Patent Publication Number: US-9850715-B2

Title: Modular compaction boring machine system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/932,004, filed on Jan. 27, 2014, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The present invention relates generally to a boring device for creating a borehole by compaction boring. 
     SUMMARY 
     In one embodiment, the invention is directed to an apparatus for boring through a subsurface comprising a modular compaction boring device. The modular compaction boring device comprises a boring head to compress the subsurface, a first anchor, a second anchor, and a thrust module. The thrust module comprises a thrust member disposed between the first anchor and the second anchor, and a first section and a second section. The first section is moveable relative to the second section to push the head response to operation of the thrust module. 
     In another embodiment, the invention is directed to a compaction boring device. The compaction boring device comprises a frame, an extendable anchor, and a boring head. The frame comprises a first end and a second end wherein the first end is reciprocally movable axially relative to the second end. The extendable anchor is supported within the frame and extendable from a first position to a second position. The boring head is connected to the first end of the frame. The first end of the frame is rotatable relative to the second end of the frame to manipulate an orientation of the head. 
     In another embodiment, the invention is directed to a method for advancing a tool through a subsurface. The method comprises orienting a boring head, extending a first anchor, longitudinally extending the tool, extending a second anchor, retracting the first anchor, and longitudinally retracting the tool. 
     An apparatus for boring through a subsurface comprising a modular compaction boring device, a controller, an electrical power source, and an umbilical cable. The modular compaction boring device comprises a forward anchor module comprising a plurality of extendable anchor arms, an aft anchor module comprising a plurality of extendable anchor arms, an extendable and retractable thrust module disposed between the forward anchor module and the aft anchor module, and a rotatable boring head disposed proximate the forward anchor module. The controller directs extension of the plurality of extendable anchor arms of the forward anchor module and the aft anchor module, extension and retraction of the thrust module, and rotation of the boring head. The umbilical cable comprises a first end and a second end, wherein the umbilical cable provides power from the electrical power source to the modular compaction boring device. 
     BACKGROUND 
     Underground emplacement of tubular and filamentary utility structures is ordinarily accomplished by construction techniques such as open-cut trenching, Horizontal Directional Drilling (HDD), microtunneling, and percussive moles. Open-cut trenching, HDD, and microtunneling all involve removal of material from the surrounding soil matrix. 
     The absence of spoils, drilling fluids, and minimal mechanical disturbance of surface soil make compaction boring technically and environmentally desirable. Compaction boring may be a preferable option for underground construction in environmentally sensitive areas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic representation of the compaction boring device for use in the present invention. 
         FIG. 2  is a side view of a boring head for use with the boring device of the present invention. 
         FIG. 3A  is a sectional side view of an anchor module for use with the boring device of the present invention. 
         FIG. 3B  is a cut-away perspective view of the anchor module of  FIG. 3A . 
         FIG. 4  is a sectional side view of a rotation module for use with the boring device of the present invention. 
         FIG. 5A  is a sectional side view of a thrust module for use with the boring device of the present invention. 
         FIG. 5B  is a partial cut-away perspective view of the thrust module of  FIG. 5A . 
         FIG. 6  is a sectional side view of a slip indicator for use with the boring device of the present invention. 
         FIG. 7  is a cross-sectional end view of an umbilical cable for use with the boring device of the present invention. 
         FIG. 8  is a flow chart illustrating a boring method for use with the boring device of the present invention. 
         FIG. 9  is a perspective view of a launch frame for use with the boring device of the present invention. 
         FIG. 10A  is a perspective view of the carriage for use with the launch frame of  FIG. 9 . 
         FIG. 10  B is a cross-sectional side view of the carriage of  FIG. 10A . 
         FIG. 11  is a flow chart illustrating a launch method for the boring device of the present invention. 
         FIG. 12A  is a perspective view of the launch frame of  FIG. 9  with the boring device removed for clarity. 
         FIG. 12B  is a top view of the launch frame of  FIG. 12A . 
         FIG. 13  is a flow chart illustrating a launch method for the boring device of the present invention. 
     
    
    
     DESCRIPTION 
     For the sake of greatest clarity, the embodiment disclosed herein is described in terms of orientations and connections relative to the surface entry point and the boring head  100  of the modular compaction boring device  10 , as will be introduced below. That portion of an element nearest the surface entry point will usually be described using the words “uphole”, “rear”, or “aft”, whereas the portion of an element nearest the boring head  100 , which pierces the soil, will usually be described using the words “downhole”, “forward”, or “fore”. Thus, the assumed orientation is that of an observer standing at the surface entry point and looking through the borehole toward the boring head  100  as it engages the soil. These descriptors are used to provide greatest descriptive clarity of configurations used as disclosed herein. However, the descriptors “downhole”, “forward”, “fore”, “uphole”, “rear”, and “aft” are not intended as limitations of this invention and should not be interpreted as limitations. 
     With reference to the figures in general and  FIG. 1  in particular, shown therein is a system  12  for boring through a subsurface  11  in accordance with the present invention. The system  12  comprises a modular compaction boring device  10 , an umbilical cable  700 , a system controller  18 , and an electrical power source  16 . The boring device  10  moves through the subsurface  11  to form a borehole. The boring device  10  has a frame which may comprise various modules including a boring head  100 , a navigational device  200 , at least one anchor module  300 A and  300 B, a rotation module  400 , a thrust module  500  and a slip indicator module  600 . The boring head  100  is located at a first, or downhole end  13  of the boring device  10 , while the umbilical cable  700  is attached to the device at a second, or uphole end  14  of the boring device  10 . As shown in  FIG. 1 , multiple modules of each of the modular units above may be utilized for optimal performance of the boring device  10  in a particular soil condition or for a particular application. For example, multiple anchor modules  300  provide additional stability for the device  10 , while additional rotation modules  400  increase the rotation rate of the boring head  100 . Additionally, while the boring device  10  shown herein utilizes the navigational device  200 , short, simple bores may be performed without such navigational tools. Therefore, the modular nature of the boring device  10  allows the system  12  to be used in multiple configurations without departing from the spirit of this invention. 
     The umbilical cable  700  enables power transfer, data communications and other conduits between the surface and subsurface elements. The umbilical cable  700  connects to the second, uphole end  14  of the boring device  10 . The umbilical cable  700  may also contain elements that are routed through each module  200 ,  300 ,  400 ,  500 ,  600  to provide communication, power and fluid connection at each module. The electrical power source  16  may be located at the surface and provides power to the component modules through the umbilical cable  700 . The system control element, or system controller  18  monitors and controls the modules  300 ,  400 ,  500 ,  600  using data received from the umbilical  700  and navigational information transmitted from the navigational device  200 . The system controller  18  is depicted herein as a computer, but one should appreciate that the controller may comprise a local computer, a remote computer, a handheld device, remote control, or a combination of the above control mechanisms or other known controllers. Controller logic performed by the system controller  18  may be automated in response to signals generated at the boring device  10 . Further, while a robust umbilical cable  700  is contemplated for transmission between the system controller  18  and boring device  10  in the borehole, components of the umbilical cable  700  at the surface may be separated and traditional wiring for data communication and electrical conductivity may be used with the system controller  18  and electrical power source  16  without departing from the spirit of the invention. 
     The anchor modules  300  allow the boring device  10  to be held stationary relative to the subsurface  11 . As described herein, two or more anchor modules  300  may be provided. As shown in  FIG. 1 , a forward anchor module  300 A and an aft anchor module  300 B are utilized. The anchor modules  300 A,  300 B work in concert to provide a “hand-over-hand” engagement with the ground to provide reaction points for the device  10  to assist it in moving through the subsurface  11 . The rotation module  400  rotates the entire device  10  between the rotation module and the boring head  100 . Constant rotation of the boring head  100  keeps the direction of travel of the boring device  10  substantially straight and aids in compaction boring. Limited rotation may be utilized to orient the boring head  100  for steering the boring device  10 . The thrust module  500  extends or retracts a distance between the downhole end  13  and the uphole end  14  of the device  10 . 
     In operation, the boring device  10  is advanced by engaging the rear anchor module  300 B with the subsurface  11  while the front anchor module  300 A is in a retracted position that is not engaged with the subsurface. The thrust module  500  extends, causing the boring head  100  to move forward. The rotation module  400  is optionally active during thrust depending on the desired direction of advancement. After extension of the thrust module  500  a desired distance is achieved, the front anchor module  300 A is engaged, the rear anchor module  300 B is disengaged, and the thrust module is retracted to pull the second, uphole end  14  of the device  10  forward toward the boring head  100 . 
     The boring device  10  comprises a plurality of surface features  20  which have a slightly larger cross-sectional area than the boring device. One of ordinary skill will appreciate that the boring head  100  may create a borehole with a slightly larger radius than the cross-sectional area of the boring device  10 . While this may be advantageous for reducing frictional forces involving the boring device  10 , contact between the boring device and subsurface  11  may dissipate heat generated by internal components of the modules  300 ,  400 ,  500 . Thus, the surface features  20  are provided to establish and generate contact between the boring device  10  and the subsurface  11 . Preferably, the surface features  20  are disposed proximate motor elements inside the modules  300 ,  400 ,  500 , as is shown in more detail with reference to  FIGS. 3-5 . 
     With reference now to  FIG. 2 , the boring head  100  comprises an asymmetrical modified conic shape, commonly called a slant-faced bit. The boring head  100  comprises a nose  102 , a slanted face  104 , and a connection point  106 . The nose  102  preferably has a small cross-section such that resistance to thrust is reduced. The nose  102  is offset from a centerline  108  of the boring head  100 . The slanted face  104  may contain a flat surface feature  110  and contacts the ground such that the boring head  100 , when advanced without rotation (or with partial rotation over a desired arc), is deflected away from the centerline  108  in the direction of the nose  102  when advancing and compacting soil. With rotation of the boring head  100 , the nose  102  travels in a roughly spiral path about the centerline  108  and proceeds in a substantially straight line. The connection point  106  enables mechanical connection of the boring head  100  with other modules of the device. As shown, the connection point  106  comprises one or more holes  112  for a pinned connection. Other types of mechanical connections such as threaded joints could also be used. The boring head  100  does not require compressed air or hydraulic fluid, thereby avoiding the compressors and pumps that normally accompany HDD operations generally and percussive or hydraulic mole drilling in particular. 
     With reference again to  FIG. 1 , the navigational device  200  may comprise a beacon  202  and an orientation sensor  204 . Because there is no percussive hammer associated with the compaction boring device  10 , the navigational device  200  is not subjected to shock forces associated with such devices. The beacon  202  may be a known device as is commonly found as a part of a HDD downhole tool assembly. Such beacons  202  transmit a dipole electric field which may be received at an above-ground tracking receiver  206 . The tracking receiver  206  is then able to determine the position and orientation of the beacon, and therefore the boring head  100 , from the measured field, as described in U.S. Pat. No. 7,952,357, issued to Cole, et al. the contents of which are incorporated herein by reference. The orientation sensor  204  is used to determine the bearing of the boring head  100  in three dimensions and generally comprises a pitch sensor to determine the front-to-back (fore-to-aft) pitch of the navigational device and a roll sensor for detecting the roll orientation of the slanted face  104  ( FIG. 2 ) of the boring head  100 , often expressed as a position on a clock face. Information detected by the orientation sensor  204  may be transmitted to the system controller  18  through the umbilical cable  700 . Further, signals may be sent to the beacon  202  through the umbilical cable  700  to cause the beacon to transmit or cease transmission of a dipole magnetic field, or to adjust the amplitude or frequency of the emitted magnetic field. The above ground tracker  206  communicates the signal received from beacon  202  with the system controller  18  via wireless or wireline communication. 
     Anchor Module 
     With reference now to  FIGS. 3A and 3B , shown therein is an anchor module  300 . The anchor module  300  comprises a motor controller  19 , an electric anchor motor  302 , an anchor actuator  304 , linkages  305 , multiple anchor arms  306 , housing  308 , window seals  312 , and a ball screw  320 . Each module of the boring device  10 , including anchor module  300 , includes a motor controller  19 . The housing  308  comprises multiple windows  318 , and otherwise covers internal components of the anchor module  300 . In the anchor module  300 , the motor controller  19  communicates with system controller  18  ( FIG. 1 ), controls the speed, power and torque of the electric anchor motor  302 , monitors internal sensors, provides communication to downhole modules, and may monitor and measure orientation with respect to gravity, internal temperature, motor current, and other data. Motor controller  19  is configurable and may vary in configuration between modules  300 ,  400 ,  500 . 
     As shown, the electric motor  302  rotates ball screw  320 , causing the anchor actuator  304  to extend the linkages  305 . The linkages  305  may comprise wedges  319 , as shown, or other advantageous geometries, linked to the anchor actuator  304 . The wedges  319  move within the housing  308 , causing the arms  306  to pivot about pivot points  322  and extend through windows  318 . Thus, as wedges  319  are moved by the anchor actuator  304 , the anchors  306  move from a retracted position to an extended position or vice versa. Travel sensors, such as Hall effect sensors (not shown) may be utilized to determine the end-of-travel of wedges  319  such that anchors  306  are not moved beyond operational limitations. Wedges  319  and anchor actuator  304  may be configured so that power is required to maintain the anchors  306  in an extended position, so that in the case of a loss of power downhole, the anchors may retract. 
     Under direction of the system controller  18  and motor controller  19  and signals sent through the umbilical cable  700  ( FIG. 1 ), the electric motor  302  operates the anchor actuator  304  such that the linkages  305  move anchor arms  306  from a first, closed, position to a second, open, position. The linkages  305  may move all of the anchor arms  306  uniformly, or may adjust the anchor arms differently, depending on the type of linkage used. For example, a linkage  305  may extend each anchor arm  306  from front-to-back or back-to-front, enabling a subset of anchor arms to be extended. Many anchor arm  306  geometries are possible. The arms  306  may be paddles, hooks, or similar structures. Particular subsurface  11  materials, such as sand, gravel, loam or clay may require different anchor arm  306  structures to optimize performance. 
     In the closed position, the anchor arms  306  are contained entirely within the housing  308 . Thus, the anchor module  300  provides minimum friction with the subsurface. In the open position, as shown in  FIG. 3A , the anchor arms  306  extend beyond the housing  308  of the of the anchor module through the windows  318 . When extended, the arms  306  engage the wall of the borehole, compacting the subsurface  11  engaged by the arms, and remain engaged with the borehole wall until retracted in response to commands issued by the system controller  18 . The anchor arms  306  engage and compress the borehole wall, resisting rotational and thrust forces applied by other tool modules to hold the anchor module  300  firmly in place in the borehole. 
     The arms  306  may be spaced to cause the arms to engage the borehole in substantially the same locations or “footprint” along the borehole wall as the boring device  10  moves through the subsurface  11 . When such a configuration is used, the thrust module  500  must be coordinated to allow the creation and maintenance of such “footprints”. Repeated use of the same anchor locations helps preserve the integrity of the borehole wall and provides improved compaction in the anchor footprint. 
     As shown in  FIG. 3B , window seals  312  are provided to prevent debris from interfering with proper operation of internal mechanisms associated with anchor actuator  304  and anchor arms  306 . Window seals  312  may comprise elastomer seals snugly fit about anchor arms  306 . Window seals  312  may also comprise a protective element (not shown) such as thin sheet metal to prevent elastomeric window seals  312  from contacting the subsurface  11  and increasing frictional forces on the boring device  10 . A space for window seals  312  and associated protectors may be provided at the perimeter of the windows  318 , such that the anchor module maintains a substantially uniform radius, except for surface elements  20 . Alternative materials may be used for window seals  312 , and the method by which seals and protectors are held in place is not limiting on the present invention. 
     The anchor module  300  is attached at each end to adjacent modules by a pinned or other mechanical connection. Electrical power, data communication connections, and fluid connections (not shown) are provided through each end of the anchor module  300 . Surface feature  20  is provided proximate the motor  302  to promote heat transfer from within the anchor module  300 . 
     Rotation Module 
     With reference now to  FIG. 4 , the rotation module  400  is shown therein. The rotation module  400  comprises a motor controller  19 , an electric rotation motor  402 , a reducing gearbox  404  and an output shaft  406 . The rotation module  400  defines a first, uphole end  408  and a second, downhole end  410 . The motor controller  19  communicates with system controller  18 , controls the speed, power and torque of the electric rotation motor  402 , monitors internal sensors, provides communication to downhole modules, and may monitor and measure orientation with respect to gravity, internal temperature, motor current, and other data. 
     The rotation motor  402  may be a direct current motor receiving its operating power through the umbilical cable ( FIG. 1 ). The gearbox  404  responds to rotation of the motor  402  and produces torque forces to rotate the output shaft  406  relative to the first end  408  of the rotation module  400 . One skilled in the art will understand that the boring head  100  ( FIG. 1 ) is located downhole (forward) of the second end  410 . The rotation module  400  is attached to the boring head  100  and downhole modules at its downhole end  410  by a pinned or other mechanical connection. Electrical power, data communication, and fluid connections (not shown) are provided through each end of the rotation module  400 . Surface feature  20  is provided proximate the motor  402  to promote heat transfer from within the rotation module  400 . 
     The gearbox  404  is connected to multiple planetary stages  412  for reducing the speed and increasing the torque transmitted to the output shaft  406  by the motor  402 . The rotation speed of the downhole end  410  relative to the uphole end  408  is therefore related to the rotation speed of the motor  402  and the number of planetary stages  412  of the gearbox  404 . The motor controller  19  communicates with the system controller  18  ( FIG. 1 ) to regulate the rotational output of the motor  402  and therefore the rotational speed provided by the rotation module  400 . Multiple rotation modules  400  may be used in the boring device  10  to enable greater rotation rates of the drill head  100 . Further, the system controller  18  ( FIG. 1 ) may be utilized to operate different rotation modules  400  at different rotation rates. In addition to continuous rotation, the rotation modules  400  enable “clocking”, or orientation of the boring head  100  for steering of the boring device  10  without rotation, accomplished by applying thrust to boring head  100  without rotation. 
     Additionally, the rotation module  400  may be utilized to cause the boring head  100  to make small limited back-and-forth angular displacements in an operation known as “dithering”. These small displacements allow the boring head  100  to steer with less thrust force and reduce the risk of borehole slippage. Thus, the rotation module  400  may be able to reverse rotation direction to enable dithering of the boring head  100 . 
     Thrust Module 
     With reference now to  FIG. 5A , the thrust module  500  is shown therein. The thrust module  500  comprises a motor controller  19 , a motor  502 , a gearbox  504 , a thrust rod  506 , a barrel  508 , and a screw drive  510  comprising a torque tube  516  and a screw nut  518 . The motor controller  19  communicates with system controller  18 , controls the speed, power and torque of the motor  502 , monitors internal sensors, provides communication to downhole modules, and may monitor and measure orientation with respect to gravity, internal temperature, motor current, and other data. 
     The thrust rod  506 , as shown, is attached to the uphole end of the thrust module  500 , and nested within the barrel  508  which is attached to the downhole end of the thrust module. The screw drive  510  comprises a first end  512  and a second end  514 . The first end  512  is attached to the gearbox  504  via the torque tube  516 . The second end  514  is attached to the barrel  508  via the screw nut  518 . As shown, the first end  512  is uphole, and the second end  514  is downhole, though reverse orientations may be utilized without departing from the spirit of the invention. 
     The screw drive  510  is operable in an extension and a retraction mode. In extension mode, operation of screw drive  510  increases the distance between the first end  512  and the second end  514 , causing the thrust rod  506  to extend from the barrel  508 , increasing a length of the thrust module  500 . In retraction mode, operation of screw drive  510  decreases the distance between the first end  512  and the second end  514 , causing the thrust rod  506  to retract into the barrel  508 , decreasing a length of the thrust module  500 . As shown in  FIG. 5B , the barrel  508  may comprise grooves  526  and the thrust rod  506  may comprise a splined portion  528  such that torque transmission occurs along the length of the thrust module  500  during the entire thrust stroke, to reduce loss of rotational force applied through the thrust module by a rotation module  400  ( FIG. 4 ). One skilled in the art will appreciate that other torque transmission mechanisms enabling constant rotation of the thrust module  500 , such as geometric thrust rods and barrels, may be utilized without departing from the spirit of the invention. 
     Multiple thrust modules  500  can be mounted in tandem to control the thrust rate. In one embodiment, multiple thrust modules mounted in tandem can increase the thrust advance rate. Boring head  100  ( FIG. 1 ) advance may be done with or without rotation, so the thrust module  500  may support full machine torque while extending or retracting. With reference again to  FIG. 5A , the thrust module  500  further comprises a cable coil  522 . A person skilled in the art will understand that the internal wiring traveling through the thrust module  500  may be constructed to withstand the change in length associated with operation of the screw drive  510 . Therefore, the cable coil  522  provides slack for internal electrical wiring in communication with the umbilical cable  700  when the thrust module is retracted. When extended, the cable coil  522  is stretched such that longitudinal force associated with extension of the thrust module  500  is not applied to the internal wiring. Electrical power, data communication, and fluid connections (not shown) are provided through each end of the thrust module  500 . Surface feature  20  may be provided proximate the motor  502  to promote heat transfer from within the thrust module  500 . 
     The thrust module further comprises an end of stroke sensor  524 . The sensor  524  may comprise a Hall effect sensor or other sensing device that detects the approach of a magnet located on the barrel  508  to indicate the approaching end of thrust stroke to the motor controller  19 . Alternatively, limit switches, magnetic position sensors, optical sensors, or their functional equivalents (not shown) may establish minimum and maximum displacement of the screw drive  510 . 
     Slip Indicator 
     With reference now to  FIG. 6 , shown therein is the slip indicator  600 . The slip indicator comprises a slip sensor  602 , a sensor mount  604 , a magnet  606 , a housing  608 , a sleeve  610  and a slip controller  612 . The slip sensor  602  may comprise a magnetostrictive Linear Displacement Transducer (LDT) mounted on the sensor mount  604  inside the slip indicator housing  608 . The magnet  606  is mounted on the sleeve  610  placed about the housing  608  proximate the slip sensor  602 . The sleeve  610  engages the borehole wall and is slidable relative to the housing  608 . While the sleeve  610  has a circular cross-section in  FIG. 6 , other geometries are possible within the spirit of this invention. 
     If there is relative motion between the sensor  602  and the magnet  606 , a condition characteristic of tool slippage or relative movement in the borehole is indicated, and the slip sensor output sends a signal to the system controller  18  ( FIG. 1 ) from the slip controller  612 . Indication of slip may suggest that forces required to advance the boring device  10  in the subsurface  11  are greater than the holding capacity of anchor modules  300 . Actions such as dithering, slowing thrust, or rotating the anchors  306  to engage fresh subsurface  11  may be required. 
     Umbilical Cable 
     The umbilical cable  700  provides electrical power for the various modules and instrument assemblies in the borehole. It also provides the data path between the system controller  18  ( FIG. 1 ) and the modules  300 ,  400 ,  500 ,  600  and navigational devices  200  in the borehole. With reference now to  FIG. 7 , a cross-section of one embodiment of the umbilical cable  700  is shown. The umbilical comprises an electric conductor  702 , a data conductor  704 , and strength members  706 . An optical fiber  710  may also be used for high-speed data communication. The umbilical cable  700  may also include a small fluid conduit (not shown) for transmission of fluid, whether liquid or gas. The electric conductors  702  carry electrical power and may comprise copper or other conductive material. Data conductors  704  may comprise a twisted pair of copper (or other conductive material) conductors, miniature coax, optical fiber, or a combination thereof. 
     As shown in  FIG. 7 , one or more strength members  706  support tension forces needed to pull the umbilical cable  700  behind the device  10  ( FIG. 1 ) while drilling or when the umbilical cable is retrieved while pulling conduit, cable, pipe, other product or even recovering the compaction boring machine  10  itself through the borehole at the end of drilling operations. The strength members  706  may comprise aramid fiber or other lightweight, high tensile-strength materials. Strength members  706  may fill the interior of a cable jacket  712  not otherwise occupied by electrical conductors  702  and data conductors  704 . 
       FIG. 7  is representative of a general construction of umbilical cable  700 . However, alternative embodiments may be utilized, for example, utilizing more than one optical fiber  710  depending on data requirements. Such modifications do not depart from the spirit of the invention. The cable jacket  712  may be fabricated from a material selected to reduce friction between the umbilical cable  700  and the borehole, and may be water resistant. 
     Cable Reel Handling and Cable Connectors 
     The umbilical cable  700  may be spooled on a cable reel (not shown) to prevent knotting, fouling, and cable damage. The boring device  10  described may be utilized to create long bores and the umbilical cable  700  length may be thousands of feet. Consequently, a cable handling device (not shown) comprises a support structure for the umbilical cable  700  and the cable reel. The support structure may provide controlled cable  700  payout during drilling, motorized umbilical cable  700  take-up during tool retrieval or product pullback, and it may provide reaction force during retrieval or pullback. The cable handling device may be engineered such that it may retrieve the boring device  10  from the borehole with the anchor module  300  having arms  306  extended in the open position ( FIG. 3 ). 
     On very long bores, it may be necessary to use more than one reel of umbilical cable  700 . Therefore, an umbilical connector (not shown) is provided to connect one length of umbilical cable  700  to a second length. The umbilical connector must therefore be able to withstand pullback loads that are common to the umbilical cable  700  itself then the connector joins the two different umbilical cable segments together. 
     Electrical Power Source 
     With reference again to  FIG. 1 , the electrical power source  16  is described in more detail. The electrical power source  16  may comprise an electrical and electronic assembly. The electrical power source  16  may also comprise electrical and electronic assemblies providing operating power and data communication between the system controller  18 , cable reel (not shown) and its controller.  FIG. 1  represents the electrical power source  16  as a single object comprising a collection of different functional elements, but those skilled in the art will recognize that various functions may be subdivided between separate units without departing from the spirit of the invention. 
     The amount of operating power is depends primarily on the number, type, and operating sequence of the machine modules  200 ,  300 ,  400 ,  500 ,  600  in the borehole. More modules may require more electrical power, for example. The device may employ DC motors in the machine modules  300 ,  400 ,  500 . The compaction boring machine  10  utilizing a DC power supply minimizes the coupling of AC power line noise on power and data conductors and makes it possible to minimize peak dielectric stress on cable insulation. The use of DC motors and DC power is a design choice, as AC motors could be substituted in each of the modules  300 ,  400 ,  500  to provide operating forces. The umbilical cable  700  may include fiber optic cable for data transmission to avoid AC power line noise corruption of the data stream. 
     Voltage amplitude and total power to be supplied by the electrical power source  16  are determined by the total load and the total resistance of the umbilical cable  700 . 
     Optional Attachments 
     This disclosure should be understood to provide for attachment of equipment needed to enlarge the borehole. For example, after creating the initial borehole in the subsurface  11 , the boring device  10  may be attached to a backreamer (not shown), which is powered by connection to the umbilical cable  700 . Alternatively, the boring device  10  may be removed from the umbilical cable  700  at the second, or uphole end  14  of the boring device  10 , and a backreamer or similar device added directly to the umbilical cable. The umbilical cable  700  is then pulled back by the cable reel assembly and electrically powered by the umbilical cable, enlarging the borehole as the umbilical cable is pulled from the borehole and respooled on the cable reel (not shown). The backreamer (not shown) may contain a product attachment clevis for use during pullback. Backreamer pullback is known in the art. One backreamer of a type that may be used is shown in U.S. Pat. No. 5,390,750. The backreamer may also be an extendable part of the boring head  100  extended during pullback of the boring device  10 . 
     Machine Control 
     With continued reference to  FIG. 1 , machine control is provided at the system controller  18 . The system controller  18  may be a personal computer or other such device capable of machine control, operational sequencing of the various modules  300 ,  400 ,  500 , data communication with the navigational device  200  and slip indicator  600 , navigation and machine performance calculations, planning, and functional display of boring device  10  status. Data connections of the umbilical cable  700  are connected either directly or indirectly to the system controller  18 . Sliprings, optically or galvanically isolated functional elements, data routers, and similar devices may be used as needed by the particular data communication technology in use at the jobsite. Many data path options are known in the art, and the particular technology employed will depend on jobsite circumstances and umbilical cable  700  construction. 
     System controller  18  allows for automated control of module  300 ,  400 ,  500  functions. One such automatic sequencing is dithering of the boring head  100 . Dither steering coordinates thrust and rotation by use of small controlled angular rotation displacements of the rotation module  400 , directional reversal of the rotation module motor  402 , and thrust of the thrust module  500  in an established sequence. First, rotation of rotation module  400  and thrust module  500  are stopped. Thrust then simultaneously begins with rotation in a first direction. Upon reaching a predetermined terminal angular displacement of the boring head  100 , thrust is momentarily discontinued and rotation direction is reversed. Thrust is resumed as opposite rotation begins to another predetermined angular displacement of the boring head  100  and the operation repeats. Similar basic operations are amenable to automation, and such automation is a specific objective of the compaction boring device  10  and its system controller  18   
     Compaction Machine Operating Sequence 
     With reference now to  FIG. 8 , an exemplary method for the ordinary operation of the compaction boring device  10  of  FIG. 1  is shown therein. For simplicity, the configuration of the boring tool  10  includes only the boring head  100 , navigational device  200 , forward anchor module  300 A, rotation module  400 , thrust module  500 , aft anchor module  300 B and slip indicator  600  shown in  FIG. 1 . The process of  FIG. 8  is a steering push followed by a non-steering push. 
     The system begins at step  800  with thrust module  500  retracted and aft anchor module  300 B properly aligned to an existing footprint of anchor arms  306  in the subsurface  11 . The aft anchor module  300 B extends its anchor arms  306  to the open position at step  802  and the forward anchor module  300 A is in the closed position at step  804 . The rotation module  400  begins rotation at  806 . When the boring head  100  is at a desired steering position, rotation ceases at step  808 . The thrust module  500  extends at step  810 . The thrust forces the boring head  100  forward. Thrust is continued until a desired amount of “turn” due to the steering position of the boring head is achieved, then thrust ceases at step  812 . The rotation module  400  activates at step  814  and the thrust module  500  begins extending at step  815 . The rotation module  400  and thrust module  500  halt when the end of thrust stroke is reached at step  816 . 
     The forward anchor section  300 A is rotated by rotation module  400  until the anchor footprint is aligned at step  818 . The anchor arms  306  ( FIG. 3 ) of forward anchor module  300 A extend at step  820 . The anchor arms  306  ( FIG. 3 ) of aft anchor module  300 B retract at step  822 . The compaction boring machine  10  is then advanced by fully retracting thrust module  500  at  824 . Retraction of the thrust module  500  ceases at step  826 . The aft anchor module  300 B is then aligned by rotation of the rotation module  400  to bring the anchor arms  306  of aft anchor module into alignment with existing footprints of anchor arms in the subsurface  11  at step  828 . 
     Assuming straight boring is desired in the next “stroke”, the aft anchor module  300 B is extended at step  830 , the forward anchor module  300 A is retracted at step  832 . Continuous rotation of the rotation module  400  begins at step  834  and extension of the thrust module  500  begins again at step  836 . The process repeats with either the directional or straight steps as the boring head  100  is advanced along a bore path. 
     Basic operations of each module  300 ,  400 ,  500  may be coordinated to produce a borehole. No spoils are generated as the compaction boring device  10  moves through the subsurface, no drilling fluid is required, and the umbilical cable  700  is dragged through the borehole behind the compaction boring device  10  as the thrust module  500  retracts. 
     Flexibility of Configuration 
     The above operating sequences illustrate the basics of compaction boring device  10  operation with a minimum number of modules. In practice, the compaction machine may contain additional modules to provide functional redundancies to preserve the borehole, to improve operational flexibility, to improve boring speed, to increase rotation rate and to prevent operational difficulties. For example, the compaction boring machine may comprise one boring head  100 , two forward anchors  300 A, two rotation modules  400 , one thrust module  500 , three aft anchors  300 B, an umbilical cable  700 , an electrical power source  18 , and a laptop computer as the system controller  18 . Multiple slip indicators  600  may be utilized for detection of slip in the reverse direction. Multiple navigation devices  200  can allow for sensing of the first end  13  and second end  14  of the boring device  10 . The makeup of a particular boring device  10  for use with the system  12  of this invention will vary greatly depending on its needed characteristics for a particular boring operation. 
     Launch and Retrieval Frame 
     With reference now to  FIG. 9 , shown therein is a launch and retrieval platform  900  for use with the system  12  to launch the boring device  10  and to retrieve the boring device from the ground. The platform  900  comprises an external frame  902 , an internal frame  904 , and a carriage  906 . The external frame  902  is attached to machine anchors (not shown) and secured to the ground at an above-ground location when launching from the surface. When launching from an excavated pit, the external frame  902  is braced against the pit wall in the front and back at braces  907 . The internal frame  904  comprises a connection point  908  and parallel rails  910  with a plurality of castellations  912 . The carriage  906  comprises a module connection point  914 , a ratchet pawl  916  and guide rollers  926  ( FIG. 10 ). 
     The internal frame  904  is movable relative to the external frame  902 , or may be pinned to the internal frame  904  at the connection point  908 . The carriage  906  is moveable along the rails  910  of the internal frame. The ratchet pawl  916  is such that when the internal frame  904  moves in a first direction, such as away from a borehole, the carriage  906  will move over the rails  910  and castellations  912  of the internal frame. When the internal frame  904  is pushed in a second direction, such as when it is forced toward a borehole, the ratchet pawl  916  will engage with the castellations  912  and transmit thrust to the carriage  906 . 
     The platform  900  is operable in a first mode and a second mode.  FIG. 9  shows the launch platform in the first mode. In the first mode, a pilot thrust module  920  is placed within the internal frame  904 , and is attached at a first end  922  to the connection point  908  of the internal frame and at a second end  924  to the external frame  902 . As shown, the first end  922  is proximate a borehole entry point while the second end  924  is distal from a borehole entry point. The pilot thrust module  920  provides relative movement between the internal frame  904  and the external frame  902  to supply thrust forces to the carriage  906 . The pilot thrust module  920  may be identical to thrust module  500  described above. 
     In the first mode, the carriage  906  is attached its module connection point  914  to the modular compaction boring device  10 . As shown, the modular compaction boring device  10  comprises two anchor modules  300 , though any modules  300 ,  400 ,  500  may be present in the first mode. The module connection point  914  may comprise a pinned connection for transmitting thrust from the carriage  906  to the boring device  10 . The module connection point  914  may also connect to launch adaptor  925  as will be described with reference to  FIG. 10  below, to enable electrical connections between the boring device  10  and electrical power source  16  ( FIG. 1 ). 
     The launch frame  900  may be used both on a surface of the ground or in an excavated pit. When utilized on a surface of the ground, the distal end of the external frame  902  relative to the entry point in the ground will be elevated. The external frame  902  may utilize legs (not shown) so that the boring device  10  is put together at an angle relative to the ground. In a pit or against a wall, the entry point of the device  10  may be at a desired depth such that legs are not necessary and the boring device will enter the ground with an attitude equivalent to the bottom of the pit or surface of the ground adjacent the wall. 
     The carriage  906  is shown in more detail in  FIGS. 10A and 10B . The carriage  906  further comprises a launch adapter  925 , and a plurality of guide rollers  926 . The launch adapter  925  provides electrical, fluid and data communication to the boring tool  10  while the launch process is underway. The launch adapter  925  comprises a uphole connection  931  for connection to the electrical power source  16  ( FIG. 1 ) and a boring module interface  942  for providing the same connection to modules  300 ,  400 ,  500 . The launch adaptor  925  also supplies thrust and torque between the carriage  906  and boring tool  10 . The boring module interface  942  comprises a number of terminals  943  for data communication, electrical conductivity, fluid flow, etc. from the umbilical cable to an attached module. The boring module interface  942  further comprises a make-up connection point  944  for transmitting thrust between the carriage  906  and an attached module. As shown in  FIG. 10A , the make-up connection point  944  is located on a sidewall of the boring module interface  942  to avoid thrust transmission through sensitive terminals  943 . The guide rollers  926  allow the carriage to move along the rails  910  of internal frame  904 . 
     The ratchet pawl assembly  916  comprises ratchet pawls  930 , a ratchet pawl spring  936 , a pawl drive lever  934  and a pawl drive pin  932 . The ratchet pawl assembly  916  shown in  FIG. 10  provides two direction levers (downhole direction lever  928   a  and uphole direction lever  928   b ), though one may be utilized when locking engagement of the carriage  906  is desired in only one direction. The ratchet pawl spring  936  may be attached to the downhole direction lever  928   a  and to the pawl drive lever  934  when downhole ratcheting movement is desired. As shown specifically in  FIG. 10B , the ratchet pawl spring  936  ( FIG. 10A ) turns the ratchet pawl  930  such that it engages castellations  912  of the internal frame  904  in the desired direction. However, alternative configurations may be utilized without departing from the spirit of the ratchet pawl assembly  916 . When ratcheting movement of the carriage  906  is desired in the opposite direction, the pawl spring  936  is moved such that it attaches to the uphole direction lever bracket  928   b . Such attachment turns the ratchet pawl  930  such that it engages the castellations  912  of the internal frame  904  in the opposite direction. 
     In operation, the launch platform  900  operates in the first mode as shown in  FIG. 11 . The boring device  10  or a component module thereof is attached to the module connection point  914  at step  1000  with the carriage  906  at a distal end of the internal frame  904 . The pilot thrust module  920  is extended at step  1002 , causing the internal frame  904  to move toward the borehole, transmitting thrust through castellations  912  to the carriage  906  and pushing the boring device  10  into the ground. Full rotation may be optionally provided at step  1002  if generally straight travel is desired, while dithering or no rotation is utilized if steering is desired. At a desired length of travel, extension of the pilot thrust module  920  is stopped at step  1004 . The pilot thrust module  920  is retracted at step  1006 , pushing the internal frame  904  away from the borehole, allowing the carriage  906  to travel over the rails  910  to an adjacent set of castellations  912 . Extension of the thrust module  920  is resumed and the process is repeated at step  1008  until the carriage  906  reaches the last set of castellations  912 . The boring device  10  is then disconnected from the launch adaptor  925  at step  1010 , the carriage  906  is moved to a distal end of the internal frame  904  at step  1012 , and a new module  300 ,  400 ,  500  is attached to the boring device  10  at step  1014 . The entire process is then repeated to continue launching the boring device  10 . 
     With reference now to  FIGS. 12A and 12B , the launch platform  900  is shown without pilot thrust module  920  ( FIG. 9 ). When pilot thrust module  920  is not present, the launch platform  900  is in the second mode. In the second mode, the internal frame  904  is pinned to external frame  902  at its connection point  908  and therefore the internal frame does not move relative to the external frame. In the second mode, advancement of the boring device  10  ( FIG. 9 ) is caused by extension of a thrust module  500  ( FIG. 1 ) attached as a part of the boring device. 
     With reference now to  FIG. 13 , the operational sequence of the launch platform  900  in the second mode is shown. The boring device  10 , which includes a thrust module  500 , is attached to the launch adaptor  925  of the carriage  906  at step  1030 . The thrust module  500  (or modules, if more than one is included with boring device  10 ) is extended at step  1032 , advancing the boring device into the subsurface  11 . One will appreciate that in the second mode, the castellations  912  of the internal frame  904  act as a fixed reaction plate for the thrust operation. Full rotation may be optionally provided at step  1032  if generally straight travel is desired, while dithering or no rotation is utilized if steering is desired. At the end of its stroke, extension of the thrust module  500  is stopped at step  1034 . The thrust module  500  is retracted at step  1036 . During retraction, frictional forces between the subsurface  11  ( FIG. 1 ) and boring tool  10  are greater than the force required to advance the carriage  906  along the rails  910 . Therefore, retraction continues at step  1036  until the carriage  906  is moved to an adjacent castellation  912  at step  1038 . Retraction of the thrust module  500  then stops and the process is repeated at step  1040  until the carriage reaches the last set of castellations  912 . The boring device  10  is then disconnected from the module connection point  914  at step  1042 , the carriage  906  is moved to a distal end of the internal frame  904  at step  1044 , and a new module  300 ,  400 ,  500  is attached to the boring device  10  at step  1046 . The entire process is then repeated to continue launching the boring device  10 . 
     While launch module  900  enables launch of the boring device  10  at a surface of the ground or within a pit, other launch mechanisms are envisioned. For example, a conventional horizontal directional drill could be utilized to drill a pilot bore, and the boring device  10  placed within that pilot bore such that there are at least a rear anchor  300 B, thrust module  500 , and front anchor  300 A in the ground. Then the conventional operation of the boring device  10  as illustrated in  FIG. 8  may be utilized to advance the boring device. 
     One of ordinary skill in the art will appreciate that while the Figures show configurations for the subject invention, modifications to the particular shape and organization of the modular boring device  10  may be made without departing from the spirit of the disclosed invention.