Abstract:
A pipe pier system for use in supporting foundations is provided. The pier system is comprised of a plurality of pipe pier sections and pipe connecting insert members. The pipe sections are adapted to be butted end to end to each other in linear arrangement with the pipe connecting insert member being placed within and connected to respective ends of the butted pipe sections. The pipe sections and insert member have aligning holes to allow for a pin to span their diameters for a stable connection. A removable guide cap is provided for the terminal end of the pier assembly to reduce friction as the pier is driven into the ground.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to piering systems used in connection with the supporting of building foundations, footings and the like. In those types of applications, as is well known to those skilled in the art, piers are hydraulically driven or forced into the ground until they encounter a substrate sufficient to bear the load necessary to support the foundation or footing under which the pier is placed. When it is necessary to reach a substantial depth, multiple pier sections assembled in a linear arrangement must be employed. 
     Most of the pipe piers currently in use in the piering market today are comprised of pier sections that are not permanently affixed to one another. The pipe sections are fitted together in various ways, and in most instances, those methods are entirely satisfactory. However, under certain conditions, the manner in which the pipe sections are joined becomes critical. For instance, when the pier is being driven through a void, such as a mine or cavern, pier sections which rely on a continual axial compressive load as its means of connection may fall apart unless they are adequately connected together. Also, the connection point must be able to withstand the considerable compressive load placed thereon when the pier is being driven into the ground. Pier sections which are merely screwed or bolted together may collapse under extreme compressive loads. There further exist pier systems whose pipe sections butt up end to end with each other by using threaded ends; however, these are expensive to manufacture and can be time-consuming to install. 
     SUMMARY OF THE INVENTION 
     By means of the instant invention there is provided a pier system for use in supporting foundation and footing structures which enables easy and efficient end to end connection of pipe sections. This arrangement provides sufficient strength and stability to withstand both compressive and tensile loads, as well as moderate lateral forces. The pier system is comprised of a plurality of pipe sections which are adapted to fit end to end with an insert section placed in the respective pipe ends. The insert section has a diameter slightly less than the pipe sections which allows a telescoping fit of the pipe ends over the insert section. Holes are disposed on the pipe ends and insert section to allow for connective alignment. The holes allow for the connector to span across the pipe and insert for a more secure and stable connection. The holes are also dimensioned to accommodate a connector so that a tight press fit of the connector within the holes can be achieved. The pipe sections can be made to be uniform in that an insert section can be manufactured into one end of each pipe section so that only one connection between discrete pipe sections need be made in the field. The user can install as many pipe sections as is necessary to reach the depth needed to achieve the desired stable foundation support. The invention also allows the pier to be easily dissembled in the event of removal. 
     The pier system may also comprise a guide cap for placement over the terminal end of the pier to reduce friction on the pier as it is driven into the ground. The guide cap has a diameter larger than that of the pier. It is removable so that if the pier is extracted from the ground, the cap will become dislodged. Hence, the pier will be more easily pulled up through the larger diameter channel in the ground made by the guide cap. 
     The above features are objects of this invention. Further objects will appear in the detailed description which follows and will be otherwise apparent to those skilled in the art. 
     For purpose of illustration of this invention a preferred embodiment is shown and described hereinbelow in the accompanying drawing. It is to be understood that this is for the purpose of example only and that the invention is not limited thereto. 
    
    
     IN THE DRAWINGS 
     FIG. 1 is an exploded perspective view showing the insert section as it fits within the pipe ends. 
     FIG. 2 is a perspective view showing an embodiment of the guide cap. 
     FIG. 3 is a perspective view showing a second embodiment of the guide cap, partially broken away. 
     FIG. 4 is a perspective view of another embodiment of the pipe sections with integrated insert members. 
     FIG. 5 is a cross sectional view in side elevation taken along lines  5 — 5  in FIG. 1 of the embodiment shown as connected together. 
    
    
     DESCRIPTION OF THE INVENTION 
     The pipe tubing pier system of the instant invention is shown in FIG.  1  and is generally indicated by the reference numeral  10 . It is comprised of pipe tube section members  34  and insert members  42 . The pipe sections  34  are constructed of steel and come in various uniform lengths ranging from five to ten feet or longer as is well understood in the art. Insert member  42  is likewise constructed of steel and has a diameter slightly less than that of pipe sections  34 , but should not be greater than that which would impede its passage within the pipe sections. Insert member  42  fits within pipe sections  34  in a telescoping manner so that a sufficient length is placed within each pipe section to allow connection therebetween and to also allow the respective pipe section ends  12  to butt up against each other as shown in FIG.  5 . 
     Each end of the pipe sections has a pair of diametrically opposed apertures  14 . Likewise, insert member  42  has two pairs of diametrically opposed holes  38 , each pair being disposed towards the ends of insert member  42 . The respective holes  38  of insert member  42  and apertures  14  of the pipe sections  34  are arranged such that they align with each other when the pipe sections are placed over the insert member as shown in FIG.  5 . This allows a connector  35 , such as a bolt or a pin, to be placed through the holes and apertures to span across the pipe section and insert member for a more secure and stable connection of the pier system. 
     Holes  38  of insert member  42  are somewhat elongated, as shown in FIGS. 1 and 5, to form a slot running in the longitudinal direction of the insert shaft. The purpose for having slotted holes is to allow the ends  12  of pipe sections  34  to butt up against one another without connector  35  impeding the fit. Connector  35  will move slightly within the slot of hole  38  in relation to the displacement of connector  35  caused by the butting together of ends  12  of pipe sections  34 . This relieves the connector  35  from being subject to the installation driving force placed on the pier and prevents connector  35  from shearing during the installation phase. Instead, the compressive force is limited to the interface between pipe ends  12 . Holes  38  are not so long, however, that an excessive amount of longitudinal movement of pipe sections  34  in relation to insert member  42  can occur after connection. 
     To ensure a tight fit of connector  35  within pipe section  34  and insert member  42 , apertures  14  of pipe sections  34  may be modified to accommodate a connector which comprises a bolt. As shown in FIGS. 1 and 5, bolt connector  35  has a head  16  and shaft  18 . Aperture  36  on pipe section  34  is drilled to a dimension approximating that of bolt head  16  such that a press fit relationship between bolt head and aperture will exist. The diametrically opposed aperture  20  on the other side of pipe section  34  is drilled to have a dimension to receive bolt shaft  18 . With this construction, the bolt is tapped into place and is tightly retained and secured. For removal, the bolt is easily tapped back out. 
     For increased efficiency in the field, a pre-formed pipe section  34  with insert member  42  in one end may be provided as shown in FIG.  4 . With this type of arrangement, the connection operation time of assembling the pier sections will be cut in half because one connection of insert member  42  between pairs of pipe sections  34  is already made. Insert  42  can be welded in place in pipe section  34  by weld  50  or by other means known to those skilled in the art, such as crimping, pinning or the like. The other end of pipe section  34  and the exposed end of insert member  42  are provided with their respective holes and apertures for connection in the manner as described above. 
     The pier system also comprises a guide cap generally indicated by reference numeral  22  in FIG.  2 . It is comprised of disk  24  attached to shaft  26 . Shaft  26  is received within pipe section  34  and is the terminal end of the pier assembly. A circumferential rubber strip  28  is provided at the lower end of shaft  26  so that guide cap  22  is press fit within pipe section  34 . Disk  24  has a diameter larger than pipe section  34  to reduce the friction along the sides of pipe sections  34  as the pier assembly is driven into the ground. Such friction would otherwise prevent the pier from reaching optimum load bearing strata. The larger diameter provided by guide cap  22  cuts a larger bore than the pier would create, and therefore the pipe section sides would not drag along the bore wall as greatly as if the bore were the same diameter of the pier. If the pier needs to be removed, guide cap  22  simply becomes dislodged and the pier can be pulled out. Another embodiment of the guide cap is shown in FIG.  3 . It comprises a cap  30  which fits directly over the end of pipe section  34 . A rubber strip  31  is placed around the end of pipe  34  to facilitate a press fit. A further advantage of the guide cap is that, by closing off the end of the pier pipe, it allows the pier assembly to become more effective as an end-bearing pier. 
     A preferred embodiment of the pipe pier system is described as follows. Pier section  34  is made from 3½ inch outside diameter structural steel tubing with 0.218 inch wall thickness. insert member  42  has a 3 inch outside diameter by 0.125 inch wall thickness with a minimum length of  12  inches. Insert member  42  is attached to pipe section  34  by connector  35  with 6 inches of the insert inside pipe section  34 , and 6 inches outside the pipe section. Holes  38  are 0.5 inches in diameter and 0.75 inches in length and located 3 inches from the ends of insert member  42 . First aperture  36  on pipe section  34  is 0.625 inches in diameter and second aperture  20  is 0.5 inches in diameter. Connector  35  is then inserted through the apertures and holes, starting from the 0.625″ diameter aperture  36  on pipe section  34 , then protruding through the 0.5″ diameter holes  38  of insert member  42 . Connector  35  is 3½ inches in length, 0.468 inches in diameter, and comes with a 0.625 inch diameter by 0.218 inch deep head. After the pin is inserted through the apertures and holes, its last 0.218 inch of travel is achieved by tapping with a hammer. The end result is a pin that is flush with the outside diameter of the pipe section, and is locked in place by the interference fit of bolt head  16  and pipe section aperture  36 . Subsequent pipe sections are adjoined in like fashion. As a pipe section is joined to the preceding pipe section, it slides over the exposed insert section and its holes are aligned with those of the insert. As pier sections are joined together, the fixed insert member from one pipe section will protrude into the leading end of the next pipe section. Accordingly, the pipe sections will butt up against one another, and share a common insert. The initial pier section is first furnished with a  4  inch outside diameter by 0.250 inch thick disk  24  on guide cap  22 . 
     The apparatus is advantageous in that it resists separation of pipe sections in situations where traditional pipe piers tend to separate, such as areas prone to seismic activity or when being installed through voids, mines, caverns or water structures. The apparatus is advantageous in that it strengthens the connection between piering sections and stabilizes sections when compressive forces are applied. The apparatus provides greater retrievability of pier sections, if required. The flush surface of the pier joints allows greater ease of installation. 
     Additionally, it is strongly believed that during periods of seismic activity, piering systems joined with permanently joined pipe sections will hold up due to the pier&#39;s potential for maintaining integrity when subjected to tensile loading. This seems especially true when compared to piers made with separable sections with inserts only that are not permanently fastened. If an insert is only 6 inches in length, a 3 inch upheaval is all that is needed to uncouple a piering system. The present invention is made with an insert that is not only 12 inches in overall length, but securely pinned to the pier sections. 
     Various changes and modifications may be made within this invention as will be apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention as defined in the claims appended hereto.