Abstract:
Pilings are installed for leveling a foundation. A first segment is driven into the ground. Then two support rods of varying length are positioned and grouted into a passage running through the segment. The first support rod is one-half of the height of the piling segment, while the second is one and one-half times the height of the piling segment. An additional piling segment is driven on top of the first segment. Support rods which are twice the height of a single segment are positioned and grouted into the passage. This process is repeated until the assembly is the required depth.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to a foundation and repair method and apparatus utilizing precast cylinder pilings with metal support rods extending axially through and bonded to the pilings to create a column which is sequentially driven into the earth to form an underground pier. 
     2. Description of the Related Art 
     One of the older methods for repairing foundations of buildings having slab-on-ground foundations uses drilled underground piers. Holes are drilled approximately eight to twelve feet in depth and filled with concrete. After the concrete has dried, jacks are placed on top of the pier and the foundation is brought to a level position. The jack is replaced by blocks, shims, and grout. A more recent and less expensive method is the use of driven precast solid concrete cylindrical pile sections, which are approximately one foot in height and six inches in diameter. These sections are driven into the earth one on top of the other to form a column or stack of concrete cylinders. The depth to which the bottom of the pier is driven into the earth depends upon the type of soil and zone of the seasonal moisture change. A cylinder having a larger diameter, or a pile cap, is a placed on top of the previously driven sections. Jacks are placed on top of the pile cap and the foundation is lifted. 
     The precast pile method relies upon the skin friction with the soil for its strength. It has the advantage of being faster since the concrete does not have to cure and precasting allows better control of concrete strength. A major disadvantage is that the one-foot cylindrical sections may shift and become misaligned during or after the driving operation. Different methods have been proposed for maintaining alignment between sections. However, most do not ensure that there is a least one support rod running completely through an individual piling section. 
     SUMMARY OF THE INVENTION 
     The precast pile in this invention is made up of piling segments that are driven into the ground one on top of the other. Each segment has a passageway running axially through each segment that aligns with the passageway of the other piling segment. A short support rod that is one-half the height of the first segment is placed in the passageway of the deepest piling segment. An intermediate support rod that is one and a half times the height of the first segment is placed in the passageway of the deepest segment next to the short support rod. A long support rod is positioned in the first and second passageways so that the long rod abuts with the top of the short support rod. The long support is twice the height of a single segment, so the long rod protrudes above the second piling segment a distance of about one-half the height of the second piling segment. 
     The method for installing the piling described above is made up of the steps as follows. A first piling segment is driven into the earth. The segment has a passage running axially through it in which a short support rod and an intermediate support rod are placed side-by-side. A second piling segment is driven on top of the first segment. A long support rod is then placed on top of the short support rod inside the passageway. Another long rod is placed on top of the intermediate support rod inside the passageway. The passageways are pre-filled with grout to secure the support rods in the piling segments. Additional pilings are driven into the earth, and additional long rods are placed and grouted into the passage on top of long rods already in place until the pilings are the desired depth. The short and the intermediate rods cause there to be at least one solid rod traversing each piling without a joint at an intersection of piling segments. This interfaces the rods at depths that are not the same as the intersections of the piling segments and helps to provide lateral support and prevent misalignment problems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 comprises a cross-sectional view of a first piling segment driven into the ground in accordance with this invention. 
     FIG. 2 comprises a cross-sectional view of a second piling segment driven into the ground in accordance with this invention. 
     FIG. 3 comprises a cross-sectional view of a third piling segment driven into the ground in accordance with this invention. 
     FIG. 4 comprises a cross-sectional view of a fourth piling segment driven into the ground in accordance with this invention. 
     FIG. 5 comprises a cross-sectional view of a fifth piling segment driven into the ground in accordance with this invention. 
     FIG. 6 comprises a cross-sectional view of a sixth piling segment driven into the ground in accordance with this invention. 
     FIG. 7 comprises a cross-sectional view of a top piling segment driven into the ground in accordance with this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-6 show the progressive steps of the preferred embodiment of the method for installing a pier assembly for leveling a foundation. Referring to FIG. 1, a first piling segment  11  is driven into the ground  13 . Piling segment  11  has a substantially flat bottom edge  15  and a substantially flat top edge  17 . Piling segment  11  is normally a precast concrete segment having a cylindrical shape. A passage  19  runs axially through piling segment  11  from bottom edge  15  to top edge  17 . 
     After first segment  11  is driven, a grouting material  22  is poured into passage  19 . A short support rod  21  is placed in grout  22  in passage  19  until the bottom of short support rod  21  is in contact with ground  13 . Short support rod  21  is shorter in height than piling segment  11 . In the preferred embodiment, short support rod  21  is approximately one-half the height of piling segment  11 . Normally short support rod  21  is an iron rod, which is commonly referred to as “rebar.” 
     An intermediate support rod  23  is placed in grout  22  in passage  19  along side of short support rod  21  until intermediate support rod is in contact with ground  13 . Intermediate support rod  23  is taller than piling segment  11  and short than two piling segments  11  stacked one on top of the other. Intermediate support rod  23  is substantially the same material as short support rod  21 . In the preferred embodiment, intermediate support rod is approximately one and one-half times the height of piling segment  11 . A grouting material  22  is preferably filled to the top of passage  19 , as shown, although it could be filled only to a point near the upper end of short support rod  21 . Grout material  22  may be any type of cement of adhesive for bonding steel to concrete. Once cured, grout  22  secures support rods  21  and  23  into passage  19 . 
     Referring to FIG. 2, a second piling segment  27  is driven into ground  13  on top of piling segment  11 . Normally segment  27  is driven in before grout  22  cures in passage  19 . Segment  27  is a precast concrete cylinder having substantially the same shape and dimensions as piling segment  11 . Passage  29  aligns with passage  19  when segment  27  is placed on top of segment  11 . Intermediate support rod  23  extends from the top of piling segment  11  into passage  29 , for about one-half of the height of piling segment  27 . Intermediate rod  23  provides a means for maintaining the alignment of passages  19  and  29  while piling  27  is driven into ground  13 . Grout  22  is placed in passage  29 . A long support rod  31  is placed in grout  22  in passage  29 , so that the bottom end of long rod  31  abuts with the top end of short rod  21 , forming a joint  33 . Any grout  22  in passage  19  above short support rod  21  must still be viscous to enable long support rod  31  to be installed. In the preferred embodiment, long rod  31  is substantially the same material as rods  21  and  23 , and is approximately twice the height of piling segment  11 . 
     Grouting material  22  also fills any remaining area of passage  19  that is not taken up by rods  21 ,  23 , and  31 . Once cured, grout  22  secures rod  31  to piling segment  11 . Grout  22  also fills the area of passage  29  around rods  23  and  31  at least up to a level below the top end of intermediate rod  23 . Grout  22  could be filled to the top of passage  29 , as shown. Rods  23  and  31  prevent misalignment between piling segments  11  and  27  when other piling segments are driven into the ground on top of segments  11  and  27 , by stopping any horizontal slippage at the level in which segments  11  and  27  are in contact. 
     Referring to FIG. 3, a third piling segment  37  is driven into ground  13  on top of piling segment  27 . Segment  37  is a precast concrete cylinder having substantially the same shape and dimensions as piling segments  11  and  27 . Passage  39  aligns with passages  19  and  29  when segment  37  is placed on top of segment  27 . Grout  22  is placed in passage  39 . Long support rod  31  extends from the top of piling segment  27  into passage  39 . In the preferred embodiment long support rod  31  extends into passage  39  for about one-half of the height of segment  37 . Long support rod  31  provides a means for maintaining the alignment of passages  19 ,  29 , and  39  while piling  37  is driven into ground  13 . A long support rod  41  is placed into passage  39 , so that the bottom end of long rod  41  is in contact with the top end of intermediate rod  23 . In the preferred embodiment, long rod  41  is substantially the same material as rods  21 ,  23 , and  31 . In the preferred embodiment, long rod  41 , like rod  31 , is approximately twice the height of piling segment  11  (or  27 , or  37 ). 
     Grouting material  22  fills the remaining area of passage  29  that is not taken up by rods  23 ,  31  and  41 . Grout  22  secures rod  41  to piling segment  27  and also fills the area of passage  39  around rods  31  and  41  at least up to a level below the top end of long rod  31 . 
     Rods  31  and  41  prevent misalignment between piling segments  27  and  37  when other piling segments are driven into the ground on top of segments  27  and  37 , by stopping any horizontal slippage at the level in which segments  27  and  37  are in contact. Furthermore, long rod  31  runs from approximately halfway in segment  11 , through segment  27 , to approximately halfway into segment  37 , therefore providing further resistance to segments  11 ,  27 , and  37  shifting out of alignment. 
     Referring to FIG. 4, a fourth piling segment  47  is driven into ground  13  on top of piling segment  37 . Segment  47  is a precast concrete cylinder having substantially the same shape and dimensions as piling segments  11 ,  27 , and  37 . Passage  49  aligns with passages  19 ,  29 , and  39  when segment  47  is placed on top of segment  37 . Grout  22  is placed in passage  49  and any remaining part of lower passage  39 . Long support rod  41  extends from the top of piling segment  37  into passage  49 . In the preferred embodiment long support rod  41  extends into passage  49  for about one-half of the height of segment  47 . Long support rod  41  in conjunction with the previously installed support rods provides a means for maintaining the alignment of passages  19 ,  29 ,  39 , and  49  while piling  47  is driven into ground  13 . A long support rod  51  is placed into passage  49 , so that the bottom end of long rod  51  is in contact with the top end of long rod  31 . In the preferred embodiment, long rod  51  is substantially the same material as rods  21 ,  23 ,  31 , and  41 . In the preferred embodiment, long rod  51 , like rods  31  and  41 , is approximately twice the height of piling segment  11 ,  27 ,  37 , or  47 . 
     Rods  41  and  51  prevent misalignment between piling segments  37  and  47  when other piling segments are driven into the ground on top of segments  37  and  47 , by stopping any horizontal slippage at the level in which segments  37  and  47  are in contact. Furthermore, long rod  41  runs from approximately halfway in segment  27 , through segment  37 , to approximately half way into segment  47 , therefore providing further resistance to segments  27 ,  37 , and  47  shifting out of alignment. 
     Referring to FIG. 5, a fifth piling segment  57  is driven into ground  13  on top of piling segment  47 . Segment  57  is also a precast concrete cylinder having substantially the same shape and dimensions as piling segments  11 ,  27 ,  37 , and  47 . Passage  59  aligns with passages  19 ,  29 ,  39 , and  49  when segment  57  is placed on top of segment  47 . Long support rod  51  extends from the top of piling segment  47  into passage  59 . In the preferred embodiment long support rod  51  extends into passage  59  for about one-half of the height of segment  57 . Long support rod  51  in conjunction with the previously installed support rods provides a means for maintaining the alignment of passages  19 ,  29 ,  39 ,  49 , and  59  while piling  57  is driven into ground  13 . A long support rod  61  is placed into passage  59 , so that the bottom end of long rod  61  is in contact with the top end of long rod  41 . In the preferred embodiment, long rod  61  is substantially the same material as rods  21 ,  23 ,  31 ,  41 , and  51 . In the preferred embodiment, long rod  61 , like rods  31 , 41 , and  51 , is approximately twice the height of piling segment  11 ,  27 ,  37 ,  47 , or  57 . 
     Grouting material  22  fills the remaining area of passage  49  located around rods  31 ,  41 ,  51 , and  61 . Grout  22  secures rod  61  to piling segment  47  and fills any remaining area of passage  59  around rods  51  and  61  at least up to a level below the top end of long rod  51 . 
     Rods  51  and  61  prevent misalignment between piling segments  47  and  57  when other piling segments are driven into the ground on top of segments  47  and  57 , by stopping any horizontal slippage at the level in which segments  47  and  57  are in contact. Furthermore, long rod  51  runs from approximately half way in segment  37 , through segment  47 , to approximately half way into segment  57 , therefore providing further resistance to segments  37 ,  47 , and  57  shifting out of alignment. 
     Referring to FIG. 6, a sixth piling segment  67  is driven into ground  13  on top of piling segment  57 . Segment  67  is also a precast concrete cylinder having substantially the same shape and dimensions as piling segments  11 ,  27 ,  37 ,  47  and  57 . Passage  69  aligns with passages  19 ,  29 ,  39 ,  49  and  59  when segment  67  is placed on top of segment  57 . Long support rod  61  extends from the top of piling segment  57  into passage  69 . In the preferred embodiment long support rod  61  extends into passage  69  for about one-half of the height of segment  67 . Long support rod  61  in conjunction with the previously installed support rods provides a means for maintaining the alignment of passages  19 ,  29 ,  39 ,  49 ,  59 , and  69  while piling  67  is driven into ground  13 . A long support rod  71  is placed into passage  69 , so that the bottom end of long rod  71  is in contact with the top end of long rod  51 . In the preferred embodiment, long rod  71  is substantially the same material as rods  21 ,  23 ,  31 ,  41 ,  51 , and  61 . In the preferred embodiment, long rod  71 , like rods  31 ,  41 ,  51 , and  61 , is approximately twice the height of piling segment  11 ,  27 ,  37 ,  47 ,  57 , or  67 . 
     Grouting material  22  is poured into passage  69  and flows into any remaining space in passage  59 . Grout  22  fills the remaining area of passage  59  located around rods  31 ,  41 ,  51 ,  61 , and  71 . Grout  22  secures rod  71  to piling segment  57  and also fills the area of passage  69  around rods  61  and  71  up at least to a level below the top end of long rod  61 . 
     Rods  61  and  71  prevent misalignment between piling segments  57  and  67  when other piling segments are driven into the ground on top of segments  57  and  67 , by stopping any horizontal slippage at the level in which segments  57  and  67  are in contact. Furthermore, long rod  61  runs from approximately halfway in segment  47 , through segment  57 , to approximately halfway into segment  67 , therefore providing further resistance to segments  47 ,  57 , and  67  shifting out of alignment. 
     Additional piling segments are driven into ground  13  on top of the segment  11 ,  17 ,  27 ,  37 ,  47 ,  57 , and  67 , and additional long rods are added, until the piling assembly reaches the desired depth, based upon the ground conditions. When the piling assembly reaches the desired depth, then the piling assembly needs to be prepared to have a pile cap (not shown) placed above the piling assembly. Referring to FIG. 7, final long rod  76  extends up from a top piling segment  77 , which has been driven into ground  13  on top of piling segments  11 ,  17 ,  27 ,  37 ,  47 ,  57 ,  67 , and any additional segments needed to reach the desired depth. Final long rod  76  had been placed and grouted into the top piling segment passage  79  in the same manner as described above. A top rod  81  is placed into passage  79  so that the bottom end of top rod  81  is in contact with the top end of a second to final rod  82 . Top rod  81  is long enough so that it extends past the top of top piling segment  77 . Top rod  81  and final long rod  76  provide a guide for aligning and placing the pile cap (not shown) onto the pile assembly. Prior to installing rod  81 , grout  22  is poured into passage  79  to a level substantially even with the top surface of top piling segment  77 . 
     With a piling assembly made in accordance with this method, the support rods are staggered in such manner that prevents the pilings from sliding out of alignment. Each interface between two piling segments is stabilized by solid portions (no joints) of the support rods, which are grouted into the passages. A piling segment should not slide or shear across the surface of another piling segment when, in accordance with this method, there are no joints located at the same level as the piling segment interface. There is only one interface between upper and lower rods located between each segment interface. 
     Further, it will also be apparent to those skilled in the art that modifications, changes and substitutions may be made to the invention in the foregoing disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in the manner consistent with the spirit and scope of the invention herein. For example, the same results and advantages would be realized if short support rod  21  were two-thirds the height of piling segment  11  and intermediate support rod were one and two-thirds the height of piling segment  11 .