Patent Publication Number: US-2022220687-A1

Title: Pile and System for Repairing a Foundation

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Application No. 63/136,479 filed on Jan. 12, 2021, the disclosure of which is incorporated herein by reference for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to foundation repair and, more particularly, to a pile system for leveling and/or raising a foundation. 
     BACKGROUND OF THE INVENTION 
     Various techniques are available today to repair a sinking, sagging, or broken concrete foundation. Foundation (slab) damage is caused by unstable ground beneath and/or around the foundation. This can be a result of soil conditions, tree roots invading the area, plumbing leaks, poor drainage, etc. To repair the damage, one technique is for pilings or other supports to be driven into the ground below the foundation and shimmed to level the slab. 
     One type of support can comprise concrete pile segment blocks and, more specifically, generally cylindrical concrete blocks or cylinders. In a well-known method of slab repair and leveling, the cylindrical piles are driven into the ground below the slab generally to the point of refusal. The plurality of cylindrical piles can be strung on a cable which extends from a starter pile which generally has a smaller cross-sectional area than the rest of the cylindrical pile in an attempt to facilitate driving of the piles into the ground to achieve a greater depth. The cable technique which is frequently used involves connecting a cable to the starter pile and threading it through the individual pile members which have a central bore therethrough. However, not all leveling systems employ the cable technique and in many cases the cylindrical piles are simply sequentially stacked on one another and driven into the ground. 
     One commonly used prior art pile segment comprises a generally cylindrical concrete block having nominal dimensions of 6 inches in diameter and 12 inches in vertical height and a smooth outer vertical surface. In actuality, the prior art piles have a diameter of around 6 inches and a nominal vertical height of 12 inches. Conventional thinking by workers using these prior art cylindrical pile segments to build a support under a slab is that an important factor is skin friction, i.e., the friction between the outer vertically extending surface of the cylindrical pile segment and the surrounding earth as the pile is driven downwardly. Thus, the belief is that if skin friction can be reduced, the piles can be driven deeper. To this end, the prior art has examples of generally cylindrical piles of the type described above, but which have various outside vertical surface configurations/formations to facilitate the driving process, all of which are aimed at reducing skin friction. However, skin friction is not the only consideration. 
     It is also widely believed that once the support comprising the pile segments has been driven to the point of refusal and the necessary shimming done to bring the slab to the desired elevation, there must be sufficient holding/gripping friction between the pile segments and the surrounding earth to maintain the leveled structure at that elevation. In this regard, this holding friction is believed to come about once the driving process is finished and the surrounding soil collapses radially inwardly against the outer vertical surface of the pile segments. Thus, while skin friction is an important consideration in the driving process, as to depth, holding friction is likewise important in terms of maintaining the support comprised of the individual pile segments from moving upwardly or downwardly allowing the slab to again heave or sink. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention relates to a system for repairing a foundation. 
     In another aspect, the present invention relates to a pile segment for use in a foundation repair system. 
     In another aspect, the present invention relates to a pile segment which reduces skin friction during driving while retaining mass sufficient to sustain the pressures during driving. 
     In another aspect, the present invention relates to a cylindrical pile segment which has increased vertical surface area when compared to a cylindrical, smooth pile segment to thereby increase the holding/gripping friction. 
     These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a pile segment according to one aspect of the present invention. 
         FIG. 2  is a side elevational view of the pile segment shown in  FIG. 1 . 
         FIG. 3  is a top plan view of the pile segment shown in  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The terms “pile segment” and “pile” refer to a single concrete body which can be used to form a stack of said segments to form a support or piling. Referring to the figures, the pile segment of the present invention shown generally as  10  and referred to sometimes herein as a pillar pile comprises a generally cylindrical concrete body  12  having a first, top planar end surface  14 , an axially spaced corresponding second, bottom end surface (not shown) and has a generally vertical, radially outwardly facing annularly extending surface between first end surface  14  and the second end surface. In general and as can be seen from the drawings, the body  12  is fluted much in the style of a Corinthian column, and in this regard has vertically extending, circumferentially spaced cogs  15  defining vertically extending and circumferentially spaced alternating crests  16  and troughs  18 , the radially outwardly facing surfaces  20  of the crests  16  lying in the outer surface of a first imaginary cylinder circumscribing the crest surfaces  20 . In one preferred embodiment, the cogs  15  are equally, circumferentially spaced. 
     The troughs  18  between the crests  16  have radiused inner surfaces  22 , the radially innermost portion of surfaces  22  lying in the outer surface of a second imaginary cylinder tangential to such innermost portion of surface  22 . Thus, the first and second imaginary cylinders are concentric, with the first imaginary cylinder having a greater diameter than the second imaginary cylinder. 
     As best seen in  FIG. 3  crest surfaces  16  and trough surfaces  22  are connected by flanks  24  and  26 . 
     As can be seen by reference to  FIG. 3 , the body  12  of the pillar pile  10  of the present invention has the following dimensional parameters, all measured in inches:
         D—the diameter measured from a first crest surface to another crest surface 180° displaced from the first crest surface   W—the circumferential length of the arc forming the crest surface   R—the radius of the radiused innermost surface portion of the trough   A—the linear distance between adjacent crest surfaces   B—the distance between the crest surface and the innermost portion of the radiused surface forming a portion of the trough   H—the height of body  12         

     With respect to the above parameters, D can range from about 5.0 to about 8.0 inches, particularly from about 5.5 to about 7.0 inches. W can range from about 0.25 to about 1.0 inches, particularly from about 0.25 to about 0.7 inches. R can range from about 0.1 to about 0.25 inches. A can range from about 0.25 to about 1.0 inches, particularly from about 0.25 to about 0.75 inches. B can range from about 0.063 to about 0.25 inches, particularly from about 0.1 to about 0.035 inches. H can range from about 8.0 to about 14.0 inches, particularly from about 9.0 to about 13.0 inches. 
     The weight of a pillar pile  10  according to the present invention is at least about 24.0 lbs., more generally about 26 lbs. or greater, e.g., up to 30 lbs. 
     The total vertical surface area of a prior art nominal 6 inch by 12 inch pile segment is approximately 217 in 2 . This is to be contrasted with a pillar pile  10  according to one embodiment of the present invention wherein within the numerical limits of the parameters set out about above, the total vertical surface area is from about 250 to about 350 in 2 . Thus, the total vertical surface area of one embodiment of the pillar pile of the present invention is about 27% greater than a prior art pile segment having a smooth outer vertical surface. 
     This increased vertical surface area increases holding friction between the pillar pile  10  of the present invention and the surrounding earth once the pillar pile stack has been driven to the desired depth. Furthermore, because of the unique design of the pillar pile  10  of the present invention, wherein the vertical surface is comprised of alternating troughs and crests, the skin friction is reduced during driving. 
     While the invention has been described with respect to the crest surfaces and trough surfaces being radiused, it is to be understood that other shapes can be used. For example, the troughs could be partially hexagonal, square, triangular or other such geometric shapes as viewed in cross-section. Further, the crest surfaces could be straight when viewed in cross-section. 
     Pillar pile  10  of the present invention provides a structure which retains the mass sufficient to bear the load from the pressure/force applied during installation, while at the same time minimizing skin friction. In this regard, the portion of the total vertical surface area which contributes to skin friction is the cumulative area of the crest surfaces which in one embodiment of the present invention can range from 30% to 70% of the total vertical surface area. 
     U.S. Pat. No. 9,022,694 (&#39;694 Patent) is incorporated herein by reference for all purposes. With respect to the system disclosed in the &#39;694 Patent, the system and method disclosed therein can incorporate the pillar piles of the present invention. 
     Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.