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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application claims the benefit of U.S. Provisional Application 62/024,759 filed on Jul. 15, 2014, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally, but not by way of limitation, to structural bored piers or pilings for the purpose of supporting overlying structures such as buildings, highways, bridges, or the like. 
       BACKGROUND OF THE INVENTION 
       [0003]    In scenarios where poor soil exists at shallow depths, or where large loads are contemplated, deep foundations may be advantageous. These foundations are effective at handling larger loads and provide lateral resistance. Bored piers and piles refer to types of foundations that are constructed by drilling into the earth and subsequently placing materials with stronger compressive strength in the excavation to form a foundation unit. These foundations are often referred to collectively as drilled-shaft foundations. The materials used traditionally to form these pier systems are concrete, steel, and cement grout. For example, in a typical drilled shaft foundation, an auger is used to drill a hole of planned diameter to the design depth. Then a full-length reinforcing steel frame is lowered into the hole and the hole is subsequently filled with concrete. The reinforced caisson, as it is sometimes called, can be used to support heavy loads like buildings, bridges, towers, etc. It resists compressive and lateral loads, as well as uplift tendencies. 
         [0004]    Unfortunately, existing construction methods suffer certain drawbacks. For example, the materials currently used, such as concrete and steel, themselves add significant weight to an already weak soil system. In addition, construction of individual piers is time consuming and difficult in the face of certain ground conditions such as excessive free water. Likewise, cure time for concrete and cement grout delays the time until the foundation can be loaded. Delays such as these are significant drawbacks where the above structure is in use, such as with a highway. A need exists for a rapid pier system and method that can be put in place in less time with less weight, but still offer high strength and bearing capacity. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present invention is directed to a method for constructing a structural pier comprising the steps of placing into a soil under a structure to be supported a casing having an inner diameter and an outer diameter, lowering an injection tube into the inner diameter of the casing, injecting an expansive material into the casing. In one embodiment, the overlying structure is already in place. In another, the structure is yet to be built. In one embodiment, the expansive material is a polymer expansion foam. In another embodiment, it is a two-component polymer that chemically reacts. The polymer, in one embodiment, has a fast rise time so that it reaches 90% compressive strength in one hour. In another embodiment, the polymer reaches 90% compressive strength in 30 minutes. In one embodiment, the casing comprises perforations for allowing some of the expansive material to be ejected from the casing into the surrounding soil to create fingers or branches for the purpose of at least adding friction. 
         [0006]    In one embodiment of the method, the injection tube is vertically raised or lowered inside the inner diameter of the casing to a region not containing expanded material and then the expansive material is injected into the casing. One embodiment of the method includes capping the casing to either keep the expansive material in a certain region of the casing, or to keep the expansive material from ejecting vertically to the surface. In one embodiment, the casing contains circular perforations. In another, the perforations are slotted. In one embodiment, the method comprises drilling a hole under the structure to be supported and injecting an expansive material into a region located between the exterior of the casing and the interior of the hole. In one embodiment, the casing is scored. In another embodiment, the perforations of the casing are engineered to direct the ejected expansive material into the surrounding soil. For example, perforations can be angled to direct the expansive material left, right, up, or down of the perpendicular axis of the casing wall. 
         [0007]    In one embodiment, multiple rapid piers are placed in a geometric configuration. Tie-in injections can then be initiated, interspersed between the rapid piers so that the fingers or branches are tied together to create a stronger pier structure. In one embodiment, an expandable container is placed beneath the rapid pier casing. This expandable container can be injected with expansive material to create a bell or base beneath the pier. 
         [0008]    The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter which form the subject of the claims herein. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present designs. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope as set forth in the appended claims. The novel features which are believed to be characteristic of the designs disclosed herein, both as to the organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which: 
           [0010]      FIG. 1  depicts an embodiment of the rapid pier according to the present disclosure; 
           [0011]      FIG. 2  shows a various stage of one embodiment of the rapid pier; 
           [0012]      FIG. 3  shows an additional stage of one embodiment of the rapid pier; 
           [0013]      FIG. 4  shows an additional stage of one embodiment of the rapid pier; 
           [0014]      FIG. 5  shows one embodiment of a rapid pier with perforations according to the present disclosure; 
           [0015]      FIG. 6  depicts one embodiment of a casing with perforations; 
           [0016]      FIG. 7  shows a casing with slots, according to one embodiment; and 
           [0017]      FIG. 8  represents one embodiment of a rapid pier using a casing having no perforations; 
           [0018]      FIG. 9  represents an alternative embodiment of the rapid pier; 
           [0019]      FIG. 10  shows a plan view of a rapid pier configuration with tie-in injections, according to one embodiment; 
           [0020]      FIG. 11  shows a plan view of a rapid pier disposed in an external borehole casing, according to one embodiment of the disclosure; 
           [0021]      FIG. 12  represents an embodiment of the rapid pier having a compressed expandable container; 
           [0022]      FIG. 13  demonstrates an embodiment of the rapid pier with an expanded expandable container; 
           [0023]      FIG. 14  shows a plan view of vertical shear walls of polyurethane-reinforced soil, according to one embodiment of the present disclosure; 
           [0024]      FIG. 15  represents a compartmentalized expansive material injection rack in a protracted configuration, according to one embodiment of the present disclosure; and 
           [0025]      FIG. 16  depicts a compartmentalized expansive material injection rack in a collapsed configuration, according to one embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Current drilled-shaft foundations incur several drawbacks, not the least of which is the addition of excess weight to the overall structure being supported. Along the same vein, prior art concrete and cement grout piers add delay to a construction or repair job because loads cannot be applied while the concrete/cement cures. Furthermore, excess water in the soil complicates installation and setting of prior art piers. 
         [0027]    The rapid pier design disclosed herein addresses these issues. According to one embodiment of the present disclosure, there is presented a method for providing improved structural support for overlying structures. In one embodiment, the method comprises drilling a hole to a desired diameter and length and subsequently inserting a lightweight casing or pipe  10 . The casing  10  can be fashioned of various materials such as, fiberglass, synthetic plastic polymers like polyvinyl chloride (PVC), or paper and adhesives like that of the brand Sonotube. Other lightweight plastics, papers, or alternatives may be used. 
         [0028]    In one embodiment, expansive material  11  is injected near the base of the casing  10 , so that the expansive material  11  expands out into the soil under and around the base of the casing to form a base or a bell  20 , which increases the bearing capacity of the pier and decreases any vertical movement of the pier. According to one embodiment, injections are then made at consecutive regions within the casing, working upwards or downwards region by region. Expansive material  11  fills the casing and the casing provides confinement of the expansive material  11  so that the material increases in compressive strength. Injection locations then shift upward or downward, where expansive material  11  continues to enter regions of the casing and expand in confinement. This continues until the top or bottom of the casing is reached. 
         [0029]    The expansion under confinement of the expansive material  11  results in a strong and rigid pier. In some embodiments, expansive material  11  with quick reaction times is used, so that the pier can be quickly ready to bear loads. In one embodiment, a two-component, high-density polymer is used as the expansive material, such as the Uretek 486 STAR line of polymers. Because the polymer is injected into the casing one region at a time, the polymer is allowed to cool after each chemical reaction, which allows the pier to quickly reach a preferred state so it can bear the load of the structure above it, whether that state is cream, gel, tack-free, or end-of-rise. In one embodiment, the polymer reaches 90% of its compressive strength within one hour of injection and 100% of its compressive strength within 24 hours of injection. This allows the pier to be put in use very quickly. In another embodiment, the polymer is formulated to reach 90% of its compressive strength within 30 minutes. In yet another embodiment, the polymer reaches 90% in 15 minutes. In one embodiment, the polymer is formulated to prevent water intrusion into the chemical reaction that forms the structural polymer, thereby ensuring the integrity of the polymer. In one embodiment, the expansive material comprises a two-part polymer that expands to at least three times its initial liquid volume in a free-rise condition. In another embodiment, the expansive material comprises a one-part polymer that expands to at least three times its initial volume in a free-rise condition. According to this embodiment, activator for the one-part polymer is contained within the soil, either naturally, or as provided prior to, or after, injection of the one-part polymer. In one embodiment, the activator is water. 
         [0030]    An embodiment of the present disclosure is shown in  FIG. 1 . There is presented the method of setting in soil under a structure a casing or pipe  10  of certain length, diameter, and construction material. According to one embodiment, a hole is pre-drilled or augered to accept pipe  10 . In another embodiment, pipe  10  is driven into the ground in situ. A tube  18  is lowered into the interior diameter of pipe  10  to the bottom portion of pipe  10 . Expansive material is then injected into tube  18 , for example by operator  16  using injection tool  14 . The expansive material exits at the bottom of pipe  10  to form a base or bell  20  under the rapid pier. After enough expansive material is injected to form base  20 , operator  16  raises tube  18  to a location situated in a lower segment  24  of pipe  10 . See  FIG. 2 . Operator  16  then injects expansive material into tube  18  where it exits tube  18  into the interior diameter of lower region  24 . 
         [0031]    In one embodiment, injection tube  18  includes a circular cap  21  of similar diameter to the inner diameter of pipe  10 . The cap can be placed at a location on injection tube  18  so that it correlates to the top or bottom of the injection region (such as region  24 ,  26 , or  28 ). The cap, as contemplated herein, reduces expansion of the expansive material in the vertical direction, thereby ensuring the expansive material reaches full compressive strength within the pier. By injecting expansive material  11  in confined or restricted space, compressive strength of material  11  is improved. The cap can be made of any material suitable to reduce the expansion flow of the expansive material  11 . One of ordinary skill in the art would understand how to affix cap  21  to the apparatus. In one embodiment, cap  21  is affixed to tube  18 . In another embodiment, cap  21  is affixed to casing or pipe  10  and tube  18  is stabbed through cap  21  prior to injection. In one embodiment, cap  21  is fashioned from sponge or sponge-like material. Though the preferred shape of cap  21  is circular to match pipe  10 , one of ordinary skill in the art would recognize that cap  21  can be of any shape that successfully reduces flow of expansive material through pipe  10 . For example, cap  21  may be made from a square malleable material that conforms to the shape of pipe  10  when inserted. In one embodiment, also contemplated herein, a layer of expansive material is first injected near the top of a given region ( 24 ,  26 ,  28 ) to fashion a barrier between regions. Once two regions are separated by this initial injection of expansive material, the region below said barrier is injected with expansive material until the required compressive strength is reached, or the requisite amount of expansive material is injected. In this way, cap  21  is not required. 
         [0032]    According to one embodiment, pipe  10  contains perforations  12 . Perforations can take many shapes and sizes. As expansive material is injected into lower region  24  of pipe  10 , small amounts of expansive material escape pipe  10  through perforations  12  to cause fingers or branches  22 . In some cases, the fingers/branches  22  link up within the soil to form wing-like shapes. These fingers  22  serve as anchor points to increase friction between the pier and surrounding soils. The design of the perforations may correlate to the consistency of the soil. For example, unusually soft soils may warrant smaller holes to prevent too much expansive material ejecting from the pipe into the surrounding soil Likewise, perforations can be slotted, as seen in  FIG. 7  or rounded as in  FIG. 6 . Slots can be oriented to best anchor pipe  10 . For example, slots can have a horizontal orientation to better reduce vertical movement when under load. Or slots can be vertically oriented to allow the expansive material to link up with material from other perforations. Other orientations and configurations are possible. 
         [0033]    Pipes can be of different diameters, depending on the load bearing preferences, the soil, cost, and other engineering design parameters. For example, pipe  10  may have a diameter on the order of inches, such as 3 inches or 5 inches. Larger diameter pipes 10 are also contemplated, for example with diameters reaching multiple feet, such as 2 or 3 feet. Likewise, pipe  10  need not be uniform in diameter, but can be individually tailored to the engineering need. For example, a pipe  10  can have a larger diameter lower portion tapering into a smaller diameter upper region, or vice versa. Pipes can be sunk at varying depths. Many built structures, for example, may only require piers having a depth of 10 feet or less. Larger structures, or structures built above loose topsoil, however, may require deeper piers. According to the present disclosure, there is presented the option of sinking pipe  10  dozens of feet below the surface, for example at 50 feet or 70 feet or deeper. For deep piers, one embodiment allows for mixing of two-part polymer expansive material below the surface, closer to the target injection area. 
         [0034]    Returning now to  FIG. 3 , operator  16  continues to prepare the pier by drawing injection tube  18  upwards to region  26 . Using impingement gun  14 , operator  16  then injects region  26  with expansive material according to the same method described above in reference to region  24 . Operator  16  may choose to delay injection of region  26  to allow expansive material  11  in region  24  to cool. 
         [0035]    In  FIG. 4 , operator  16  injects into the top region  28  of pipe  10 . The top of pipe  10  can be capped (not shown) to prevent expansive material  11  from ejecting to the surface through the exposed inner diameter opening at the top of pipe  10 . According to one embodiment, perforations  12  in region  28  are specifically shaped to eject expansive material under structure  30  to further add structural load bearing capacity. In another embodiment, casing  10  is sunk under the lower level of structure  30  so that structural patches to structure  30  rest on the finished pier, thus providing bearing capacity. 
         [0036]    In another embodiment, operator  16  injects from the top down, as shown in  FIG. 9 . The top down approach has the added benefit of building a reaction mass above the injection to provide resistance to the expansive material  11 . In this embodiment, multiple tubes  18  may be used. For example, three tubes  18  may be lashed together and inserted through three corresponding caps  21 . Each tube  18  has a different vertical terminating height. In this embodiment, operator  16  first injects expanding material in upper region  28 , located between caps  51  and  52 . Because operator  16  knows the volume of upper region  28 , operator  16  can estimate the amount of expansive material  11  required for that region. After injecting in upper region  28 , operator  16  may then wait for the expanding material to cool, or operator  16  can begin injecting into middle region  26  through the second tube  18 . Likewise, operator  16  finishes by injecting into lower region  26  near the bottom of pipe  10 . As mentioned, this embodiment provides a stiff horizon, or reaction mass. The reaction mass confines the injected polymer, making it denser and stronger. 
         [0037]    In one method, the operator injects a prescribed amount of expansive material  11  into casing  10  based on the conditions and project objective in order to attain the preferred compressive strength and load bearing conditions. For example, a designer or engineer may calculate the injection amount considering the soil conditions, namely the volume of any void, the soil type, soil stiffness, moisture content, and other conditions. The amount of expansive material to be injected may also depend on the magnitude of loading to be resisted and/or the magnitude and uniformity of settlement to be resisted. This information is transferred to the operator who accordingly injects the requisite amount of expansive material into each region of casing  10 . In another embodiment, there is provided a pressure monitoring apparatus  32 , such as a hydraulic pressure bulb. The pressure monitoring apparatus can be one of any type of pressure monitoring devices known in the art. The pressure monitoring apparatus  32 , in one embodiment, is affixed to the inner surface of casing  10 , as represented in  FIG. 1 . As expansive material  11  is injected into casing  10 , internal pressure is monitored at the surface by way of a gauge that reads information from pressure monitoring apparatus  11 . Operator  16  can terminate the injection at a certain pressure level, taking into account the rise time of the expansive material. In another embodiment, the pressure monitoring apparatus is lowered into casing  10 , for example, attached to injection tube  18 . Pressure monitoring apparatus  32 , in one embodiment, can be affixed to the outside of casing  10 , where there is enough space between casing  10  and a borehole. See discussion related to  FIG. 8  below. 
         [0038]      FIG. 5  represents a completed pier. Fingers or branches  22  of expansive material are shown extruding from the casing and a bell or base  20  is shown at the bottom of the casing. Depending on the expansive material  11  used, and on the soil injected into, fingers or branches  22  may link up to create fin-like shapes. 
         [0039]    In one embodiment, rapid piers have side injection ports. This embodiment is useful where the upper end of pipe  10  is blocked, such as where a structure  30  is already in place above pipe  10 . Flexible hoses can attach to the side injection port of the rapid pier in order to provide access to the interior region of pipe  10 . In one embodiment, tubes  18  (or expansive injection pathways) are already in place when pipe  10  is sunk in the foundation soil. Flexible hoses attached to side ports provide fluid communication with these pathways so that operator  16  can inject expansive material  11  at any time during a construction build. As contemplated herein, injection tubes  18  can be prefabricated within a casing  10 , prior to insertion in the soil, such that injection tubes  18  have injection ports available to operator  16 . Each tube, or pathway, may terminate in a selected region  24 ,  26 ,  28 . 
         [0040]    Likewise, rapid piers may be placed under a built structure  30  by method of tunneling, so as to leave the above structure  30  untouched. In one embodiment, pipes  10  telescope. By way of directional drilling, boreholes  42  can be prepared under a built structure from a point of origin away from the side of the structure. The operator can then tunnel to the borehole  42  and sink pipe  10 , which telescopes its way to the bottom of borehole  42 . In another embodiment, pipe  10  is sunk piecemeal, connecting each segment by way of threaded connection known in the casing industry. In another embodiment, segments of pipe  10  are not connected, but rather rest on each other under weight from above, such as where a stiff horizon is created. In another embodiment, pipe  10  is flexible, and can be unfurled or unfolded by air compression, or by way of expansive material  11  injection itself. In yet another embodiment, horizontal pipes  10  are embedded in the foundation soil, providing a lattice structure under a foundation. 
         [0041]    The upper edge of a rapid pier can be embedded in the soil below the foundation of a built structure, within the foundation of a built structure, level with the surface of the foundation, or above it. One of ordinary skill in the art would understand the preferred placement of the top edge of pipe  10  according to the design parameters of the task at hand. Contrast, for example,  FIG. 1 , showing the termination of the upper edge of pipe  10  within the foundation  30 , with  FIG. 8 , showing the upper edge terminating just below the foundation  30 . 
         [0042]    In the embodiment shown in  FIG. 8 , a casing  40  with no perforations is lowered into borehole  42 . In this embodiment, operator  16  still injects a bell or base  20  at the bottom of non-perforated casing  40 . The diameter of borehole  42  may be larger than the outer diameter of unperforated casing  40 . To increase friction between unperforated casing  40  and the soil, operator  48  injects expandable material into the space between the exterior of unperforated casing  40  and the inner wall of borehole  42 .  FIG. 8  shows operator  48  directing exterior injection tube  46  down borehole  42 , attached to exterior impingement gun  44 . After unperforated casing  40  is injected with expansive material, operator  48  then injects expansive material  11  through exterior injection tube  46  into the space between casing  40  and borehole  42 . The expansive material  11  used in the space between unperforated casing  40  and borehole  42  can be the same as used inside unperforated casing  40 , or it can be tailored for use in improving friction Likewise, the exterior surface of casing  40  can be scored to improve the bond between the casing surface and the expansive material  11 . In the present embodiment, the injection into the space between the unperforated casing  40  and borehole  42  can be performed by operator  16  using impingement gun  14  after unperforated casing  40  is filled with expansive material. Although this embodiment describes injection in the annulus between the exterior surface of unperforated casing  40  and the interior surface of borehole  42 , it is understood that the same method can be used with perforated casing as well Likewise, the exterior injection can occur prior to the interior injection, or the two can occur at the same time. One of ordinary skill in the art would also recognize that different types of expansive material  11  can be utilized as between the interior of unperforated casing  40  and the annulus located between the exterior of unperforated casing  40  and the interior of borehole  42  Likewise, variations of expansive material  11  may be used within different regions of pipe  10  itself, depending on the nature of the soil at varying depths and other design parameters of the job. 
         [0043]      FIG. 10  shows an example of a slab plan view according to one embodiment of the present disclosure, where placed piers  60  are situated in a geometric configuration at a distance away from each other. A person of ordinary skill in the art would understand placement to be dependent on the engineering requirements of the load. Tie-in injections  64  may be used to provide additional support to the rapid pier configuration, with placement of tie-in injections  64  in between piers  60 . Upon injecting expansive material  11 , such as expanding polymer, in pipes  10  to create piers  60  having fingers  22 , additional injections are made into the soil in between piers  60 . These tie-in injections  64  link up with fingers or branches  22  of the piers  60  to provide a lattice of expanding polymer-reinforced soil. According to one embodiment, tie-injections are made at a depth of  3  feet from the surface. Other depths are possible, and can be selected based on the specifications of the foundation soil and the requirements of the job. 
         [0044]    The rapid pier design is freely scalable to meet the geotechnical engineering needs of a foundation. For example, rapid piers can be sunk to many depths, such as 10 feet or 70 feet. Further depths are possible still. For unusually deep injections, the operator may elect a combination of top down and bottom up injections, drawing up tubes  18  as injections are made. The operator may elect to inject near the top to first create at stiff horizon. Tie-ins can be established at varying depths by injecting into the soil according to deep injection methods known in the art, for example, as disclosed in U.S. Pat. No. 6,634,831. Users of the rapid pier system may also employ aggregate filler within pipes  10 . Aggregate takes up some of the interior volume of pipe  10 , thereby reducing the required expansive material  11 . It also provides tangible material for which expansive material to adhere to. According to one embodiment, aggregate is pumped into pipe  10  and vibrated to fill in any spaces. 
         [0045]    Certain soils may present difficulties in setting pipe  10 . As mentioned, pipe  10  may be sunk into the ground in situ. Or it may be placed into an open pre-drilled hole. Certain situations exist where loose soil becomes a concern, such as where the borehole  42  collapses prior to setting the pipe  10 , or where soft soil falls into pipe  10  through perforations. In those cases, an operator may choose to first run an external borehole casing  70  into the hole. See  FIG. 11 . Pipe  10  is then sunk into the borehole casing  70  and the external borehole casing  70  is removed. This protects against soil entering pipe  10  prior to injecting the expanded material. This method can also create a void between the outer surface of pipe  10  and the inner surface  72  of the borehole  42 , for use in further stabilization as disclosed in  FIG. 8  and its accompanying text. 
         [0046]    In addition to fingers or branches  21  assisting in support of a vertical load, the rapid pier may also benefit from an expanded base or bell  20  at the bottom of pipe  10 , as described in  FIG. 1  and accompanying text. According to one embodiment, expansive material  11  is injected into the soil under pipe  10  and around its bottom portion, either from within the interior of pipe  10  or from outside, as shown in  FIG. 8 .  FIG. 12  presents an alternative embodiment, having an expandable container  80  located below pipe  10 . As expansive material is injected into expandable container  80 , container  80  expands, whether by stretching or unfolding as described below, and densifies foundation soil in the immediate area, as seen in  FIG. 13 . Expandable container  80 , in its expanded form, also provides a large base for improving the vertical load capability of the rapid pier. 
         [0047]    Expandable container  80  may be made of container materials that readily accept and contain expansive material  11 . These materials may be stretchable or elastic in nature, such as rubber, elastane, neoprene, spandex, or other stretchable fabrics known in the art. Expandable container  80 , however, need not be fashioned from elastic material, but instead can employ folds. Exemplary materials for expandable container  80  include paper, mesh, fiberglass, polyester, textile, fabric, and other materials with similar characteristics. According to one embodiment, parachute fabric is used. As used herein, expandable container  80  need not stretch, but rather can employ folds so that container  80  is concertinaed or collapsed during placement under pipe  10 . Upon receipt of expansive material  11 , container  80  unfolds to densify the surrounding soil. 
         [0048]    In one embodiment, expandable container  80  is placed elsewhere along pipe  10 . For example, container  80  may be designed to exist midway between the vertical top and bottom of pipe  10 , so that expansion forces portions of container  80  through perforations  12 . Parts of container  80  designed to exit pipe  10  through perforations  12  can be specifically geometrically fashioned according to the load needs of the user. 
         [0049]    Expandable container  80  may be connected to pipe  10  prior to pipe  10  being placed in borehole  42  or within external borehole casing  70  (if used). Or container  80  can be lowered into pipe  10 , such as on the end of tube  18 . In one embodiment, tube  18  also lowers a cap  21  above container  80  to reduce blowback of expansive material up pipe  10 . 
         [0050]    Tests were performed using one embodiment of the present disclosure, sinking four polyvinyl chloride pipes  10  with perforations  12  in simulated foundation soil. Piers were situated four feet from each other and were sunk approximately nine feet. As represented in  FIG. 10 , nine tie-in injections  64  were made, interspersed between piers  60  approximately two feet from each other and 2.8 feet from piers  60 . Tie-in injections were made approximately three feet below the surface. At the time of the test, it was thought excavation would reveal only fingers  21  extending from the rapid pier core into the surround soils.  FIG. 14  is a simple representation of the results of the test from a top point of view, showing the unexpected formation of polyurethane-reinforced vertical shear walls emanating from the core of the rapid pier. These shear walls demonstrate the embodiment as creating a tied-together network of reinforced foundation soil, having the rapid piers at the core of the network. 
         [0051]      FIG. 15  shows another embodiment according to the present disclosure. In this embodiment, pipe  10  is substituted with compartmentalized expansive material injection rack  90 . One version of rack  90  is a self-contained pipe/casing unit having rigid, or semi-rigid wall  99 , and compartments  92  for accepting expansive material  11 . Compartments  92  are separated by compartment cap rings  94 . Rings  94  remain in place while rack  90  is lowered into the hole, and also remain in place after the injection is complete. According to the embodiment shown in  FIG. 15 , rings  94  are solid enough to seal off the inner diameter of rack  90  from one compartment  92  to the next. In one embodiment, ring  94  comprises at least one injection tube hole  96  for allowing an injection tube  18  to pass from one compartment  92  to the next. Injection tube hole  96  preferably has a diameter slightly larger than the outer diameter of injection tube  18 , though this need not be the case. In one embodiment, multiple injection tubes  18  can be threaded through a single larger injection tube hole  96 . As one of ordinary skill in the art would understand, higher compartment cap rings  94  would require more (or larger) injection tube holes  96  in order to supply the lower compartments  92 .  FIG. 15  shows a compartment ring  98  having a hollow, or open, center region. Compartment ring  98 , as one of ordinary skill in the art would understand, is interchangeable with compartment cap ring  94 . When using compartment ring  98 , an operator  16  injecting expansive material  11  would place a cap  21  on or over ring  98  to reduce the expansion of expansive material  11  from one compartment  92  to another. 
         [0052]      FIG. 16  shows an alternative embodiment of compartmentalized expansive material injection rack  90 . In this embodiment, rack  90  comprises flexible walls  99  (shown in  FIG. 16  in a collapsed state). In the collapsed state, rack  90  takes up a fraction of the vertical space, which can allow for easier transportation to a jobsite. After a hole is drilled, collapsed compartmentalized expansive material injection rack  90  is lowered into the hole, unfurling as it drops to the bottom. With this design, operators can align injection tube holes  96  in cap rings  94  and thread injection tubes  18  prior to lowering injection rack  90 . Flexible walls  99  can be fashioned from several types of material, including loose fitting mesh or burlap fabric. In one embodiment, flexible wall  99  fabric is permeable enough to allow some expansive material  11  to permeate into the surrounding foundation. In another embodiment, flexible wall  99  fabric is impermeable and instead contains perforations  12 . In one embodiment, flexible wall  99  fabric is both permeable and contains perforations  12 . 
         [0053]      FIGS. 15 and 16  are shown having expandable container  80  connected to compartmentalized expansive material injection rack  90 , though rack  90  need not include the expandable container  80  element. In an alternative embodiment, the lower most compartment  92  of rack  90  takes the place of expandable container  80 . In this embodiment, sides  99  of the lower most compartment  92  comprise materials that readily accept and contain expansive material  11  and are stretchable or elastic in nature, such as rubber, elastane, neoprene, spandex, or other stretchable fabrics known in the art. Because the fabric of flexible wall  99  of the lower most compartment  92  is stretchable, injection of expansive material  11  stretches flexible wall  99  into the foundation to create a bell shape. 
         [0054]    Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the design as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification.

Summary:
A method and apparatus for rapidly constructing a structural pier comprising the steps of placing into a soil under a structure to be supported a casing having an inner diameter and an outer diameter, positioning an injection tube into the inner diameter of the casing, and injecting an expansive material into the casing. Optional perforations in the casing allow some of the expansive material to be ejected from the casing into the surrounding soil to create fingers or branches for the purpose of adding friction to the structural pier.