Abstract:
An apparatus adapted for movement through a passage formed in the ground includes an elongate element and means for positioning a shroud around at least part of the elongate element for engagement against the periphery of the passage to provide a space through which the elongate element can move. The shroud is of flexible construction and is arranged to be progressively installed in position as the elongate element moves along the passage. The apparatus is adapted for introducing an inflation fluid into the region between the shroud and the elongate element in order to inflate the shroud and maintain it in engagement against the periphery of the passage.

Description:
The present application is a continuation of U.S. patent application Ser. No. 08/809,852 filed Apr. 3, 1997, now U.S. Pat. No. 5,971,667, which issued Oct. 26, 1999, under 35 U.S.C. § of PCT/AU95/00667, filed Oct. 6, 1995, with priority from Australia Application No. PN 8650 filed Oct. 7, 1994, priority under 35 U.S.C. §§ 120 and 371 therefrom is hereby claimed. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to apparatus for movement along an underground passage and to a method of moving an apparatus along an underground passage. 
     DISCUSSION OF THE PRIOR ART 
     The invention has been devised particularly, although not exclusively for use in an underground mining operation which utilises a mining head positioned at one end of an elongate element, such as a pipe string, whereby the mining head can be manoeuvred to, and through, an underground formation by movement of the elongate element. The mining head creates a passage along which the elongate element passes. A difficulty with this arrangement is that in situations where the passage is formed in soft sandy deposits and the like, material surrounding the passage can collapse around the pipe string with the result that the pipe string can become jammed in the ground. 
     Traditionally, underground mining operations of the type described above do not allow hard wiring of the mining head and rely on other means or control and operation of motors and telemetry. For example, “mud” motors running on pressurised bentonite fluid and the use of “mud” pulsing for telemetry purposes has limited the drilling capacity of this form of underground mining. If the mining head were able to be hard wired drilling capacity could be increased by the use of electro/hydraulic power and through direct control of the mining head by the use of telemetry cabling. 
     It would be advantageous to provide a shroud around the pipe string for lining the passage so as to prevent surrounding material from collapsing onto the pipe string. The apparatus and method of the present invention have as one object thereof to overcome the above-mentioned problems. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides an apparatus adapted for movement through a passage formed in the ground, characterised by an elongate element and means for positioning a shroud around at least part of the longitudinal periphery of the elongate element for supporting engagement with the periphery of the passage to provide a space through which the elongate element can move, the shroud being of flexible construction and being arranged to be progressively installed in position as the elongate element moves along the passage, and means for introducing an inflation fluid into the region between the shroud and the elongate element for inflating the shroud and maintaining it in supporting engagement with the periphery of the passage, wherein the shroud is delivered to the elongate element from a remote storage point for installation. 
     The shroud may be assembled from flexible material which turns around a location on the elongate element to provide an inner section which is conveyed with the elongate element and an outer section which is turned back with respect to the inner section and which provides the shroud, the outer section being fixed in relation to the passage whereby the flexible material turns around from the inner section to the outer section to provide the shroud as the elongate element moves along the passage. 
     The flexible material may comprise two or more elongate sections arranged such that the longitudinal sides thereof are joined one to another at the outer section to provide the shroud. 
     The longitudinal sections may have complimentary connector elements on their longitudinal sides for joining the longitudinal edges thereof together. 
     The flexible material may be turned around from the inner section to the outer section at turning means such as rollers moving with the elongate element. Conveniently, the rollers are mounted on the elongate element. The rollers may be accommodated within a protective casing positioned around a leading end of the elongate element. 
     The inner section of the flexible material may be accommodated in one or more longitudinal passages provided on the outer periphery of the elongate element. 
     In circumstances where the elongate element is required to be particularly long it is preferable that driving means be provided in or adjacent to the longitudinal passages thereby facilitating the travel of the inner section of flexible material. Still preferably, the driving means may be provided so as to specifically engage and facilitate the travel of the connector elements of the inner section of flexible material thereby facilitating the travel of the flexible material itself. 
     A seal may be provided between a fixed end of the outer section of the flexible material and the elongate element to define the outermost end of the shroud, the seal permitting sliding movement of the elongate element therethrough as it moves within the passage. 
     A further seal may be provided between the outer section of the flexible material and the elongate element to define an innermost end of the shroud. 
     The flexible material may be stored in roll form and unwound from the roll and progressively delivered to the elongate element as it advances through the passage to provide the inner section and thereby allows deployment of the shroud over long distances. The rolls of flexible material may be stored at ground level. 
     The inflation fluid may comprise a slurry such as Betonite slurry. 
     The present invention further provides an elongate structure adapted to be moved axially through an underground passage, comprising an elongate element and means for positioning a shroud around at least part of the longitudinal periphery of the elongate element as it advances through the passage for engagement against the periphery of the passage to provide a space through which the elongate element can move, the shroud being assembled from flexible material which is delivered from a remote storage point and turns around a location moving with the elongate element to provide an inner section which is conveyed with the elongate element and an outer section which is turned back with respect to the inner section to provide the shroud, wherein the outer section is fixed in relation to the passage, there being further provided means for introducing as inflation fluid into the region between the shroud and the elongate element. 
     Preferably, the outer section of the flexible material defines an inner region and an inflation fluid is delivered into the inner region to urge the outer section into supporting engagement with the periphery of the passage. 
     The present invention still further provides a connector means for use in the releasable hermetic fixing together of elongate sections of flexible material of which is comprised a shroud, the connector means comprising first and second connector elements of complimentary configuration whereby such may be pressed together and force applied to pull such apart acts to strengthen the grip therebetween, the connector elements requiring an unpeeling or unzipping action to separate same. 
     Each connector is preferably elongate and extends along one longitudinal side of an elongate section of flexible material. The first connector element may be provided in a male configuration with the second connector element provided in a complimentary female configuration. 
     The first and second connector elements further have complimentary longitudinal ridges and recesses provided thereon and arranged such that force applied to pull same apart acts to strengthen the grip of the second connector element about the first connector element. 
     The present invention also provides a method for facilitating movement of apparatus underground, characterised by the deployment and positioning of a shroud about at least a part of a longitudinal periphery of that apparatus as it advances through a passage created thereby for supporting engagement with the periphery of the passage, the shroud being assembled from a flexible material delivered to the apparatus from a remote storage point, an inflation fluid fluid being introduced into the region between the shroud and the apparatus for inflating the shroud and maintaining it in supporting engagement with the periphery of the passage. 
     The flexible material of the shroud is characterised in that the flexible material of the shroud is turned around a location moving with the apparatus to provide an inner section which is conveyed with the elongate element and an outer section which is turned back with respect to the inner section to provide the shroud, the outer section being fixed in relation to the passage. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood by reference to the following description of one specific embodiment thereof as shown in the accompanying drawings in which: 
     FIG. 1 is a schematic side view illustrating an underground mining operation utilising apparatus according to the embodiment; 
     FIG. 2 is a schematic view illustrating the head end section of the apparatus according to the embodiment and a mining head associated therewith; 
     FIG. 3 is a schematic view of a tail end section of the apparatus; 
     FIG. 4 is a cross-sectional view of part of the apparatus; 
     FIG. 5 is a cross-sectional view similar to FIG. 4 but showing further detail; 
     FIG. 6 is a fragmentary schematic view of the head end section of the apparatus; 
     FIG. 7 is a schematic view of the head end section of the apparatus showing deployment of the shroud; 
     FIG. 8 is a fragmentary schematic cross-sectional view of the head end section; 
     FIG. 9 is a schematic view illustrating connection means employed for forming the shroud, the connection means being shown in a separated condition; 
     FIG. 10 is a view similar to FIG. 9 with the exception that the connection means are shown in a connected position; and 
     FIG. 11 is a cross-sectional view of a pipe string and longitudinal sections of an apparatus in accordance with a second embodiment of the present invention within a deployed outer section of flexible material; and 
     FIG. 12 is a view similar to that of FIG. 11 with the exception that driving means are provided in the longitudinal passages to facilitate deployment of the flexible material. 
    
    
     DESCRIPTION 
     The embodiments are directed to apparatus for use in an underground mining operation for recovering materials from underground formations which are normally extremely difficult to access, such as deep leads covered by an overburden of mud, sand and basalt. 
     One proposal for accessing the underground formations involves a mining apparatus  10  of the type generally shown in FIG. 1 of the drawings comprising a mining head  11  provided at one end of a pipe string  13 . The mining head  11  is delivered to the underground formation where the mining operation is performed. The mining head  11  progressively excavates material from the underground formation and conveys the excavated material to the ground surface  15  by way of the pipe string  13 . The pipe string  13  and head  11  may be manipulated to manoeuvre the mining head  11  within the underground formation. The head  11  providing the whole or part of the motive power. The path of the mining head provides an access passage  16 , shown in FIG. 3, along which the pipe string  13  extends during the mining operation. The pipe string  13  extends from a structure  17  provided at a station  19  situated at ground level. The structure  17  may be erected on the ground or in a launch pit or recess within the ground. 
     The pipe string  13  comprises a plurality of pipe string sections which are connected one to another at the station  19  as the mining head  11  and pipe string  13  advance through the ground. Similarly, the pipe string sections are progressively dismantled at the station  19  when the pipe string  13  and mining head  11  are being retrieved from the ground. 
     The mining head  11  is delivered to the underground formation by progressively excavating material to create a path for itself and the pipe string  13  trailing behind it, as shown in FIG.  2 . The difficulty with this arrangement is that the passage  16  excavated by the mining head  11  can collapse about the pipe string  13 , particularly in circumstances where the surrounding material  14  is unstable, such as in soft sandy conditions. 
     The present embodiment provides a casing or shroud  20  about the pipe string  13  for lining the passage  16  so as to prevent the surrounding material  14  from collapsing onto the pipe string  13 . 
     The shroud  20  is formed from flexible material delivered in two sections  21 ,  22  and then assembled to form the shroud around the pipe string  13 . Each section  21 ,  22  of flexible material is stored in roll form at station  19  on the ground and is unwound from the roll as the pipe string  13  advances. 
     The pipe string  13  comprises an inner tube  31 , seen in FIGS. 4 and 5, defining a central flow path  33  and an outer tube  35  positioned around, and in spaced apart relation to, the inner tube  31  such that an outer flow path  37  is defined between the inner tube  31  and the outer tube  35 . The inner flow path  33  is provided to convey excavated slurry from the mining head  11  to the ground surface. The outer flow path  37  is provided to convey water under pressure from the ground surface to the mining head  11  for use in the mining operation. 
     The pipe string  13  further comprises a casing  41  mounted on the exterior of the outer tube  36 , as is best seen in FIG.  5 . The casing  41  provides a longitudinal space  43  which extends along the pipe string for accommodating service lines (such as power and telemetry cabling) which extend between the station  19  at ground surface and the mining head  11 . The space  43  may also incorporate sensing means  44  to measure distance between the pipe string  13  and the shroud  20  to provide a warning of any impending collapse at the shroud. 
     The space  43  also incorporates two longitudinal passages  48 ,  49  along which the sections  21 ,  22  of flexible material can be conveyed in a compact condition from the station  19  to the head end section  50  of the apparatus. 
     At the head end section  50  of the apparatus, shown in FIGS. 6 to  8 , there are provided two rollers  51 ,  52  one corresponding to each section  21 ,  22  of the flexible material. The rollers  51 ,  52  are so positioned that the flexible material which is drawn along the longitudinal passages  48 ,  49  in a compact condition each turns about itself on the respective roller to provide an inner section  53  and an outer section  55 . The outer sections  55  emerging from the longitudinal passages  48 ,  49  spread from the compact condition and are subsequently brought together in a manner to be described later to form the shroud  20 . 
     The rollers  51 ,  52  are accommodated in a casing  57  which surrounds the head end section  50 . The casing  57  is in spaced apart relationship with the pipe string  13  whereby an annular space  58  is defined therebetween. The casing  57  incorporates protuberances  59  to accommodate the rollers  51  and  52 , as best seen in FIG. 8 of the drawings. 
     The space  58  provides a path along which the outer section  55  of each section  21 ,  22  of the flexible material can be deployed with the longitudinal sides of the sections brought together to form the shroud  20 . 
     Each flexible section  21 ,  22  has two longitudinal sides provided with a connector means  61 , comprising a first connector element being a male element  61   a  and a second connector element being a female connector element  61   b . The arrangement is such that the male connector element  61   a  of each flexible section is arranged for hermetic engagement with the female connector element  61   b  of the other flexible section in the manner of a zipper. In this way, the longitudinal sides of the two flexible sections  21 ,  22  can be zipped together to form the shroud, as best seen in FIG.  4 . The longitudinal sections of the two sections  21 ,  22  are progressively brought towards each other and then subsequently zipped together by way of guide roller assemblies  58  positioned along the casing  57 . 
     The male connector element  61   a  comprises a head portion  100  and a trail portion  102 . The trail portion  102  is affixed to the longitudinal side of the flexible section  22 . The head portion  100  has provided thereon a series of recesses  104 . The female connector element  61   b  comprises a channel portion  106  and a tail portion  108 . The tail portion  108  is affixed to the longitudinal side of the flexible section  21 . The channel portion  106  has provided on an inner surface  110  thereof a series of ridges  112  complimentary to the recesses  104  of the male connector element  61   a . Upon zipping together of the connector elements  61   a  and  61   b  the head portion  100  is received within the channel portion  106 . 
     The ridges  112  and recesses  104  engage in a manner such that a force applied to pull the connector elements  61   a  and  61   b  apart causes the channel portion  106  to grip the head portion  100  with greater force by accentuating positive engagement of the ridges  112  and recesses  104 . 
     It is envisaged that means be provided to ensure that the connector means  61  is firmly fastened before it is released from the head  11 . These means can cover electrical, magnetic and visual means for checking before release. 
     A lower seal (not shown) is provided between the outer periphery of the pipe string  13  and the inner periphery of the shroud  20  at a location adjacent the region in the head section  50  at which assembly of the two sections  21 ,  22  is completed to form the shroud. The inner seal can be a complex of inflating and flexible seals which in turn can be used to pressure test the shroud  20  and connector means  61  before release from the elongate element. The lower seal is fixed in relation to the pipe string  13  so as to advance and withdraw with the pipe string, and slidingly engages the outer section  55 . 
     Similarly, an upper seal  81  is provided adjacent ground level or at the water table between the shroud  20  and the pipe string  13 , as shown in FIG.  3 . The upper seal  81  is arranged to permit sliding movement of the pipe string therethrough as it advances along the passage  16 . 
     The inner and upper seals define a sealed zone  90  within the shroud  20  which provides an inflation chamber  91 , seen best in FIGS. 4 and 5. An inflation fluid such as Betonite slurry is introduced into the inflation chamber  91  for the purposes of inflating the shroud  20  and urging it into engagement against the periphery of the passage  16  around the pipe string  13 . In this way, the shroud  20  provides support for the material  14  adjacent the periphery of the passage  16  for the purposes of preventing collapsing of the passage around the pipe string. The inflation fluid is introduced into the inflation chamber through inlet port  93  which communicates with a delivery line  95  accommodated within the casing  41  on the pipe string  13 . The delivery line  95  extends to the station  19  at ground level to receive the inflation fluid. 
     In operation, the apparatus according to the embodiment progressively deploys the shield  20  which supports the passage  16  formed by the mining head  11  as it advances through the ground. The shroud  20  is continually deployed as the pipe string  13  advances, the sections  21 ,  22  of flexible material being drawn along the longitudinal passages  48  in the casing  41  on the pipe string, and then being turned about themselves on the rollers  51 ,  52  and subsequently brought together to form the shroud in the manner described. With this arrangement, the shroud  20  is progressively deployed at the head end section  50 , the outer section  51  of the shroud being stationary with respect to the passage  16  once it has been deployed to form the shroud. 
     At the completion of the mining operation, the pipe string  13  and mining head  11  can be retracted along the passage  16 . During retraction of the pipe string and mining head, the sections  21 ,  22  of flexible material are also retracted and returned to the rolls on which they are stored. During the retraction process, the connecting elements  61  unzip with respect to each other and the sections  21 ,  22  are drawn into and along the longitudinal passages  48  within the casing  41 . 
     A cleaning means (not shown) may be provided for performing a cleaning operation on the sections  21 ,  22  of flexible material before they are returned to the roll form. The cleaning means may comprise sprays from which a cleaning fluid such as water is sprayed onto the sections. 
     In FIG. 11 there is shown a second embodiment of the apparatus of the present invention. The embodiment is substantially similar to that of FIGS. 1 to  10  and like numerals denote like parts. The second embodiment comprises a pipe string  120  substantially circular in cross-section in which is provided the inner tube  31  defining the central flow path  33 . 
     The pipe string  120  further carries two water lines  122  replacing the outer tube  35  of the first embodiment and the variously required service lines for power and telemetry cabling, shown generally at  124 . Still further, flotation or buoyancy material  126  may be provided therein so as to buoy the pipe string  120  within the inflation chamber  91 . 
     The longitudinal passages  48 ,  49  are provided within the pipe string  120  and such may also have the sections  21 ,  22  of flexible material conveyed therethrough in a compact condition. The operation of the second embodiment is substantially the same as that of the first embodiment. A delivery line  128  for cleaning water is shown within the pipe string  120 , the cleaning water being utilised to clean the sections  21 ,  22  of the flexible material before they are returned to the roll form. 
     In FIG. 12 there is shown a modification of the pipe string  120  in which longitudinal passages  130 ,  132  have the sections  21 ,  22  of flexible material provided with driving means comprising conveyor roller pairs  134  and power means  136  associated therewith. The roller pairs  134  receive therein the connector elements  61   a  or  61   b  and facilitate the travel of the inner section  53  of the flexible material within the passages  130 ,  132 . Such is advantageous when the flexible material is to be conveyed within the pipe string  120  over long distances. 
     From the foregoing it is evident that the embodiment provides a system for supporting the passage  16  to allow the pipe string  13  to move freely therealong without being jammed by collapsible material. 
     It is envisaged that the connector means for joining the longitudinal sides of the flexible sections  21 ,  22  may alternatively be replaced by a means for achieving either the stitching, welding or bonding together of the longitudinal sides. 
     It is still envisaged that the present invention will provide advantages in relation to both petroleum exploration and the re-lining of pipe-lines. With regard to the former the present invention should relieve the necessity for multiple sized drill casings and allow use in environments prone to collapse. The reverse telescoping nature of the casings presently used in these applications is prone to jamming in such environments. 
     The relining of piping presently often involves depositing a fresh surface within an inner surface of the pipe from which an old surface has been removed. Use of the present invention will allow a low friction surface to be deployed within the pipe. Preferably such would be comprised of polyethylene or similar material. 
     The shroud of the present invention may be deployed with an adhesive and possibly a filler material on the surface exposed to the inner surface of the pipe to facilitate placement. 
     A still further embodiment of the present invention may allow a soft flexible material to be deployed as the shroud, the material being such that once it is in position, it will harden independently or can, upon exposure to a suitable catalyst, cure or set such that the shroud becomes inflexible or rigid. 
     It is further envisaged that the apparatus and method of the present invention may be used in applications aimed only at tunnelling. For example, two substantially concentric shrouds may be deployed and between which a settable material can be injected, for example concrete. The concrete sets for form a pipe in situ. The innermost of the shrouds deployed in this manner may or may not be reclaimed. If left in situ the innermost shroud would actively prevent penetration of materials through the settable material and into the void of the pipe being created.