Helical pile leads and extensions

{
  "publication_number": "US10221538B2",
  "country": "US",
  "kind": "B2",
  "title": "Helical pile leads and extensions",
  "abstract": "The present disclosure provides helical pile leads and extensions with closely spaced perimeter shear helical plates that develop a cylindrical failure surface between the perimeter shear helical plates and soil as the helical pile is rotated into the ground, mobilizing soil-to-soil shear strength, and thus increasing the stability, stiffness and load capacity of the helical pile.",
  "claims": [
    "1. A helical pile, comprising: a lead having a lead shaft with an end portion, a head portion configured to connect to an extension, and at least one load bearing helical plate attached at the end portion of the lead shaft; and an extension having an extension shaft with an end portion configured to connect to the head portion of the lead, a head portion, and a plurality of perimeter shear helical plates each having the same diameter that is less than a diameter of the at least one load bearing helical plate, the plurality of perimeter shear helical plates being attached to the extension shaft, each perimeter shear helical plate having a leading edge and a trailing edge separated from the leading edge a distance substantially equal to a pitch of the helical plate; wherein the plurality of perimeter shear helical plates on the extension shaft are spaced apart on the extension shaft a distance of less than three times the diameter of the perimeter shear helical plates so as to facilitate the creation of a cylindrical failure surface between the plurality of perimeter shear helical plates and soil when the helical pile extension is driven into the ground; and wherein the perimeter shear helical plate on the extension shaft closest to the lead is spaced from the at least one load bearing helical plate a distance that promotes the individual load bearing capacity of the at least one load bearing helical plate.",
    "2. The helical pile according to claim 1, wherein the distance that creates a cylindrical failure surface between the plurality of perimeter shear helical plates and soil is equal to about 1.5 times the diameter of the perimeter shear helical plates.",
    "3. The helical pile according to claim 1, wherein the distance that promotes the individual load bearing capacity of the at least one load bearing helical plate is greater than one foot.",
    "4. The helical pile according to claim 1, wherein the lead shaft is square.",
    "5. The helical pile according to claim 1, wherein the lead shaft is round.",
    "6. The helical pile according to claim 1, wherein the extension shaft is square.",
    "7. The helical pile according to claim 1, wherein the extension shaft is round.",
    "8. The helical pile according to claim 1, wherein a diameter of each of the plurality of perimeter shear helical plates ranges between about 4 inches and about 10 inches.",
    "9. The helical pile according to claim 1, wherein a diameter of the at least one load bearing helical plate ranges between about 12 inches and about 16 inches.",
    "10. A helical pile, comprising: a lead having, a lead shaft with an end portion and a head portion, wherein the head portion is configured to connect to an extension; at least one load bearing helical plate attached at the end portion of the lead shaft; and a plurality of perimeter shear helical plates each having the same diameter that is less than a diameter of the at least one load bearing helical plate, the plurality of perimeter shear helical plates being attached to the lead shaft, each perimeter shear helical plate having a leading edge and a trailing edge separated from the leading edge a distance substantially equal to a pitch of the helical plate; wherein the plurality of perimeter shear helical plates on the lead shaft are spaced apart on the lead shaft a distance of less than three times the diameter of the perimeter shear helical plates so as to facilitate the creation of a cylindrical failure surface between the plurality of perimeter shear helical plates and soil when the helical pile is driven into the ground; and wherein the perimeter shear helical plate closest to the at least one load bearing plate is spaced from the at least one load bearing helical plate a distance that promotes the individual load bearing capacity of the at least one load bearing helical plate; and an extension having, an extension shaft with an end portion configured to connect to the head portion of the lead, and a head portion; a plurality of perimeter shear helical plates each having the same diameter that is less than a diameter of the at least one load bearing helical plate, the plurality of perimeter shear helical plates being attached to the extension shaft, each perimeter shear helical plate having a leading edge and a trailing edge separated from the leading edge a distance substantially equal to a pitch of the helical plate; wherein the plurality of perimeter shear helical plates on the extension shaft are spaced apart on the extension shaft a distance of less than three times the diameter of the perimeter shear helical plates so as to facilitate the creation of a cylindrical failure surface between the plurality of perimeter shear helical plates and soil when the helical pile extension is driven into the ground.",
    "11. The helical pile according to claim 10, wherein the distance that creates a cylindrical failure surface between the plurality of perimeter shear helical plates attached to the lead shaft and to the extension shaft and soil is equal to about 1.5 times the diameter of the perimeter shear helical plates.",
    "12. The helical pile according to claim 10, wherein the lead shaft is square.",
    "13. The helical pile according to claim 10, wherein the lead shaft is round.",
    "14. The helical pile according to claim 10, wherein the extension shaft is square.",
    "15. The helical pile according to claim 10, wherein the extension shaft is round.",
    "16. The helical pile according to claim 10, wherein a diameter of each of the plurality of perimeter shear helical plates attached to the lead shaft and to the extension shaft ranges between about 4 inches and about 10 inches.",
    "17. The helical pile according to claim 10, wherein the diameter of the at least one load bearing helical plate ranges between about 12 inches and about 16 inches."
  ],
  "description_excerpt": "Field\n\nThe present disclosure relates generally to helical piles, and more particularly to leads and extensions for helical piles having perimeter shear helical plates.\n\nDescription of the Related Art\n\nPiles are used to support structures, such as buildings, when the soil underlying the structure would be too weak alone to support the structure. To effectively support a structure, a pile has to penetrate the soil to a depth where competent load-bearing stratum is found. Conventional piles can be cast in place by excavating a hole in the place where the pile is needed, or a hollow form can be driven into the ground where the pile is needed, and then filled with cement. These approaches are cumbersome and expensive.\n\nHelical or screw piles are a cost-effective alternative to conventional cement piles because of the speed and ease at which a helical pile can be installed. Helical piles are rotated such that load bearing helical plates at the lower end of the pile effectively screw the pile into the soil to a desired depth. Referring to FIG. 1, a helical pile 10 is typically made of galvanized straight steel square or round shafts sequentially joined together. The bottom most piece of a helical pile is known as the lead 12, which has a lead head portion 14 and a lead end portion 16. The lead end portion 16 is configured to first penetrate the soil, and terminates at a pointed tip 17. As seen in FIGS. 1 and 2, the lead end portion 16 typically has one or more spaced apart load bearing helical plates 18 arranged on the lead shaft typically in the lead end portion 16 to penetrate the soil.",
  "cpc": [
    "E02D 13/02",
    "E02D 5/801",
    "E02D 7/22"
  ],
  "ipc": [
    "E02D 13/02",
    "E02D 5/80",
    "E02D 7/22"
  ],
  "assignees": [
    "Hubbell Inc"
  ],
  "inventors": [
    "Alan James Lutenegger",
    "Gary Leonard Seider"
  ],
  "filing_date": "2014-11-25",
  "publication_date": "2019-03-05",
  "grant_date": "2019-03-05",
  "priority_date": "2014-11-25",
  "application_number": "US-201414553733-A",
  "family_id": "56009630",
  "cited_by_count": 7,
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}