Abstract:
A screw pile substructure support system is provided. In one embodiment, the invention relates to a screw pile substructure support system including a tubular pile having a centerline, wherein the tubular pile includes a first cylindrical section and a second cylindrical section attached by a weld, a pile tip including a first pile tip end attached to the tubular pile, an end plate having a substantially flat surface disposed perpendicular to the centerline of the tubular pile, a tapered portion disposed between the first pile tip end and the end plate, and a helical flight attached to an exterior surface of the tapered portion, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the tapered portion, wherein the end plate is fixedly attached to the pile tip.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/657,857, filed Mar. 2, 2005, the disclosure of which is incorporated fully herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the installation of foundation piles in a soil bed, and particularly to a method and apparatus for the installation of a high capacity rotational substructure piling system. 
     BACKGROUND OF THE INVENTION 
     The installation of conventional foundation piles has previously been accomplished by driving a precast concrete pile or steel beam or vibrating an H pile into a soil bed. When driving a foundation pile, the soil surrounding the pile may be compacted in various ways as well as disrupted by the seismic shocks of the pile driver itself. When driving a pile into hard ground, earth displaced by the pile causes the ground surrounding the pile to heave. In contrast, when driving a pile into soft ground, settling of the surrounding soil may be caused. All of these conditions can cause problems for any standing structures in the area of the pile being driven. 
     The installation of conventional piles has also previously been accomplished by pre-drilling a hole in a soil bed using an auger and lowering a pre-molded pile into the hole. A hybrid system also exists between the driving and drilling methods whereby an open ended pile such as a pipe pile is driven into a soil bed, after which point the soil inside the pile is augered out and concrete is poured in the cavity formed therein. Cast and hole methods as well as casons may also be used, specifically where there are concerns for preserving nearby buildings against the problems discussed above. However, all these methods can prove either costly and/or slow to carry out in the field. Furthermore, where the ground in a job site is deemed to be contaminated, any soil removed from the ground, such as that produced by an auger, must be disposed of properly presenting an additional problem and associated cost. 
     A more complex system is known whereby a pile is attached to a drill head which is substantially larger than the diameter of the pile itself. The pile is turned together with the drill head by a drilling rig to create a passage in the soil bed through which the pile may pass. A conduit is provided through the center of the pile for water or grout to be pumped down and out the tip of the drill head to either float away debris or anchor the pile in its final resting place in the soil bed. Another system, known as an under-reamer system, features a double torque head which turns a drill in the center of a pipe, which pipe is itself turned in the opposite direction from the drill. Although they do have certain advantages over other known systems, both of these drilling systems are obviously substantially more complex, and therefore more costly than the first several prior art systems discussed. 
     Both driving and drilling systems used to place foundation piles rely in part on brute force to either force a pile into a soil bed, or to cut and remove material. What is needed is a more elegant approach to foundation pile placement providing such benefits as may include a faster pile placement speed, lower cost and greater ease of use as well as higher load capacity piles. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the invention relates to a screw pile substructure support system including a tubular pile having a centerline, wherein the tubular pile includes a first cylindrical section and a second cylindrical section attached by a weld, a pile tip including a first pile tip end attached to the tubular pile, an end plate having a substantially flat surface disposed perpendicular to the centerline of the tubular pile, a tapered portion disposed between the first pile tip end and the plate, and a helical flight attached to and exterior surface of the tapered portion, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the tapered portion, wherein the end plate is fixedly attached to the pile tip. 
     In another embodiment, the invention relates to a screw pile substructure support system including a tubular pile having a centerline, wherein the tubular pile includes a first cylindrical section and a second cylindrical section attached by a weld, a shaped pile tip including a first pile tip end attached to the tubular pile, a second pile tip end, a helical flight attached to and exterior surface of a portion of the shaped pile tip, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the portion of the shaped pile tip, and an end plate disposed at the second pile tip end, the end plate having a substantially flat surface disposed perpendicular to the centerline, wherein a diameter of the second pile tip end is less than a diameter of the first pile tip end, and wherein the end plate is fixedly attached to the shaped pile tip. 
     In yet another embodiment, the invention relates to a screw pile substructure support system including a tubular pile having a centerline, a pile tip including a tapered portion including a first end having a first diameter and a second end having a second diameter, wherein the first diameter is greater than the second diameter, and wherein the first end is attached to the tubular pile, a first helical flight attached to and exterior surface of a portion, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the tapered portion, a cylindrical shaft coupled to and extending outward from the second end, a second helical flight attached to an exterior surface of the cylindrical shaft, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the cylindrical shaft. 
     In still yet another embodiment, the invention relates to a screw pile substructure support system including a tubular pile having a centerline, wherein the tubular pile includes a first cylindrical section fixedly attached to a second cylindrical section, a pile tip including a first pile tip end attached to the tubular pile, and end plate having a substantially flat surface disposed perpendicular to the centerline of the tubular pile, a tapered portion disposed between the first pile end and the end plate, and a helical flight attached to an exterior surface of the tapered portion, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the tapered portion, wherein the end plate is fixedly attached to the pile tip. 
     In a further embodiment, the invention relates to method for installing a screw pile substructure support system including attaching a shaped pile tip to at least one cylindrical pile section to form a first pile unit, wherein the shaped pile tip includes a first pile tip end attached to the at least one cylindrical pile section, a second pile tip end, a helical flight attached to an exterior surface of a portion of the shaped pile tip, wherein the helical flight extends along the exterior surface for a distance of at least one quarter of a circumference of the portion of the shaped pile tip, and an end plate disposed at the second pile tip end, the end plate having a substantially flat surface disposed perpendicular to the centerline, wherein a diameter of the second pile tip end is less than a diameter of the first pile tip end, and wherein the end plate is fixedly attached to the shaped pile tip, positioning the first pile unit above a preselected location of ground, attaching a drilling rig to the first pile unit, and turning the first pile unit to facilitate penetration of the ground. 
     In another embodiment, the invention relates to a screw pile substructure support system, including a tubular pile having a centerline and a first diameter, wherein the tubular pile includes a first cylindrical section and a second cylindrical section attached by a weld, a substantially conically shaped pile tip sharing a centerline with the tubular pile, the substantially conically shaped pile tip having a first end and a second end, the first end being connected to the tubular pile and having a second diameter, a helical flight attached to an exterior surface of the substantially conically shaped pile tip, wherein the helical flight extends along the exterior surface for a distance of at least one third of a circumference of the substantially conically having a substantially flat surface disposed perpendicular to the centerline of the tubular pile, wherein the first diameter is substantially similar to the second diameter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a conical pile tip according to one embodiment of the present invention; 
         FIG. 2  shows a concrete-filled steel pipe pile according to a further embodiment of the present invention; 
         FIGS. 3A ,  3 B and  3 C show specific detailed views taken along the lines  3 A,  3 B, and  3 C shown in  FIG. 2 ; 
         FIG. 4  shows another embodiment of a conical pile tip; 
         FIG. 4A  shows still another embodiment of a conical pile tip; 
         FIG. 5  shows yet another embodiment of a conical pile tip; 
         FIG. 6  show various embodiments of cutter teeth for use with a conical pile tip; 
         FIG. 7  shows an end bearing surface area detail of another embodiment of a pile tip; 
         FIG. 8  shows another end bearing surface area detail of a further embodiment of a pile tip; 
         FIGS. 9A-9B  show embodiments of a steel pipe pile provided with a series of driver pin holes  90 ; and 
         FIG. 10  shows an embodiment of a reusable driver tool for installing the screw pile of the present invention. 
     
    
    
     Before any embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangements of components set forth in the following description, or illustrated in the drawings. The invention is capable of alternative embodiments and of being practiced or being carried out in various ways. Specifically, numerical dimensions where they are referenced herein represent those of exemplary embodiments only and may be modified by one skilled in the art as conditions warrant. Also, it is to be understood, that the terminology used herein is for the purpose of illustrative description and should not be regarded as limiting. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A method and apparatus is provided for the installation of a foundation pile in a soil bed. In contrast to prior art drilled foundation pile systems which use a low torque and an efficient drill tip which must be retrieved from the drilling site after drilling is complete, in an exemplary embodiment of the present invention a pile is provided with a fixed tip having a helical flight thereon which draws the pile into a soil bed when a torque is applied to the pile.  FIG. 1  shows a conical pile tip  10  connected to a pile  1  according to one embodiment of the present invention, wherein the pile tip  10  allows the pile  1  to be set into a soil bed by applying a torque to the distal end of the pile  1  (not shown) using a standard drilling rig. The rig may additionally apply a crowd pressure to the pile  1  along with the torque to further aid in placement of the pile  1  in the soil bed to provide substructure support system for a large scale construction project. 
     In one embodiment, the pile tip  10  is comprised of a substantially conically shaped body sharing a centerline with the pile  1  to which it is attached, as well as a helical flight  15  attached to the outside surface of the pile tip  10 , and cutter teeth  16  extending out radially from the centerline of the pile tip  10 . The helical flight  15  helps draw the pile tip  10  down into a soil bed during placement, and the cutter teeth  16  serve to break up the soil to allow the pile tip  10  to better penetrate into the bed. In an exemplary embodiment, the flight  15  is formed from a half-inch thick plate, has a pitch of three inches and is attached to the body of the pile tip  10  so that its lowest edge lies three inches above an end plate  19 . The end plate  19  caps off the end of the conical body of the pile tip  10 , closing it off from the soil in which it is to be placed. A point shaft  17  and cutter teeth  18  are provided extending out axially from the end plate  19  of the pile tip  10 . The point shaft  17  helps keep the pile tip  10  centered during installation of the pile  1  in a soil bed and both the point shaft  17  and the cutter teeth  18 , like the cutter teeth  16 , serve to break up the soil to allow the pile tip  10  to better penetrate into the bed. In one embodiment, the pile tip  10  is provided with seven cutter teeth in total. 
     The pile tip  10  may be fabricated from individual pieces which are cut out and formed to specification before being welded together. The main body of the pile tip  10 , as well as the flight  15  and the end plate  19  may all be cut from pieces of plate stock. The main conical body and the flight may be rolled, heated and otherwise formed into the required shape before being welded together along with the end plate  19  along the welds  11 . In one embodiment, full penetration welds may be used for this purpose. The cutter teeth  16 , point shaft  17  and cutter teeth  18  may also be fabricated from steel stock and welded onto the pile tip  10 . In one embodiment, A35-grade standard milled steel may be used for these components. In a further embodiment, the pile  1  is 12.75″ in diameter and has ⅜″ walls, and the pile tip  10  may be attached to the pile  1  using the same type of weld  11  utilized in the fabrication of the pile tip  10  itself. As a cost saving measure, material for the pile  1  may be supplied by recycled gas piping. Those skilled in steel fabrication will understand that numerous alternatives are available for the fabrication of the pile tip  10  and the assembly of the pile tip  10  and the pile  1  without deviating from the principles of the invention described herein. For example, the pile tip  10  could be cast as a single unit rather than hand fabricated from separate pieces of steel stock. 
       FIG. 2  shows an assembly comprising a complete pile  1  together with a pile tip  10  installed in a soil bed. As is known in the art, pile substructure systems are commonly used in soil beds comprising a fill layer and potentially a liquid layer, beneath which lies a solid layer  20  which may be a sand or granular layer. The solid layer  20  may lie as much if not more, than 40′ or 50′ below the surface of the soil. As such, the pile  1  must pass down through many feet of looser soil components before it is able to anchor several feet into the solid layer  20 . To provide a pile  1  of sufficient length, several pieces of pipe may be joined together lengthwise as shown through the use of the pipe splices  22 , which may be full penetration welds of the type shown in  FIG. 1  by the welds  11 . In one embodiment, the pile  1  may be a concrete-filled steel pipe pile. Various numbers of spliced members may be assembled into a complete pile  1  of various lengths depending on the depth of the solid layer  20  at the installation site of the pile. After installation of the pile  1 , a pile cap  23  may be placed thereon to support a slab  24 , which may be a poured concrete lab. 
     A standard drilling rig may be used to turn the assembly of the pile  1  and the pile tip  10  into the soil bed, and ultimately the solid layer  20 . The specifics of the method of attachment of the pile  1  to the rig are shown in detail in later figures. In most if not all embodiments, there will be no need for pre-drilling the installation site for the pile  1 , soil conditions permitting. Rather, the pile  1  with the attached pile tip  10  will be set up in a standard drilling rig and turned into the previously undisturbed soil bed, while simultaneously a downward crowd pressure is applied by the rig on the pile  1 . As described in reference to  FIG. 1 , the inclusion of the helical flight  15  on the pile tip  10  helps draw the pile  1  down into the soil bed as it is turned by the drilling rig, and the cutter teeth  16  and  18  as well as the point shaft  17  help break up the soil to ease the passage of the pile tip  10  downward through the soil bed. 
     As is known in the art, tie downs to adjacent and previously installed piles or another suitable anchor may be used to prevent uplift of the drilling rig as the crowd pressure is applied. Again, depending on the requirements imposed on the job by existing soil conditions, varying levels of crowd pressure and torque may be required, including amounts up to 50 or 60 thousand pounds of crowd and 212 thousand foot pounds of torque, which levels are within the capacities of standard, commercially available drilling rigs. 
     The exemplary embodiment of a pile  1  equipped with a pile tip  10  described herein performs exceedingly well when being installed in soils with a high clay content, including those with hard clays. The screw pile or TORQUE DOWN pile, TORQUE DOWN is a trademark of Substructure Support Inc. of Oakland, Calif., may also be installed in sandy soils, though possibly with more difficulty, particularly with soils containing very fine or light sands. However, the embodiment of the present torque down pile system may still be installed with considerably less difficulty when compared to known methods of installing driven piles in such sandy soil conditions. Furthermore, the present screw pile system may be installed in conditions, such as in fine sandy soils such as those with blow counts above approximately 50 and up to between approximately 60 and 70, in which driven piles may be installed only with extreme difficulty if they may be installed at all. 
     As further described in reference to  FIG. 1 , the helical flight  15  may be provided as part of the pile tip  10  having a pitch of three inches. This pitch could be varied depending on expected soil conditions; for example it could be lessened slightly to 2¾″ if slightly harder soils are expected. Given that lessening the pitch of the flight decreases the speed at which the pile tip  10  turns into the soil while allowing harder soil conditions to be penetrated, and increasing the pitch of the flight has the opposite effect in both cases, it is desirable to provide an embodiment of flight  15  having a pitch which minimizes the disturbance to the soil surrounding the pile  1  as the pile  1  is sunk into the soil bed. As discussed above, prior art methods of pile placement, whether through driving or drilling, significantly disturb the soil surrounding the pile  1 . However, the present screw pile may be placed close to pre-existing structures without the concern that heaving, settling or seismic disturbance will damage the structure. Furthermore, in contrast to prior art systems, with the embodiment of the present invention described herein while a volume of soil equal to the volume of the pile and tip is displaced as the pile is sunk, the remainder of the soil remains either compacted or undisturbed. The compacted nature of the soil provides excellent stability when a pile  1  and pile tip  10  assembly are installed in a soil bed as shown in  FIG. 2 . 
     The improved stability provides much better support for the pile itself, leading to increased load tolerances for piles installed in this manner, and the ability to use smaller diameter piles to support a load requirement. As is known in the art, installed piles may be tested with a jack tester to verify their integrity. TORQUE DOWN piles 12.75″ in diameter and having ⅜″ thick walls as well as poured concrete interiors placed in representative soil conditions have been tested in this manner and found to be capable of supporting approximately one million pounds; far more than is possible with a driven or drilled pile of a similar diameter. Accordingly, the load which these TORQUE DOWN piles is capable of supporting exceeds the mandated structural tolerances of the pile itself. 
     In addition to supporting increased loads over prior art piles, the screw pile according to the embodiment of the present invention described herein can be installed much faster than prior art piles. While speed is as always dependent on the soil conditions it is known in the art that with conventional driven piles, the best that can be expected in favorable soil conditions is to drive approximately two piles between forty and sixty foot in length each per hour. In contrast, between approximately three and four of the present screw piles of the same length can be turned into a similar soil bed in the same amount of time. As such, a job with a defined number of piles can be finished more quickly with the same size crew as compared to prior art pile systems. This provides a cost savings to the foundation contractor, which savings will of course be multiplied as the size of a job increases. 
       FIGS. 3A ,  3 B and  3 C show specific detailed views taken along the lines  3 A,  3 B, and  3 C shown  FIG. 2 . In  FIG. 3A , a pile cap  23  is shown attached to the top of a pile  1  in a manner known in the art. Reinforcing steel  30  may also be provided.  FIG. 3B  shows a cross-section of a concrete filled pile  1  having the dimensions specified.  FIG. 3C  shows a individual sections of material joined by pipe splices  22  to form a unitary pile  1  of an appropriate length for a specific job. 
       FIGS. 4 and 5  show alternative embodiments of a conical pile tip  40  comprised of a substantially conically shaped body sharing a centerline with the pile  41  to which it is attached, as well as a helical flight  45  attached to the outside surface of the pile tip  40 , and cutter teeth  46  extending out radially from the centerline of the pile tip  40 . In the embodiment shown, the cutter teeth  46  are provided disposed in a spiral pattern on the outside surface of the pile tip  40  and spaced vertically apart from one another in one inch intervals. An end plate  49  is provided as a bottom surface to the conical body of the pile tip  40 . Welds  42  secure the end plate  49  and the pile  41  to the conical body. Triangular cutter teeth  48  are provided extending out axially from the end plate  49  of the pile tip  40 , which pile tip  40  is not provided with a point shaft in the embodiment shown in contrast with the pile tip  10  of  FIG. 1 . In the embodiment illustrated in  FIG. 4 , the endplate  49  has a diameter of 8 inches and the helical flight has a end to end width of 15 inches. Also, the height of the conically shaped body, from the pile  41  to the endplate  49 , is 18 inches and the diameter of the pile  41  is 12.75 inches. The embodiments of pile tips illustrated in  FIGS. 1 ,  2 ,  4 A,  5 ,  7 , and  8  can have similar dimensions. 
     In an alternative embodiment, a bifurcated point shaft may be provided as a component of the pile tip  40  having two prongs, and in a further alternative embodiment these prongs may be twisted in a helix to better serve to break up soil to allow the pile tip  40  to more easily be turned into a soil bed. In another embodiment, the pile tip  40  may be provided with hardened or carbide tipped cutter teeth  46  or  48  to better stand up to harder soil conditions; the edge of the flight  45  may also be hard surfaced for the same reason. In yet another alternative embodiment, additional flights  45  could be added on the outside surface of the pile tip  40 . In yet another alternative embodiment, the pile tip  40  may be provided with an extended shaft thinner in diameter than the end plate  49  and extending out axially from the end plate  49  in place of a point shaft. This extended shaft may include its own helical flight or flights separate from the flight  45  provided on the outside surface of the pile tip  40 .  FIG. 4A  illustrates the extended shaft with its own helical flight. 
       FIG. 6  show various embodiments of cutter teeth for use with a conical pile tip. Namely, a point shaft  62  and cutter tooth  63  are shown which may be provided extending out axially from the end plate of a pile tip  40 . A cutter tooth  63  is also shown which may be provided extending out radially from the centerline of a pile tip. 
       FIG. 7  shows an end bearing surface area detail of another embodiment of a simplified pile tip  70  assembled and attached to a pile  71  along welds  72 . An end plate  79  is also provided attached to the remainder of the pile tip  70  using welds  72 . The force vectors shown in  FIG. 7  reflect the forces a pile tip  70  exerts on the surrounding soil bed as it is driven into the soil by the crowd pressure applied by a drilling rig connected to the distal end of the pile  71  (not shown). Likewise, the surrounding soil bed exerts reaction forces on the pile tip  70  in response to the force vectors shown. These forces, while significant, are not of as great a magnitude as those encountered when placing driven and drilled pile systems. As such, the disturbance to the soil surrounding the pile  71  is minimized as the pile  71  is sunk into the soil bed, which allows the surrounding soil to be packed tighter and therefore provide a more solid support for the pile  71 , leading to greater ultimate load capacities.  FIG. 8  shows another end bearing surface area detail of a further embodiment of a pile tip  80  assembled and attached to a pile  81  along welds  82 . An end plate  89  is also provided attached to the remainder of the pile tip  80  using a welds  82 . 
       FIGS. 9A-9B  show embodiments of the distal end of the pile  1  of  FIG. 1 , wherein the pile  1  is provided with a series of driver pin holes  90 . These driver pin holes are provided so that the pile  1  may be secured to the reusable driver tool  100  shown in  FIG. 10  which may be used to install a screw pile according to one embodiment of the present invention. The driver tool  100  may be secured to a standard drilling rig head  110  using an adaptor  119 . The adaptor  119  consists of one or more adaptor brackets  120  provided with holes  121  which match corresponding holes on the driver tool  100  so that the adaptor brackets  120  may be attached thereto, an adaptor plate  130  which attaches to a standard drilling rig head  110 , and an adaptor pivot  125  connecting the adaptor brackets  120  and the adaptor plate  130 . With one end of the approximately tubular driver tool  100  connected to the adaptor  119  which allows the driver tool  100  to pivot with respect to the drilling rig head  110 , the opposite end is provided with a series of holes  190 . These holes  190  match the corresponding holes  90  in the pile  1  so that a pile  1  may be slid over the end of the driver tool  100  and held there with a series of pins passed through the holes  190  and their corresponding holes  90 . 
     The driver tool  100  allows for a pile  1  to be quickly set up for use with a drilling rig head  110 . A crew need only raise the driver tool  100  to a substantially horizontal position using a cable  102  connected to the attachment point  101  of the driver tool  100 . The opposite end of the cable  102  may be secured at an overhead crane or winch for this purpose. Once the driver tool  100  is in a horizontal position, a pile  1  may be raised, and maneuvered over the end of the driver tool  100  before being secured there by the series of through-pins. A forklift or other piece of equipment may be used to raise the pile  1 . In one embodiment, the pins passed through the holes  90  and  190  to secure the pile  1  to the driver tool  100  are themselves held in place in either by gravity or friction as the pile  1  is turned by the driver tool  100 . 
     In an alternative embodiment, the rig head  110  shown in  FIG. 10  may be replaced with a hydraulic chuck and the adaptor  119  may be dispensed with, so that the hydraulic chuck of the drill rig grasps the pile  1  directly, a portion of which pile passes upwards through an opening in the chuck as the pile is being turned into the soil bed. Although in this embodiment an operator would not be able to easily set up a pile in the horizontal position, allowing for excess lengths of pile to pass through the chuck permits much longer lengths of pile to be set up and installed. Some currently available drill rigs only allow the rig head a certain amount of vertical travel, so that it would be impractical to turn a single pile longer than approximately 65′ into a soil by using the adaptor  119 . With a hydraulic chuck allowing for an additional length of pile to pass upwards and through the rig head. Therefore with such a chuck installed, one could turn a certain length of the pile into the soil bed, loosen the chuck and run it back up the pile to repeat the operation as necessary until the oversized pile was completely turned into the soil. 
     In yet another alternative embodiment, a torque gauge can be applied to a pile during installation to determine the load rating of a particular pile in a manner roughly analogous to testing the depth of insertion of a driven pile for a specific force blow of the driver. The vertical travel of the pile is compared to the require torque for inducing the travel to estimate the solidity of the pile&#39;s engagement with the underlying soil bed and therefore its estimated load rating.