Piering device with adjustable helical plate

Abstract

A piering device includes a shaft having a polygonal cross-section with a series of notches spaced at intervals along the vertices of the shaft. For example, the shaft can have a square cross-section with rounded corners. The helical plate has a passageway with a cross-section to slide along the shaft when the helical plate is in a first rotational position on the shaft. However, notches within the passageway of the helical plate engage the notches on the shaft when the helical plate is rotated to a second rotational position, thereby preventing the helical plate from sliding along the shaft. A key is inserted between the shaft and helical plate to hold the helical plate in the second rotational position and thereby fix the axial position of the helical plate on the shaft.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of helical pilings or screw piles. More specifically, the present invention discloses a piering device having an adjustable helical bearing plate.

2. Statement of the Problem

Piering systems have long been used to lift and stabilize foundations of structures, and also in new construction. Some systems employ piles that are driven into the ground adjacent to the foundation, while other piering systems employ helical piles that are screwed into the ground. These piles are also used to anchor structures (e.g., large antennas, or pylons for high voltage lines) that are subject to large wind loads.

Conventional helical piles have an elongated shaft with a helical bearing plate permanently attached to the shaft adjacent to its lower end. The shaft can either be solid or tubular. For example, A.B. Chance Company of Centralia, Mo., markets helical piles having a solid shaft with a substantially square cross-section. The lower end of the shaft is beveled to form a point. The helical bearing plate is welded to the lower end of the shaft adjacent to the bevel. The length of the shaft is fixed, as are the diameter and location of the helical plate. In addition, some installations require several helical plates of different diameters spaced along the shaft. All of this can result in an substantial inventory problem to ensure that the appropriate helical piles are in stock for each job, particularly due to the size and expense of these helical piles.

It is also difficult to accurately predict the length of the piles that will be required for a specific job. Helical pilings are typically screwed into the ground to a point at which a predetermined torque limit is reached. It is difficult to predict what the depth of insertion will be when this torque limit is reached, due primarily to the unpredictable nature of local soil conditions. Therefore, it is often necessary to add an extension to the shaft of the helical pile. For example, A.B. Chance Company markets an extension shaft having a square socket that fits over the upper end of the helical pile shaft. A bolt can be passed through aligned holes in the socket of the extension shaft and the upper end of the helical pile shaft to secure the extension shaft to the helical pile. However, these holes significantly weaken the assembly.

A related problem arises if the shaft of the helical pile is too long. In this case, the upper end of the shaft must be cut off and a new hole must be drilled through the shaft to secure the shaft to the support bracket needed to engage the foundation. This can be difficult and time-consuming in the field.

Thus, a need exists for a helical piling system that is modular in design so that helical plates of various sizes and diameters can be used interchangeably, and various helical plates can be interchangeably combined with a shaft of a desired length. In addition, there is a need to be able to quickly and easily connect shafts to one another in the field to create a shaft assembly of desired length.

3. Prior Art

Other examples of helical pilings are disclosed in the following patents:

	Inventor	Patent No.	Issue Date
	Gray	414,700	Nov. 12, 1889
	Grimaud	France 561,975	Mar. 10, 1925
	Williams	2,234,907	Mar. 11, 1941
	Henderson et al.	2,467,826	Apr. 19, 1949
	Petersen	3,016,117	Jan. 9, 1962
	Schirm	PCT WO 82/00672	Mar. 4, 1982
	Gillen	4,239,419	Dec. 16, 1980
	Pardue et al.	4,290,245	Sep. 22, 1981
	Dziedzic	4,334,392	Jun. 15, 1982
	McFeetors et al.	4,833,846	May 30, 1989
	Gregory et al.	4,911,580	Mar. 27, 1990
	Norman et al.	4,979,341	Dec. 25, 1990
	Hamilton et al.	5,011,336	Apr. 30, 1991
	Holdeman et al.	5,120,163	Jun. 9, 1992
	Hamilton et al.	5,139,368	Aug. 18, 1992
	Hamilton et al.	5,171,107	Dec. 15, 1992
	Hamilton et al.	5,408,788	Apr. 25, 1995
	Seider et al.	5,213,448	May 25, 1993
	Reinert	5,570,975	Nov. 5, 1996
	Jones	5,800,094	Sep. 1, 1998
	Jones	6,352,391	Mar. 5, 2002

The applicant's U.S. Pat. No. 6,352,391 (Jones) discloses a piering device having a threaded shaft and an adjustable helical plate held in place by a removable key. However, applicant submits that this patent is not prior art to the present application because the patent was issued less than one year prior to the filing date of the present application and the device disclosed in the patent has not been on sale, in public use, or described in a printed publication more than one year prior to the filing date of the present application.

Gillen discloses a conically-shaped tapered concrete piling with a metallic reinforcement core.

Henderson et al. disclose a lifting slip joint for use in sinking concrete piles into the ground.

Pardue et al. disclose an earth anchor having a shank with a helical blade affixed thereto. A series of shank portions can be connected together axially.

Gray discloses a threaded pile with a threaded helical plate. After the pile has been driven into the ground, the plate is advanced into the ground by rotating a handle attached to a removable sleeve.

Dziedzic discloses a modular screw anchor having an earth-penetrating lead that is separate from the helical plate. In the embodiment shown in FIGS. 2-6 of Dziedzic, the earth-penetrating lead and plate assembly are connected to a rectangular shaft. In the embodiment shown in FIGS. 7-10 of Dziedzic, the shaft is round with threads at its lower end to engage the earth penetrating lead.

Seider et al., Holdeman et al. and Gregory et al. disclose other examples of an apparatus for stabilizing the foundation of a building using a conventional helical piling that has been screwed into the ground.

U.S. Pat. Nos. 5,139,368 and 5,171,107 to Hamilton et al. disclose a system for underpinning a foundation that uses a helical pile with a connecting bracket secured to the foundation.

Schirm discloses a tie rod having a helical plate and a moving foot that can slide along the rod limited by the position of a nut threaded on the rod.

Grimaud is believed to relate to a pile foundation.

Reinert discloses a mobile foundation installation system having a push-it carriage that can push a metal foundation into the ground by hydraulic cylinders pushing against a header frame held and secured in adjustable positions on a mobile tower.

McFeetors et al. disclose a ground anchor system for supporting a structure. A fixed-length helical pile is driven into the ground. The upper end of the piling device includes a screw that allows adjustment of the height of the support head beneath the foundation.

Petersen discloses a screw anchor that receives a square shaft. The anchor is held in place by a pin extending through the anchor and the shaft.

Williams, Norman et al., and Hamilton et al. (U.S. Pat. No. 5,408,788) show examples of screw anchors that can be threaded onto the lower end of a shaft.

The Jones '094 patent discloses a support bracket for attachment to the top of a conventional helical piling.

4. Solution to the Problem

None of the prior art references discussed above show a helical piling with an adjustable helical plate that can slide along the piling shaft to a desired position, and then be fixed in place by slightly rotating the helical plate on the shaft and inserting a removable key between the helical plate and shaft. This approach allows one or more helical plates of appropriate size to be placed at desired locations along the length of the shaft to meet the specific needs of each job. The shaft can also be cut to the desired length without waste.

The shaft and helical plate of a helical piling are subject to enormous torsional loads during installation, and very large axial loads (either in compression or tension) after the helical piling has been placed in use. None of the prior art references listed above teach or suggest the present mechanism for removably attaching a helical plate to the shaft to transmit these loads.

SUMMARY OF THE INVENTION

This invention provides a piering device with an adjustable helical plate. The shaft of the piering device has a polygonal cross-section with a series of notches spaced at intervals along the vertices of the shaft. For example, the shaft can have a square cross-section with rounded corners. The helical plate has a passageway with a cross-section to slide along the shaft when the helical plate is in a first rotational position on the shaft. However, notches within the passageway of the helical plate engage the notches on the shaft when the helical plate is rotated to a second rotational position, thereby preventing the helical plate from sliding along the shaft. A key is inserted between shaft and helical plate to hold the helical plate in the second rotational position and thereby fix the axial position of the helical plate on the shaft.

These and other advantages, features, and objects of the present invention will be more readily understood in view of the following detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more readily understood in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of the present invention.

FIG. 2 is an exploded perspective view of the present invention corresponding to FIG. 1 .

FIG. 3 is a horizontal cross-sectional view of the helical plate.

FIG. 4 is a horizontal cross-sectional view of the helical plate in a first rotational position on the shaft allowing the helical plate to slide along the shaft.

FIG. 5 is a horizontal cross-sectional view corresponding to FIG. 4 showing the helical plate after it has been rotated to a second rotational position on the shaft so that the helical plate cannot slide along the shaft.

FIG. 6 is a vertical cross-sectional view corresponding to FIG. 4 showing the shaft and helical plate in the first rotational position.

FIG. 7 is a vertical cross-sectional view corresponding to FIG. 5 showing the shaft and helical plate in the second rotational position.

DETAILED DESCRIPTION OF THE INVENTION

Turning to FIG. 1 , a perspective view is provided of the present device. A corresponding exploded perspective view is shown in FIG. 2 . In general terms, the present device consists of a piering shaft 10 and a helical bearing plate 20 that can be removably attached at a desired location along the length of the shaft 10 .

The shaft 10 has a generally polygonal cross-section with a plurality of vertices extended along its length. For example, the shaft 10 can have a substantially square cross-section with rounded corners, as illustrated in the drawings. A series of notches 12 are spaced at intervals along the shaft at the vertices. In the embodiment shown in drawings, these sets of notches 12 are axially aligned to form partial threads around the shaft 12 . The faces of the shaft 10 between the vertices can be flat or curved, but should be at an effective radius from central axis of the shaft 10 that is less than that of the notches 12 , so as not to interfere with rotation of the notches 12 within the passageway 22 of the helical plate 20 , as described below. In the preferred embodiment, the notches 12 extend along the entire length of each vertex of the shaft 10 . This simplifies fabrication of the shaft 10 and allows the helical plate 20 to be positioned virtually anywhere on the shaft 10 . This also makes the present device more modular by enabling two or more shafts 10 , 11 to be connected in series using a coupler 30 , as shown in FIGS. 1 and 2 . Any of a variety of thread configurations can be used on the shaft 10 . In the preferred embodiment of the present invention, the notches 12 are rounded to form a partial rope thread. The rounded shape of the thread makes its easier to handle and somewhat less susceptible to damage. Here again, the thread 12 could be limited to selected portions of the shaft, such as the lower end of the shaft 10 to provide a range of positions for the helical plate 20 . The upper end of the shaft 10 can also be threaded to engage a coupler 30 , if necessary, as shown in FIG. 1 . It should be expressly understood that the term “notches” as used in this application should be construed broadly to include all types of indentations, protrusions, grooves, and threads of any type.

The helical bearing plate 20 has a passageway 22 with a cross-section as shown in FIGS. 3-7 . This passageway allows the helical plate 20 to slide along the shaft 10 when the helical plate 20 is in a first rotational position on the shaft 10 , as illustrated in the orthogonal cross-sectional views shown in FIGS. 4 and 6 . The passageway 22 of the helical plate 20 has a series of notches 28 that engage the notches 12 on the shaft 10 when the helical plate 20 is rotated to a second rotational position on the shaft 10 , so that the helical plate 20 cannot slide along the shaft 10 , as illustrated in FIGS. 5 and 7 . For example, if the shaft 10 has a square cross-section as shown in the drawings, the helical plate 20 is rotated by approximately 45 degrees between the first and second rotational positions. In the preferred embodiment of the present invention, the notches 28 in the passageway 22 of the helical plate 20 are axially spaced at regular intervals along the passageway 22 to form partial threads. In the first rotational position, the notches 28 in the passageway 22 of the helical plate 20 are not aligned with the notches 12 on the shaft 10 , and therefore do not prevent the helical plate 20 from sliding freely along shaft 10 . As shown in FIGS. 4 and 6 , the notches 12 on the shaft 10 align with the unthreaded corners in the passageway 22 of the helical plate 20 . However, in the second rotational position, these sets of notches 12 , 28 engage one another and prevent axial relative movement between the shaft 10 and helical plate 20 , as shown in FIGS. 5 and 7 . In particular, if the notches form partial threads, these threads do not engage one another in the first rotational position, but do engage one another in the second rotational position.

The helical plate 20 can have any of a wide variety of configurations and sizes. In the embodiment shown in the figures, the helical plate 20 has a generally cylindrical hub with a partially threaded passageway 22 extending completely through the hub. Alternatively, the hub of the helical plate 20 could have a hexagonal outer cross-section so that it can be grasped by a wrench. The helical plate is typically welded onto this hub, although other fastening means could be used.

A key 26 is inserted between the shaft 10 and helical plate 20 to hold the helical plate 20 in the second rotational position and thereby fix the axial position of the helical plate 20 on the shaft 10 , as illustrated in FIG. 1 . Preferably, two keys are inserted on opposite sides of the shaft 10 . The key 26 has a cross-section selected to allow it to be inserted into one of the corners of the passageway 22 of the helical plate 20 in the second rotational position.

A coupler 30 can be used to join two shafts 10 , 11 , if an especially long shaft is required, as depicted in FIG. 1 . The coupler 30 is shown in greater detail in the exploded view provided in FIG. 2 . It has a partially threaded passageway 32 extending between two axially-aligned openings that receive the shafts 10 and 11 . For example, the embodiment depicted in the figures shows a coupler 30 having a partially threaded passageway with a polygonal cross-section, similar to that of the helical plate 20 . The shafts 10 , 11 are inserted from opposite ends of the coupler 30 (in the first rotational position) until the ends of the shafts 10 , 11 abut. The coupler 30 is rotated by a fraction of a turn until the partial threads in the coupler engage the partial threads on each shaft 10 , 11 in the second rotational position. The coupler 30 is then removably secured to the shafts 10 , 11 by inserting a key 36 between the shafts 10 , 11 and the coupler 30 . This configuration is advantageous in that the shafts 10 and 11 , rather than the coupler 30 , carry most of the large axial loads after installation of the pier. Alternatively, two shorter keys can be inserted from opposite ends of the coupler 30 .

In another embodiment, the coupler 30 is simply a threaded cylindrical collar that engages the partial threads 12 on the ends of each shaft 10 , 11 . However, other configurations of the coupler 30 are possible. In addition, the coupler 30 could have a hexagonal outer cross-section so that it can be readily grasped by a wrench.

A variety of optional features can be used with the present device. As shown in FIGS. 1 and 2 , a cutting tip 40 can be threaded onto the lower end of the shaft 10 . This cutting tip 40 is equipped with a threaded passageway 42 to engage the shaft 10 , and a set of cutting blades 45 to drill into the ground beneath the helical plate 20 and thereby reduce resistance as the helical piling is advanced into the ground. In one embodiment, the cutting tip 40 has a hub with a cylindrical threaded passageway 42 to engage the shaft 10 . Alternatively, the cutting tip 40 could have a hub with a polygonal, partially-threaded passageway, as similar to that of the helical plate 20 . In addition, the hub of the cutting tip 40 could have a hexagonal outer cross-section so that it can be grasped by a wrench.

A flat support bracket 50 can be threaded onto the upper end of the shaft 10 to support a building structure 60 as illustrated in FIG. 1 . Other types of support brackets or attachment means can be placed onto the upper end of the shaft to attach a load to the helical pile either in tension or compression. Here again, the support bracket can either be equipped with a threaded cylindrical passageway or a partially-threaded polygonal passageway to engage the upper end of the shaft. For example, the rabbit-ears attachment can be made an integral part of the concrete foundation of a building, as shown in the Applicant's U.S. Pat. No. 6,352,391. Another type of adjustable support bracket that could be readily adapted for use with the present invention is disclosed in the Applicant's U.S. Pat. No. 5,800,094.

The above disclosure sets forth a number of embodiments of the present invention. Other arrangements or embodiments, not precisely set forth, could be practiced under the teachings of the present invention and as set forth in the following claims.

Claims

1. A piering device comprising:a shaft having a polygonal cross-section and a plurality of vertices, with a plurality of notches axially spaced at intervals along the shaft at the vertices; a helical plate having a passageway with a cross-section to slide along the shaft in a first rotational position on the shaft, and having notches within the passageway to engage at least one of the notches on the shaft when the helical plate is rotated to a second rotational position on the shaft so that the helical plate cannot slide along the shaft; a key insertable between the shaft and helical plate to hold the helical plate in the second rotational position and thereby fix the axial position of the helical plate on the shaft.

2. The piering device of claim 1 wherein the shaft has a substantially square cross-section.

3. The piering device of claim 1 wherein the vertices are rounded.

4. The piering device of claim 1 further comprising a coupler having a passageway with two axially-aligned openings to receive the ends of two of the shaft.

5. The piering device of claim 1 further comprising a cutting tip having a cutting blade and a passageway to receive the end of the shaft.

6. The piering device of claim 1 wherein the notches on the vertices of the shaft have uniform spacing and are aligned to form partial threads around the shaft.

7. The piering device of claim 6 wherein the notches in the passageway of the helical plate engage threadingly engage the notches of the shaft in the second rotational position of the helical plate.

8. The piering device of claim 6 further comprising a coupler having a threaded passageway with two axially-aligned openings to receive and engage the ends of two of the shaft.

9. A piering device comprising:a shaft having a polygonal cross-section and a plurality of vertices, with a plurality of notches axially spaced at intervals along the shaft at the vertices and aligned to form partial threads around the shaft; a helical plate having a passageway with a cross-section to slide along the shaft in a first rotational position on the shaft, and having threads within the passageway to engage the partial threads on the shaft when the helical plate is rotated to a second rotational position on the shaft so that the helical plate cannot slide along the shaft; and a key insertable between the shaft and helical plate to hold the helical plate in the second rotational position and thereby fix the axial position of the helical plate on the shaft.

10. The piering device of claim 9 wherein the shaft has a substantially square cross-section.

11. The piering device of claim 9 further comprising a coupler having a threaded passageway with two axially-aligned openings to receive and engage the ends of two of the shaft.

12. The piering device of claim 9 further comprising a cutting tip having a cutting blade and a threaded passageway to receive and engage the end of the shaft.

13. A piering device comprising:a shaft having a substantially square cross-section with a plurality of notches axially spaced at intervals along the corners of the shaft and aligned to form partial threads around the shaft; a helical plate having a passageway with a cross-section to slide along the shaft in a first rotational position on the shaft, and having threads within the passageway to engage the partial threads on the shaft when the helical plate is rotated to a second rotational position on the shaft so that the helical plate cannot slide along the shaft; and a key insertable between the shaft and helical plate to hold the helical plate in the second rotational position and thereby fix the axial position of the helical plate on the shaft.

14. The piering device of claim 13 wherein the corners of the shaft are rounded.

15. The piering device of claim 13 further comprising a coupler having a threaded passageway with two axially-aligned openings to receive and engage the ends of two of the shaft.

16. The piering device of claim 13 further comprising a cutting tip having a cutting blade and a threaded passageway to receive and engage the end of the shaft.