US20110194901A1

US20110194901A1 - System for terminating helical piles and tiebacks

Info

Publication number: US20110194901A1
Application number: US12/703,602
Authority: US
Inventors: Robert L. Jones
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-02-10
Filing date: 2010-02-10
Publication date: 2011-08-11
Also published as: CA2728995A1

Abstract

A threaded termination for helical piles has an elongated shaft and a substantially square cross-section. A series of uniformly-spaced notches on the corners of the termination shaft are aligned to form partial threads around the termination shaft. A coupler on an end of the termination shaft has a socket with a substantially square cross-section. In use, a helical pile is initially screwed into the ground. The coupler of the termination is then attached to the upper end of the helical pile with the shafts of the termination and helical pile axially aligned. The assembly can then be screwed further into the ground by applying torque to the termination. The upper portion of the shaft of the termination can be cut off, as need, and a load transfer device is then threaded onto the upper end of the shaft of the termination.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to the field of helical piles and tiebacks. More specifically, the present invention discloses a threaded termination for helical piles and tiebacks.
2. Statement of the Problem
Helical piles have been used for many years in a variety of applications. For example, helical piles are widely used to lift and stabilize structures, and also in new construction. In these applications, helical piles are often called upon to carry large compressive loads. Helical piles are also used to anchor structures, such as large antennas or pylons for high voltage lines, that are subject to large wind loads. Helical piles are also employed for lateral earth retention and shoring. In these fields, helical piles are often required to carry large tensile loads. For the purposes of this patent application, the terms “helical pile” and “helical pier” are used interchangeably.
Conventional helical piles have an elongated shaft with a substantially square cross-section. The shaft can either be solid or tubular. One or more helical bearing plates are permanently welded to the shaft adjacent to its lower end. The length of the shaft is fixed, as are the diameter and location of the helical plate. The helical pile is screwed into the ground by a power drive head that engages the upper end of the shaft and applies torque that is carried by the shaft to the helical plate. An axial force is also applied to the shaft of the helical pile. Helical piles 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 soil conditions. Therefore, it is often necessary to add an extension or “termination” to the upper end of the shaft of the helical pile. One conventional type of termination has an extension shaft with a substantially square cross-section and a coupler on its lower end with a square socket that fits over the upper end of the helical pile shaft. A plurality of these extensions can be attached in series, if needed, before termination.
After a helical pile has been driven into the ground, the exposed upper end of the shaft must be cut off at a desired elevation and coupled to the building structure, cable, etc. as required for the specific job. This usually entails securing a load transfer device or support bracket to the exposed upper end of the shaft, typically by welding or redrilling a hole and then inserting a bolt. These last two steps can be difficult and time-consuming in the field. Thus, a need exists for a simpler and more cost-effective means for terminating a helical pile in the field. In particular, a need exists for a simpler means for securing a load transfer device to the exposed upper end of the helical pile assembly that is capable of handling large loads in both tension and compression.
More recently, modular helical piering systems have been invented, as shown for example in the Applicant's U.S. Pat. Nos. 6,352,391, 7,037,045 and 6,817,810. These modular systems can be extended to any required length by connecting multiple shafts together in series with couplers having a socket to engage the end of an adjacent shaft. In particular, U.S. Pat. No. 7,037,045 discloses a modular helical piering system that employs couplers with substantially square sockets.
In addition, the Applicant's U.S. Pat. No. 6,682,267 shows a modular helical piering device having threaded square shafts connected by couplers. Each coupler has a partially threaded passageway with a polygonal cross-section. Shafts are inserted from opposite ends of the coupler (in a first rotational position) until the ends of the shafts abut. The coupler is then rotated by a fraction of a turn until the partial threads in the coupler engage the partial threads on the corners of the shafts in a second rotational position. The coupler is then removably secured to the shafts by inserting keys between the shafts and the coupler. However, this configuration has shortcomings. This type of coupler is limited to use with threaded shafts, and cannot accommodate unthreaded shafts that remain the standard in the industry.
Threaded adapters have also been used for many years in the industry for terminating helical piles intended for tensile loads, such as lateral earth retention and shoring. A threaded adapter has a square coupler on one end of a round threaded shaft. After a helical pile has been driven into the ground to the desired elevation, The coupler of the threaded adapter is secured to the exposed end of the pile. The end of the shaft of the threaded adapter is passed through a hole in a plate or waler used to support the tensile load. A nut is then threaded onto the shaft of the threaded adapter to secure the assembly. However, a threaded adapter is not used for driving the helical pile due to its round shaft.
Solution to the Problem. None of the prior art references discussed above show a termination with a threaded square shaft and a square coupler. The threaded shaft enables a load transfer device to be quickly and easily threaded onto the upper end of the shaft to carry either compressive or tensile loads. The square cross-section of the shaft of the termination allows it to be screwed into the ground using a conventional drive head in the same manner as conventional helical pile shafts. The square coupler on the lower end of the termination readily attaches to the upper end of a conventional helical pile shaft and is capable of handling high torque.

SUMMARY OF THE INVENTION

This invention provides a threaded termination for helical piles having an elongated shaft and a substantially square cross-section. A series of uniformly-spaced notches on the corners of the termination shaft are aligned to form partial threads around the termination shaft. A coupler on one end of the termination shaft has a socket with a substantially square cross-section. In use, a helical pile is initially screwed into the ground. The coupler of the termination is then attached to the upper end of the helical pile with the shafts of the termination and helical pile axially aligned. The assembly can then be screwed further into the ground by applying torque to the termination. The upper portion of the shaft of the termination can be cut off, as need, and a load transfer device is then threaded onto the upper end of the shaft of the termination.
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 a termination 10 embodying the present invention.

FIG. 2 is a side view of the lead segment 20 of a helical pile being driven into the ground.

FIG. 3 is a side view corresponding to FIG. 2 showing a termination 10 attached to the upper end of the lead segment 20.

FIG. 4 is a side view showing the assembly of the termination 10 and lead segment 20 of the helical pile being driven further into the ground.

FIG. 5 is a side view showing the upper portion 18 of the termination 10 being cut off at a desired elevation.

FIG. 6 is a side view showing a load transfer cap 40 being threaded onto the upper end of the termination 10.

FIG. 7 is a side view showing a rabbit-ears load transfer attachment 32 being threaded onto the upper end of the termination 10.

FIG. 8 is a perspective view showing the left-over piece 18 of the threaded shaft of the termination in FIG. 5 reused as the lead segment in a new modular helical pile assembly by attaching a helical plate 42.

DETAILED DESCRIPTION OF THE INVENTION

Turning to FIG. 1, a perspective view is provided showing an embodiment of the present termination 10. The termination 10 includes an elongated shaft 12 having a substantially square cross-section with slightly rounded corners. A series of notches 14 are uniformly spaced along each of the corners and aligned to form partial threads around the shaft 12. For example, these notches 14 can be formed by milling or rolling the shaft 12.
A coupler 16 with a substantially square socket 17 is secured (e.g., welded) onto one end of the shaft 12. The coupler is intended to receive and engage the upper end of the square shaft of a helical pile, as will be discussed below. A hole 13 is formed through the other end of the shaft 12.
FIGS. 2 through 6 illustrate one method for using the termination 10 in the field. FIG. 2 is a side view of a conventional lead segment of a helical pile 20 being screwed into the ground by a torque applied to the upper end of its shaft. The helical pile 20 has a helical plate 22 adjacent to its lower end. FIG. 3 is a side view showing a termination 10 attached to the upper end of the helical pile 20 by placing the termination coupler 16 over the upper end of the helical pile 20. The shaft 12 of the termination 10 is axially aligned with the shaft of the helical pile 20. A bolt 25 can be inserted through holes in the termination coupler 16 and the hole 23 in the upper end of the helical pile 20 to secure this assembly.
FIG. 4 is a side view showing the assembly of the termination 10 and helical pile 20 being screwed further into the ground by applying torque to the upper end of the shaft 12 of the termination 10. The termination coupler 16 transfers this torque to drive the helical pile further into the ground by mechanical interference between the coupler socket 17 and the upper end of the shaft of the helical pile 20.
FIG. 5 is a side view showing the upper portion 18 of the shaft 12 of the termination being cut off at a desired elevation. This is an optional step that can be done using a power saw or other conventional means. Next, a load transfer device can be threaded on the upper end of the shaft 12 of the termination 10 to interface with the building structure, cable, etc. as required to carry the compression or tensile loads associated with a specific job.
Any of a wide variety of load transfer devices can be attached to the upper end of the shaft 12 of the termination 10. For example, FIG. 6 depicts a load transfer device 30 having a flat cap for supporting a building structure. Other cap configurations could be readily substituted. FIG. 7 illustrates a rabbit-ears load transfer attachment 32 suitable for being embedded in concrete to carry primarily compression loads. Other types of load transfer devices could be substituted having bars or other elements to be embedded in concrete. Alternatively, a nut, threaded hub, or threaded coupler can threaded onto the upper end of the termination 10, especially to handle tensile loads.
FIG. 8 is a perspective view showing the left-over piece 18 of the threaded shaft 12 of the termination 10 from FIG. 5 reused as the lead segment in a new modular helical pile assembly by attaching a helical plate 42. A conventional extension shaft 44 with a coupler 46 can be secured to the upper end of the lead segment by a bolt 25.
The above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings. Those skilled in this art will appreciate that various changes, modifications, other structural arrangements, and other embodiments could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims.

Claims

1. A termination for a helical pile having an elongated shaft with a substantially square cross-section and an upper end, said termination comprising:

an elongated shaft having opposing ends and a substantially square cross-section;

a series of uniformly-spaced notches on the corners of the shaft aligned to form partial threads around the shaft; and

a coupler on an end of the shaft having a socket with a substantially square cross-section for receiving and engaging the upper end of the shaft of a helical pile, said coupler transmitting torque between the threaded shaft and the shaft of the helical pile by mechanical interference between the coupler socket and the end of the shaft of the helical pile.

2. The termination of claim 1 further comprising a hole extending through the coupler and the upper end of the shaft of the helical pile to receive a bolt to secure the helical pile to the coupler.

3. The termination of claim 1 wherein the shaft further comprises rounded corners.

4. A method for terminating a helical pile assembly comprising:

providing a helical pile having an elongated shaft with a substantially square cross-section and an upper end;

screwing the helical pile into the ground by applying torque to the upper end of the shaft of the helical pile;

providing a termination having:

(a) an elongated shaft having opposing ends and a substantially square cross-section;

(b) a series of uniformly-spaced notches on the corners of the termination shaft aligned to form partial threads around the termination shaft; and

(c) a coupler on an end of the termination shaft having a socket with a substantially square cross-section;

attaching the coupler of the termination to the upper end of the shaft of the helical pile with the shafts of the termination and helical pile axially aligned;

screwing at least a portion of the termination into the ground by applying torque to the termination, with the coupler transferring torque to drive the helical pile further into the ground by mechanical interference between the coupler socket and the end of the shaft of the helical pile; and

threading a load transfer device on the upper end of the shaft of the termination.

5. The method of claim 4 further comprising the step of cutting off the upper end of the shaft of the termination at a desired elevation prior to threading a load transfer device on the upper end of the shaft of the termination.

6. The method of claim 4 wherein the load transfer device handles compression loads.

7. The method of claim 4 wherein the load transfer device handles tensile loads.

8. The method of claim 4 wherein the load transfer device comprises a flat load transfer cap.

9. The method of claim 4 wherein the load transfer device comprises a rabbit-ears attachment.

10. The method of claim 4 wherein a hole extends through the coupler and the upper end of the shaft of the helical pile, and further comprising the step of placing a bolt through the hold to secure the helical pile to the coupler.