass through the soil displacement assembly. The thickness "T" of each helical plate <NUM> and <NUM> may be between about <NUM> (<NUM>/<NUM> inch) and about <NUM> (<NUM>/<NUM> inch).

Referring again to <FIG>, positioned between the upper and lower helical plates <NUM> and <NUM> is the at least one soil displacement plate <NUM>. In the configuration of <FIG>, one soil displacement plate <NUM> is positioned between the helical plates <NUM> and <NUM> and secured to the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM> by, for example, welding or mechanical fasteners. The soil displacement plate <NUM> is also attached to each of the upper and lower helical plates <NUM> and <NUM> by, for example, welding or mechanical fasteners. Attaching the soil displacement plate <NUM> between the upper and lower helical plates <NUM> and <NUM> increases the strength of the soil displacement plate <NUM> facilitating displacement of the soil as described herein. Each soil displacement plate <NUM> has a soil contacting surface <NUM>, and extends radially from the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM> to an outer edge of each helical plate. Preferably, each soil displacement plate <NUM> is a curved plate, as shown in <FIG>, and is secured to the helical plates <NUM> and <NUM> so that the soil displacement plate curves in a counterclockwise direction proceeding radially from the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM> such that the soil contacting surface <NUM>, here the convex surface, of the soil displacement plate <NUM> is positioned to contact and displace the soil to create the cavity <NUM> for forming the pile column <NUM>. More specifically, as the helical plates <NUM> and <NUM> rotate clockwise the convex surface <NUM> of the soil displacement plate <NUM> contacts the soil and displaces it radially outward away from the shaft <NUM> of the lead <NUM> or away from the shaft <NUM> of the extension <NUM> creating the displaced soil cavity <NUM>.

The soil displacement plate <NUM> may be secured to the lead shaft <NUM> or extension shaft <NUM> and the helical plates <NUM> and <NUM> anywhere along the helical plates. In the configuration shown in <FIG>, one end of the soil displacement plate <NUM> is positioned adjacent a leading edge <NUM> of the upper helical plate <NUM> and adjacent a leading edge <NUM> of the lower helical plate <NUM>. The soil displacement plate <NUM> is illustrated in <FIG> as having a soil contacting surface <NUM> over a relatively small circumferential portion of the upper and lower helical plates <NUM> and <NUM>. However, the soil displacement plate <NUM> may have a soil contacting surface <NUM> that extends along a more substantial portion of the circumference of the upper and lower helical plates <NUM> and <NUM>. More specifically, if the soil displacement plate has a curvature, the radius of the curvature of the soil displacement plate <NUM> may vary depending upon, for example, the type of soil to be encountered and the relative density of the soil to be encountered. The radius of the curvature of the soil displacement plate <NUM> may be in the range of about <NUM> degrees to about <NUM> degrees. In an alternative configuration, the soil contacting surface <NUM> may vary and may be irregular so long as the soil contacting surface <NUM> is capable of displacing soil outwardly as the soil displacement pile <NUM> is being rotated.

The vertical orientation of the soil displacement plate <NUM> may vary depending upon a number of considerations such as the location along the helical plates and the radius of curvature. For example, in the configuration shown in <FIG>, the soil displacement plate <NUM> is secured to the helical plates <NUM> and <NUM> so that the soil displacement plate is substantially vertical relative to the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM>. As another example, the soil displacement plate <NUM> may be angled or tilted relative to the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM>.

Referring to <FIG>, another exemplary configuration of a soil displacement assembly is shown. The soil displacement assembly <NUM> includes coupling tube <NUM>, a pair of helical plates <NUM> and at least one soil displacement plate <NUM>. The coupling tube <NUM> is configured to fit over shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM>, and can be secured to the shaft <NUM> or <NUM> via a mechanical fastener, such as a set screw <NUM> and threaded aperture <NUM>, that are threaded into matching threaded apertures in the respective shaft <NUM> or <NUM>. Alternatively, the set screw <NUM> when tightened in the threaded aperture <NUM> on the respective shaft <NUM> or <NUM> can create a friction force between the coupling tube <NUM> and the shaft thus binding the soil displacement assembly <NUM> in position on the shaft. Each helical plate pair <NUM> comprises an upper helical plate <NUM> and a lower helical plate <NUM>. The upper and lower helical plates <NUM> and <NUM> are secured to the coupling tube <NUM> by for example welding the plates to the coupling tube. The upper and lower helical plates <NUM> and <NUM> are separated by a longitudinal distance "Lp" creating a void <NUM> between the upper and lower helical plates. Positioned between the upper and lower helical plates <NUM> and <NUM> is the at least one soil displacement plate <NUM>, as described above and for the ease of description is not repeated. In this exemplary configuration, the soil displacement assembly can be secured to existing helical piles to form the soil displacement pile <NUM> of the present disclosure.

Referring to <FIG>, another exemplary configuration of a soil displacement assembly is shown. The soil displacement assembly <NUM> includes coupling tube <NUM>, a pair of helical plates <NUM> and at least one soil displacement plate <NUM>. The coupling tube <NUM> is configured to fit over shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM>, and a coupling <NUM> at a top of the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM> prevents the coupling tube <NUM> from separating from the shaft when the lead <NUM> or extension <NUM> is being inserted into the ground. To secure the soil displacement assembly <NUM> on the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM> adjacent the coupling <NUM>, a mechanical fastener, such as a set screw <NUM> and threaded aperture <NUM>, can be used to create a friction force between the coupling tube <NUM> and the respective shaft <NUM> or <NUM>, thus binding the soil displacement assembly <NUM> in position on the shaft. Similar to the configuration of <FIG>, each helical plate pair <NUM> comprises an upper helical plate <NUM> and a lower helical plate <NUM>. The upper and lower helical plates <NUM> and <NUM> are secured to the coupling tube <NUM> by for example welding the plates to the coupling tube. The upper and lower helical plates <NUM> and <NUM> are separated by a longitudinal distance "Lp" creating a void <NUM> between the upper and lower helical plates. Positioned between the upper and lower helical plates <NUM> and <NUM> is the at least one soil displacement plate <NUM>, as described above and for the ease of description is not repeated. In this exemplary configuration, the soil displacement assembly can be secured to existing helical piles to form the soil displacement pile <NUM> of the present disclosure.

Referring to <FIG> and <FIG>, another exemplary configuration of a soil displacement assembly <NUM> is shown. In this configuration, the soil displacement assembly <NUM> includes two helical plates forming a pair <NUM> and a pair of soil displacement plates 44a and 44b. The helical plate pair <NUM> comprises an upper helical plate <NUM> and a lower helical plate <NUM> which are described above and for the ease of description are not repeated. In this configuration, the first soil displacement plate 44a is positioned the same as the soil displacement plate shown in the configuration of <FIG>. The second soil displacement plate 44b is also attached between the helical plates <NUM> and <NUM> and oriented the same as the first soil displacement plate 44a as shown. However, the second soil displacement plate 44b is attached to the helical plates at an angular distance "β" from the first soil displacement plate 44a as shown in <FIG>. The angular distance "β" may be from about <NUM> degrees to about <NUM> degrees. For example, the angular distance "β" may be <NUM> degrees.

<FIG> illustrates another exemplary configuration of the soil displacement assembly according to the present disclosure. In this configuration, the soil displacement assembly <NUM> comprises a helical plate pair <NUM> where the diameter of the upper helical plate <NUM> and the diameter of the lower helical plate <NUM> differ. In the configuration shown, the upper helical plate <NUM> has a larger diameter than the lower helical plate <NUM>. However, one skilled in the art would readily appreciate that the upper helical plate <NUM> can have a smaller diameter than the lower helical plate <NUM>. The soil displacement plate <NUM> is attached between the upper helical plate <NUM> and the lower helical plate <NUM>. The different diameter between the upper and lower helical plates <NUM> and <NUM> facilitates the displacement of soil and the pulling of the soil displacement pile <NUM> into the ground because the distance "R" between an outer edge of the larger diameter helical plate, here plate <NUM>, and the soil displacement plate <NUM> permits more of the helical plate <NUM> to grip the soil.

<FIG> illustrate another exemplary configuration of the soil displacement assembly <NUM> according to the present disclosure. In this configuration, the soil displacement assembly <NUM> includes two helical plates forming a pair <NUM> and a pair of soil displacement plates 44a and 44b. The helical plate pair <NUM> comprises an upper helical plate <NUM> and a lower helical plate <NUM> which are described above and for the ease of description are not repeated. In this configuration, the first soil displacement plate 44a is positioned the same as in, for example, the configurations of <FIG> and <FIG>. The second soil displacement plate 44b is attached to the upper helical plate <NUM> and the shaft <NUM> of the lead <NUM> or the shaft <NUM> of the extension <NUM> near the trailing edge <NUM> of the upper helical plate <NUM>. The second soil displacement plate 44b provides additional soil displacement further facilitating the formation of the cavity <NUM> in which the pile column <NUM>, seen in <FIG>, is formed.

Referring now to <FIG> and <FIG>, an example of the insertion of a lead <NUM> into the ground and the pouring of filler into the cavity created by the soil displacement assembly of the present disclosure will be described. Initially, as the shaft <NUM> of the lead <NUM> is rotated in a clockwise direction the leading edge <NUM> and outer edge of the lower helical plate <NUM> grips the soil to start pulling the lead <NUM> into the ground. As the lead <NUM> rotates the soil contacting surface <NUM> of the soil displacement plate <NUM> displaces the soil cut by the leading edge <NUM> and outer edge of the lower helical plate <NUM> radially outwardly away from a shaft <NUM> of the lead <NUM> to begin to form a cavity <NUM> in which filler is poured. The leading edge <NUM> and outer edge of the upper helical plate <NUM> then grips the soil to assist in pulling the lead <NUM> into the ground. The upper helical plate <NUM> also helps to mix any loose residual soil within the cavity <NUM> with the filler. The gap <NUM> in the helical plates <NUM> and <NUM> permits the filler being poured into the cavity to fill the void <NUM> between the upper and lower helical plates, and permits the filler to pass through the soil displacement assembly <NUM> to provide a uniform pour of the filler.

When the second soil displacement assembly <NUM> enters the cavity <NUM> the leading edge <NUM> and outer edge of the lower helical plate <NUM> grips the soil to assist in pulling the lead <NUM> into the ground. As the lead <NUM> rotates the soil contacting surface <NUM> of the soil displacement plate <NUM> displaces any soil cut by the leading edge <NUM> of the lower helical plate <NUM> radially outwardly away from a shaft <NUM> of the lead <NUM> to continue to form the cavity <NUM> in which filler is continued to be poured. The leading edge <NUM> and outer edge of the upper helical plate <NUM> then grips the soil to assist in pulling the lead <NUM> into the ground. The upper helical plate <NUM> also helps to mix any loose residual soil within the cavity <NUM> with the filler. Again, the gap <NUM> in the helical plates <NUM> and <NUM> permits the filler being poured into the cavity to fill the void <NUM> between the upper and lower helical plates <NUM> and <NUM> of the second soil displacement assembly <NUM>, and to permit the filler pass through the soil displacement assembly to provide a uniform pour of the filler.

When the third soil displacement assembly <NUM> enters the cavity <NUM> the leading edge <NUM> and outer edge of the lower helical plate <NUM> grips the soil to assist in pulling the lead <NUM> into the ground. As the lead <NUM> rotates the soil contacting surface <NUM> of the soil displacement plate <NUM> displaces any soil cut by the leading edge <NUM> of the lower helical plate <NUM> radially outwardly away from a shaft <NUM> of the lead <NUM> to continue to form the cavity <NUM> in which filler is continued to be poured. The leading edge <NUM> and outer edge of the upper helical plate <NUM> then grips the soil to assist in pulling the lead <NUM> into the ground. The upper helical plate <NUM> also helps to mix any loose residual soil within the cavity with the filler. Again, the gap <NUM> in the helical plates <NUM> and <NUM> permits filler being poured into the cavity to fill the void <NUM> between the upper and lower helical plates <NUM> and <NUM> of the third soil displacement assembly <NUM>, and permits the filler to pass through the soil displacement assembly to provide a uniform pour of the filler. When the filler cures, the filler with the embedded pile <NUM> form a composite pile column <NUM>.

The present disclosure describes a way of displacing soil for the purpose of creating a pile column with an embedded soil displacement pile. The one or more helical soil displacement assemblies displace soil so that filler may be poured into a cavity created by the one or more soil displacement assemblies around the soil displacement pile forming a pile column at the job site. The soil displacement assembly of the present disclosure permits the use of larger diameter shafts and helical plates for the lead and/or extensions which facilitates displacement of more soil and results in the formation of pile columns having larger diameters and therefore improved load capacity.

The helical plate pairs can be placed close together with one or more soil displacement plates connected between the helical plate pairs. The helical plates help loosen the soil and provide strength to keep the soil displacement plate in position when screwing the soil displacement pile into the ground. By using a hollow or solid shaft as a centerpiece of the lead and extensions, and larger helical plates, the soil displacement pile of the present disclosure can displace a greater volume of soil to create larger pile columns. The lead shaft and extension shafts and helical plates provide additional stiffening to the soil displacement assemblies while the filler provides the larger diameter, skin friction, and higher load capacities.

The soil displacement pile and soil displacement assembly of the present disclosure can be adapted to form any size pile column needed for a particular job. For example, the soil displacement pile and soil displacement assembly of the present disclosure can easily form pile columns that are greater than <NUM> (eight inches) in diameter.

Claim 1:
A soil displacement pile (<NUM>) for forming a composite pile column, the soil displacement pile comprising:
a lead (<NUM>) comprising:
a lead shaft (<NUM>); and
at least one lead soil displacement assembly (<NUM>) attached at least partially to the lead shaft, the at least one lead soil displacement assembly including;
an upper helical plate (<NUM>) having
an outer edge portion and a central opening defining an inner edge portion;
a lower helical plate (<NUM>) having an outer edge portion and a central opening defining an inner edge portion, wherein the lower helical plate is spaced a predefined distance from the upper helical plate (<NUM>) along a longitudinal axis of the soil displacement assembly (<NUM>); and
a curved soil displacement plate (<NUM>) having a first edge portion attached to the upper helical plate (<NUM>) and a second edge portion attached to the lower helical plate (<NUM>) such that a convex surface of the curved soil displacement plate forming a soil contacting surface extends from the inner edge portions of the upper helical plate (<NUM>) and the lower helical plate (<NUM>) to the outer edge portions of the upper helical plate (<NUM>) and the lower helical plate, and such that the convex surface is oriented to contact soil when the soil displacement assembly (<NUM>) is driven into the soil to displace the soil from the inner edge portions of the upper helical plate (<NUM>) and the lower helical plate (<NUM>) toward the outer edge portions of the upper helical plate and the lower helical plate so as to create a cavity in the soil; and
at least one extension (<NUM>) comprising:
an extension shaft (<NUM>); and
at least one extension soil displacement assembly (<NUM>) attached to the extension shaft.