Patent Publication Number: US-2006008326-A1

Title: Apparatus to form columns of granular material

Description:
BACKGROUND OF THE INVENTION  
      This invention is a Continuation in Part of patent application Ser. No. 10/364,066, and the rest of the essential and non-essential information is hereby incorporated by reference. This application relates to apparatus to form columns of granular material by rotating a hollow shaft to form a cavity in soil for substantially the full length of the hollow shaft, with the means reasonably fixed in the near vicinity of the base of the apparatus to rotate the hollow shaft for at least a portion of its advance to a depth required for column formation. The outer dimension of the hollow shaft is configured to approximate the outer dimension of its forward end to install columns of granular material, i.e. “sand drains” when the granular material is predominantly sand; “micro piles” when the columns include granular aggregate, cement and water; as well as other columns of granular materials, which may include natural, crushed as well as powdered components. The equipment for column installation is configured to minimize weight and other force or forces applied to advance the cavity forming hollow shaft element, termed “mandrel”, which is rotated at least in part, in its advance to form the cavity in which the column of granular material is formed. Although the mandrel is shown herein to be circular for simplicity, the mandrel can have any desired external shape provided that its interior is open and reasonably continuous to permit passage of granular material. All major elements that power the advance and rotation of the hollow shaft are positioned at or near the base of the apparatus for ease of maintenance. The hollow shaft passing through the apparatus rotational drive element provides a degree of support during its withdrawal to maintain cavity shape enabling it to be filled with granular material to form the column.  
     DESCRIPTION OF THE PRIOR ART  
      Equipment used for the installation of columns of granular material in soil, such as in U.S. Pat. No. 5,647,690, has a hopper mounted on a cavity forming tool, and incorporates means to interrupt flow of granular material from the hopper after each column is formed to retain material to fill cavities at additional column locations. The dimensions and weight of the hopper and granular material contained to form more than one column requires movable or mobile apparatus to support and move the equipment to a succession of column locations. The column formation cycle, which includes moving from one column location to the next, is interrupted each time the quantity of granular material in the hopper mounted with the cavity forming tool diminishes to the point where granular material needs to be added to complete one or more subsequent columns. When the column of granular material has a circular drain, its diameter is may be on the order of 2″ or more and the cavity forming tool commonly at least 10′ in length, whereas micro-piles may be on the order of 3″ or more in diameter. With the weight of the hopper and contained material applied at or near the top of cavity forming tool as it advances into soil, the tool needs to be supported incrementally to avoid rupture due to overstress and structural fatigue associated with lateral deflection under the weight of the hopper and granular material during its advance into soil when the cavity forming tool is rotated.  
      Rotary drives positioned at the top of hollow shaft cavity forming tools are used to form cavities in soil. Where the column is of fluid saturated granular material, such as concrete and mortar, a conduit is connected to the cavity forming tool through which the fluidic material is pumped into the soil cavity, as is the case for “micr-piles” which are relatively small in diameter.  
      With no means available to coact with a flight auger, available rotary drives positioned at the lower end of support equipment used in column formation commonly drive a rectangular “Kelly Bar” to which a flight auger is formed at its forward end to excavate a cavity in soil. Whereas the Kelly Bar needs to be long enough to extend the flight auger full depth into the cavity for the desired column, the length of the auger section is limited to the space between the rotary drive and the ground surface after the Kelly Bar retracted. As cavity depth is often longer than the length of the flight auger section, the rotary drive is positioned as high as possible above the support unit with incremental and repetitive advance and retraction of the Kelly Bar and short section of flight auger needed to complete the excavation. Also, support of the formed cavity often is involved, requiring separate installation of pipe or other elements to allow the columnar material to be placed by separate equipment, making the operation time consuming and costly.  
     SUMMARY OF THE INVENTION  
      It is the object of this invention to reduce the cost of granular column installation and increase the durability of the cavity forming tool, such as by reconfiguring equipment disclosed in U.S. Pat. Nos. 5,647,690, 3,690,109 and others; to minimize the weight supported by the tool advanced into soil to form the cavity; to avoid interruption of a column forming cycle when the supply of granular material diminishes and needs to be replenished to continue column formation; to position the elements related to rotating the cavity-forming tool at or near the base of the apparatus to simplify and minimize the cost of its maintenance; and to permit column formation in a continuous manner to avoid delays and the expense associated with current column formation practice.  
      The term “soil” used herein denotes natural deposits and/or other material that may range from soft to hard. The procedure to form columns includes: a storage hopper at or near the base of the equipment to hold sufficient granular material, termed “backfill” to complete at least one column; a hollow shaft tool or drill, termed “mandrel”, supported by the equipment in a manner that enables force to be applied in its advance into and withdrawal from soil to form a cavity; means to rotate the mandrel during at least a portion of its advanvce; means to move backfill from the storage hopper to and through the mandrel to fill the cavity to form the column; and means to relocate the equipment and storage hopper as needed to form subsequent columns. Locating the hopper at or near the base of the equipment enables it to be replenished with granular material without interrupting the apparatus column forming cycle. The weight of the mandrel and conjoined elements may be sufficient to advance the tool into the soil; however, added linear and rotational force or forces may be applied to increase its rate of advance and reduce cycle time to form the cavity which is filled to complete the column. Variations in equipment arrangement as described, and means to expedite cavity formation and use of forces in the context of the invention will be evident to those familiar in the art.  
      Where granular backfill material cannot be moved by pumping, it is moved as needed from the storage hopper to a feed tank at or above the hollow shaft by a conveyor system, or by applying fluid pressure or a combination of these. In the present invention, where the feed tank is used it need only contain sufficient backfill to form a single column at a time. The feed tank, which need not be circular, is configured with an inlet to accept the granular material and an outlet through which backfill passes into the formed cavity and through the hollow shaft tool. A valve which may be remotely controlled, may be used at or below the outlet end of the feed tank and elsewhere to interrupt the flow of backfill to minimize waste. Where non-fluidic backfill is supplied to the feed tank, its inlet is closed and fluid under pressure is introduced in a manner to cause the backfill to move through the feed tank outlet into and through the hollow shaft tool and into the cavity formed as the hollow shaft tool is withdrawn from the soil to complete a column. The feed tank size of this invention is small as compared to that of U.S. Pat. No. 5,647,690, as it needs to contain granular material to form a single column at a time.  
      As the weight of the feed tank and granular material is less than required in U.S. Pat. No. 5,647,690, the frequency of repair and related costs and interruption to production are expected to decrease. The small feed tank may be easily separated from the hollow shaft tool until backfill is supplied to and through the hollow shaft tool during its removal from soil to form the cavity to complete the column. The feed tank is positioned to receive granular material without interfering with hollow shaft tool advance into and removal from the soil. As a limited quantity of granular material is needed to form a single column, the quantity needed in the feed tank may often be transferred during the time interval in moving the apparatus from one column location to the next so as not to interfere with production. Under specific circumstances, it may be expedient to store granular material in an intermediate feed hopper positioned at the upper end of the apparatus to permit supply the needed quantity granular material more rapidly to the feed tank. Where fluid material is used to form the column, granular material may be pumped from the supply source at the base of the apparatus through a pipe or other closed conduit and directly to and through the hollow shaft of the mandrel used to form the cavity for the required column as the mandrel or drill is withdrawn from the soil. A foaming agent may be added to granular material to render it suitable for pumping. While foaming agents may degrade over a period of time, commercially available defoaming agents may be introduced into the granular material to rapidly eliminate the effects of the foaming agent in the backfill of the completed column.  
      The need for a feed tank may be avoided when the granular material is moved by connecting the system through which backfill is pumped to the inlet of the hollow shaft tool in a manner to move the granular material into the cavity at a rate needed to it fill the cavity formed as the hollow shaft is withdrawn from the soil to properly complete the column. When a feed tank is used in conjunction with pumping, the backfill is pumped into the tank, where a defoaming agent may be used to restore the quality of the original granular material that is then moved into and through the hollow shaft tool to form the column as previously described.  
      The mandrel may be circular or angular, where one or more external projections may be applied axially to increase the rigidity of the hollow shaft tool to reduce its deflection and better support forces applied in its advance during cavity formation as well as to enable the mandrel to be rotated as it is advanced into and withdrawn from the soil. A mandrel with helical flight projections, termed “flight auger”, may be used to minimize soil displacement as described in U.S. Pat. No. 3,096,622. The force or forces for the linear and rotational advance into soil of the mandrel with and without projections may be applied to the hollow shaft element directly or indirectly through an element or elements conjoined to the mandrel. The shape of the mandrel as well as projections from the mandrel may be utilized to transmit force for its rotation in its advance into the soil as well as to define the shape of the cavity and column formed; and in this configuration the means applying rotational force to the mandrel may be positioned at any point along the mandrel length including the lowest accessible point of the equipment.  
      The invention also provides a configuration of a circular cavity forming tool, such as a flight auger, to be configured with notches so as to be rotated by a drive positioned at the low end of the support equipment in a manner to enable the substantially entire mandrel to be a flight auger rotated into the soil to form the required cavity by a single advance and withdrawal of the mandrel. Where a circular cavity is required, the segment of the mandrel below the rotary drive element after full mandrel withdrawal need not be notched as required for flights that pass through the rotary drive element. Where notched or circular elements are used for the full length of the mandrel, the mandrel is best rotated during withdrawal to develop a circular column. Where the formed column needs to reflect the mandrel shape with or without projections, the mandrel can be withdrawn without rotation. Elements and means to implement aspects of the invention not detailed in the drawings will be evident to those familiar in the art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be more fully understood by reference to the following descriptions in conjunction with the attached drawings. Whereas the drawings show the mandrel to be circular and hollow, its shape can be rectangular or take any other appropriate form, and needs to be hollow only when the formed cavity needs to be filled on its withdrawal.  
       FIG. 1  shows one embodiment of the present invention which utilizes a mandrel rotated by a drive positioned at or near the base of a movable or mobile support unit, a form of bucket conveyor used to fill a feed hopper, as well as a feed tank, a drill and guide elements related to installing columns of granular material, such as sand drains and micro piles, of a dimension that will accommodate passage of granular material. Although the mandrel shown has no lateral projects such as flights, lateral projects and/or flights can be added without altering the intent of  FIG. 1  to form a column of granular materials in soil rotating the cavity forming mandrel.  
       FIG. 2  shows a configuration of the feed hopper outlet where the backfill tank portal is weighted or spring loaded to be normally closed, and is forcibly opened by the outlet of the feed hopper at the feed tank. In this configuration, as the feed hopper obstructs passage of the feed tank, the feed hopper would be positioned sufficiently high on the equipment to permit the mandrel to be fully withdrawn from the soil. While not detailed in  FIG. 2 , the feed tank inlet may be configured to open and/or close by means other than the feed hopper outlet, in which instance the feed hopper outlet need not obstruct passage of the feed tank and as a result the feed hopper can be positioned at any location along the equipment that can be reached by the feed tank. In either configuration the movement of backfill from the feed hopper to the feed tank may be by gravity and may be assisted by vibration, air flow or other means.  
       FIG. 3  is an embodiment of the present invention which utilizes the drive system mounted at or near the base of the movable or mobile unit to rotate and advance the mandrel configured as a flight auger into the soil. Where the granular material is fluidic and can be pumped, the feed hopper is not needed in which instance the conveyor is replaced with a flexible hose connected to the mandrel and the fluidic material, such as concrete or material with a foaming agent, may be pumped directly to the mandrel and through its hollow shaft as the mandrel is withdrawn from the soil to form the column. Mandrel advance into the soil may be expedited by rotation of the flight auger, the shape of which induces axial forces. Axial forces may be applied directly to the elements that guide the alignment of mandrel advance when needed.  FIG. 3  has a flight auger mandrel cnfiguration which can be implemented by rotating a mandrel with axial projections as well as with different lateral projections.  
       FIG. 4  supplements  FIG. 3 , shows the mandrel and guide system elements when substantially fully advanced, as well as the positioning and support of the rotary drive system in the vicinity of the base of the apparatus.  
       FIG. 5  shows a possible feed tank arrangement to avoid the use of a feed hopper used in  FIG. 1  to guide the conveyed granular material through its inlet. While  FIG. 5  shows an arrangement with the swivel above the feed tank, indicating use of a rotating tank, the swivel system may be positioned below the feed tank, in which instance the tank need not rotate and granular backfill material can be more easily directed through the feed tank inlet.  
       FIG. 6  shows a mandrel with two of various possible forms of notches that can be applied to helical flights affixed to the mandrel in a manner to permit the flight auger to move axially through the rotational drive positioned in the vicinity of the base of the apparatus, as shown in  FIG. 3  and  FIG. 4 , as rotational force is applied to rotate the mandrel.  
       FIG. 7  shows a mandrel with at least one external projection, which may be discontinuous, and may include an internal or external conduit or pipe means to apply a defoaming agent or other medium to the granular material as it fills the cavity to form the column. Water or a fluidic mix, such as mortar, that can be moved by pump can introduced to and mixed with the granular material by rotating the mandrel as the granular material is moved into the cavity. An external axial projection is needed for the mandrel to be rotated through the soil, and extension of one or more axial projections beyond the outlet end of the mandrel may be cutters to scarify dense or stiff soil to enable the mandrel to more easily displace and advance into and through the soil.  
       FIG. 8  shows a variation of the helical flights in  FIG. 6  where the flights are shaped in a manner to be rotated by the drive system and also pass through the drive system as the shaft advances into the soil. In this instance, the flights may be in any irregular shape, even ovate, that can be engaged by and move axially through the rotary drive system. It is noted that where the formed cavity is required to be circular or any other shape, the segment at the cutting end of the cavity forming tool may be shaped to conform to the required column dimension. It is preferred that the cavity cross-section formed by the drill end of the mandrel be similar to that of the cavity supported by the mandrel configuration moving through the rotary drive at the apparatus base. Although at least one continuous axial projection is desirable, the projections passing through the drive need not be continuous as rotation of the drive element system are aligned axially along the shaft, and even discontinuous projection segment will mesh with the rotating drive shaft as the mandrel is advanced into the soil. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      The  FIG. 1  embodiment of the invention incorporates unit  1  to provide mobile support and operational capability to the equipment shown conjoined with granular material storage hopper  2 , track support  13 , and other elements that comprise the apparatus to install columns of granular material  11  in soil. Carriage  5 , which moves on track support  13 , may be used to align and support feed tank  12  which contains material  11  used to backfill the cavity formed by a pipe or hollow mandrel  15  to form column  14 . Hose/swivel combination  19 / 25  supplies air under pressure to feed tank  12  to aid in moving backfill  11  from feed tank  12  through mandrel  15  and into cavity  10  to form column  14 . Drive  40  supported on extension  47  at the lower end of unit  1  may be used to maintain the alignment of mandrel  15  during its advance and removal from soil  6 . Jib  7  and one or more pulleys  29  can be used to guide flexible cable  8  fixed to feed tank  12  to control travel of conjoined mandrel  15  toward and through soil  6  and its withdrawal outward from soil  6  in the column forming process. Drive  30  is positioned to operate conveyor  4  to move backfill material  11  from storage hopper  2  to feed hopper  9  on track support  13 . Granular material storage hopper  2  may be separated from unit  1  but needs to be available to or follow unit  1 . Feed hopper  9  containing backfill material  11  is aligned with its outlet  17  toward entry  18  to permit passage of backfill material  11  to open the entry of feed tank  12  as mandrel  15  is withdrawn from soil  6 . Delivery of material by cradles  45  on conveyor  4  to feed hopper  9  can be monitored, (system not shown) to deliver at least the amount of backfill  11  for transfer to tank  12  to form column  14 . With the introduction of air under pressure to tank  12  with entry  18  closed, backfill  11 , which may arch at outlet  32  at the base of tank  12  when air pressure is not applied, will be caused to flow rapidly as air flows through tank  12  into mandrel  15  to fill the cavity formed as mandrel  15  is withdrawn. The air pressure and backfill  11  support cavity  10  as column  14  is formed. Weight of mandrel  15 , tank  12 , backfill material  11  and other elements moving with arm  48  of carriage  5  and possibly other forces, such as cable  33  to carriage  5  bellow tank  12  and passing over pulley  34  at the lower end of guide support  13  attached to unit  1 , may be used to assist the advance of mandrel  15  into soil  6 . Cap  3 , which is initially open causing tank  12  to lose its pressure, is closed when mandrel  15  positioned at the point of column formation causes cap  3  to contact soil  6  which keeps cap  3  in position to close the forward end of mandrel  15  during its advance through soil  6  to required depth  26 . As mandrel  15  is withdrawn, soil cavity  10  leaves cap  3  causes unsupported and cap  3  opens as air and granular backfill material  11  move from feed hopper  12  through mandrel  15  to form column  14 . As such, the cross-section of column  14  substantially reflects the shape of cavity  10  and mandrel  15 .  
      Backfill material  11  is moved upward from storage hopper  2  to feed hopper  9  by means of conveyor  4  with cradles  45  sized and spaced as needed moved by drive  30 . Conveyor  4  can be activated at any time during column formation and during the time interval for relocating unit  1  to its next column location. Full mandrel withdrawal causes unsupported cap  3  to open mandrel  15  causing tank  12  to lose its pressure. With mandrel  15  fully extracted from soil  6  at the completion of column  14 , and feed hopper  9  with its outlet  17  aligned with inlet  18  open in tank  12 , backfill material  11  is again caused to flow from feed hopper  9  to feed tank  12  through entry  18  and the column forming process is repeated. The time to move granular material from storage hopper  2  by conveyor  4  to feed hopper  9  and feed tank  12  at the highest level of track support  13  may be controlled to closely reflect time between the start of soil cavity formation and the time unit  1  is positioned at its next location so as to avoid interrupting the column forming cycle. Storage hopper  2  may be refilled at any time, and is best that it hold sufficient material to have refilling done at scheduled breaks in production.  
      Feed hopper  9  may be eliminated in various ways. One way to alter the feed hopper  9  embodiment in  FIG. 1  is to temporarily separate feed tank  12  from mandrel  15  so as to hold feed tank  12  at the point on track support  13  where conveyor  4  can supply granular material  11  to feed tank  12 . Feed tank  12  with its granular material  11  can be conjoined with mandrel  15  before starting to withdraw mandrel  15  when it reaches required depth  26  in soil  6 . Valve  53 , which may be remotely controlled or otherwise activated, may be fixed at the bottom of feed tank  12  to minimize loss of granular material  11 , or at the top of mandrel  15  to control granular material  11  flow in forming column  14 .  
      One or more movable restraints  46  can be flexibly supported by guide  5  through a rope, chain or similar means  50  to establish a safe distance between successive points of mandrel support to avoid flexural overstress and possibility of related structural failure. Use of a different type of track support  13 , such as “box leads”, may have specially designed restraint  46  in fixed positions.  
       FIG. 2  shows a configuration of outlet  17  of hopper  9 , where normally closed pivoted portal  27  is shaped in a manner that on contacting the edge of inlet frame  23  of tank  12  pivoted portal  27  opens and with outlet  17  of feed hopper  9  shaped to open pivoted inlet portal  18  of feed tank  12  at the same time to permit material  11  to pass from feed hopper  9  to feed tank  12 . Vibrator  28  mounted on hopper  9  is one of various means to expedite flow of material  11 . Feed hopper  9  containing backfill  11  aligns with its outlet  17  toward entry  18  which opens on contacting inlet frame  23  of feedtank  12  to permit backfill  11  to move into feed tank  12  at entry  18  each time auger  21  is fully withdrawn from soil  6 . Under static conditions granular material  11  arches at the base of tank  12  and little or no flow of granular material  11  will occur through hollow shaft auger  21  without fluid flow or other force.  
       FIG. 3  is an embodiment of the invention incorporating unit  1  to operate the equipment and provide movable or mobile support for elements such as backfill material storage hopper  2 , track support  13 , and other components such as carriage  5  and arm  48  to support swivel  25  conjoining mandrel  15 . Mandrel  15  is configured with helical flights  35 , which are preferred out not required to be continuous, to form flight auger  21 . Storage hopper  2  mounted on or moving with unit  1  carries fluidic granular material  11  which is pumped through hose  22  connected and its more rigid segment or pipe  51  to the inlet of swivel  25  conjoined mandrel  15  supported by arm  48  of carriage  5  which slides along track support  13 . Valve  53 , which may be remotely controlled or otherwise activated, may be included on pipe  51  or any other appropriate location to interrupt and limit flow of fluidic granular material  11  to cavity  10  to form column  14 . The pump system, which may also provide fluidic granular material  11  through hose  24  to hopper  2 , may be separate from yet move with unit  1  to feed granular material  11  through hose  22  into the hollow of rotating mandrel  15  through swivel  25 . Flight auger  21  advances into soil by virtue of its weight and that of conjoined elements as well as a result of rotation of its helical flight inclined plane projections to create forces that in effect pulls itself into soil  6 . Cable  33  connected to arm  48  and riding over pulley  34  also may be used to aid advance of flight auger  21  in excavating cavity  10 . Drive  40  positioned on extension  47  at the base of unit  1  is used to rotate mandrel  15  through the aligned notches in flight  35 . Pulley  29  on jib  7  is used to guide flexible cable  8  to control travel of flight auger  21  in its advance into and withdrawal from soil  6 . The quantity of backfill  11  moved by elongated system  22  to feed hopper  9  and feed tank  12  may be controlled in a manner to limit waste in the quantity of granular material used to form column  14  that extends to column depth  26 .  
      To form a column, flight auger  21  is positioned at the point of column formation in a manner for cap  3  to be held in its closed position by the ground surface and soil  6  during its advance to depth  26 . The rotation and weight of auger  21  and tank  12  with backfill material  11  advance auger  21  into soil  6 . Cap  3  displaces to open the flow path of material  11  to cavity  10  formed as flight auger  21  is withdrawn from soil  6 . With cap  3  open in soil  6 , fluid pressure or other means applied at tank  12  causes and/or assists the flow of backfill  11  from tank  12  to flight auger  21  and into cavity  10  to form column  14 . Withdrawal of the auger  21  from the soil is normally done without reverse rotation, and column  14  reflects the cross-section and depth of flight auger  21  advance. Feed tank  12  loses pressure with cap  3  open above ground. One or more movable restraints  46 , can be flexibly supported by guide  5  through a rope, chain or similar means  50  to establish a safe distance between successive points of mandrel support to avoid flexural overstress and possibility of related structural failure. Use of a different type of track support  13 , such as “box leads”, may allow use of specially designed restraint  46  in fixed positions.  
       FIG. 4  shows a variation of the embodiment of  FIG. 1  and  FIG. 3 , where support  5  and drive system  40  are positioned on support  47  in the vicinity of the base of unit  1 , to permit the passage of backfill  11  through swivel  25  and mandrel  15  with radial, helical, axial and other forms of projection configuration to permit its rotation. It is noted that on full withdrawal of mandrel  15  from soil  6 , a portion of the mandrel may remain below output drive shaft  38 . The configuration of the mandrel segment below output drive shaft  38  may be configured specially when needed to better drill through one or more soil stratifications to be encountered in advancing mandrel  15  to form the required column. The mandrel segment at the forward end of mandrel  15  is likely subject to greater wear than the remainder of the mandrel, and as such the mandrel may be configured with a removable and placeable end segment.  
       FIG. 5  shows a configuration of which eliminates feed hopper  9  by configuring feed hopper  12  with an extended open collar  36  to guide granular material  11  moved in cradles  45  of by conveyor  4  or pumped from the storage hopper to feed tank  12 . Although not shown, feed tank  12  may be configured to receive backfill  11  pumped from storage hopper  2 , and tank  12  may be configured with a means to add defoaming agent to backfill  11  when needed to substantially counteract the effects of foaming agent added to backfill  11  to render it fluidic for pumping. Other elements included in  FIG. 5  generally reflect descriptions provided in  FIG. 1  and others.  
       FIG. 6  shows a configuration where helical flight  35  projects from circular mandrel  15 . One or more sections of helical flight  35  may be used and each may have one or more notches,  37 , positioned within hollow drive shaft,  38 , with key  39  attached to drive shaft  38  interior element  49  in a manner to rotate flight  35  and mandrel  15 . As the notch  37  is dimensioned to slide axially along key  39  which is fixed to drive shaft  38 , mandrel  15  and flight  35  can move within drive  40  as drive shaft  38  is rotated as well as when drive shaft  38  is not rotated. Drive  40  can be positioned at any location along the mandrel, including at or near the low end of support  13  in  FIG. 3  where mandrel  15  and helical projection  35  form flight auger  21 . A variation of this configuration involves using segments of flight  35 , in which instance the notch  39  effectively extends fully through flight  35  as illustrated where key  41  is fixed to shaft  38 . Key  39  and key  41  can be in any convenient shape and location as well as a desired length to engage projections of hollow shaft  15  and one or more flights.  
       FIG. 7  shows a configuration the mandrel  15  with one or more axial projections  41 . Withdrawal of the mandrel from soil  6  after advancing to the required depth with the outlet end of mandrel  15  closed by cap  3  results in an irregular cavity periphery,  44 . Where backfill  11  is moved through mandrel  15  by pumping backfill  11 , cap  3  is displaced permitting backfill  11  to fill the cavity to form the column. When the backfill is required to be treated with a defoaming agent, pipe  42  can be provided as a projection to permit introducing a defoaming agent into backfill  11  at the outlet end of mandrel  15 . In this instance cap  3  includes an added segment,  43 , such that when cap  3  is positioned to close the outlet end of mandrel  15  during its advance to prevent the intrusion of soil  6 , segment  43  closes the outlet end of pipe  42  to also prevent the intrusion of soil  6  into pipe  42 . The configuration permits water or any pumped material or mix, such as mortar, to be introduced to and combined with the granular material by rotating mandrel  15  as granular material  11  is moved into the cavity  10  to form the column  14 . Pipe  42  may be positioned externally and also used as a projection enabling mandrel  15  to be rotated by drive  40 . Whereas cap  3  may be smaller than the dimension of mandrel  15  for it to open freely into cavity  10 , with cap  3  seated at the inside of mandrel  15 , as illustrated in  FIG. 7 , plate  43  added to cap  3  to fit within constraint  52  to insure cap  3  is not dislodged from its closed position by rotational forces induced on the hinged cap as mandrel  15  rotates in its advance into and through soil  6 .  
       FIG. 8  shows the interior  49  of drive shaft  38  of drive  40  in two of various possible shapes to rotate mandrel  15 . Where flights  35  are fixed to mandrel  15  the flights can be irregularly shaped, and even ovate, so as to permit the interior of drive shaft  38  to and irregular form  49  to transmit rotary motion to mandrel  15  through flight  35 . Sections of helical flight  35  may be used and each may have one or more notches  37  positioned within hollow drive shaft  38  with interior element  49  shaped in a manner to rotate mandrel  15  through flight  35  as it is advance through soil  6 . As shape  37  of flight  35  slides axially along element  49  fixed to drive shaft  38 , mandrel  15  and flight  35  can move within drive  40  as drive shaft  38  is rotated as well as when drive shaft  38  is not rotated. Drive  40  can be positioned at any location along the mandrel, and preferably at or near the low end of support  13  as indicated in  FIG. 1  and  FIG. 3  where mandrel  15  and helical projection  35  form flight auger  21 . The separate segment in  FIG. 8  shows projection  41  attached axially to mandrel  15  which is used in a manner similar to flight  35  configured to transmit the rotational force of drive  40  through drive shaft  38  to rotate mandrel  15 , in which instance element  49  is shaped to contact projection  41  to rotate mandrel  15  in its advance into and through soil  6  to depth  26 .  
      Variations in methods, embodiments and equipment described and/or illustrated will be evident to those familiar in the art without deviating from the teachings presented in this disclosure. The use of shaft segments can be applied to the hollow shaft equipment of the present invention with modifications for the needed cavity formation and fill placement teachings of the present invention which may be further varied by applying selected teachings of U.S. Pat. No. 5,647,690 and others.