Abstract:
A method and apparatus for installing remedial piers in which substantially vertical piers are located in close proximity to the wall and footing of an existing structure and are drilled to a substantial depth to penetrate a rock stratum or debris-laden soil. The piers support the structure upon eccentric brackets to transfer the structural load from the footing to the piles. Installation of the piers is followed by a continuous lift of the structure via hydraulic manifold.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the prior filed, provisional application Ser. No. 61/149,344, filed Feb. 3, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and associated apparatus for lifting, stabilizing and supporting a pre-existing building structure, and more particularly, a method for using a series of brackets to attach a building structure to piers drilled vertically into the ground proximate the building structure, and lifting the brackets substantially concurrently to raise the building structure relative to the piers. 
     2. Description of the Related Art 
     Methods for lifting pre-existing building structures upon piers driven into the ground around a portion of the structure typically utilize hydraulic rams that drive steel pier pipes into the ground until either sufficient ground resistance is achieved or the lower end of the pier strikes a suitable load-bearing rock stratum. Because hydraulic rams require relatively little horizontal space, a ram assembly may be positioned relatively close to a structure. Piers may thereby be installed in relative close proximity to the structure foundation, which is preferred in most cases. Helical and threaded piers are drilled into the ground using a drill rig assembly, rather than via hydraulic ram, and may offer advantages in certain substrates. Because of the dimensions of a typical drill rig assembly, however, which typically includes a base, stand and drill head, a vertically drilled pier cannot typically be installed as close horizontally to a building structure as a hydraulically driven vertical pier. Typical solutions in the prior art for installing drilled piers closer to a structure include notching the structure footing or drilling the pier into the ground as an angle so that the lower portion of the pier may lie in closer proximity to the footing. Each such solution presents disadvantages in that the first may compromise the structural integrity of the footing, as well as increase installation labor, and the second solution yields a pier unable to bear the same load as a vertically oriented pier. 
     What is needed is a method and apparatus that allows use of drilled piers in close proximity to a building structure so that piers may be drilled a substantial distance into a rock stratum while maintaining a substantially vertical disposition. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention comprise means for stabilizing and lifting a building structure using continuous lift methodologies in combination with hollow, threaded bar piers installed proximate to foundations of preexisting structures. In particular, certain embodiments utilize relatively small diameter, threaded, micro piles drilled into the ground using a rotary drill head. Other embodiments utilize larger diameter, unthreaded, pier pipes installed via hydraulic ram. A micro pile typically comprises a hollow, threaded, steel bar that carries concrete slurry, also referred to as grout, through its central cavity to flow from one or more apertures proximate a drill bit. The micro pile and drill bit are driven by a rotary drill head attached to the end of the micro pile distal from the drill bit. The grout is under pressure and as the micro pile is drilled into the ground, grout flowing from the apertures fills the space between the walls of the shaft created by the drill bit and the micro pile, which is of smaller diameter than the drill bit. 
     The micro pile is attached to the structure to be stabilized or lifted by an offset or eccentric pier bracket. The eccentric pier bracket allows for additional space between the micro pile and the structure, thereby providing sufficient room for a drill head and associated support apparatus. 
     Other advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example several embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of micro pile or micro pier drilled into ground proximate a building structure footing with the pier attached to the footing using an eccentric pier bracket. 
         FIG. 2  is a side view of a pipe pier hydraulically driven into ground proximate a building structure footing with the pier attached to the footing using an eccentric pier bracket. 
         FIG. 3  is a side view of a pipe pier hydraulically driven into ground proximate a building structure footing with the pier attached to the footing using an eccentric pier bracket of increased width relative to the brackets shown in  FIGS. 1 and 2 . 
         FIG. 4  is a side view of an eccentric pier bracket. 
         FIG. 5  is a side view of an alternative embodiment of an eccentric pier bracket. 
         FIG. 6  is a back view of an eccentric pier bracket. 
         FIG. 7  is a side view of a drilling rig mounted to an eccentric pier bracket. 
     
    
    
     DETAILED DESCRIPTION 
     As required, a detailed embodiment of the present invention is disclosed herein; however, it is to be understood that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
     Referring now to the drawings.  FIGS. 1 through 7  illustrate several embodiments of a pier driving system, and elements thereof, for stabilizing and lifting preexisting structures built upon foundations such as poured concrete or masonry footings. 
       FIG. 1  is a side view of a micro pile pier  100  including a hollow micro pile shaft  105  drilled into ground  110  proximate a building structure footing  115  with the pier  100  attached to the footing  115  using an eccentric pier bracket  120 . As illustrated, soil has been excavated from an area proximate the footing  115 , and the desired location of a pier  100  and bracket  120 , to form a hole  125  for positioning the pier assembly. (In the figures, footings, slabs, walls, grout columns, and soil and rock strata are shown in cross section). In general, holes  125  are excavated along the perimeter, or along the side, of a portion of a structure to be lifted. An eccentric bracket  120  is shown secured to the footing  115  so that the horizontal bearing plate  130  underlies the footing  115 . Fasteners  135  such as screws or bolts adapted for secure fastening to concrete, are driven into the foundation or footing surface adjoining the vertical plate  140  through one or more holes  145  (see  FIG. 4 ) provided in the vertical plate  140  in order to attach the bracket  120  securely to the footing  115 . 
     The vertical plate  140  and horizontal bearing plate  130  form a right angle bracket  150 . The horizontal bearing plate  130  is supported by a pair of triangular support plates  155  that are attached to, or integral with, rectangular side plates  160 . The left side plate  160   a  and left support plate  155   a  of a bracket are shown in several of the figures including  FIGS. 1 and 4 . The back view of a bracket  120  provided in  FIG. 6 , shows both left  160   a  and right  160   b  side plates. 
     A guide or lift rod support collar  165  is welded or otherwise attached to the outside surface of each side plate  160  in vertical orientation. An adjustable, threaded lift rod  170  passes through each collar  165  and terminates at the lower end with a threaded nut  175 . A pier cap  180  spans both lift rods  170  and crosses over the space between and over the side plates  160 . A nut  185  at the upper end of each lift rod  170  secures the pier cap  180 . The channel or space between the side panels  160  is sized to accommodate a pier sleeve  190  for holding either a pier pipe  195  or micro pier shaft  105 . After the sleeve  190  is placed within the channel, it is retained by installing the upper  200   a , middle  200   b  and lower  200   c  face plates. 
     With particular reference to  FIGS. 4 through 6 , an eccentric pier bracket  120  differs from brackets in the prior art in that the axis  205  of the pier is moved further from the building structure to allow room for machinery used to drive the pier  100  into the ground. In the embodiments shown herein, this is accomplished by increasing the width of the side plates  160  (side plate width runs left to right as shown in  FIGS. 1 through 5 ) so that the pier axis  205 , as well as the threaded lift or guide rods  170  and collars  165 , are moved a further distance from the right angle bracket  150 . 
       FIG. 1  illustrates a micro pile  105  drilled into the ground  110  proximate the footing  115  of an existing structure. Because the micro pile  105  is fitted with a sacrificial drill bit  210 , it may be drilled not only to reach a suitable load bearing rock stratum  215  but may also be drilled into the rock to create and fit within a pocket  220 . As the drill bit  210  moves downward, grout  225  is forced through apertures (not shown) proximate the drill bit  210  to fill the void  230  surrounding the micro pile  105 . When hardened, the grout  225  forms a load-bearing column  235 . Because of the irregular outer surface of the grout column  235 , the pier  100  provides strong frictional and mechanical resistance to vertical movement once the grout  225  sets, even if a pier  100  is installed without reaching rock  215 . 
     Micro piles  105  are drilled into the ground  110  using a drill rig  240  (see  FIG. 7 ) typically comprising a base  245  that attaches to the pier bracket  120 , and a vertically disposed stand  250  that projects upward from the base  245 . A rotary drill head  255  is mounted to and slides along the stand  250 . Threaded, hollow micro pile  105  is coupled to the drill rotor  260 . The drill head  255  moves downward along the stand  250  as the pile  105  is drilled into the ground  110 . Typically, the drill head  255  is hydraulically powered. As shown, because the pier bracket  120  is eccentric, sufficient space between the pier axis  205  and the building structure (wall  265 ) is provided to accommodate the drill rig  240 . 
       FIG. 2  is a side view of a pipe pier  100 A hydraulically driven into ground  110  proximate a building structure footing  115  with the pier  100 A attached to the footing using an eccentric bracket  120 . The eccentric bracket  120  allows for installation of the pier  100 A by providing sufficient additional space from the pier axis  205 A to the structure wall  265  (including siding  270 ) to accommodate a hydraulic ram (not shown). 
       FIG. 3  is a side view of a pipe pier  100 B hydraulically driven into ground  110  proximate a building structure footing  115  with the pier  100 B attached to the footing  115  using an eccentric bracket  120 A (see also  FIG. 5 ) of increased width (offset) relative to the brackets  120  shown in  FIGS. 1 and 2 . By way of example, embodiments of the bracket  120  shown in  FIGS. 1 and 2  may provide a 4½ inch pier offset (the distance between the vertical plate  140  and the pier axis  205 ) while the bracket  120 A shown in  FIG. 3  may provide a 6½ pier offset. 
     Further embodiments of an eccentric pier bracket may include a vertical plate and a horizontal plate abutting one another at a substantially right angle therebetween to form a right angle bracket. The horizontal plate is supported by one or more support plates positioned below the horizontal plate to receive force applied downward to the horizontal plate. A left side plate and an opposing right side plate are spaced apart and positioned generally parallel to one another. Each side plate is attached to the rearward face of the vertical plate and extends below the vertical plate and the horizontal plate to attach to the support plate. Downward and lateral forces applied to the bracket are thereby substantially transferred to said side plates. The side plates each have a longitudinal axis traversing the center portion of each side plate. These longitudinal axes have generally vertical dispositions when the eccentric bracket is operatively positioned in a pier assembly attached to a building structure. A cylindrical support collar has a longitudinal axis and is vertically disposed between the side plates and rearward of the vertical plate so that the support collar longitudinal axis is rearward of the side plate longitudinal axes. 
     Another embodiment of a pier bracket system for lifting a building structure such as a foundation or footing and the like may include a horizontal plate having a top surface and a bottom surface, a front edge and a rear edge, the horizontal plate being used for insertion at its front edge under a building structure. A vertical plate is mounted at its lower edge to a rearward portion of the top surface of the horizontal plate and extends substantially across and over the rear edge. A left side plate and a right side plate, each vertically oriented, are spaced apart and joined by attachment of the front edge of each side plate to the rear surface of the vertical plate, which spans the front edges of the side plates. A left gusset and a right gusset support the horizontal plate. The left gusset has a horizontal top edge attached along a portion of the bottom surface of the horizontal plate proximate the left margin of the horizontal plate. The left gusset has a rearward facing vertical rear edge attached to a lower portion of the front edge of the left side plate. The right gusset has a horizontal top edge attached along a portion of the bottom surface of the horizontal plate proximate the right margin of the horizontal plate. The right gusset has a rearward facing vertical rear edge attached to a lower portion of the front edge of the right side plate. The side plates are spaced apart horizontally by a distance sufficient to accommodate a pier support sleeve therebetween. The side plates each have a vertically oriented longitudinal axis and the pier support sleeve has a vertically oriented longitudinal axis. The pier support sleeve is positioned between the side plates so that the longitudinal axis of the pier support sleeve is positioned rearward of the longitudinal axes of the side plates. In this manner, the side plates are forwardly eccentric of the pier sleeve and the distance between the vertical bracket and the pier support sleeve is increased sufficiently to allow accommodation of a drill head above the pier support sleeve. 
     It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable equivalents thereof.