Patent Publication Number: US-6659692-B1

Title: Apparatus and method for supporting a structure with a pier and helix

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to the field of structural pier devices designed to support structural foundations and footings in order to counter the effects of settling and ground movement. 
     BACKGROUND OF THE INVENTION 
     Many structures, such as residential homes and low rise buildings, are constructed on foundations that are not in direct contact with a stable load bearing underground stratum, such as, for example, bedrock. These foundations are typically concrete slabs or a footing upon which a foundation wall rests. The footing is generally wider than the foundation wall in order to distribute the structure&#39;s weight over a greater surface area of load bearing earth. Therefore, the stability of these structures depends upon the stability of the ground underneath or supporting the foundation. With time, the stability of the underlying soil may change for many reasons, such as changes in the water table, soil compaction, ground movement, or the like. When the stability of the support ground changes, many times the foundation will move or settle. The settling of a structure&#39;s foundation can cause structural damage reducing the value of the structure or total property. 
     For instance, structural settling can cause cracks in foundation walls. Unsightly cracks can appear on the interior or exterior of building walls and floors. In addition, settling can shift the structure causing windows and doors to operate poorly. Inventors have recognized the foundation-settling problem and have developed various devices and methods to correct its effects. 
     One common device and method to correct foundation settling consists of employing hydraulic jacks in conjunction with piers to lift the foundation. Piers, also known as piles or pilings, are driven into the ground by hydraulic mechanisms until the pier reaches bedrock or until the pier&#39;s frictional resistance equals the compression weight of the structure. Once these piers are secured in a stable underground stratum or several stable underground strata, further lifting by the hydraulic jacks raises the level of the foundation. When the foundation is raised to the desired level, the piers are permanently secured to the foundation. The hydraulic jacks are then removed. This method of correcting the level of a foundation generally requires the excavation of a hole adjacent to or underneath the foundation in order to position and operate the lifting equipment. 
     Steel piers are well known and exist in many varieties. One common type of a pier is a straight steel pier that is driven down until it reaches bedrock or stable soil weight bearing layer. These straight steel piers are rammed straight down into the ground. Another style of pier known to the art is a helical pier. On the end of a long pier shaft is a large helix. This helix distributes the weight of the pier over a larger surface area of soil making it a highly desirable pier structure to use. Unlike straight piers that are driven straight through the earth, it is necessary to screw the helical piers into the earth through rotating the pier shaft. 
     The use of a screwed-in-helix with a steel shaft is very common in supporting the footings and foundations of structures. For instance, a plurality of helical piers are typically installed at structurally strategic positions along the footing or foundation of a structure. These piers are then anchored together and interconnected by setting them all within reinforced concrete. In other instances, a plurality of steel piers are installed at various angles with respect to the building. These piers are then tied together to the footing or foundation with re-enforcing bars or pin connections. These bars or pin connections are then encapsulated within concrete. 
     When the helical steel pier is installed to support a footing or foundation of an existing structure, the pier is installed at an angle with respect to the building in order to accommodate the mechanical equipment necessary to screw the helical pier into the earth. This angle causes the building to place a lateral force on the pier resulting in an eccentric loading. When the top of the pier extends above the bottom of the footing or foundation and the load is carried on the top of the pier shaft, the eccentricity of the load is unnecessarily extended and weakens the load bearing capacity of the pier. 
     A helical pier shaft is disclosed in U.S. Pat. No. 5,171,107. This patent teaches a method wherein a helical anchor is screwed down into the earth. Importantly, this patent teaches that the helical anchor extends above the footing of the building. In addition, this patent teaches that the helical anchor extends off to the side of the footing creating an eccentric loading condition. Ideally, only vertical forces will exist in the final helical pier and foundation structure. However, because the pier taught by this patent extends to the side of the footing, the foundation places a lateral force against the pier that tends to push the pier outwardly. Through this lateral force that causes an eccentric loading, the building shifts laterally over the pier until the pier no longer supports the vertical weight of the building. Consequently the pier&#39;s effectiveness is neutralized and the building subsides. It is highly desirable to design a pier that reduces the degree of this eccentric loading to prevent the lateral movement of the helical pier and footing or foundation. 
     Further, U.S. Pat. No. 5,171,107 teaches that a bracket assembly is needed to secure the helical pier to the footing. This bracket assembly requires a costly preparation of the footing. The bottom surface of building footers is typically very rough due to the manner in constructing the footer. In order to attach the bracket for the helical pier to the bottom surface of the footer, it is necessary to prepare the footer. Otherwise, if the pier bracket is placed against the uneven surface, stress fractures will occur in the footing damaging the structure and retarding the ability of the helical pier to support the building. 
     Preparing the footer is a labor intensive process that requires the use of concrete chippers or saws. These mechanical devices are used by laborers to smooth the bottom surface of the footer. It is therefore highly desirable to develop a pier system that can eliminate this costly and time consuming process. In addition, the bracket assembly is a complicated piece of equipment that greatly adds to the cost of the helical pier. 
     There are other foundation support technologies known to the art. For instance, Ortiz, U.S. Pat. No. 5,492,437, teaches a lifting device that is made of one or more power cylinders that are pivotally linked to a pier and to a foundation bracket assembly. The pivotal linkage results in self-alignment between the longitudinal axis of the pier and the axis along which compressive pressure is applied to the pier. This patent requires the pier to be lifted above the bracket in order to position the pier within the bracket. 
     West et al., U.S. Pat. No. 5,246,311, discloses a pier driver having a pair of opposing first upright members straddling a pier support. The upright members are temporarily attached to the foundation and a pair of opposing first foot members operably extending beneath the foundation. A plurality of secondary lifting mechanisms, in cooperation with the piers previously installed by the pier driver, are adapted to lift the foundation. The pier supports of the pier heads are then permanently fixed to the respective piers with a bracket to provide permanent support to the foundation. This patent requires the pier to be lifted above the bracket in order to position the pier within the bracket. 
     Bellemare, U.S. Pat. No. 5,253,958, describes a device for driving stakes into the ground, particularly a foundation stake used for stabilizing, raising, and shoring foundations. The device disclosed has two rods secured to two hydraulic jacks, the hydraulic jacks and the rods being parallel to the driving axis of the stake. A driving member with a hammering head is provided to drive the stake into the ground. This patent requires that the pier to be lifted above the bracket in order to position the pier within the bracket. 
     Despite these known designs, there is a very distinct need in the art to develop an improved pier design that reduces the amount of eccentric loading on the pier to reduce the lateral movement of the footing or foundation. Still further, there is a great need in the art to develop a pier that eliminates the costly bracket assembly. 
     SUMMARY OF THE INVENTION 
     The present invention is a helical pier that supports a footing or foundation of a residential or commercial building. The helical pier of the present invention has a helix secured to the end of a pier shaft. An area of earth is excavated around and beneath the footing or foundation of the structure for the helical pier. The pier is inserted in to the excavated area with the shaft extending through a notch formed in the foundation. Mechanical devices are then used to apply torque and drive the shaft into the ground. The pier is driven to a level where there is sufficient compression in the soil to support the distributed load of the structure. 
     A pier-cap stabilizer is driven with force down over the pier shaft until the top of the pier meets a stop pin secured in the pier cap. A platform screw jack is placed op top of the pier cap under the footing or foundation. The jack screws are extended down onto the pier cap until the required support contact is achieved between the pier cap stabilizer and the footing or foundation. 
     The bottom surface of building footers is typically very rough. In order to attach a helical pier to the bottom surface of the footer, it is necessary to prepare the footer. The present invention prepares the footer by inserting a flexible bag filled with unhardened concrete between the top surface of the screw jack platform and the bottom surface of the footer. The unhardened concrete fills in the voids and contours on the bottom surface of the footer creating a structurally sound flat surface. 
     The pier-cap stabilizer includes a vertical stabilizing section that attaches to the side of the footing. With the jacks screws extended and the vertical stabilizing section attached, the installation of the helical pier is complete if the structure is at a desired height and level with respect to the ground. However, it is commonly necessary to lift the structure in height on the piers. This lifting is achieved through placing a hydraulic power ram between the top of the pier cap and under the platform screw jack. As the structure is raised by the hydraulic ram, the jack screws are turned down on to the top of the pier cap. When the screws are extended fully, the hydraulic ram is then removed and installation is complete. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts a preferred present embodiment of the invention. 
     FIG. 2 depicts a preferred manner of preparing a structural footing to receive a pier shaft of a present embodiment of the invention. 
     FIG. 3 depicts a preferred manner of installing a helical pier in accordance to a preferred present embodiment of the invention. 
     FIG. 4 depicts an installed pier shaft and helix assembly in accordance to a preferred present embodiment of the invention. 
     FIG. 5 depicts a preferred manner of installing a pier cap stabilizer on to a helical pier in accordance to a preferred present embodiment of the invention. 
     FIG. 6 depicts a preferred present embodiment of the invention in a preferred manner of installation where a jack screw is placed on a pier cap stabilizer. 
     FIG. 7 depicts a preferred present embodiment of the invention in a preferred manner of installation where a hydraulic ram is placed under a jack screw in order to lift a footing of a structure vertically. 
     FIG. 8 depicts a preferred present embodiment of the invention in a preferred manner of installation where a hydraulic ram has completed lifting a footing of a structure vertically. 
     FIG. 9 depicts a preferred present embodiment of the invention in its final stage of installation. 
     FIG. 10 depicts a preferred screw jack configuration of a preferred present embodiment of the invention. 
     FIG. 11 depicts an alternative screw jack configuration of a preferred present embodiment of the invention. 
     FIG. 12 depicts an alternative embodiment of the present invention. 
     FIG. 13 depicts a disassembled view of an alternative embodiment of the present invention. 
     FIG. 14 depicts side and top views of shelf structure of an alternative embodiment of the invention. 
     FIG. 15 depicts an alternative embodiment of the present invention at a stage of installation where a shelf structure is installed on a helical pier. 
     FIG. 16 depicts an alternative embodiment of the present invention at a final stage of installation. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     Referring to the figures by characters of reference, FIG. 1 depicts a preferred present embodiment of the invention. The two piece helical pier assembly  2  has a helix  4  at the bottom of a pier shaft  6 . Helix  4  distributes the downward pressure from a building over an area of earth. On top of the pier shaft  6  is a pier cap stabilizer  8 . A bolt  10 , commonly referred to as a pin secured to pier cap stabilizer  8  prevents pier cap stabilizer  8  from sliding down along pier shaft  6 . 
     A shelf  12  is secured to pier cap stabilizer  8  using shelf gussets  14 . Shelf  12  provides support for a jack screw assembly  15 . Jack screw assembly  15  is made of a jack platform  16  and two or more jack screws  18 . Jack screws  18  have a threaded shaft  20 , nuts  22 , and jack sleeves  24 . Jack screws  18  are welded to jack platform  16 . Nuts  22  are welded to jack sleeves  24 . Through rotating jack sleeves  24 , it is possible to extend and lower jack screw assembly  15 . A clamp  26  is provided to attach the top of pier cap stabilizer  8  against the side of the building. 
     FIG. 2 depicts a preferred manner of preparing a structural footing  28  to receive pier shaft  6  of a present embodiment of the invention. Footing  28  has a bottom surface  30 . An excavated area  32  is dug around footing  28  in order to install helical pier  2 . A notch  34  is formed in footer  28  in order to guide and stabilize pier  6  as it is driven into earth  36 . It is possible to form notch  34  in a variety of ways. One preferred method is through using a concrete saw. Alternatively, a concrete drill or a concrete chipping device could function to form notch  34 . Other known ways of forming a notch in concrete can be used such as using a concrete core drill to form a hole. Note that excavated area  32  is dug around and below footer  28  to expose the bottom surface of footer  28 . 
     FIG. 3 depicts a preferred manner of installing helical pier  2  in accordance to a preferred present embodiment of the invention. Helical pier  2  is shown positioned in notch  34 . Pier  6  is driven into earth  36  by torque motor  38 . Through rotating helical pier  2  with motor  38 , helix  4  screws its way down through earth  36  until the pier&#39;s  2  frictional resistance equals the compression weight of the structure. During this screw process, notch  34  serves to guide and stabilize pier  6  during the operation. Note that during this stage in the process of installing pier  2 , only helix  6  and pier shaft  4  are involved. Note that in FIG. 3 it is necessary to install pier  2  at an angle in order to accommodate motor  38 . 
     FIG. 4 depicts an installed pier shaft  4  and helix assembly  6  in accordance to a preferred present embodiment of the invention. Once helix  4  screws its way down through earth  36  until the pier&#39;s frictional resistance equals the compression weight of the structure, the top of pier shaft  6  is cut off below the bottom surface  30  of footer  28 . At this stage, the installation of pier shaft  4  and helix assembly  6  is complete. 
     FIG. 5 depicts a preferred manner of installing a pier cap stabilizer  8  on to a helical pier  2  in accordance to a preferred present embodiment of the invention. In step (A), the pier cap stabilizer  8  is placed on top pier shaft  6 . Pier cap stabilizer  8  is driven in step (B) down through earth  36  until bolt  10  comes into contact with the top of pier shaft  6 . In step (C), pier cap stabilizer  8  is rotated 180 degrees until shelf  12  extends under bottom surface  30  of footer  28 . Note that the shelf  12  is mounted at a slight angle with respect to pier cap stabilizer  8  in order to compensate for the slight angle that pier shaft  6  is driven into earth  6 . This slight angle is provided in order to have shelf  12  parallel to bottom surface  30 . Through having shelf  12  parallel to bottom surface  30 , it is possible to place the load of footer  28  onto pier cap stabilizer  8 . 
     In step (D), stabilizer pier cap  8  is shown in its final rotated position with shelf  12  extending under footer  28  in a parallel manner. Finally, pier cap stabilizer is driven further into earth  36  in order to create a space between footer  28  and shelf  12  so that it is possible to insert screw jack assembly  15  onto shelf  12 . 
     FIG. 6 depicts a preferred present embodiment of the invention in a preferred manner of installation where a jack screw  15  is placed on a pier cap stabilizer  8 . At this stage of installation, clamp  26  is fastened to footer  28  with one or more bolts  27 . Clamp  26  functions to secure the top of pier cap stabilizer  8  to footer  28 . Jack screw  15  is positioned such that jack platform  16  is at the top and threaded shafts  20  extend toward the bottom. The threaded shafts  20  rest upon shelf  12 . Note that pier cap stabilizer  8  is driven down on pier shaft  6  such that bolt  10  rests upon the top surface of pier shaft  6 . 
     Pier cap stabilizer  8  serves a variety of functions. First, it supports shelf  12  that is the resting platform for screw jack  15 . Through having pier cap stabilizer  8  separate from pier shaft  6 , the installation process is greatly simplified. Having pier cap stabilizer  8  enables pier shaft  6  to be installed without having a complex bracket assembly mounted to footer  28 . Further, through having pier cap stabilizer  8  separate ensures that pier cap stabilizer  8  is not damaged while the pier shaft  6  is driven into the earth  36 . 
     In addition, note in FIG. 6 that the pier shaft  6  overlaps pier cap stabilizer  8  for a region where gussets  14  mount to pier cap stabilizer  8 . The position where gussets  14  are mounted to pier cap stabilizer  8  is a potential device failure point due to buckling. However, in the design of the present invention, the side-wall thickness of pier shaft  6  combines with the side-wall thickness of pier cap stabilizer  8  to reduce the possibility of buckling. 
     FIG. 7 depicts a preferred present embodiment of the invention a preferred manner of installation where a hydraulic ram  40  is placed under a jack screw  15  in order to lift footing  28  of the structure vertically. Settling and subsidence can lower the level of the footing  28  with respect to earth  36 . Further, this settling can occur in an uneven manner causing parts of footing  28  to settle more than others. Piers  2  can remedy this problem by using hydraulic rams  40 . Hydraulic rams  40  are placed on top of shelf  12  under jack platform  16 . Hydraulic ram  40  pushes platform  16  up against bottom surface  30  of footing  28 . 
     When platform  16  comes into contact with footing  28 , hydraulic ram  40  pushes footing  28  upwards. The force of the house is transferred through shelf  12  and gussets  14  into the pier cap stabilizer  8 , pier shaft  6 , and finally helix  4 . 
     Bottom surface  30 , while shown flat, of building footer  28  is typically very rough. In order to create footer  28 , construction workers typically dig a trench. Side-wall forms are placed along the sides of the trench to give the footer  28  its shape. The top surface of the footer  28  is smooth to receive the remainder of the building structure. However, the form that shapes the bottom surface  30  of the footer  28  is the bare ground. The concrete poured into the side-walls forming the footer  28  takes the shape of the ground&#39;s contours, the rocks, gravel, and dirt clods. Consequently, the bottom surface  30  of the footer  28  is typically very rough. 
     In order to attach helical pier  2  to bottom surface  30  of footer  28 , it is necessary to prepare footer  28 . To have a solid mechanical connection between the screw jack  15  and the bottom of footer  28 , it is necessary to address the unevenness of bottom surface  30  of footer  28 . Otherwise, if screw jack  15  is placed against uneven surface  30 , stress fractures will occur in footing  28  damaging the structure and retarding the ability of helical pier  2  to support the building. 
     The present invention prepares footer  28  by inserting a flexible bag  42  filled with unhardened concrete  44  between the top surface of screw jack platform  16  and bottom surface  30  of footer  28 . As jack screws  18  are turned until the required support contact is achieved between the pier cap stabilizer  8  and footing  28 , bag  42  of unhardened concrete  44  is compressed between top plate  16  of screw jack  15  and bottom surface  30  of footer  28 . Unhardened concrete  44  fills in the voids and contours on bottom surface  30  of footer  28  between footer  28  and top of the jack screw  16 . When concrete  44  hardens, a flat surface is created between jack screw  15  and bottom  30  of footer  28 . Consequently, this design reduces the presence of stress cracks at the position where footer  28  is supported by jack screw  15 . Further, the use of bag  42  of unhardened concrete  44  is a very simple and cost effective means of preparing bottom surface  30  of footer  28 . Consequently, the use of bag  42  greatly reduces the material and labor costs on installing helical pier  2 . 
     FIG. 9 depicts a preferred present embodiment of the invention in its final stage of installation. In this figure, hydraulic ram  40  has completed lifting footer  28  to its final resting position. Note the changes in screw jack  15 . Platform  16  is pressed firmly against bottom surface  30  of footer  28  with concrete  44  pressed firmly between. Jack sleeves  24  are rotated down until they firmly press against shelf  12 . Note that now threaded shafts  20  are exposed. In this final stage of installation hydraulic ram  40  is removed from pier  2 . Earth  36  is then filled in around the hole excavated to install pier  2 . With the filling of earth  36 , the installation of pier  2  is complete. 
     FIG. 10 depicts a preferred screw jack configuration of a preferred present embodiment of the invention. In a preferred embodiment, two jack screws  18 , formed of a threaded shaft  20 , nut  22 , and jack sleeve  24  are used for jack screw  15 . 
     FIG. 11 depicts two alternative screw jack configurations of a preferred present embodiment of the invention. In alternative embodiment, configurations of three or four jack screws  18  are used to form jack screw  15 . 
     DETAILED DESCRIPTION OF AN ALTERNATIVE EMBODIMENT 
     FIG. 12 depicts an alternative embodiment of the present invention. The preferred embodiment of the invention has a single piece pier cap stabilizer  8 . The alternative embodiment has a two piece pier cap stabilizer assembly  46 . Two piece pier cap stabilizer assembly  46  is comprised of a vertical stabilizer  48  and a shelf structure  50 . Shelf structure  50  is comprised of a shelf  12 , a tube  52 , and three gussets  14 . Tube  52  has a hole  54  drilled through it to allow the insertion of bolt  56 . Vertical stabilizer  48  has a hole  58  drilled through it to also allow the insertion of bolt  56 . 
     FIG. 13 depicts a disassembled view of an alternative embodiment of the present invention. In this figure are the three basic components of the alternative embodiment of the present invention. The three components are the vertical stabilizer  48 , the shelf structure  50 , and the pier shaft  6  and helix  4 . 
     FIG. 14 depicts side and top views of shelf structure  50  having shelf  12 , tube  52 , and three gussets  14 . Tube  52  has hole  54  drilled through it to allow the insertion of bolt  56 . 
     FIG. 15 depicts an alternative embodiment of the present invention at a stage of installation where shelf structure  50  is installed on pier shaft  6 . At this stage of installation, pier shaft  6  and helix  4  have been driven to a depth where pier  6  reaches bedrock or until the pier&#39;s frictional resistance equals the compression weight of the structure. Pier shaft  6  is then cut off at the top just below footer  28 . Separating shelf structure  50  from cap stabilizer assembly  46  eliminates the need to rotate shelf  12  into position under footer  28  as is required by a preferred embodiment of the present invention. 
     FIG. 16 depicts an alternative embodiment of the present invention at a final stage of installation. The process for going from FIG. 15 to the final stage of installation requires that vertical stabilizer  48  be driven through tube  52  down over pier shaft  6  in order for holes  54  and  58  to align just above the top of pier shaft  6 . Bolt  56  is then inserted through holes  54  and  58  and is then secured. From this stage on, the remaining installation processes for installing this alternative embodiment are identical to the process required to install a preferred embodiment described above. 
     Although the present invention has been described in detail, it will be apparent to those of skill in the art that the invention may be embodied in a variety of specific forms and that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention. The described embodiments are only illustrative and not restrictive and the scope of the invention is, therefore, indicated by the following claims.