PILE MANDREL WITH EXTENDABLE REAMING MEMBERS
A set of one or more reaming members is secured to a pile mandrel. Each reaming member is moveable between a first position where the reaming member extends a first distance from a center of the pile mandrel, and a second position where the reaming member extends a second distance from the center of the pile mandrel. An apparatus including a pile mandrel and one or more reaming members attached to the mandrel is driven into soil, creating a hole extending down from a surface of the soil. While the reaming member(s) are below the surface of the soil, the reaming member(s) are extended to an extended position; the pile mandrel is rotated with the reaming member(s) extended to ream a section of the hole to a second diameter that is larger than the first diameter; the reaming member(s) are retracted, and the mandrel is removed from the hole.
The description relates generally to forming piles and more particularly to a pile mandrel with extendable reaming members.
BACKGROUNDIn modern engineering practice, piles in the ground are used to improve naturally poor foundations. By the use of piles, structural loads are transmitted to lower levels of the soil (as used herein, soil refers to loose soil as well as compacted soil and rock), generally via friction, but sometimes by bearing, or a combination of both. A piled foundation is often a requirement of the building codes where unsuitable soil fails to provide the required level of support to foundations and footings. This is done to prevent the settling or collapse of structures due to insufficient foundation support, and to ensure even and equal settling of a structure after construction.
Many different types of support piles have been used. Timber was perhaps the first piling material while other materials including steel and concrete were used later. Steel piles include HP sections and steel pipe (usually concrete filled). Concrete piles can be either precast (including both the reinforced and pre-stressed types) or cast-in-place. Cast-in-place concrete piles can further be separated into the non-displacement type (typically auger-cast-piles where soil is removed from the hole and brought to the surface) or the displacement type (where soil is forced to be displaced downwardly and/or to the side of the hole, but the soil is not brought to the surface). Cast-in-place concrete displacement piles may be cast directly against the surrounding soil. Enlarged base piles are also cast directly against the surrounding soil. Cast-in-place concrete displacement piles may also be cast against a metal pipe or metal shell, which has previously been driven into the ground. It has been known to vibrate a pile pipe, or even to turn it with a drill, to break the pipe free from the surrounding soil and remove it.
One displacement-type method of forming cast-in-place concrete piles includes driving a hollow steel mandrel into the ground with a boot or foot covering a hole at the bottom of the mandrel. After the mandrel is driven to the desired depth, the steel mandrel is removed, and the boot remains in the ground at the bottom of the resulting hole. Concrete is fed through the steel mandrel to fill the hole as the mandrel is being driven into the ground, as it is being removed from the ground, or both. After the mandrel is removed, rebar or some other reinforcing material may be inserted into the concrete before the concrete solidifies.
One type of cast-in-place concrete pile is the bell pile. A bell pile includes one or more bottom or mid-sections that flare outward and downward in a frustroconical or bell shape. Thus, these sections have larger diameters than the remainder of the pile. Such large diameter sections below the surface can be advantageous because they increase the pile's resistance to upward forces on the pile. As an example, a typical process for forming a bell pile includes: (1) centering, (2) starting to drill, (3) inserting a stand pipe, (4) feeding bentonite into the hole in the soil, (5) drilling to the specified depth, (6) inserting a belling bucket, (7) reaming the bore hole bottom with the belling bucket, (8) measuring the depth, (9) setting up an iron reinforcement cage, (10) inserting a tremie tube, (11) cleaning slime with an air lift, (12) filling the hole with concrete, and (13) removing soil that was brought to the surface during drilling and belling.
SUMMARYThe present inventor recognized shortcomings of prior pile forming tools and techniques. For example, bell piles are difficult and expensive to form because of the steps involved, and because bell piles are formed with a non-displacement process. Non-displacement processes result in soil being brought to the surface. Thus, that soil must be disposed of, which can be a costly and difficult process, especially if the subterranean soil has been contaminated. Displacement-type steel pipe pile techniques that fill the pipe with concrete and leave the pipe in the ground are expensive because of the price of the steel pipes, and such piles do not produce sufficient resistance to upward lift forces in many situations. Displacement-type concrete pile techniques that remove the steel pipe-type mandrel from the ground can also suffer from insufficient resistance to upward forces in many situations, and it is often difficult to remove the mandrel because of frictional forces between the mandrel and the surrounding soil.
Accordingly, there existed a need to provide a way to form piles that overcomes one or more of these problems. The described embodiments address this need, which has not heretofore been recognized and addressed.
According to one embodiment, a pile mandrel can be adapted to be driven into soil by a pile hammer. The pile mandrel can define a top opening located near a top end of the pile mandrel, with the top opening being positioned to receive grout to be fed through the pile mandrel. The pile mandrel can also define a bottom opening located near a bottom end of the pile mandrel, with the bottom opening being positioned to pass grout from the pile mandrel. A set of one or more reaming members can be secured to the pile mandrel. Each of the one or more reaming members can be moveable between a first position where the reaming member extends a first distance from a center of the pile mandrel, and a second position where the reaming member extends a second distance from the center of the pile mandrel.
When the pile mandrel has been driven into soil, interaction between the one or more reaming members and the soil can bias each of the one or more reaming members between the first and second positions. In addition, rotating the pile mandrel in a first direction can bias each of the one or more reaming members toward the first position, and rotating the pile mandrel in an opposite second direction can bias each of the one or more reaming members toward the second position.
According to another embodiment, a set of one or more reaming members can be mounted on a pile mandrel. Each of the one or more reaming members can be moveable between a first position where the reaming member extends to a first radius from a center of the pile mandrel and a second position where the reaming member extends to a second radius from the center of the pile mandrel. In addition, a hammer can be adapted to drive the pile mandrel into soil, and a drill can be adapted to rotate the pile mandrel while the pile mandrel is at least partially in the soil. Rotation of the pile mandrel while the one or more reaming members are in the soil can bias the one or more reaming members between the first and second positions.
According to yet another embodiment, an apparatus is driven into soil. The apparatus can include a pile mandrel and one or more reaming members attached to the mandrel. Driving the apparatus into the soil can include displacing the soil outwardly and downwardly from the pile mandrel, creating a hole extending down from a surface of the soil. While the one or more reaming members attached to the pile mandrel are below the surface of the soil, the one or more reaming members can be extended from a retracted position to an extended position; the pile mandrel can be rotated with the reaming member(s) in the extended position to ream a section of the hole to a second diameter that is larger than the first diameter; and the one or more reaming members can be retracted from the extended position. The pile mandrel can be removed from the soil, the hole can be filled with a substantially liquid material, such as grout, and the substantially liquid material can be allowed to solidify.
This Summary is provided to introduce a selection of concepts in a simplified form. The concepts 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 to limit the scope of the claimed subject matter. Similarly, the invention is not limited to implementations that address the particular techniques, tools, environments, disadvantages, or advantages discussed in the Background, the Detailed Description, or the attached drawings.
The description and drawings may refer to the same or similar features in different drawings with the same reference numbers.
DETAILED DESCRIPTIONReferring to
These tools and techniques produce substantial benefits that are not present in or predictable from prior pile forming tools and techniques. Because the pile can include a subterranean large diameter section, the pile can have a greater resistance to upward forces than conventional cylindrical piles with no such large diameter sections. Such conventional piles can be pulled up without displacing a significant amount of soil. However, for the pile with the large diameter section to be pulled up, the soil above the large diameter section would have to be displaced. In addition, cast-in-place piles can be formed inexpensively with the tools and techniques described herein. This is in part because the described technique is a displacement technique that does not bring significant amounts of soil to the surface, so there is no need to dispose of such surface soil. In addition, typically only a small boot on the bottom of the mandrel of the driven apparatus is left in the ground. Thus, the material cost for each pile is less than in many prior displacement cast-in-place techniques, where an entire steel pipe was left in the ground for each pile.
The subject matter defined in the appended claims is not necessarily limited to the benefits described herein. A particular implementation of the invention may provide all, some, or none of the benefits described herein. Although operations for the various techniques are described herein in a particular, sequential order for the sake of presentation, it should be understood that this manner of description encompasses rearrangements in the order of operations, unless a particular ordering is required. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Techniques described herein with reference to flowcharts may be used with one or more of the systems described herein and/or with one or more other systems. In addition, the apparatuses defined herein may be used in a manner other than the described methods or techniques. For example, in some situations the driven apparatus described below may be driven into the ground, rotated only in the forward direction or not rotated at all, and removed without extending the reaming members. This could result in a pile without the large diameter section described below (such as the pile hole of
Referring still to
Referring still to
An interface plate (150), which can be a generally rectangular plate as illustrated, is secured to the top of the mandrel (112). The interface plate (150) can be secured by welding or in some other manner. The interface plate (150) defines a centrally located top grout hole (152) (see
Referring to
As illustrated in
Referring now to
Referring still to
The drill head (270) can be formed of steel plates, and can include a ceiling (272), walls (276) that extend down from the ceiling (272), a bottom lip (278) that extends in from the bottom of the walls (276). (See
The opening (280) in the drill head (270) is sized so that it can receive the interface plate (150) of the driven apparatus (110). (See
As noted above, the driven apparatus (110) can be positioned so that the top end (114) of the mandrel (112) extends into the cavity (282) in the drill head (270), as illustrated in
Referring now to 10-15, the use of the pile forming apparatus (200) will be described. As illustrated in
More specifically, referring to
The hammer (240) (see
As illustrated in
Once a desired size of the large diameter hole section (430) has been reamed, then the remaining driven apparatus (110) is rotated in the forward direction (170) and is continued to be raised, as illustrated in
The resulting pile (510) illustrated in
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. For example, the reaming members could be used with another type of mandrel, such as a mandrel with additional flow spaces to assist in the flow of grout into the pile hole. Such a mandrel and associated apparatus is described in U.S. Pat. No. 4,992,002, issued Feb. 12, 1991, which is incorporated herein by reference. As another example, the reaming members may be positioned in some other manner on a driven apparatus. For example, the reaming members could be located closer to the bottom of the mandrel than in the illustrations shown herein.
Claims
1. An apparatus comprising:
- a pile mandrel that is adapted to be driven into soil by a pile hammer, the pile mandrel defining: a top opening located near a top end of the pile mandrel, the top opening being positioned to receive grout to be fed through the pile mandrel; and a bottom opening located near a bottom end of the pile mandrel, the bottom opening being positioned to pass grout from the pile mandrel; and
- a set of one or more reaming members secured to the pile mandrel, each of the one or more reaming members being moveable between a first position where the reaming member extends a first distance from a center of the pile mandrel, and a second position where the reaming member extends a second distance from the center of the pile mandrel, the second distance being different from the first distance.
2. The apparatus of claim 1, wherein each of the one or more reaming members comprises a curved bar.
3. The apparatus of claim 1, wherein each of the one or more reaming members is pivotally connected to the pile mandrel.
4. The apparatus of claim 1, wherein, when the pile mandrel has been driven into soil, interaction between the one or more reaming members and the soil can bias each of the one or more reaming members between the first and second positions.
5. The apparatus of claim 1, wherein, when the pile mandrel has been driven into soil, rotating the pile mandrel in a first direction biases each of the one or more reaming members toward the first position.
6. The apparatus of claim 1, wherein, when the pile mandrel has been driven into soil, rotating the pile mandrel in a first direction biases each of the one or more reaming members toward the first position, and rotating the pile mandrel in an opposite second direction biases each of the one or more reaming members toward the second position.
7. The apparatus of claim 1, wherein the set of one or more reaming members comprises multiple reaming members.
8. The apparatus of claim 1, wherein the set of one or more reaming members comprises multiple rows of reaming members.
9. An apparatus comprising:
- a pile mandrel;
- a set of one or more reaming members mounted on the pile mandrel, each of the one or more reaming members being moveable between a first position where the reaming member extends to a first radius from a center of the pile mandrel and a second position where the reaming member extends to a second radius from the center of the pile mandrel, the second radius being different from the first radius;
- a hammer that is adapted to drive the pile mandrel into soil; and
- a drill that is adapted to rotate the pile mandrel while the pile mandrel is at least partially in the soil;
- wherein rotation of the pile mandrel while the one or more reaming members are in the soil biases the one or more reaming members between the first and second positions.
10. The apparatus of claim 9, wherein:
- rotation of the pile mandrel in a first direction while the one or more reaming members are in the soil causes the one or more reaming members to engage the soil to bias the one or more reaming members toward the first position; and
- rotation of the pile mandrel in a second direction, which is opposite to the first direction, while the one or more reaming members are in the soil causes the one or more reaming members to engage the soil to bias the one or more reaming members toward the second position.
11. The apparatus of claim 9, wherein the drill is adapted to engage the pile mandrel to lift the pile mandrel while the pile mandrel is at least partially in the soil.
12. The apparatus of claim 11, wherein the drill is adapted to simultaneously rotate and lift the pile mandrel while the pile mandrel is at least partially in the soil.
13. The apparatus of claim 9, wherein each of the one or more reaming members is able to pivot between the first position and the second position.
14. The apparatus of claim 9, wherein the drill and the hammer are secured to a single support structure.
15. A method comprising:
- driving an apparatus into soil, the apparatus including a pile mandrel and one or more reaming members attached to the mandrel, wherein driving the apparatus into soil includes displacing the soil outwardly and downwardly from the pile mandrel, creating a hole extending down from a surface of the soil, the hole having a first diameter;
- while the one or more reaming members attached to the pile mandrel are below the surface of the soil: extending the one or more reaming members from a retracted position to an extended position; rotating the pile mandrel with the one or more reaming members in the extended position to ream a section of the hole to a second diameter that is larger than the first diameter; and retracting the one or more reaming members from the extended position;
- removing the pile mandrel from the soil;
- filling the hole with a substantially liquid material; and
- allowing the substantially liquid material to solidify.
16. The method of claim 15, wherein extending the one or more reaming members comprises rotating the pile mandrel in a first direction.
17. The method of claim 16, wherein extending the one or more reaming members comprises engaging the soil with the one or more reaming members.
18. The method of claim 16, wherein retracting the one or more reaming members comprises rotating the pile mandrel in a second direction.
19. The method of claim 18, wherein retracting the one or more reaming members comprises engaging the soil with the one or more reaming members.
20. The method of claim 15, further comprising lifting the pile mandrel while rotating the pile mandrel with the one or more reaming members in the extended position.
Type: Application
Filed: May 16, 2008
Publication Date: Nov 19, 2009
Applicant: W.T.W. CONSTRUCTION, INC. (Portland, OR)
Inventor: William Wright (Portland, OR)
Application Number: 12/122,632
International Classification: E02D 13/00 (20060101);