Abstract:
The present invention provides methods and apparatus for soil stabilization. First, a void is formed in the compromised soil strata. Then, an expandable member containing expandable materials is placed into the void. As the material expands to fill the void, the surrounding soil is compressed. This in situ compression if the soil increases the load bearing capacity and compressive strength of the soil. Additionally, the present invention provides a method for isolating the injected materials from the environment at the injection and/or polymerization point.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/172,438, filed Apr. 24, 2009, the entire contents of which are hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to soil compression. The present invention also relates to a method and apparatus for increasing the load bearing capacity and compressive strength of the soil. Additionally, the present invention relates to a method for isolating the injected materials from the environment at the injection and/or polymerization point. 
       BACKGROUND OF THE INVENTION 
       [0003]    The bearing capacity of base soil material is not always sufficient for the intended structure&#39;s design and use. A notable example is the Tower of Pisa. Construction of the first floor of The Tower of Pisa began on Aug. 9, 1173. The tower began to sink after construction progressed to the third floor in 1178. This was due to a mere three-meter foundation, set in weak, unstable subsoil. Construction was subsequently halted for almost a century. This allowed time for the underlying soil to settle. Unfortunately, to wait a century for the foundation to settle is not acceptable. 
         [0004]    Since then, a variety of methods and designs have been used to improve the bearing capacity of unstable subsoil. Typically, the bearing capacity is improved by increasing the confined compressive strength of the base soil material. Various methods for remedial stabilization of the subsoil and/or lifting of the structure to correct structural settlement include driving pilings, piers, segmented cylinder piles, and/or micro-piles. Also, other systems that transfer the structural weight to deeper more solid soils have been used. 
         [0005]    Also, conventional stabilization and/or lifting systems include the method described in U.S. Pat. No. 4,567,708. This patent discloses the injection of an expandable substance beneath a built structure to fill voids and the polymerization the substance which results in an expansive force that increases in volume to fill voids. 
         [0006]    U.S. Pat. No. 6,634,831, which is incorporated by reference herein in its entirety, discloses injecting an expandable substance through holes or tubes into the soil to produce compaction of the contiguous soil. This system fails to account for and/or monitor unknown and unexpected migration of the expandable substance away from the injection site. This migration is common due to fracturing of the soil at the point of injection and the injected materials following the path of least resistance. Additionally, the uncontrolled migration of the expandable material creates undesired surface lifting some distance away from the desired location. 
         [0007]    U.S. Pat. No. 6,521,773, which is incorporated by reference herein in its entirety, discloses polyurethane forming reaction mixtures having a water insoluble diluent. The compositions provided permit the formation of polyurethanes in the presence of excess water. This composition addresses the degradation of a typical polyurethane foam composition when excess water is incorporated into the mixture. 
         [0008]    The methods and compositions of the prior art have not met the need for controlling the unknown and unexpected migration of the injected material away from the injection point. Additionally, the methods of the prior art have not met the need for isolating the injected material from environmental contaminants. 
         [0009]    The present invention provides methods for controlling the placement of materials when injected through a hole or tube, isolating the injected materials to insure that the injected materials are not compromised by environmental contaminants, and/or stabilizing unstable subsoil, increasing the load bearing and compressive strength of soil. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The present invention is directed to a system and method for stabilizing soil. In general this method comprises the steps of creating a void in compromised soil strata, placing an expandable member in the void, and injecting the expandable member with an expandable material. 
         [0011]    In some embodiments of the present invention, the step of creating a void is selected from the group consisting of forming a hole, inserting a tube, inserting a pipe, drilling, pressing, and vibration intrusions. In additional embodiments, the expandable member is selected from a group consisting of a high burst strength bladder, a high temperature bladder, a rubber bladder, a plastic bladder, and a bladders made of at least one synthetic material. In specific embodiments, the expandable member further comprises at least one blow out membrane. In other embodiments, the step of injecting the expandable material is controlled by a plug. 
         [0012]    In additional embodiments of the present invention, a method for stabilizing soil comprises the steps of creating a plurality of voids in compromised soil strata, placing at least one tube in the void, securing an expandable member to a location in the tube, and injecting the expandable member with an expandable material. In some embodiments, the step of creating a plurality of void is selected from the group consisting of forming a hole, inserting a tube, inserting a pipe, drilling, pressing, vibration intrusions and a combination thereof. In other embodiments, the expandable member is selected from a group consisting of a high burst strength bladder, a high temperature bladder, a rubber bladder, a plastic bladder, a bladders made of at least one synthetic material and a combination thereof. In specific embodiments. the expandable member further comprises at least one blow out membrane. In yet another embodiment, the step of injecting the expandable material is controlled by a plug. 
         [0013]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its 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 invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    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: 
           [0015]      FIG. 1  shows schematic of how the tubes are placed, the expandable bladder is inserted and the expandable material is injected; and, 
           [0016]      FIG. 2  shows an expanding bladder coupled to tubing using a collar and a tube crimp. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Once it is discovered that the soil underneath a structure is unstable, the methods and apparatus provided by the present disclosure may be used to stabilize the soil. In general, the method for stabilizing the soil includes creating a void, placing an expandable member in the void, and injecting the expandable member with an expandable material. 
         [0018]    In some cases, the soil is unstable due to the natural formation of a void in the subsoil. In other cases, the soil is unstable because the soil is not settled or compressed enough to support the structure. In this situation, a void must be created. The methods for creating a void include, but are not limited to, forming a hole, inserting a tube or pipe, drilling, pressing, or vibration intrusions into compromised soil strata. Compromized soil strata is characterized by less than desirable confined soil strength sub-surface locations. For example, a tube may be placed in the hole. The lower end of the tube is protected to allow the dispensing of material through the tube and the material is allowed to exit at the lower end. 
         [0019]    The means for placing the expandable member in the void is accomplished in a number of ways. In some non-limiting examples, a collar device that holds the expanding bladder is inserted into a tube and placed at a location in the tube,  106 , where it is desired for the injected material to expand. In particular examples, this location is the proximate end of the tube. The location of the holder, the collar deviced,  102 , used to place the expandable member,  103 , is controlled by a stop crimping element,  101 , placed in the tube prior to inserting the tube into the ground. 
         [0020]    In some examples, the holder is placed in the tube either by the force of the injected materials moving the holder through the tube, or by using an advancer rod,  107 , to push the collar and bladder to the desired location. 
         [0021]    In the examples where the collar is placed by the pressure generated from the injected material, the expandable member may be protected by a blow out membrane to prevent the expansion of the capsule during the travel through the tube. In some cases, the expandable member is a bladder. In other cases, the expandable member includes, but is not limited to high burst strength bladders, high temperature bladders, bladders that have at least one blow out membrane designed for bladder protection, rubber bladders, plastic bladders, bladders made of synthetic materials, and/or bladders made of various combinations of synthetic materials. 
         [0022]      FIG. 1  shows schematic of how the tubes are placed, the expandable bladder is inserted and the expandable material,  104 , is injected. First, a hole is drilled and a tube is put in place. The tube contains an internal crimp,  101 . Next, an advancer rod,  107 , is used to secure the expandable member,  103 , at the end of the tube,  106 . Once the expandable member is secured at the end of the tube, the advancer rod is removed and the expandable material,  104 , is injected resulting in an expandable member filled with expandable material which is shown as  105  in  FIG. 1 . 
         [0023]    In some aspects of the present invention, a stepped metal or plastic collar is used to attach an expanding bladder at the end of the injection tube. The injection tube is inserted into a hole and the expandable material is injected. For example,  FIG. 2  shows an expanding bladder,  205  coupled to a ⅝ inch tubing,  201 , using a 9/16 inch collar,  202 , and a 7/16 inch inner diameter tube crimp,  204 , with the rim of the expanding bladder,  203 , positioned between  204  and  202 . The skilled artisan would readily recognize that larger and smaller diameter tubing, collars and/or tube crimps are within the spirit and scope of the present invention. 
         [0024]    In some aspects of the present invention, the expandable member is made of material, which will both expand to a sufficient size and is chemically inert with respect to the injected materials. 
         [0025]    Some aspects of the present invention include a means for attaching the expanding bladder at a given position at the bottom of the injection tube and/or hole. 
         [0026]    In some cases, the present invention provides a means for controlling the placement of the collar and the attached expandable member near the end of the tube. 
         [0027]    In an additional example, a plug is placed on the collar for the expandable member. This provides a means to control the flow of expandable material into the expanding member. 
         [0028]    In additional examples, the methods and apparatus used to stabilize the soil includes placing a collar equipped with an expandable member directly in the void without using tubes and injecting the expandable member with an expandable material. 
         [0029]    In some cases, the expandable material will cause the expandable member to rupture, leak and/or burst. 
         [0030]    Additionally, a network of tubes equipped with expandable members may be used in combination to stabilize the subsoil. In some examples, the network may constructed by placing a collar equipped with an expandable member directly in the void without using tubes and/or placing tubes equipped with expandable members into the void. 
         [0031]    Although the present invention 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 invention 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 disclosure of the present invention, 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 invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.