Apparatus to form columns of granular material

Abstract

This invention, as a Continuation in Part of application Ser. No. 10/364,066, involves a drive syustem positioned at the base of an apparatus to install columns of granular material in soil. The present invention, with its rotary drive system positioned at the base of the apparatus, broadens the original invention by also utilizing a specially shaped cavity forming means to initially describe the cavity periphery and then form the cavity in a contiuous fashion, rather than the incremental fashion heretofore in use. Whereas the advance in the original involves advancing a hollow shaft element into soil at least in part by rotation, and adding equipment such as a storage and feed hoppers containing and feeding granular material to and through the hollow shaft element to fill the cavity in soil as the hollow shaft element is withdrawn to form a column, the present invention, with its rotary drive at the base of the apparatus can be used to produce the column in the same manner, but its novelty relates to being able to produce a cavity in soil by advancing the mandrel to its full depth with the rotary drive positioned at the base of the apparatus, as more fully described herein. While positioning the rotary drive on the support unit of the apparatus has been used, the position of the rotary drive has not been at the base of the support unit, and as the length of the element forming the cavity periphery in soil was limited to the distance between the rotary drive the ground surface, cavity formation heeded to be done incrementally and cavity support may have been required when soil is not self-supporting.

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.

Claims

1. Movable or mobile support apparatus to form a cavity in soil comprising a rotary drive means with a rotating hollow output shaft supported by said apparatus, said hollow output shaft is configured to mesh and coact with the external shape of a cavity forming shaft means in a manner to enable said cavity forming means to slide through said hollow output shaft as said cavity forming means advances into and through soil at least in part by rotation to define said cavity periphery, said cavity being formed as said cavity forming shaft means is withdrawn from said soil.

2. The apparatus of claim 1 applied to forming a column of granular material in soil by use of a conveyor means to supply said granular material from a storage hopper to a closable feed tank conjoined to a hollow cavity forming means with a movable cap at its forward end held in position by pressure from soil prevented from entering said hollow cavity forming means advancing into and through said soil to define said cavity, said feed tank is closed and pressurized with fluid as said hollow cavity forming means is withdrawn from said soil to form said cavity causing said cap to displace into said cavity as said granular material flows from said feed tank through said hollow cavity forming means into said cavity to form said column of said granular material in said soil.

3. Apparatus of claim 2 wherein said hollow cavity forming means has projections to move axially through said hollow output shaft as said projections which coact and mesh with said hollow output shaft to cause said hollow cavity forming means to rotate at least in part in advancing axially into and through said soil.

4. Apparatus of claim 2 with a feed hopper to hold a quantity of said granular material to supply said feed tank with said granular material to form at least one said column.

5. Apparatus of claim 1 wherein said cavity forming means is hollow and configured with at least one external projection to mesh and coact with said rotating hollow output shaft.

6. Apparatus of claim 4 where said projections orient axially along said hollow cavity forming means to define said cavity.

7. Apparatus of claim 4 wherein said projections orient in a helical manner around said hollow shaft to define said cavity.

8. Apparatus of claims 5 wherein said rotary drive means conjoins said axial said projections in a manner to enable said drive to rotate said hollow cavity forming means and define said cavity periphery.

9. Apparatus of claims 6 wherein said rotary drive means conjoins gaps in said projections in a manner to enable said drive to rotate said hollow cavity forming means and displace at least a portion of said soil upward to form said cavity as said hollow cavity forming means is withdrawn from said soil.

10. Apparatus of claim 2 wherein said conveyor means used to move said granular material from said storage hopper is positioned to discharge said granular material into a feed hopper configured to guide said granular material from said storage hopper into said feed tank.

11. Apparatus of claim 2 where movement of said granular material from said storage hopper to said tank is assisted by fluid pressure.

12. Apparatus of claim 2 wherein said granular material is made fluidic and able to be pumped by adding a foaming agent, and incorporating a pump means at an appropriate location to move said material as needed to and through the said hollow cavity forming means and into said cavity to form said column.

13. The apparatus of claim 11 wherein said granular material treated with a foaming is treated with a defoaming agent when its fluidic condition is no longer needed to form said column.

14. The apparatus of claim 2 wherein said granular material is predominantly sand and the column formed is a sand drain used to expedite consolidation of soft compressible soil.

15. The apparatus of claim 1 applied to form a column of wherein said granular material includes at least one additives to render said granular material fluidic so as to be conveyed by pumping from a storage hopper through a pipe or conduit to an inlet end of a hollow cavity forming means with a movable cap at its outlet end, with said cap held in position by the pressure of soil that is prevented from entering said hollow cavity forming means advancing into and through said soil axially and at least in part by rotation to define said cavity to the required depth, and withdrawal of said hollow cavity forming means to form said cavity causing said cap to displace into said cavity as said granular material flows through said hollow cavity forming means into said cavity to form said column.

16. The apparatus of claim 15 wherein said granular material is a mix which includes granular aggregate, cement and water to form fluidic concrete.

17. The apparatus of claim 15 wherein said granular material includes a foaming agent to render said granular material fluidic, and later adding a defoaming agent to undo the fluidic characteristic in the formed column.

18. The apparatus of claim 1 wherein said cavity is filled with suitable granular material to for a column in said soil.

19. The apparatus of claim 18 wherein said columns are contiguous to form a barrier in said soil.

20. The apparatus of claim 15 wherein said columns are contiguous to form a barrier in said soil.