Method and apparatus for installing a helical pile
An apparatus and a method to assist in the installation of a helical pile. The apparatus comprises a drive mechanism having an engaged and a disengaged configuration. When in its engaged configuration the drive mechanism operatively grips the exterior surface of the helical pile. When in its disengaged configuration the drive mechanism operatively releases the exterior surface of the helical pile. Movement of the drive mechanism when in its engaged configuration causes rotational movement of the pile. When in its disengaged configuration the drive mechanism moves without rotation of the pile.
This invention relates to a method and an apparatus that may be used to install a helical or screw pile.
BACKGROUND OF THE INVENTIONHelical or screw piles have been used for decades to help support the foundation of buildings, bridges and other civil engineering structures. Traditionally helical piles were used primarily in areas of weak or wet soil and their application was somewhat limited as their installation was difficult without mechanical assistance. However, more recently helical piles have become considerably more widespread in use due to the advent of high torque motors that are used to rotate the piles and drive them into the ground. The resistence of a helical pile to both upward and carrying loads makes it attractive for use in a wide range of different situations. Today helical or screw piles are commonly used in foundation support for commercial and residential buildings, to help support temporary structures, as a support for street light standards, for the support of oil and gas drilling and pumping equipment, for bank retention, and for a wide variety of anchoring applications.
Typically a helical pile is installed through the use of a boom truck having a high torque motor positioned on the end of a boom that may be connected to the upper end of the pile in order to rotate the pile and drive it into the ground. Torque is transferred from the motor to the pile through the use an intermediary coupling that is either physically welded to the end of the pile or fastened thereto through the use of bolts, pins or some other mechanical fastener. While such a structure is effective in transmitting rotational movement from the motor to the pile, it can also require a considerable amount of labour to put into operation on account of the need to weld, bolt, pin or otherwise secure the torque coupling to the end of the pile.
In many instances piles of significant length are required, which either necessitates the use of a large boom truck having an extended reach or requires that a number of lengths of shorter piling be welded or fastened together as they are driven into the ground. Where a large boom truck is used to drive a lengthy helical pile, difficulties can arise when trying to maintain the pile in a vertical orientation due to the length of the pile and the weight of the drive motor that is attached to its upper end.
The cost of utilizing a trunk having an extruded boom can be significant. Large boom trucks also restrict the ability to work in confined areas. In cases where a pile is to be installed in sections, existing equipment makes it necessary to physically attach (and then later remove) the intermediary drive member, to each length of pile. Attaching, removing and subsequently re-attaching the drive member is both time consuming and costly.
There is therefore a need for an improved apparatus for installing a helical or screw pile, particularly where the pile is of significant length.
SUMMARY OF THE INVENTIONThe invention therefore provides a method and an apparatus that may be used to install a helical or screw pile whereby the need for the use of a large boom truck is eliminated or minimized, as is the requirement for physically welding, bolting or pinning an intermediary drive member or torque coupling to the end of the pile in order to connect the pile to the motor of a drive head. The invention provides for a drive mechanism that imparts rotational movement to a pile without appreciable movement or displacement of the drive mechanism in a direction generally parallel to the longitudinal axis of the pile.
Accordingly, in one of its aspects the invention provides an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source, said power source causing said drive mechanism to move in a first direction and then subsequently in a second direction in a reciprocating fashion, said drive mechanism having an engaged and a disengaged configuration, when in said engaged configuration said drive mechanism operatively gripping the exterior surface of said helical pile, when in said disengaged configuration said drive mechanism operatively releasing the exterior surface of said helical pile, movement of said drive mechanism in said first direction placing said drive mechanism in said engaged configuration and causing rotational movement of said helical pile, movement of said drive mechanism in said second direction placing said drive mechanism in said disengaged configuration without rotation of said helical pile.
In a further aspect the invention provides a method of installing a helical pile, the method comprising the steps of operatively connecting a drive mechanism having an engaged and a disengaged configuration to a power source, when in said engaged configuration said drive mechanism capable of gripping the exterior surface of the helical pile, when in said disengaged configuration the drive mechanism releasing the exterior surface of the helical pile; with said power source operating said drive mechanism to move said drive mechanism in a first direction that places said drive mechanism in said engaged configuration such that further movement of said drive mechanism in said first direction causes rotational movement of said pile; and, thereafter, causing said power source to move said drive mechanism in a second direction thereby placing said drive mechanism in said disengaged configuration without rotation of said helical pile.
The invention also provides an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism having an engaged and a disengaged configuration, when in said engaged configuration said drive mechanism operatively gripping the exterior surface of said helical pile, when in said disengaged configuration said drive mechanism operatively releasing the exterior surface of said helical pile, wherein movement of said drive mechanism when in said engaged configuration causes rotational movement of said pile, when in said disengaged configuration said drive mechanism moving without rotation of said pile.
In another aspect the invention concerns a method of installing a helical pile, the helical pile being of the type having a generally hollow longitudinally orientated bore extending therethrough, the method comprising the steps of (i) with a drive mechanism imparting rotational movement to the pile to cause the pile to be rotated into the ground; and, (ii) extracting at least a portion of any accumulated soil or debris from within the pile's hollow bore.
The invention also provides an apparatus to assist in the installation of a helical pile of the type having a generally hollow longitudinally orientated bore extending therethrough, the apparatus comprising a drive mechanism and a soil extractor, said drive mechanism imparting rotational movement to the pile to cause the pile to be rotated into the ground, said soil extractor operable to extract at least a portion of any accumulated soil or debris from within the pile's hollow bore.
In a further alternate embodiment the invention provides an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source, said power source causing said drive mechanism to move in a first direction and then subsequently in a second direction in a reciprocating fashion, said drive mechanism operatively connected to the exterior surface of said helical pile such that reciprocal movement of said drive mechanism causes rotational movement of said helical pile without appreciable movement or displacement of said drive mechanism in a direction generally parallel to the longitudinal axis of said pile.
In yet as further aspect the invention concerns an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source and to the exterior surface of said helical pile, said power source causing said drive mechanism to impart rotational movement to said helical pile without appreciable movement or displacement of said drive mechanism in a direction generally parallel to the longitudinal axis of said pile.
Further aspects and advantages of the invention will become apparent from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGSFor a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which show the preferred embodiments of the present invention in which:
The present invention may be embodied in a number of different forms. However, the specification and drawings that follow describe and disclose only some of the specific forms of the invention and are not intended to limit the scope of the invention as defined in the claims that follow herein.
By way of introduction,
According to the invention there is provided an apparatus 4 to assist in the installation of a helical or screw pile 2. Apparatus 4 is comprised generally of a drive mechanism 5 that is operatively connected to a power source 6. It is expected that in most instances power source 6 will be comprised of a hydraulic pump capable of providing pressurized hydraulic fluid to the various components of apparatus 4 where required. Alternately, power source 6 could be pneumatic or electrical in nature. In any event, power source 6 is operatively connected to drive mechanism 5 in order to allow for movement of the drive mechanism in a first direction, and then subsequently in a second direction, in a generally reciprocating fashion. In the embodiment of the invention shown in
As is shown particularly in
Once hydraulic cylinder 7 has reached the end of its movement in its first direction away from pile 2, the flow of hydraulic fluid may be reversed to allow the piston to be drawn outwardly from the cylinder toward the pile thereby relieving the tension in drive chain 8. As the tension in the drive chain is relieved, drive mechanism 5 will proceed to a disengaged configuration where chain 8 is released from its gripping contact with the exterior surface of helical pile 2. The chain will then be pulled or slid in an opposite direction (ie with second end 10 moving away from the pile) through the operation of tensioning device 11. With the extension of hydraulic cylinder 7 and the movement of drive chain 8, the operation of tensioning device 11 causes the drive mechanism to return to a disengaged configuration while the drive chain slides loosely around the exterior surface of helical pile 2. This movement may be referred to as a return stroke and occurs without rotating the pile.
It will be appreciated by those skilled in the art that the reciprocal movement of drive mechanism 5 between the power and return strokes described above will cause drive mechanism 5 to repeatedly engage and disengage the exterior surface of the helical pile, effectively causing the pile to be ratchetted into the ground through the application of successive, spaced apart, power strokes. Depending upon the hardness and characteristics of the ground through which helical pile 2 is to be driven, the relative strength of tensioning device 11 may have to be adjusted to prevent slippage of chain 8 about the pile's surface. Where tensioning member 11 is a spring, the spring may be replaced with a stronger string having a greater spring constant. In addition, a spring tensioner 14 (see
The drive mechanism described above will permit helical pile 2 to be rotated and screwed into the ground without the need to attach a large high torque motor to the upper end of the pile. Drive mechanism 5 may also be mounted in close proximity to the ground avoiding the need for large boom trucks when driving lengthy piles. It will also be appreciated that drive mechanism 5 does not require the welding or bolting of drive couplings onto the surface of the helical pile, and does not present a hindrance to maintaining the pile in a desired orientation. In one preferred embodiment of the invention hydraulic cylinder 7 and tensioning device 11 are rotatably attached to the frame 12 to allow both devices to be displaced in a generally vertical plane so that they may be tipped in a downward direction as the pile is screwed into the ground during a power stroke. On the return stroke hydraulic cylinder 7 and tensioning device 11 will tend to swing in an upward direction until they are approximately horizontal once again. Accordingly, the described structure allows helical pile 2 to move in a vertical direction as it is rotated without interference from drive mechanism 5.
It should also be noted that each successive power stroke will entail the application of force to a different portion of the exterior surface of helical pile 2 as the pile slowly moves downward into the ground. Any tendency for the walls of the pile to become damaged through contact with chain 8 is therefore minimized. Further, depending upon the speed at which it is desired to turn the pile a single drive mechanism 5 may be utilized (see
It should be appreciated by those skilled in the art that a variety of other reciprocating drive mechanisms could be utilized in place of the chain drive mechanism described above. Three such alternate embodiments of the invention are shown in
In the embodiments shown in
The embodiment of the drive mechanism shown in
In operation, when the piston of cylinder 7 is retracted the loose connection between pin 29 and bore 30 will effectively cause first jaw portion 21 to rotate about pin 28 driving grippers 31 into the exterior surface of the helical pile until bore 30 prevents any further movement of the jaw members relative to connecting rod 24. At that point further retraction of the piston into cylinder 7 will effectively result in a rotational force being applied to helical pile 2 through grippers 31. When the movement of cylinder 7 is reversed, with the piston extracted from the cylinder, first jaw portion 21 will rotate slightly in a counterclockwise direction about pin 28 until further movement of the jaw member relative to connecting rod 24 is halted by engagement of pin 19 with the side of bore 30. However, the small counterclockwise rotation is sufficient to disengage grippers 31 from the exterior surface of helical pile 2 such that further withdrawal of the piston from cylinder 7 enables the jaw members to be rotated in a counterclockwise direction about the exterior surface of the pile without rotation of the pile itself. In this manner the reciprocal movement of cylinder 7 will effectively be transformed into a clockwise rotational movement of pile 2. Reversing the relative positions of pins 28 and 29 so that pin 28 is a smaller pin received within a larger diameter bore, will permit the embodiment of drive mechanism 5 shown in
Yet a further embodiment of drive mechanism 5 is shown in
As the helical pile is continuously rotated the drive chain will engage the exterior surface of the pile and be rotated in unison therewith around the pile in a generally helical or screw-like path. As portions of the chain come into contact with the surface of the pile other portions will be released permitting both the pile and the chain to be rotated, while at the same time permitting vertical movement of the pile (in either an upward or downward direction) without appreciable or significant movement or displacement of the drive mechanism in a direction generally parallel to the longitudinal axis of the pile. To help facilitate the relative movement of the chain and the pile, particularly in instances where the pile is rapidly advanced into or out of the ground, drive gear 62 may be inclined relative to the axis of helical pile 2. It should also be noted that while the embodiment shown in
Referring again to
Apparatus 4 may further include a soil extractor situated above the end of pile 2. In
Since helical piles are generally hollow structures with a cylindrical bore extending through them, as they are rotated into the ground their centre cavities tend to become filled or partially filled with soil. Soil within the pile tends to increase the resistance of the pile to rotational movement which has a corresponding increase in the amount of torque required to rotate the pile into or out of the ground. In addition, as soil builds up within the interior of the pile the soil tends to plug the pile's internal bore such that as the lower end of the pile is rotated further into the ground the surrounding soil can no longer enter the hollow interior of the pile and must be laterally displaced. For small diameter piles in soft formations, displacing the soil at the tip of the pile may not present much difficulty. However, for large diameter piles and in hard soil formations laterally displacing the soil at the tip of the pile can have a very significant impact on the amount of torque required to drive the pile into the ground. The presence of soil or other debris within the internal bore through pile 2 also has little effect on the weight bearing capacity of the pile. Accordingly, through inserting auger 37 into the hollow interior of helical pile 2 at least a portion of any soil or other debris situated within the pile can be removed, effectively reducing the overall weight of the structure and enhancing the ability of the pile to be driven into the ground through providing a space into which additional soil may be displaced as the pile is driven downwardly. The result is that less energy and less torque is required to drive the pile into the ground. In addition, extending the lower end of the auger down to the bottom tip of the pile provides the ability to loosen the soil as the pile is rotated, further reducing the amount of torque required to set the pile.
An alternate embodiment of the invention where the soil extractor is a vacuum tube 55 and a vacuum head 56 is shown in
In accordance with another one of the preferred embodiments of the invention, apparatus 4 further includes a vertical loading head 40. As indicated in
Referring to
While vertical loading head 40 is applying a longitudinally oriented force to the pile it must also permit the pile to freely rotate. To this end, in the embodiment of the invention shown in
With a complete and thorough understanding of the preceding description of apparatus 4, it will be understood that the apparatus presents a means to rotate and to assist in the installation of a helical pile through the use of a drive mechanism that may be mounted close to the ground without the need for large boom trucks or derricks. The apparatus also allows for the rotation of the pile without the use of couplings or drive members that must be welded, bolted or otherwise fixed to the pile. The described apparatus provides a simple, efficient and cost effective manner of rotating the pile and turning it into the ground. Through the use of one or more pile guides 32, the vertical orientation of the pile can be maintained at virtually any desired angle. The incorporation of vertical loading head 40 into apparatus 4 provides an operator with the ability to apply a vertical load to the pile (in either an upward or downward direction) to assist in either installing or extracting a pile. In situations where hard or wet ground formations are encountered, auger 37 may be operated to extract a portion of the dirt or other debris within the hollow interior of the pile to further aid in its installation or removal.
As discussed, apparatus 4 may include one, two or more drive mechanisms that may be operated in unison to increase the amount of rotational force available to be applied to the pile. Alternatively the drive mechanisms may be operated sequentially so that the combined reciprocal movement of each individual drive member results in a constant rotation of the pile. Furthermore, relatively simple adjustments to drive mechanism 5 allows the drive mechanism to rotate the pile in either a clockwise or counterclockwise direction as may be necessary to install or extract a pile. Where the drive mechanism is a chain drive, reversing the direction of pile rotation is as simple as wrapping the chain around the pile in the opposite direction. Where tensioning device 11 is a hydraulic cylinder, a pneumatic cylinder, an electric solenoid or similar device, reversing the direction of pile rotation can be achieved through reversing the stroke on cylinder 7 and device 11. In the case where the tensioning device is a hydraulic or pneumatic cylinder reversing the operation of the cylinders could be accomplished through the use of reversing values on the cylinder supply and return lines.
The described structure also presents the ability to construct a compact device that can easily fit on the back of a truck or that could be independently mounted on a skid having a dedicated power source. The embodiment shown in
It is to be understood that what has been described are the preferred embodiments of the invention and that it may be possible to make variations to these embodiments while staying within the broad scope of the invention. Some of these variations have been discussed while others will be readily apparent to those skilled in the art.
Claims
1. An apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source, said power source causing said drive mechanism to move in a first direction and then subsequently in a second direction in a reciprocating fashion, said drive mechanism having an engaged and a disengaged configuration, when in said engaged configuration said drive mechanism operatively gripping the exterior surface of said helical pile, when in said disengaged configuration said drive mechanism operatively releasing the exterior surface of said helical pile, movement of said drive mechanism in said first direction placing said drive mechanism in said engaged configuration and causing rotational movement of said helical pile, movement of said drive mechanism in said second direction placing said drive mechanism in said disengaged configuration without rotation of said helical pile.
2. The device as claimed in claim 1 including at least one pile guide, said pile guide engaging the exterior surface of said helical pile to assist in maintaining said pile at a desired inclination.
3. The device as claimed in claim 1 including a vertical loading head having an engaged position, when in said engaged position said vertical loading head releasably secured about the exterior surface of said helical pile and permitting the application of a longitudinally oriented force to said pile while permitting rotational movement of said pile through operation of said drive mechanism.
4. The device as claimed in claim 3 wherein said vertical loading head has a disengaged position, when in said disengaged position said vertical loading head free from contact with the exterior surface of said helical pile.
5. The device as claimed in claim 1 wherein said drive mechanism includes a drive chain received about the exterior surface of said helical pile, said drive chain having a first end and a second end, said first end of said drive chain secured to a reciprocating drive member, said second end of said drive chain secured to a tensioning device.
6. The device as claimed in claim 5 wherein said reciprocating drive member is a hydraulic cylinder, a pneumatic cylinder, or an electric solenoid.
7. The device as claimed in claim 6 wherein said tensioning device comprises a spring, a pneumatic cylinder, a hydraulic cylinder or an electric solenoid.
8. The device as claimed in claim 1 including an auger, said auger operatively connected to a rotary drive mechanism such that upon rotation and insertion of said auger into said helical pile said auger extracts at least a portion of any soil and other debris situated within said helical pile.
9. The device as claimed in claim 1 wherein said drive mechanism includes a pair of jaw members, movement of said drive mechanism in said first direction causing said jaw members to grip the exterior surface of said helical pile and causing rotational movement of said pile, movement of said drive mechanism in said second direction disengaging said jaw members from the exterior surface of said helical pile without rotation of said pile.
10. The device as claimed in claim 1 including two drive mechanisms, said power source causing said drive mechanisms to move in an opposed reciprocating fashion to permit continuous rotation of said helical pile.
11. A method of installing a helical pile, the method comprising the steps of:
- (i) operatively connecting a drive mechanism having an engaged and a disengaged configuration to a power source, when in said engaged configuration said drive mechanism capable of gripping the exterior surface of the helical pile, when in said disengaged configuration the drive mechanism releasing the exterior surface of the helical pile;
- (ii) with said power source operating said drive mechanism to move said drive mechanism in a first direction that places said drive mechanism in said engaged configuration such that further movement of said drive mechanism in said first direction causes rotational movement of said pile; and,
- (iii) thereafter, causing said power source to move said drive mechanism in a second direction thereby placing said drive mechanism in said disengaged configuration without rotation of said helical pile.
12. The method as claimed in claim 11 including the further steps of repeatedly operating said drive mechanism to move firstly in said first direction and secondly in said second direction to cause repeated reciprocal movement of said drive mechanism.
13. The method as claimed in claim 11 including the further step of applying a force generally parallel to the longitudinal axis of said pile while permitting rotational movement of said pile through the operation of said drive mechanism.
14. The method as claimed in claim 11 including the step of maintaining said pile at a desired inclination through the use of one or more pile guides engaging the exterior surface of said pile.
15. The method as claimed in claim 11 including the further step of inserting a rotating auger into said helical pile to extract at least a portion of any soil or debris situated therein.
16. An apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism having an engaged and a disengaged configuration, when in said engaged configuration said drive mechanism operatively gripping the exterior surface of said helical pile, when in said disengaged configuration said drive mechanism operatively releasing the exterior surface of said helical pile, wherein movement of said drive mechanism when in said engaged configuration causes rotational movement of said pile, when in said disengaged configuration said drive mechanism moving without rotation of said pile.
17. The device as claimed in claim 16 including at least one pile guide, said pile guide engaging the exterior surface of said helical pile to assist in maintaining said pile at a desired inclination.
18. The device as claimed in claim 16 wherein said drive mechanism includes a drive chain received about the exterior surface of said helical pile, said drive chain having a first end and a second end, said first end of said drive chain secured to a reciprocating drive member, said second end of said drive chain secured to a tensioning device.
19. The device as claimed in claim 18 wherein said reciprocating drive member causes a reciprocal movement of said drive chain and stepped rotational movement of said helical pile.
20. A method of installing a helical pile, the helical pile being of the type having a generally hollow longitudinally orientated bore extending therethrough, the method comprising the steps of:
- (i) with a drive mechanism imparting rotational movement to the pile to cause the pile to be rotated into the ground; and,
- (ii) extracting at least a portion of any accumulated soil or debris from within the pile's hollow bore.
21. The method as claimed in claim 20 wherein said step of extracting at least a portion of any accumulated soil or debris from within the pile's hollow bore is carried out while the pile is being rotated into the ground.
22. The method as claimed in claim 20 wherein said pile is partially rotated into the ground prior to the extraction of soil or debris from within the pile's hollow bore.
23. The method as claimed in claim 20 wherein said step of extracting at least a portion of any accumulated soil or debris from within the pile's hollow bore is carried out through inserting a rotating auger into said bore.
24. The method as claimed in claim 20 wherein said step of extracting at least a portion of any accumulated soil or debris from within the pile's hollow bore is carried out through inserting a vacuum tube into said bore.
25. An apparatus to assist in the installation of a helical pile of the type having a generally hollow longitudinally orientated bore extending therethrough, the apparatus comprising a drive mechanism and a soil extractor, said drive mechanism imparting rotational movement to the pile to cause the pile to be rotated into the ground, said soil extractor operable to extract at least a portion of any accumulated soil or debris from within the pile's hollow bore.
26. The apparatus as claimed in claim 25 wherein said soil extractor is an auger operatively connected to a rotary drive mechanism.
27. The apparatus as claimed in claim 25 wherein said soil extractor is a vacuum tube insertable into said hollow bore of said pile.
28. The apparatus as claimed in claim 27 including a water jet insertable into said hollow bore of said pile with said vacuum tube.
29. An apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source, said power source causing said drive mechanism to move in a first direction and then subsequently in a second direction in a reciprocating fashion, said drive mechanism operatively connected to the exterior surface of said helical pile such that reciprocal movement of said drive mechanism causes rotational movement of said helical pile without appreciable movement or displacement of said drive mechanism in a direction generally parallel to the longitudinal axis of said pile.
30. The device as claimed in claim 29 wherein said drive mechanism includes at least 2 actuating cylinders, said cylinders having reciprocating pistons connected to a drive gear such that alternating reciprocating movement of said pistons causes continuous rotation of said drive gear.
31. The device as claimed in claim 30 having a drive chain operatively engaging the exterior surface of said helical pile, said drive chain further engaging said drive gear such that rotation of said drive gear causes said drive chain to rotate said helical pile.
32. An apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source and to the exterior surface of said helical pile, said power source causing said drive mechanism to impart rotational movement to said helical pile without appreciable movement or displacement of said drive mechanism in a direction generally parallel to the longitudinal axis of said pile.
33. The device as claimed in claim 32 wherein said drive mechanism continuously rotates said helical pile.
34. The device as claimed in claim 32 wherein said drive mechanism includes a reciprocating drive that causes staggered rotational movement of said pile.
35. The device as claimed in claim 32 wherein said drive mechanism includes a drive chain received about the exterior surface of said pile, movement of said drive chain imparting rotational movement to said pile.
Type: Application
Filed: Dec 1, 2004
Publication Date: May 17, 2007
Inventor: Joseph Nimens (Ontario)
Application Number: 10/581,559
International Classification: E02D 13/00 (20060101);