Spiral Tip to a Helical Pier

Abstract

A helical pier with a spiral tip is disclosed. The helical pier is comprised of an elongated hollow shaft, one or more helical plates attached to and extending outward from the shaft, and the spiral tip. The spiral tip acts as an attack bit that contacts and penetrates the ground and subsurface soil layers prior to other parts of the helical pier. The spiral tip provides initial breakup of the ground where the helical pier is being driven. The spiral tip is comprised of a longitudinal edge and a spiral rim between a penetrating lead end and a terminating spiral end on the longitudinal edge.

Description

TECHNICAL FIELD

This disclosure relates to a steel pier. The disclosure particularly relates to a steel pier having one or more helical plates and a spiral tip formed on the periphery of the steel pier.

BACKGROUND

Helical piers are deep foundation elements used to support compression, tension and/or lateral loads from buildings and structures. Helical piers of hollow tubular sections may have varying lengths and diameters. The shaft of a pier transfers the supported load from the structure to deep competent soil via helical (or helix) bearing plates. Piers include helical plates welded to the shaft, where the number of helices, their diameter, position on the shaft, and their thickness affect the efficacy of receiving and transferring the structure's load based on surrounding ground conditions.

Piers are rotated (or screwed) into the ground by the application of torque using a rotary drive head mounted to a machine or hand-held equipment. Machines applying the torque may vary; for example, machine may be a small walk-behind excavator, rubber-tired backhoe, or large track excavator. When advancing a pier into the ground, operators try to limit disturbance to the soil where the pier penetrates because soil disturbance may adversely affect the soil bearing capacity and the capacity of the pier when it is put in service. Therefore, the tip of a pier section may be designed to improve the process of breaking through the ground and subsequent subsurface soil layers to the depth necessary to provide the structure with adequate support and stability.

The ability to advance a pier into soil is affected by many factors, some of which include the drive head capacity and the size and weight of the installation equipment. The soil or bedrock type, strength, and nature of deposition may also prove to hinder pier installation. Soil and rock mechanics will change depending on geography and soil characteristics, such as soil types and soil layers. For instance, in Nebraska, Iowa, Kansas, and Missouri, there are distributions of loess sediments. Loess is a clastic and mostly silt-sized sediment formed by the accumulation of wind-blown dust. Calcium carbonate lightly cements the composition of clay, sand and silt. The sediment is highly porous with vertical capillaries that permit fracturing. In contrast to loess, bentonite and montmorillonite clays in places like Denver, Colo. are absorbent clays that swell and shrink, respectively, from water absorption and evaporation of rainfall and melting of snowfall. These expansive clays, which can be found in Colorado, Wyoming, and South Dakota, can fluctuate in resistance to pier penetration when the clay is saturated with water compared to when it is fissured (or dried). Differences in soil types affect installation factors such as the torque needed to advance a helical pier or the ability to advance the pier at the proper penetration rate.

Therefore, completing foundation repairs and new construction support solutions requires careful selection of helical piers (shaft size, helical plate configuration, specialty lead details, etc.) based on knowledge of the soil conditions of the project site. What is needed is a helical pier for drier, compact soils, thin layers of dense soils, and lightly to moderately-cemented soils with a lead tip that improves pier installation by maintaining consistent penetration rate and avoiding excess disturbance of the soil as the pier advances into and through the ground.

SUMMARY OF THE INVENTION

The present disclosure provides a helical pier with a spiral tip. The helical pier is comprised of an elongated hollow shaft, one or more helical blades (or plates) attached to and extending outward from the shaft, and the spiral tip. The spiral tip acts as an attack bit that contacts and penetrates the ground and subsurface soil layers prior to other parts of the helical pier. The spiral tip provides initial breakup of the ground where the helical pier is being driven. Using a helical pier with a spiral tip more easily penetrates cemented soils and thin layers of dense soil, helps seat piers into weathered bedrock, hard clay and dense sand, and allows for a more consistent penetration rate. A helical pier with a spiral tip may be installed, for example, with a rotary drive head.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The Detailed Description is described with reference to the accompanying figures.

FIG. 1 is an angled profile view of a spiral tip on a helical pier held in a lateral position.

FIG. 2 is a front profile view of a spiral tip on a helical pier held in a lateral position.

FIG. 3 is a side profile view of a spiral tip on a helical pier held in a vertical position.

FIG. 4 is a transparent profile view of a spiral tip and helical blade.

FIG. 5 is a cross-sectional view of a helical pier with a spiral tip in the process of being driven into soil.

FIG. 6 is a cross-sectional view of a helical pier with a spiral tip in its final resting place driven into soil.

DETAILED DESCRIPTION

Referring generally to FIGS. 1 through 6 (FIGS. 1-6), a helical pier with a spiral tip is illustrated and described herein. For purposes of this disclosure, the term “helical pier” is interchangeable with and may mean a pier, pile, anchor, helical pile, or helical anchor and applies in the field of helical foundation supports.

FIGS. 1 through 3 (FIGS. 1-3) show multiple perspective views of a helical pier 100 with a spiral tip 101. FIG. 4 (FIG. 4) shows a transparent profile view of a spiral tip 101 and helical blade 201 that may comprise a helical pier 100. FIGS. 5 and 6 (FIGS. 4 and 5) exemplify embodiments of the helical pier 100 with a spiral tip 101 connected to a one or more additional helical piers 501, where the helical pier 100 includes a plurality of helical blades 201 between the spiral tip 101 and a trailing end 301.

As seen in FIG. 1, the helical pier 100 comprises an elongated hollow shaft 302 with a longitudinal axis 401, a spiral tip 101, a helical blade 201, and a peripheral surface 303. The longitudinal axis 401 is intangible and at the center of the elongated hollow shaft 302, about which the helical pier 100 rotates when driven into the ground by a rotary steel pipe driver. The peripheral surface 303 is between the spiral tip 101 and the trailing end 301 of the helical pier 100. The peripheral surface 303 spans the length of the helical pier 100.

The spiral tip 101 is formed by cutting out a spiral portion of the helical pier 100 at a penetrating end opposite the helical pier's 100 trailing end 301. The spiral cutout is made starting along an edge of the penetrating end of the helical pier 100 and cutting in a spiral direction. The spiral cutout may be made using equipment such as a tube laser at a manufacturing facility; however, the spiral cutout may also be made as a field modification using portable equipment such as a band saw.

The result of the spiral cutting process is a spiral tip 101 which includes a longitudinal edge 102 that is substantially parallel to the longitudinal axis 401 of the helical pier 100. The longitudinal edge 102 has a penetrating lead end 104 and a spiral terminating end 105. The spiral tip 101 also includes a spiral rim 103 defined by a spiral rim portion of the helical pier 100 between the penetrating lead end 104 and the spiral terminating end 105. The spiral tip 101 may be a variety of sizes based on the size of the helical pier 100 (e.g., the diameter of the helical pier 100). The length of the longitudinal edge 102 may also vary based factors such as the desired pitch of the spiral rim 103 and the diameter of the helical pier 100. The pitch of the spiral rim 103 is a rim pitch. The length of the longitudinal edge 102 may affect the rate with which the helical pier 100 penetrates a particular ground site. Measurements of the rim pitch correspond with measurements of the longitudinal edge 102—an increase in the degree of the rim pitch corresponds to a longer longitudinal edge 102 measurement.

In addition to the spiral tip 101, the helical pier 100 may also have a helical blade 201. The helical blade 201 attaches to the peripheral surface 303 of the helical pier 100, preferably by welding. A helical blade 201 may have a single turn that traverses a spiral (or arc) path about the peripheral surface 303 of a helical pier 100 (i.e., welding the helical blade 201 along the peripheral surface 303 approximately three-hundred sixty degrees). Even with only one turn, the helical blade 201 may have a blade pitch that is substantially constant (i.e., does not vary significantly in slope from one end (or edge) of the helical blade 201 to the other end). The helical blade 201 has a diameter from the peripheral surface 303 to its outward edge, where the diameter is a defining size feature of the helical blade 201. The thickness of the helical blade 201 is another defining size feature of the helical blade 201, which may vary. The size features of a helical blade 201 affect the load capacity of the helical pier 100, as well as the level of disturbance of soil during the application of torque advancing the helical pier 100 into soil. The blade pitch of the helical blade 201 helps advance the helical pier 100 into the soil.

The blade pitch of the helical blade 201 may correspond with the rim pitch of the spiral tip 101. For example, the blade pitch of the helical blade 201 may be three inches, and the rim pitch of the spiral tip 101 may also be three inches. In other helical piers 100, though, the blade pitch of the helical blade 201 may be different from the rim pitch of the spiral tip 101. For example, the blade pitch of the helical blade 201 may be four inches, and the rim pitch of the spiral tip 101 may be two inches.

A helical blade 201 may also have a plurality of (or multiple) turns that follow a spiral path about the peripheral surface 303 of a helical pier 100. A helical blade 201 with a plurality of turns may spiral greater than three-hundred sixty degrees (e.g., five-hundred forty degrees or seven-hundred twenty degrees). A helical blade 201 with multiple turns may have a substantially constant pitch (or slope), as the material comprising the helical blade 201 (e.g., steel) spirals about the peripheral surface 303 of the elongated hollow shaft 302.

In other embodiments of the helical pier 100, it may have a plurality of helical blades 201. That is, the helical pier 100 may have two or more helical blades 201 spaced along the elongated hollow shaft 302, each helical blade 201 spiraling about the peripheral surface 303 for one or more turns. A plurality of helical blades 201 may have positions along the elongated hollow shaft 302 such that spacing between each consecutive pair of blades is approximately equal. Each helical blade 201 may have a substantially constant pitch (or slope) in embodiments of the helical pier 100 with a plurality of helical blades 201. Furthermore, in embodiments, each helical blade 201 from the plurality of helical blades 201 may each have substantially equal blade pitches.

A helical blade 201 includes a first radial edge 202 and a second radial edge 203. The second radial edge 203 is distal to the first radial edge 202 due to the spiraling of the helical blade 201 about the peripheral surface 303 of the elongated hollow shaft 302. As seen in FIG. 4, a helical blade 201 may be attached to the helical pier 100 such that the blade's first radial edge 202 and second radial edge 203 are aligned with each other along the peripheral surface 303 to the elongated hollow shaft 302. The first radial edge 202 in FIG. 4 demonstrates an ability to shape the edge to include a slanted face (or surface) corresponding to the rotational direction for driving the helical pier 100 into soil. Such a slant to the first radial edge 202 may improve advancement of the helical pier 100 into the soil compared to an edge with a flat vertical face. In contrast, the second radial edge 203 in FIG. 4 is shaped to have a slanted face at a substantially parallel angle to the first radial edge 202. Such a second radial edge 203 may improve load bearing resistance compared to an edge with a flat vertical face.

Further, in one embodiment of the present disclosure where there is only one helical blade 201 attached to the helical pier 100, the first radial edge 202 of the helical blade 201 may be proximal to the spiral terminating end 105 of the spiral tip 101. In another embodiment of the present disclosure where the helical pier 100 is comprised of a plurality of helical blades 201, one helical blade of the plurality may have a first radial edge 202 proximal to the spiral terminating end 105 of the spiral tip 101.

As seen in FIGS. 5 and 6, by similar means known in the art for other helical pier types, the helical pier 100 with a spiral tip 101 may be fastened to another helical pier 501. The helical pier 100 may be the lead pier in a series of helical piers 501 fastened together to reach the desired depth for load transference from the building or other structure in need of foundation support to more solid soil deeper in the ground. FIG. 5 demonstrates a second helical pier 501 being attached to the helical pier 100 that has been driven into the soil. FIG. 6 illustrates a final resting condition for a series of helical piers 501 fastened together with the lead helical pier being a helical pier 100 with a spiral tip 101, as described in this disclosure.

Although the subject matter has been described in language specific to structural features, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features described above. Rather, the specific features described above are disclosed as example forms of implementing the claims.

Claims

1. A helical pier comprised of:

an elongated hollow shaft having a spiral tip, a helical blade, a trailing end, and a peripheral surface between the spiral tip and the trailing end, where the helical blade is arranged about and extends outward from the peripheral surface of the elongated hollow shaft; and the spiral tip includes a longitudinal edge and a spiral rim formed between a penetrating lead end of the longitudinal edge and a terminating spiral end of the longitudinal edge.

2. The helical pier of claim 1, wherein the helical blade has one turn with a blade pitch that is substantially constant.

3. The helical pier of claim 2, wherein the spiral rim has a rim pitch that is substantially equal to the blade pitch of the helical blade.

4. The helical pier of claim 3, wherein the helical blade includes a first radial edge proximal to the terminal spiral end on the spiral tip and a second radial edge distal to the first radial edge, the first radial edge being substantially parallel to the second radial edge.

5. The helical pier of claim 1, wherein the helical blade has a plurality of turns having a substantially constant pitch.

6. The helical pier of claim 5, wherein the spiral rim has a rim pitch that is substantially equal to the substantially constant pitch of the plurality of turns to the helical blade.

7. The helical pier of claim 6, wherein the helical blade includes a first radial edge proximal to the terminal spiral end of the spiral tip and a second radial edge distal to the first radial edge, the first radial edge being substantially parallel to the second radial edge.

8. A helical pier comprised of:

an elongated hollow shaft having a spiral tip, a plurality of helical blades, a trailing end, and a peripheral surface between the spiral tip and the trailing end, where each helical blade is arranged about and extends outward from spaced positions along the peripheral surface of the elongated hollow shaft; and the spiral tip includes a longitudinal edge and a spiral rim formed between a penetrating lead end of the longitudinal edge and a terminating spiral end of the longitudinal edge.

9. The helical pier of claim 8, wherein each helical blade includes a first radial edge and a second radial edge distal to the first radial edge, the first radial edge being substantially parallel to the second radial edge.

10. The helical pier of claim 9, wherein each helical blade has one turn with a blade pitch that is substantially constant.

11. The helical pier of claim 10, wherein one of the plurality of helical blades has a first radial edge proximal to the terminal spiral end on the spiral tip.

12. The helical pier of claim 11, wherein the spiral rim has a rim pitch that is substantially equal to the substantially constant pitch of the plurality of helical blades.

13. A helical pier comprised of:

an elongated hollow shaft having a spiral tip, a plurality of helical blades, a trailing end, and a peripheral surface between the spiral tip and the trailing end, where each helical blade is arranged about and extends outward from spaced positions along the peripheral surface of the elongated hollow shaft; each helical blade includes a first radial edge and a second radial edge distal to the first radial edge, the first radial edge being substantially parallel to the second radial edge; and the spiral tip includes a longitudinal edge and a spiral rim formed between a penetrating lead end of the longitudinal edge and a terminating spiral end of the longitudinal edge.

14. The helical pier of claim 13, wherein each helical blade has one turn with a blade pitch that is substantially constant.

15. The helical pier of claim 14, wherein one of the plurality of helical blades has a first radial edge proximal to the terminal spiral end on the spiral tip.

16. The helical pier of claim 15, wherein the spiral rim has a rim pitch that is substantially equal to the substantially constant pitch of the plurality of helical blades.

17. The helical pier of claim 14, wherein each helical blade has a plurality of turns, each turn having a blade pitch that is substantially constant and substantially equal to the at least one other helical blade.

18. The helical pier of claim 17, wherein the spiral rim has a rim pitch that is substantially equal to the substantially constant pitch of the plurality of turns of each helical blade.