Abstract:
A portable extraction tool facilitates soil stabilization applications that utilize compaction grouting. Compaction grouting involves installing grout injection casing into the ground in fixed-length sections to depths limited by soil compaction or bedrock. The casing is then removed in stages. Between stages, grout is pumped through the casing and into the soil at high pressure. The extraction tool provides the power, gripping strength, stability and operator control required to pull casings from the ground at a desired rate. Pulling power is provided by a pair of hydraulic cylinders. Gripping strength is provided by a progressive chuck mechanism that secures injection casings on upward movements of the cylinders and releases casings on downward movements, without damaging the reusable casings. Stability and strength are provided by a heavy, large-footprint base plate. The base plate and chuck have aligned, open-face slots to provide easy positioning of the tool on installed casings and to utilize casings for lateral support. Inherent tool stability and multiple integrated steps allow a person to safely stand on the tool. This enables an operator to monitor a grout pressure gauge and pump stroke counter and to perform casing disassembly high above the tool, eliminating the need for external ladders or platforms. The tool is provided with turf tires and a handle and designed to be easily moved and operated in rough earth and limited access conditions by one or two persons. The tires are suspended above ground in the tool operating position to avoid destabilizing the tool.

Description:
BACKGROUND OF THE INVENTION 
     Geological grouting is a versatile construction technique used in a variety of applications. Injection casing or piping is driven into the ground. Grout is then pumped under pressure through the above-ground end of the installed casing, out the underground end, and into the surrounding soil. The grout itself can be made from many different materials proportioned in a wide range of amounts depending on the specific grouting application. Cementitious grout, for example, is a mixture of hydraulic cement and water, with or without aggregates and with or without admixtures. Hydraulic cements react with water to form a hardened paste that maintains its strength and durability in water and also maintains its properties upon drying. 
     Grouting applications include slabjacking, subsealing and soil grouting. In slabjacking, pressure grouting is used to raise a depressed section of pavement or other concrete element by forcing a flowable grout under it. Subsealing is where a cement-grout mixture is pumped under pressure through a packer installed in an access hole drilled in a slab to fill voids and depressions under the slab and reduce damage caused by excessive pavement deflections. For soil grouting, soil is grouted to increase its bearing capacity, reduce or halt settlement, increase shear resistance to stabilize it against lateral movement, reduce waterflow, or increase the cohesive strength of friable ground prior to excavation. Soil grouting includes permeation grouting, where a thin grout is used to permeate the soil and fill pores and voids between soil particles; deep-soil mixing, where soil and injected grout are mixed together to make a soil-cement material in place; jet grouting, where a cement-and-water grout is injected under very high pressure to form a concrete-like column; and compaction grouting, described below. 
     Compaction grouting is a soil stabilization process where weak or compromised sub-soils are re-compacted. This technique involves driving injection casing into the soil in five to eight foot sections until good refusal is achieved, usually when the casing reaches bedrock or bearing strata. Pressure grouting is then performed in vertical stages throughout the length of the casing hole. The vertical stages are created by extracting a section of casing a fixed length, typically one to three feet, and then pumping a quantity of stiff, sand-and-cement grout through the casings. An operator monitors an external pressure gauge and pump stroke counter at a pump head attached to the casing end. The operator also records the pressures achieved and the quantity of grout injected at each stage. A fully extracted section of casing is removed between stages, the pump head is reattached, and the extraction and grouting sequence is repeated. The stiff grout does not permeate the soil but maintains a grouted mass, three feet or more in diameter. By displacing the soil and forming a bulblike or columnlike form, the grout significantly increases the soil density at a radial distance of one to six feet or more from the soil-grout interface. 
     SUMMARY OF THE INVENTION 
     In compaction grouting applications, injection casings are essentially nailed into the ground and require great power and lift capability to extract. Thus, an effective tool and method of extracting injection casings between stages of grout pumping is required. Prior devices for pulling elongated objects from the ground typically suffer from limitations in the areas of transportability, strength, grip effectiveness, casing reusability and stability that severely hamper their overall effectiveness for compaction grouting. The portable injectioncasing extractor apparatus and method according to the present invention provides injection casing extraction capability in compaction grouting applications without these limitations. 
     For example, pulling devices typically suffer from a combination of insufficient lifting power and structural strength to meet the demands of many compaction grouting jobs, resulting in frequent failure and breakdowns. Further, the puller chucking mechanisms used to secure elongated objects to a lifting device frequently require multiple manual operations to engage and disengage, greatly slowing an extraction process conducted in stages. Some puller chucking mechanisms also lack gripping strength or tend to damage casing by denting, gouging or crushing the casing wall. 
     By contrast, the portable injection-casing extractor apparatus and method (“extraction tool”) according to the present invention has dual hydraulic cylinders for a lifting force capable of pulling sections of grout injection casing out of the ground at an operator-controlled rate. A heavy-duty base plate and chassis provide the structural strength to support operation of the dual cylinders. The cylinders are powered by a remote hydraulic power unit or “mule.” The cylinders have an attached progressive chuck mechanism that provides sure engagement of the injection casing at the beginning of a lifting stage and release at the end of a lifting stage, without manual intervention between stages or the use of complex automatic control mechanisms. The amount of force applied to casing walls by the progressive chuck is self-limiting, protecting the casings from damage. The teeth of the progressive chuck are advantageously maintained generally flush to the casing wall during gripping and extraction steps, which avoids gouging, denting and crushing movements that would also damage the casings. These features advantageously allow casings to be reused after removal by the extraction tool. 
     Further, pulling devices are often awkward to transport to a construction site. If wheels are provided for transportation, they are in contact with the ground at all times, creating extractor instability during operation. Further, these devices are frequently difficult to position on installed casings. Operators are often required to lift a heavy pulling device and place it over the end of an installed casing that is protruding from the ground. In addition, these devices typically require external ladders and steps for the tool operator to remove casing sections and to disassemble, reassemble and monitor the pump head and gauges located high above the tool. 
     The extraction tool according to the present invention is compact for limited access applications, and, being mounted on turf tires, the tool is easily moved and operated by one or two workers in typically rough terrain conditions. An integrated handle facilitates transporting and positioning of the tool and allows sufficient leverage for a single operator to move the tool between its operating position and its transport position. The tool is so well-balanced and stable that it can maintain either its operating position or its transport position without operator support. An open-face base plate and chuck design allows the tool to be rolled into position on injection casings without lifting the tool. The installed injection casings held within the open-face base plate and chuck also provide lateral support for the tool, further increasing its stability. The weight and balance of the extraction tool provide sufficient stability for adult male to safely stand on tool. Integrated steps and platforms provide operator access to locations high above the tool. These features allow an operator to disassemble casing sections, disassemble and reassemble the pumping hose connection and to monitor pressure and stroke gauges at the casing end without the need for external platforms and ladders. The turf tires are offset from the ground in the tool&#39;s operating position, also enhancing its stability. 
     One aspect of the present invention is an extraction tool for progressively jacking a shaft from its surrounding media. The extraction tool has a lift with a stationary end and a moveable end, a block assembly attached to the moveable end, and a plurality of opposing grips. The block assembly defines an interior space configured to accommodate the shaft. The grips can be positioned within the interior space in contact with the shaft. The grips are configured to have loose and tight positions around the shaft. As the lift extends, the grips move from the loose to the tight position, securing the shaft to the block assembly. As the lift retracts, the grips move from the tight to the loose position, releasing the shaft from the block assembly. 
     In a particular embodiment, the grips have a plurality of tooth rows which are positioned flush against the shaft while the grips are in either the loose or tight positions. In another particular embodiment, the block assembly has a pair of chuck blocks and the grips are a pair of wedges corresponding to the pair of chuck blocks. The chuck blocks each having an angular face generally facing and sloping away from the interior space. The wedges each have a first face, an opposite second face and a wide end between the first and second faces. Each of said wedge first faces contacts and slides against a corresponding block angular face, so that as the lift extends the blocks move relatively toward the wide ends of the wedges and move the wedges from an loose to a tight position. A particular angle between the wedge faces is in the range of 12 to 20 degrees. The extraction tool may include a hinge attached to the block assembly. One end of a retainer is rotatably attached to the hinge and a grip is rotatably mounted to the other end of the retainer. In this manner, the grip is retained by the block assembly and can be moved from an open position outside of the block assembly to a closed position within the interior space. 
     Another aspect of the present invention is a method of extracting an installed shaft from its surrounding media, the shaft having a protruding end extending from the media. A lift is positioned near the protruding shaft end. The lift has a moveable end and a stationary end. The surrounding media supports the lift stationary end and the lift moveable end supports a chuck. A first portion of the shaft protruding end is loaded into the chuck and a grip is positioned near the first shaft portion. A gripping element mounted on the grip is positioned so that its surface is in flush contact with the first shaft portion. Extension of the lift moveable end is initiated and, in response, the grip secures the shaft portion. Extension of the lift is completed with the shaft portion secured to the chuck, at least partially removing the shaft from its surrounding media. Retraction of the lift moveable end is initiated, releasing the shaft portion from the grip in response. Retraction of the lift moveable end is completed with the shaft portion released from the chuck and the chuck is positioned on a second shaft portion of the protruding end nearer the media from the first shaft portion. 
     In a particular embodiment, the gripping element surface is a toothed face having a plurality of tooth rows. In another particular embodiment, the grip secures the shaft portion by translating initial extension of the lift into an initial movement of the grip against the first shaft portion. In yet another particular embodiment, the grip is a wedge and the translating step involves initiating movement of an angular block portion of the chuck relative to the wedge in a direction from a narrow end to a wide end of the wedge, increasing pressure of a wedge face containing the gripping element against the shaft portion. In still another particular embodiment, the grip is a wedge and the releasing step involves initiating movement of an angular block portion of the chuck relative to the wedge in a direction from a wide end of the wedge to a narrow end of the wedge, reducing pressure of a wedge face containing the gripping element from the shaft portion. 
     Yet another aspect of the present invention is an extraction tool having an operating position and a transport position. The tool has a generally planar base plate with a first face, an opposite second face and a back edge between the first and second faces, where the first face contacts the ground and the second face is opposite the ground in the tool&#39;s operating position. The tool also has a frame attached to the back edge that extends generally perpendicularly away from the second face. Tires are mounted on each side of said frame and offset from the ground in the operating position. The tires and the back edge contact the ground in the transport position so that the tool is stable and self-standing in both its operating and transport positions. The tool further has a chuck moveably mounted to the base plate. 
     In a particular embodiment, the extraction tool also has a handle attached to the frame and extending generally perpendicularly away from the second face. The handle provides leverage for moving the tool between the operating and transport positions. In another particular embodiment, the extraction tool also has a number of integrated steps, at least one step is located on each of the frame and the handle. The base plate has a sufficient weight and footprint so that the tool can support a person standing on any of the steps without external support for the tool. In a specific embodiment, the weight of the base plate is at least about 90 pounds and the footprint of the base plate is at least about 470 square inches. In yet another particular embodiment, both the base plate and the chuck have an open-face slot configured to accommodate shafts. 
     An additional aspect of the present invention is an extraction tool having a base means for supporting the tool, a lift means for extending and retracting a chuck plate and a progressive chuck means for securing a shaft as the chuck plate is extended and for releasing a shaft as the chuck plate is retracted. The lift means is mounted to the base means and the chuck means is mounted to the chuck plate. The extraction tool may also have a plurality of step means for supporting a person standing on the tool. The extraction tool may also have an open-face means for loading and retaining shafts within the chuck means. The extraction tool may also have a transport means for moving the tool. Also, the extraction tool may have a handle means for positioning the tool. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration of compaction grouting under a foundation utilizing a portable injection-casing extractor apparatus and method (“extraction tool”) according to the present invention; 
     FIG. 2A is a front perspective view of an extraction tool embodiment shown in its operating position; 
     FIG. 2B is a back perspective view of an extraction tool embodiment; 
     FIG. 2C is a perspective view of an extraction tool embodiment shown in its transport position; 
     FIG. 3 is an exploded view of the hydraulic cylinder rods and mounting sleeves; 
     FIG. 4 is a perspective view of the chassis base plate; 
     FIG. 5 is a perspective view of the chuck block assembly; 
     FIG. 6 is a perspective view of the hydraulic assembly; 
     FIG. 7A is a perspective view of the chassis; 
     FIG. 7B is a perspective view of the wheel assembly; 
     FIG. 8 is a perspective view of the gripping assembly; 
     FIG. 9 is a perspective view of the gripping assembly teeth; 
     FIG. 10A is a perspective view of an extraction tool with the gripping assembly in an open position and the tool positioned on an installed injection casing; 
     FIG. 10B is a perspective view of an extraction tool with the gripping assembly closed on an installed injection casing and the cylinders in a retracted position; 
     FIG. 10C is a perspective view of an extraction tool with the cylinders in an extended position after extracting a portion of injection casing; and 
     FIG. 10D is a perspective view of an extraction tool with the cylinders in a retracted position after extracting a portion of injection casing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates compaction grouting under a foundation  110 . Injection casings  120 , generally 1½″ to 2″ in diameter, are driven down in a grid pattern  130  to bearing strata. An extraction tool  200  according to the present invention is positioned on an injection casing, extracting the casing in stages. A mobile grout plant  180  feeds a high pressure grout pump  140  on the surface. The pump  140  injects cementitious grout into the casings  120  between stages of casing extraction, building a vertical column  170  of grout balls. A completed grout column  150  causes radial densification of the surrounding soil particles  160 . The operator monitors an external pressure gauge and pump stroke counter at each lifted stage of pumping and, upon completion of extracting one section of injection casing, disconnects the pumping head and spent section of injection casing. 
     FIGS. 2A and 2B illustrate front and back views, respectively, of one embodiment of an extraction tool  200  according to the present invention. As shown in FIGS. 2A and 2B, the extraction tool  200  is constructed of an extractor assembly  202  driven by a hydraulic control assembly  204  and integrated with a tire-mounted chassis  206 . As shown in FIG. 2A, the extractor assembly  202  has hydraulic cylinders  210 , a chuck block assembly  220  and a gripping assembly  230 . Also shown in FIG. 2A, the chassis  206  has a machine frame  260 , a base plate  270 , a handle  280  and a wheel assembly  290 . Shown in FIG. 2B, the hydraulic control assembly  206  has a hydraulic control valve  240  and a hydraulic flow divider  250  (see also FIG.  2 A). 
     In compaction grouting applications, the hydraulic force needed to compact the sub-soils may also grip the injection casings. Thus, it is desirable for the extraction tool  200  (FIG. 2A) to be capable of applying substantial pulling force to the casings. In the extraction tool embodiment shown in FIG. 2A, this pulling force is supplied by dual hydraulic cylinders  210  acting in unison. Suitable hydraulic cylinders  210  are CHIEFWP brand cylinders, part number 4024WP, available from Bailey Manufacturing Corp., Knoxville, Tenn. These cylinders  210  each have a 24″ stroke, a 2″ rod, a 4″ bore and operate with a hydraulic pressure up to 3000 psi. 
     Although FIGS. 2A-B illustrate an embodiment utilizing dual hydraulic cylinders positioned on either side of an injection casing (see also FIGS.  10 A-D), one of ordinary skill will recognize other embodiments within the scope of the present invention having fewer or more cylinders. For example, a single cylinder configured to accommodate an injection casing through a hollow core or any number of multiple cylinders evenly positioned around an injection casing would also provide a balanced pulling force to the casings. Further, it would be obvious to one of ordinary skill that other embodiments employing any apparatus that generates a pulling or lifting force, including the powered hydraulic cylinders shown in FIGS. 2A-B in addition to manual or power-driven jacks, gears and screws (generally “lifts”) are within the scope of the present invention. 
     FIG. 2C shows the extraction tool  200  in its transport position. The tool  200  is easily moved by one person between its operating position (FIG. 2A) and this transport position. Further, the tool  200  will maintain this transport position without operator support, resting on the base plate  270  and tires  770 . In this manner, the tool  200  is portable, easily transportable, and can be moved and operated by one or two persons in limited access areas. These advantageous transport features are the result of a balance between the base plate  270  weight, leverage available from the handle  280  and the chassis height  704  (FIG.  7 A), and the clearance  790  (FIG. 7B) between the tires  770  (FIG. 7B) and ground in the tool&#39;s operating position, specifics of which are given below. 
     As illustrated in FIG. 3, the hydraulic cylinders  210  have stationary ends  310  and moveable ends  320 . To accommodate the force applied by the cylinders  210 , the stationary ends  310  of the cylinders  210  are mounted on a heavy duty chassis base plate  270  (see also FIG. 4) and secured with conventional ⅝″×1½″ bolts  330 . The moveable ends  320  of the cylinders  210  are attached to a chuck base plate  510  (see also FIG. 5) with conventional 1″×3½″ bolts  342  threaded through chuck plate mounting sleeves  340  and holes  322  in the cylinder moveable ends  320 . In an alternative embodiment, the cylinders can be inverted so that the moveable ends  320  are attached to the chassis base plate  270  and the cylinder stationary ends  310  are attached to the chuck base plate  510 . This advantageously allows the chuck assembly to be mounted to the cylinder walls, somewhat reducing the overall extended height of the extraction tool. 
     FIG. 4 illustrates the chassis base plate  270 . In addition to supporting the cylinders  210  (FIG.  3 ), the chassis base plate  270  functions to supply stability and balance to the extraction tool  200  (FIG.  2 A), advantageously allowing the tool to safely support a person standing in various positions on the tool during operation, as described below with respect to FIG.  7 A. During operation of the extraction tool  200  (FIG.  2 A), the base plate  270  is positioned flush against the ground. The base plate  270  has substantial weight and a relatively large footprint, providing a stable low center-of-gravity for the tool and resistance to lateral movement. The large base plate footprint also prevents the tool from sinking into soft earth during application of its substantial pulling force. A further base plate feature is an open-face slot  450  that accommodates injection casing. This feature utilizes the casing to hold the extraction tool  200  (FIG. 2A) in place, providing further extraction tool stability. The open-face design also facilitates positioning the extraction tool  200  (FIG. 2A) on an installed casing by simply sliding the casing into the open-face slot  450 , eliminating the need to lift a heavy extractor apparatus over the top of an installed casing. 
     In the embodiment illustrated in FIG. 4, the chassis base plate  270  is constructed of 1″ thick hot rolled steel and weighs approximately 90 pounds. The base plate  270  has a 23″ depth  420 ; a 23″ front width  430  and a 15½″ back width  440 . Ignoring the open-face slot  450 , the base plate has an area of approximately 470 sq. in. The open-face slot  450  has a 7-¾″ length  452  and a 3″ width  454 . The slot  450  ends in a semi-circular shape  458  having a diameter matching the slot width  454 . The dimensions of the open-face slot  450  advantageously accommodate 1-½″ schedule  80  injection casings having 2⅛″ outer diameters. These casings are loose enough so that the tool  200  is easy to position on the casings, yet tight enough so that the casings provide support and stability to the tool. Mounting holes  460  are located in the face of the base plate  270  on either side of the slot  450  for attaching the dual hydraulic cylinders  210  (FIG. 3) to the base plate  270 . 
     FIG. 5 illustrates further detail of the chuck block assembly  220 . The chuck block assembly  220  retains and supports the gripping assembly  230  (FIG.  2 A). The combination of the chuck block assembly  220  and the gripping assembly  230  (FIG. 2A) provides a progressive chuck mechanism that securely holds an injection casing during extension of the hydraulic cylinders  210  (FIG. 3) and that releases the injection casing upon retraction of the hydraulic cylinders  210  (FIG.  3 ). The chuck block assembly  220  has a chuck base plate  510 , a pair of chuck blocks  520 , a chuck back plate  530  and chuck front plates  570  (only one shown), which together define an interior space configured to accommodate casings and the gripping assembly  230  (FIG.  2 A). 
     Shown in FIG. 5, the chuck base plate  510  has several functions. The chuck base plate  510  provides a connection to the hydraulic cylinder moveable ends  320 . The chuck base plate  510  supports the remainder of the chuck block assembly  220  and the associated gripping assembly  230  (FIG.  2 A). The chuck base plate  510  has an open-face slot  540  that accommodates injection casing, providing increased stability to the extraction tool  200  (FIG. 2A) in similar fashion to the chassis base plate  270  (FIG.  4 ), as described above with respect to FIG.  4 . Further, the base plate top face  550  on either side of the chuck blocks  520  provides a step for a person to stand on the extraction tool  200  (FIG. 2A) during operation of the tool. In the embodiment shown in FIG. 5, the chuck base plate  510  is made of 1″ thick hot rolled steel having a 6″ depth  514  and an 18″ width  516 . The open-face slot  540  has a 3″ width  542  and a 3½″ depth  544 , ending in a semi-circular shape with a diameter matching the slot width  542 . Support sleeves  340  are welded to the base plate bottom face  560  and mounted on the cylinder moveable ends  320  (FIG. 3) as described above with respect to FIG.  3 . 
     Also shown in FIG. 5, the chuck blocks  520  are machined with an angled face  521  at an angle  591  between 12° and 20° from the side face  529 . In a particular embodiment, the angle  591  is 15° degrees. The block bases  523  each have a 4″ width  594  and a 3″ depth  595 . The blocks  520  each have a 7″ height  596 . The block tops  522  have a 2″ width  598  and a 3″ depth  595 . 
     FIG. 5 also shows that the chuck back plate  530  is welded to each back face  527  of the chuck blocks  520 . The back plate  530  functions to add mechanical strength to the chuck blocks  520  and as a guide for positioning the wedges  810  (FIG. 8) of the gripping assembly  230  (FIG.  2 A). The back plate  530  is made of ¼″ thick cold or hot rolled steel and has a 11″ length  532  a 5″ height  534 . In a particular embodiment, a separate front plate  570  is welded to each front face  528  of the chuck blocks  520  (only one front plate shown). Like the back plate  530 , these front plates  570  function as a guide for positioning the wedges  810  (FIG. 8) of the gripping assembly  230  (FIG.  2 A). Each front plate  570  is made of ¼″ thick, 3″×4″ cold or hot rolled steel. 
     FIG. 6 illustrates the hydraulic control assembly  204 , which has a hydraulic valve  240  and a hydraulic flow distributor  250 . The valve  240  is standard 4-way control valve rated at 20 gpm (gallons per minute), such as item number 2010-B596 available from Northern Hydraulics, Burnsville, Minn. The control valve  240  is bolted to a mounting plate  610 , which, in turn, is welded to the handle  280  (FIG.  2 A). The valve  240  has an input port  622  and an return port  624  for pressurized hydraulic fluid from an external hydraulic power unit or “mule” (not shown). The power unit provides hydraulic fluid to the extraction tool&#39;s dual cylinders  210  at nominally 1500-2500 psi and 8-16 gpm. Under control from a valve handle  630  that positions a valve switch  632 , hydraulic flow from the input  622  is directed either to a first output port  640  or to a second output port  680 . 
     Also shown in FIG. 6, a flow divider line  644  connects the first output port  640  to the flow divider input  642  of the flow divider  250 . The flow divider  250  can be a two section, 9-18 gpm, rotary flow divider such as a Barns Hydraulics HALDEX brand device, item number 13006327 available from Bailey Manufacturing Corp., Knoxville, Tenn. The lower cylinder ports  650  are connected to the flow divider outputs  652  with the lower cylinder lines  654 . When the valve handle  630  is in a first position, the flow divider  250  evenly distributes the hydraulic pressure between the lower cylinder ports  650 , providing equal extension force in the two cylinders  210  during injection casing extraction. 
     FIG. 6 further shows the second output port  680  is connected to the upper cylinder ports  670  with the upper cylinder lines  684 . When the valve handle  630  is in a second position, the control valve  240  directs pressurized hydraulic fluid to the upper cylinder ports  670 , forcing retraction of the two cylinders  210  after a cycle of injection casing extraction, as described further below with respect to FIGS. 10A-D. 
     FIG. 7A illustrates the chassis  206 , which has the machine frame  260 , chassis base plate  270 , and handle  280 . The machine frame  260  is constructed of ½″ thick hot rolled steel and has an 8″ depth  742  and 20″ height  744 . The machine frame  260  is welded to the chassis base plate  270 . Welded on top of the machine frame  260  is a platform  710  made of ¼″ thick diamond plate having a 10″ depth  714  and 28″ width  712 . The handle  280  is made of 1″ steel pipe mounted through the platform  710 . The handle  280  is welded to the platform  710  and to the machine frame  260  along the length of the handle portion  752  below the platform  710 . The handle has a 34″ length  702  above the platform  710  and a 9½″ handle portion  752  below the platform  710 . Including the handle  280 , the chassis  206  has a 54″ overall height  704 . This advantageously provides sufficient leverage for an individual operator to move the tool  200  (FIG. 2A) between its operating position, shown in FIG. 2A, and its transport position, shown in FIG.  2 C. 
     FIG. 7A also illustrates that the chassis  206  has a number of structurally integrated platforms and steps. These advantageously provide safe footing for a person who may be required to climb on the extraction tool  200  (FIG. 2A) to disassemble spent injection casings and the pumping head located at a position high above the extraction tool  200  (FIG.  2 A). Further, during operation, a person may need to monitor pump pressure and stroke counts from meters which are also located high above the extraction tool  200  (FIG.  2 A). The operator platform  710  was described above. Also, a first operator step  720  is welded to the handle  280 , below the control valve mounting plate  610 . The step  720  is constructed of ¼″ thick diamond plate having a 3″ depth  714  and a 13″ width  712 . In addition, a second operator step  730  is provided at the top of the handle  280 . The second step  730  may be a diamond-hatched portion of the handle  280  or, alternatively, a small piece of ¼″ thick diamond plate welded to the handle top to allow sure footing. The platform  710 , first step  720  and second step  730 , in addition to the chuck base plate face  550  (FIG.  5 ), all provide footing for a person climbing on the extraction tool  200  (FIG. 2A) to facilitate set-up and operation of injection casing extraction. The first step  720  and platform  710  also add structural strength to the chassis  206 . 
     FIG. 7B illustrates the wheel assembly portion  290  of the chassis  206 . The wheel assembly  290  has turf tires  770  mounted onto wheels  760 . The tires  770  are sized 18.5″×8.5″×8″, such as item number 1219-G051, available from Northern Hydraulics, Burnsville, Minn. The turf tires advantageously allow the extraction tool  200  (FIG. 2A) to be transported between casing locations over typically rough terrain conditions. Each wheel  760  is mounted onto an axle portion  750 . These are available as an ATV Tire, Wheel, Hub and Axle Kit, item number 135012-G051, also from Northern. The axle portions  750  for each wheel are welded inside a 1½″ square tubing  780 , which is welded to the machine frame  260 . Holes are drilled along a portion of the length of the tubing  780  to gain access inside the tubing  780  to weld the axle portions  750 . The tubing  780  is advantageously mounted a 9″ distance  792  above the chassis base plate  270 . This provides a 1″ clearance  794  between the tires  770  and the ground in the tool&#39;s operating position. This clearance  794  prevents tire contact with the ground during operation of the tool, which would tend to unstabilize the tool as an operator platform. The clearance  794  also allows the tool be maintained in the transport position (FIG. 2C) without operator support, i.e, with the tool stable while at rest on both the tires  770  and the back edge of the chassis base plate  270 . 
     FIG. 8 illustrates one of the two identical halves of the gripping assembly  230 . The gripping assembly  230  has a wedge  810 , wedge retainers  830 , a hinge  840  and teeth  860 . The hinge  840  is a 3″ length of ½″ wall pipe having a ⅝″ opening. This pipe section is welded to a top face  522  (FIG. 5) of a corresponding chuck block  520  (FIG.  5 ). The wedge  810  is mounted between the wedge retainers  830  with a 3″×⅝″ bolt assembly  832  mounted through a ⅝″ retainer hole  834  (not visible) in each retainer  830  and a wedge through-hole  812  in the wedge  810 . The wedge retainers  830 , in turn, are attached to the hinge  840  with a 3×⅝″ bolt assembly  842  mounted through the hinge  840  and adjustment slots  836  in the retainers  830 . The ⅝″×2-⅝″ adjustment slots  836  allow the wedge  810  to be aligned in contact with the chuck block angled face  521  (FIG. 5) and within the interior space between the chuck blocks  520  (FIG.  5 ). 
     As shown in FIG. 8, the wedge  810  has an angled face  821  and a perpendicular face  823 , both extending from a wedge wide-end  825  to a wedge narrow-end  827 . The wedge  810  is machined from a bar of cold rolled steel. The wedge wide-end  825  has 2″×3″ dimensions, and the wedge length  826  is 7″. The angled face  821  is constructed at an angle  828  of between 12° and 20° with the perpendicular face  823  to match the angle  591  (FIG. 5) of the chuck block angled face  521  (FIG.  5 ). In a particular embodiment, the angle  828  is 15°. The teeth  860  are advantageously attached in a removable manner to the perpendicular face  823  via a pin (not shown) inserted through a {fraction (3/16)}″ wedge pin hole  814  and through a teeth retaining hole  910  (FIG.  9 ). This allows the teeth, which can be dulled, damaged or broken during tool operation, to be readily replaced. 
     A pair of wedges  810  (FIG. 8) forms a gripping assembly  230  that together with the chuck block assembly  220  (FIG. 5) provides a progressive chuck mechanism that secures an injection casing  1010  (FIG. 10B) between a pair of teeth  860  on an upward movement or extension of the cylinders  210  (FIG. 10B) and that releases the injection casing  1010  (FIG. 10D) on a downward movement or retraction of the cylinders  210  (FIG.  10 D). The retainers  830  retain the wedges  810  outside the chuck block assembly  220  (FIG. 2A) when disconnecting or connecting sections of injection casing. In one embodiment, a U-shaped piece of ⅝″ steel rebar can be welded to the top face  822  of each wedge  810  to function as a handles for moving the wedges  810  either outside or inside the chuck block assembly  220 . 
     FIG. 9 illustrates the teeth  860 , which is one of a pair of identical gripping elements for the gripping assembly  230 . The teeth  860  have a 1-¾″ length  934 , ⅝″ depth  936 , and 1-¼″ width  938 . The teeth  860  have a toothed face  920  containing multiple tooth rows  960 , a base  930 , a tongue  940  and a retaining hole  910 . The tongue  940  is set into a slot in the perpendicular wedge face  823  (FIG.  8 ). Further, a portion of the perpendicular wedge face  823  (FIG. 8) is recessed and accommodates an ⅛″ portion  932  of the base  930 . In this manner, the teeth  860  are retained by the wedge  810  (FIG. 8) and secured by a pin through the retaining hole  910 , as described above with respect to FIG.  8 . The teeth  860  are available as a Ridgid Tool brand Heel Jaw &amp; Pin, item number 182-6528, from Grainger Parts Operation, Northbrook, Ill. The above item is modified by cutting an additional tooth row  950  at one end of the toothed face  920 . This modification provides an additional gripping surface on the toothed face  920 . 
     One of ordinary skill will appreciate that other gripping elements can be mounted on the perpendicular wedge face  823  (FIG. 8) in lieu of the teeth  860  illustrated in FIG.  9 . Multiple gripping elements can be mounted on each wedge face. For example, each wedge face could have one or more wedge-shaped or contoured teeth with tooth rows that mate with the curvature of a casing wall. Alternately, each wedge face could have one or more rough-surfaced elements that provide sufficient friction to grip a casing. 
     FIGS. 10A-D illustrate the operation of the extraction tool  200 . FIG. 10A illustrates the extraction tool  200  positioned on an injection casing  1010  with the gripping assembly  230  in an open position. The extraction tool  200  is in its operating position with the steel plate  270  positioned against the ground and the tires  770  offset from the ground. The gripping assembly  230  is initially placed in an open position with the wedge retainers  830  rotated around the hinges  840  so that the wedges  810  are positioned away from the angled faces  521  of the chuck blocks  520 . The extraction tool  200  is then positioned on an installed injection casing  1010  by sliding the casing  1010  into the open-face slots  450 ,  540  of the chassis and chuck base plates  270 ,  510 . In this manner, the casing  1010  runs parallel between the cylinders  210  and within the interior space between the chuck blocks  520 . 
     FIG. 10B illustrates the extraction tool gripping assembly  230  in a closed position just prior to initiating extraction of the injection casing  1010 . The wedge retainers  830  are rotated around the hinges  840  so that the wedges  810  are positioned within the interior space formed by the chuck blocks  520 . In this closed position, each wedge face  821  and a corresponding chuck block face  521  are in mutual contact and the wedge teeth  860  (FIG. 8) of each wedge  810  are positioned generally flush against opposite surfaces of the wall of the casing  1010 . As the cylinders  210  push upward on the chuck base plate  510  at the beginning of an extension portion of the extraction cycle, the chuck blocks  520  are forced upward relative to the wedges  810 . This relative movement also creates a movement of the wedges  810  toward each other, resulting in a tight grip position with increasing sideways pressure of the teeth  860  (FIG. 8) against the casing  1010 . The relative movement of the wedges  810  continues until there is sufficient gripping force on the casing  1010  so that the extension of the cylinders  210  is translated into an extraction movement of the casing  1010  from the soil. The relative movement of the wedges  810  and resulting sideways pressure of the teeth  860  (FIG. 8) is advantageously self-limiting, increasing only to the point at which the casing  1010  begins to move from the ground, which avoids crushing the casing  1010 . Advantageously, the wedge teeth  860  (FIG. 8) have multiple tooth rows  960  (FIG. 9) that remain generally flush against the casing  1010 , distributing the pressure from the teeth  860  across an area of the casing wall rather than at a few points. These damage prevention features allow reuse of extracted casings. 
     FIG. 10C illustrates the extraction tool  200  just after the cylinder extension portion of an extraction cycle has been completed. In this position, the operator reverses the control valve  630 , causing the cylinders  210  to begin retracting. This reverses the process described with respect to FIG.  10 B. As the cylinders  210  withdraw at the beginning of the retraction portion of the extraction cycle, a downward force is applied to the chuck base plate  510 , the chuck blocks  520  move downward relative to the wedges  810 . This relative movement causes a movement of the wedges  810  away from each other to a loose grip position and decreasing sideways pressure of the teeth  860  (FIG. 8) against the casing  1010 . The relative movement continues until the gripping force on the casing  1010  is released and the gripping assembly  230  releases the casing  1010  as the cylinders  210  move to their retracted position. 
     FIG. 10D illustrates the extraction tool  200  just after the cylinder retraction portion of an extraction cycle. The gripping assembly  230  is loose around the casing  1010  and the cylinders  210  are in a position to begin extension under pressure, beginning another extraction cycle, as shown in FIG.  10 B. In this manner, the chuck block assembly  220  (FIG. 2A) and gripping assembly  230  provide a progressive chuck mechanism that alternately grips and releases a casing on each extension/retraction cycle of the cylinders  210 . The extraction tool  200  utilizes this progressive chucking effect to jack a casing from the ground in multiple stages. 
     The extraction tool  200  (FIGS. 10A-D) has been disclosed with respect to a compaction grouting application, where injection casings are pulled from the ground in stages. One of ordinary skill, however, will recognize the extraction tool&#39;s applicability to any application involving the extraction of casings, poles, pipes, rods, cables or other elongated articles (generally “shafts”) from a surrounding media, such as soil, stone, bricks, concrete, mortar or sand forming the ground, floors, walls, foundations or similar structures. The dimensions of the embodiments disclosed herein can be readily scaled to accommodate and extract shafts of smaller or larger dimensions than 1½″ schedule  80  casings, such as 2″ schedule  80  casings, sign poles, fence posts, utility poles, and oil-well casings to name a few. 
     A typical extraction application utilizes the extraction tool positioned on the ground, pulling a shaft vertically. One of ordinary skill will recognize that the extraction tool can be positioned against any external support structure or media and utilized to extract a shaft in any direction. For example, the chassis base plate could be positioned against a vertical wall to horizontally extract an embedded rod from the wall. Further, the extraction tool can be used for applications other than extraction, such as testing shaft strength or the holding strength of the surrounding media. For example, the extraction tool combined with a strain gauge could test the strength of a retaining wall tieback. Another non-extraction use of the extraction tool is to pre-stress a cable or pull one cable end so as to exert a force on a load at the other cable end. 
     The portable injection-casing extractor has been disclosed in detail in connection with various embodiments of the present invention. These embodiments are disclosed by way of examples only and are not to limit the scope of the present invention, which is defined by the claims that follow. One of ordinary skill in the art will appreciate many variations and modifications within the scope of this invention.