The present invention relates to a sacrificial tip for a friction pile, such as a sacrificial drill tip and, more particularly, to a rotatably driven sacrificial tip and friction pile for ground anchoring and foundations.
By way of background, conventional piles are well known in the construction industry for ground anchoring and forming foundations of structures and buildings. While all piles are generally driven into the ground for installation, an augered friction pile is rotatably driven into the ground until it reaches an installation depth for a particular application or loading. Friction piles traditionally include a hollow casing and a sacrificial tip secured to and closing off the terminal end thereof. The sacrificial tip, such as a sacrificial drill tip, facilitates advancement of the friction pile into the ground and remains in the ground attached to the friction pile even after installation.
Sacrificial tips operatively advance the friction pile into the ground much like a screw or auger. For example, a rotary drill, such as a track-mounted mobile ram with a drill head, operatively rotates the friction pile and, in turn, rotates the sacrificial tip against the ground. A typical sacrificial tip may include a generally conical body, a helical flight, and a plurality of teeth. As the sacrificial tip rotates, the teeth loosen and work the ground while the helical flight engages the ground to effectively pull the conical body deeper toward the installation depth. The conical body acts as a wedge to force surrounding ground away from the terminal end of the friction pile so that the friction pile may similarly advance into the ground. Once the installation depth is reached, the friction pile and sacrificial tip remain anchored in position by the compression caused by the surrounding ground.
However, in order for the sacrificial tip to survive installation, the conical body, helical flight, and plurality of teeth must be formed from a relatively strong, durable, hard, and malleable material, such as steel. Forming steel into the conical body requires a significant amount of time, skill, and material, thereby adding cost to the sacrificial tip. Furthermore, the teeth are relatively small and may be dislodged during installation. Moreover, imperfections created during the relatively complicated and expensive manufacturing process of the sacrificial tip may lead to one or more teeth being improperly attached, and can fail to perform properly. In either situation, the ground may not be effectively loosened, which, in turn, tends to create additional mechanical stress on the remainder of the sacrificial tip, friction pile, and rotary drill. This additional mechanical stress may effectively shorten the useful life of any one of the sacrificial tip, the friction pile, or the rotary drill.
There is a need for a sacrificial tip and method for effective installation of a friction pile that addresses issues such as those discussed above.
The present invention provides a sacrificial tip for a friction pile which is less costly, simpler to manufacture, and more reliable than conventional sacrificial tips. To that end, and in accordance with the present invention, the sacrificial tip includes a connective plate sized to secure to the friction pile, and a smaller diameter pipe projecting from the connective plate to a penetrative aspect, with a helical flight and several gussets secured to the pipe, the gussets extending longitudinally along the pipe and tapering radially inwardly from the plate toward the penetrative aspect. The plate, gussets, and helical flight can all be formed from relatively inexpensive plate stock, and the pipe can be formed from relatively inexpensive pipe stock manufactured in a bulk extrusion process. They can be assembled together using well-known techniques such as welding Advantageously, at least one of the gussets intersects with the helical flight, and may be secured to the helical flight thereat and/or may extend through a notch in the helical flight thereat. Further advantageously, the connective plate includes a slot, and a gusset includes a tab received in the slot to further secure the gusset to the pipe.
To install the friction pile and sacrificial tip to an installation depth, a terminal end of the friction pile is attached to the connective plate, and a driven end of the friction pile is operatively rotated by a rotary drill. At least a portion of the friction pile rotates in order to rotate the sacrificial tip while the penetrative aspect is positioned against the ground. The penetrative aspect pierces the ground, and the helical flight engages the ground. In doing so, the rotating helical flight advances the sacrificial tip further into the ground with the rotating gussets. Thus, by rotating the sacrificial tip, the pipe and gussets respectively pierce and clear ground from the terminal end of the friction pile similar to the teeth and conical body of conventional sacrificial tips, but with improved manufacturability, cost, and reliability. Once driven to the installation depth, the sacrificial tip remains attached to the friction pile within the ground for forming a portion of a building foundation or other ground anchoring application.
By virtue of the foregoing, there is thus provided a sacrificial tip which is simpler to manufacture, less costly, and more reliable than conventional sacrificial tips. These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
In reference to
In order to rigidly attach and mate the sacrificial tip 12 to the friction pile 14, a plurality of welds (not shown) secure the connective plate 30 to an annular end face 40 of the terminal end 18. More particularly, the connective plate 30 has an outer plate edge 41 that defines a plate diameter 42 and is generally circular, whereas the annular end face 40 defines a pile diameter 44 that is also generally circular. The connective plate 30 is welded directly to the annular end face 40 with the plate diameter 42 and pipe 32 coaxially aligned with the pile diameter 44 and covering an interior space 46 of the friction pile 14. As such, the alignment between the outer plate edge 41 and the annular end face 40 is generally smooth and essentially free of lips or stepped edges. According to an exemplary embodiment, the plate diameter 42 is between 5 inches and 12 inches and, more particularly, between 7 inches and 10 inches. Even more particularly, the plate diameter 42 is approximately 8⅝ inches. With respect to an exemplary embodiment of the friction pile 14, the pile diameter 44 is between 5 inches and 12 inches and, more particularly, between 7 inches and 10 inches. Even more particularly, the plate diameter 42 is approximately 8⅝ inches.
While
The plurality of gussets 36 are secured to and positioned about the pipe 32 for providing structural rigidity to the sacrificial tip 12 and clearing the ground 26 away from the terminal end 18 of the friction pile 14, as shown in
The gussets 36 taper radially inwardly at a constant slope such that the gussets 36 define a gusset diameter that is transverse to the longitudinal direction of the pipe 32. The gusset diameter generally decreases from the connective plate 30 to the penetrative aspect 38. Thus, when the gussets 36 rotate, the gussets 36 collectively define a frustoconical shape positioned coaxial to the pipe 32, friction pile 14, and the connective plate 30. Notably, the largest gusset diameter of the sacrificial tip 12 is approximately equal to the pile diameter 44. The plurality of gussets 36 extend to the penetrative aspect 38, but do not extend longitudinally further along the penetrative aspect 38. Alternatively, one or more of the gussets 36 may extend along the penetrative aspect 38.
In addition, the gussets 36 are equiangularly spaced from one another about the pipe 32. As such, an exemplary embodiment has each gusset 36 angularly spaced approximately 120° from the nearest gusset 36. Alternatively, any other number of gussets 36 may extend along the pipe 32 and may be spaced with different or like angles relative to each other. Thus, it will be appreciated that the invention is not intended to be limited to three gussets 36 spaced equiangularly as described herein.
The helical flight 34 secured about the pipe 32 spirals longitudinally along the pipe 32 toward the penetrative aspect 38. More particularly, the helical flight 34 is a right-handed helicoid that extends continuously from a first leading edge 56 to a trailing edge 58. The helical flight 34 defines an outer flight diameter 59 and a pitch from the first leading edge 56 to the trailing edge 58 that, when rotated as described below, engages the ground 26 (See
The helical flight 34 further includes a second leading edge 60 along the helical flight 34 between the first leading edge 56 and the trailing edge 58. The second leading edge 60 projects radially outward from the pipe 32 further than the first leading edge 56 and, as such, the helical flight 34 between the first and second leading edges 56, 60 defines a smaller radial diameter than a larger radial diameter defined by the helical flight 34 between the second leading and trailing edge 60, 58. In this way, the first leading edge 56 is generally smaller than the second leading edge 60 for slicing into the ground 26 (See
As shown in
A plurality of notches 62 extend through helical flight 34 and respectively receive the plurality of gussets 36. In this respect, the gussets 36 effectively intersect the helical flight 34 so that an inner edge 68 of the helical flight 34 may abut directly against the pipe 32. According to an exemplary embodiment, the helical flight 34 includes four notches 62 along the one revolution of helical flight 34. More particularly, the first leading edge 56 and trailing edge 58 each include one notch 62 to receive the same adjacent gusset 36. The remaining two notches 62 are spaced equiangularly from each other to receive the remaining gussets 36 approximately 120° apart. Of course, due to the increasing slope of the gussets 36 described above, the notches 62 increase in size from the first leading edge 56 to the trailing edge 58 to receive the radially tapering gussets 36.
As shown in
In use, the apparatus 10 having the sacrificial tip 12 rigidly secured to the terminal end 18 of the friction pile 14 is rotatably driven into engagement with the ground 26, as shown in
The rotating pipe 32 causes the plurality of gussets 36 to similarly rotate within the ground 26. The rotating gussets 36 effectively loosen and clear a portion of the ground 26 from the terminal end 18 so that the connective plate 30 and friction pile 14 follow behind. As the pipe 32 moves into the ground 26, another portion of the ground 26 is forced through the opening 50 and into the hollow 52 within the pipe 32. Of course, once the hollow 52 fills with the ground 26, other portions of the ground 26 are simply deflected around the pipe 32 and cleared away by the rotating plurality of gussets 36. The plurality of gussets 36 clear the portion of the ground 26 from the terminal end 18, but maintain a sufficient amount of ground 26 around the friction pile 14 to compress the friction pile 14 with the surrounding ground 26.
The rotary drill 22 continues to rotate the friction pile 14 and sacrificial tip 12 as described above until the sacrificial tip 12 reaches the installation depth for anchoring into the ground 26. Rather than remove the sacrificial tip 12, the attachment of the sacrificial tip 12 to the terminal end 18 is maintained once the installation depth is reached. Thus, the apparatus 10 at the installation depth is effectively installed for forming a portion of a building foundation or other ground anchoring application.
While the present invention has been illustrated by embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features shown and described herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. For example, the sacrificial tip may not include cooperating tabs and slots and may instead be assembled with welds and/or fasteners. Also, various features of the prior art, such as teeth, may be secured to or form a portion of the sacrificial tip. Furthermore, the penetrative aspect may be conical, serrated, pointed, sharp, or generally any other shape for piercing the ground. While the gussets shown and described above are generally triangular and planar, it will be further appreciated that the gussets may alternatively be bent, arcuate, or another shape that may be positioned about the pipe. In this respect, it will be appreciated that the particular sizes and shapes discussed above may be augmented or scaled to accommodate other sizes or types of piles, or even other soil types and applications. The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be from such details without departing from the scope of the general inventive concept.
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Foundation Piledriving Contractors, Fundex Piles: Vibration-Free Soil Displacement Cast-In-Place Concrete Pile, http://www.foundationpiledriving.com/fundex-piles, © 2014, 4 pp. |