INTERLOCKING TUBULAR WITH SECTIONED PARTS AND RELATED METHOD

Abstract

An interlocking independent tubular with multiple circumferential sections allows a borehole to advance by encasing with a single pass, the structurally independent tubular. The independent tubular is single layered, having a major arc and a minor arc forming circumferential sections. The minor arc may be defined by less than 180 degrees, and the major arc may be a circumferential section defined by greater than 180 degrees. The major arc and minor arc align longitudinally to form the independent tubular. Installation may involve partially radially collapsing the major arc, inserting the major arc and minor arc through a previously installed tubular, reexpanding the major arc and connecting the major arc and minor arc to form the independent tubular downhole from the previously installed tubular, and joining the independent tubular to the previously installed tubular. The tubes may be joined by interlocking female and male ends of the tubes.

Claims

1. An interlocking tube for use in encasement of a borehole comprising: a first section extending in a longitudinal direction, the first section comprising a first sidewall defining a minor arc extending in a circumferential direction along a first arclength less than 180 degrees; a second section extending in the longitudinal direction, the second section comprising a second sidewall defining a major arc extending in the circumferential direction along a second arclength greater than 180 degrees; wherein the first section and the second section are separable for insertion into the borehole; and wherein upon insertion into the borehole, the first section is adapted for connection to the second section to form an assembled interlocking tube with an assembled sidewall extending 360 degrees in the circumferential direction.

2. The interlocking tube of claim 1, wherein the assembled interlocking tube comprises a first end with a first connector adapted to connect the assembled interlocking tube with a first adjacent interlocking tube on a proximal side of the borehole from the assembled interlocking tube.

3. The interlocking tube of claim 2, wherein the first connector is a non-threaded connector.

4. The interlocking tube of claim 2, wherein the assembled interlocking tube comprises a second end with a second connector adapted to connect the assembled interlocking tube with a second adjacent interlocking tube on a distal side of the borehole from the assembled interlocking tube.

5. The interlocking tube of claim 1, wherein the first section and the second section do not overlap one another in the assembled interlocking tube.

6. An interlocking tube for use in encasement of a borehole comprising: a first section extending in a longitudinal direction, the first section comprising a first sidewall defining a first arc extending in a circumferential direction; a second section extending in the longitudinal direction, the second section comprising a second sidewall defining a second arc extending in the circumferential direction; wherein the first section and the second section are separable for insertion into the borehole; and wherein upon insertion into the borehole, the first section is adapted for connection to the second section to form an assembled interlocking tube with an assembled sidewall including the first sidewall and the second sidewall, the assembled sidewall extending 360 degrees in the circumferential direction, wherein the first sidewall and the second sidewall do not overlap one another along the circumferential direction in the assembled sidewall.

7. The interlocking tube of claim 6, wherein the first arc extends in the circumferential direction an arclength less than 180 degrees.

8. The interlocking tube of claim 7, wherein the second arc extends in the circumferential direction an arclength greater than 180 degrees.

9. The interlocking tube of claim 6, wherein the assembled interlocking tube includes a first end with a first connection and a second end with a second connection, each of the first connection and second connection being adapted to connect the assembled interlocking tube to an adjacent interlocking tube.

10. The interlocking tube of claim 9, wherein the first connection and the second connection are non-threaded connections.

11. A system of interlocking tubes for use in encasement of a borehole comprising: a first tube including a first end with a first non-threaded connector; a second tube comprising, in an unassembled configuration, a first section extending in a longitudinal direction, the first section comprising a first sidewall defining a first arc with arclength less than 360 degrees extending in a circumferential direction; and a second section extending in the longitudinal direction, the second section comprising a second sidewall defining a second arc with arclength less than 360 degrees extending in the circumferential direction; wherein the first section and the second section are separable for insertion through an interior of the first tube; wherein upon insertion through the first tube, the first section is adapted for connection to the second section along at least one longitudinal seam to form an assembled configuration of the second tube; and wherein the assembled configuration of the second tube comprises a second end with a second non-threaded connector adapted to engage the first non-threaded connector to form a connection between the first tube to the second tube; wherein the connection includes a gap in the longitudinal direction and is adapted to allow angular deflection of the second tube from the first tube with respect to the longitudinal direction.

12. The system of claim 11, wherein an outer diameter of the first tube is equal to an outer diameter of the assembled configuration of the second tube.

13. The system of claim 12, wherein the first section defines an arclength of greater than 180 degrees and is adapted for radial contraction from the outer diameter of the assembled configuration to a smaller contracted diameter for insertion through the interior of the first tube, and the first section is further adapted for re-expansion to the outer diameter of the assembled configuration upon forming the assembled configuration.

14. The system of claim 11, wherein connection comprises the first non-threaded connector radially outside the second non-threaded connector.

15. The system of claim 11, wherein the second non-threaded connector is adapted to be expanded into an inner diameter of the first non-threaded connector to form the connection.

16. The system of claim 11, wherein the first connector and the second connector comprise corresponding connector walls, said connector walls extending in the longitudinal direction, and wherein at least one of the longitudinally extending walls includes an angle of deflection with respect to the longitudinal axis such that, within the connection, at least a portion of the connector wall of one of the first connector and the second connector is neither parallel nor perpendicular to a radially corresponding portion of the connector wall of the other of the first connector and the second connector.

17. The system of claim 16, wherein the angle of deflection is between 1 and 10 degrees with respect to the longitudinal axis.

18. The system of claim 11, wherein one of the first connector and the second connector comprises a convex connector wall extending in the longitudinal direction and the other of the first connector and the second connector comprises a concave connector wall extending in the longitudinal direction, such that within the connector, the convex connector wall and the concave connector wall are adapted for angular movement therebetween, allowing for relative rotation between the first tube and the second tube.

19. The system of claim 11, further comprising a shim extending partially around the circumference of the connection within the gap, thereby holding a relative angular position between the first tube and the second tube.

20. The system of claim 19, wherein the shim is crescent-shaped.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG. 1 is a schematic view of an assembled tube in accordance with one embodiment of the present invention;

[0055] FIG. 2 is a schematic view of the tubular of FIG. 1 with first section separated from a second section;

[0056] FIG. 3 is a schematic of the tubes installed in a tunneling system using a tunnel bore machine (TBM);

[0057] FIGS. 4A and 4B show a single tube using a connecting strip;

[0058] FIGS. 5A-5F show a series of schematic views diagraming a method of install a distal tube within and through a previously installed proximal tube;

[0059] FIGS. 6A-6C illustrate a cross sectional view of a distal tube being installed and connected to a proximal tube;

[0060] FIG. 7 is an enlarged cross-sectional view of first embodiment of a connection between adjacent tubes;

[0061] FIG. 8 is an exploded view of adjacent tubes including the connection of FIG. 7;

[0062] FIGS. 9A-9B illustrate enlarged cross-sectional views of a second embodiment of a connection between adjacent tubes;

[0063] FIGS. 10A-10C illustrate enlarged cross-sectional views of a third embodiment of a connection between adjacent tubes;

[0064] FIGS. 11A-11C illustrate enlarged cross-sectional views of a fourth embodiment of a connection between adjacent tubes;

[0065] FIGS. 12A-12B illustrate enlarged cross-sectional views of a fifth embodiment of a connection between adjacent tubes; and

[0066] FIGS. 13A-13B illustrate a system of tubes and installation thereof in a vertical drilling environment.

DETAILED DESCRIPTION OF THE INVENTION

[0067] The present invention relates to a system of interlocking tubes. This system may be used in a tunneling system to advance a borehole. For example, after a first tubular has been installed in the borehole, a second tubular may be inserted through the first tubular in a collapsed position, such as sliding within and through the previously installed tubular. This insertion of the second tubular may be accomplished in a section nearest the bottomhole of the borehole. The installed tubulars, being made up of a first section and second section, maintain their structural properties following installation and each tubular may be stationary once installed in accordance with the present invention.

[0068] Turning to FIG. 1 there is shown an interlocking tube 102. The interlocking tube 102 may comprise a first section 100 and a second section 101. Each of the first section 100 and the second section 101 may extend in a longitudinal direction along a longitudinal axis of the interlocking tube 102. A seam 110 may connect the first section 100 to the second section 101. This seam 110 may be a longitudinal seam and may extend in a longitudinal direction along the length of the interlocking tube 102. As shown in FIG. 1, two longitudinal seams 110 may be provided for connecting each side of the first section 100 and the second section 101 together.

[0069] The interlocking tube 102 may further include a first end 103 and a second end 105, the first and second ends being adapted for connecting to adjacent interlocking tubes, such as within a borehole. In addition, one or more seals 108, such as an outer diameter sealing ring, which may be waterproof, may be provided for sealing between an outside of the interlocking tube 102 and the borehole in which the tube is installed.

[0070] As shown in FIG. 2, the first section 100 and the second section 101 may be separable from one another, such as for insertion and/or installation in a borehole as described herein. For example, the first section 100 and the second section 101 may be separable along the one or more longitudinal seams 110. One or more reinforcing strips 117, such as a weld backing strip, may be provided for connecting the first section 100 and the second section 101. During the installation process, as described herein, the reinforcing strips 117 may be used to physically connect the first section 100 to the second section 101, such as by welding, and more specifically, by internal electrode welding.

[0071] The first section 100 may be defined by a first sidewall 104, and the second section 101 may be defined by a second sidewall 106. The first sidewall 104 may define a first arclength, which may be less than 180 degrees. Thus, the first sidewall 104 may define a minor arc. The second sidewall 106 may define a second arclength, which may be greater than 180 degrees. Thus, the second sidewall 106 may define a minor arc.

[0072] In an unassembled configuration, such as that illustrated in FIG. 2, the first end 103 of the assembled interlocking tube 102 (as illustrated in FIG. 1) may be composed of first end portions 103a, 103b, which may be located at the first ends of the first and second sidewalls 104, 106, respectively. Similarly, in the unassembled configuration, the second end 105 may be composed of second end portions 105a, 105b, which may be located at the second ends of the first and second sidewalls 104, 106, respectively.

[0073] In one aspect, the second sidewall 106 may be expandable and contractable in a radial direction, such as for installation in the borehole, as is described herein. For example, in an assembled configuration, the second sidewall 106 may have a first diameter equal to a diameter of the assembled interlocking tube 102. In an unassembled configuration, the second sidewall 106 may be adapted for contraction to a second diameter, smaller than the first diameter. Thus, the second section 101 may be contracted for insertion through a tubular formation (e.g. a borehole or a previously installed interlocking tube) having a diameter equal to (and in some instances smaller than) a final diameter of the interlocking tube 102 made of the second section 101 being installed.

[0074] One or more tube size modifiers or expansion and contraction devices 112 may be provided for expanding and contracting the second section between an assembled diameter and a smaller installation diameter. The expansion and contraction device 112 may comprise a mechanical, hydraulic, electronic, or other mechanism (e.g. a hydraulic cylinder). The expansion and contraction device 112 may be connected at one or more points within the second section 101, and thus may pull and/or push the second sidewall in order to expand and contract the diameter of the second section 101.

[0075] Turning to FIG. 3, a series of installed interlocking tubes 102, including first interlocking tube 102′ and second interlocking tube 102″, is illustrated within a borehole 115. A tunnel bore machine (TBM) 120 may be used to advance the borehole 115. The TBM may include a TBM tail 122 that may at least partially envelopes the forwardmost tube 102″. In one aspect, the TBM tail 122 may envelop at least a portion of the next proximal interlocking tube 102′. The seal 108 may provide a leakproof seal between the outer diameter of the tube 102 and the inner side of the TBM tail 122. As the TBM 120 advances the borehole 115 further along the bottomhole 116, the TBM tail 122 may envelope enough of a proximal tube 102′ to install the subsequent tube 102″ while protecting the proximal tube 102′ and maintaining a leakproof seal. As a distal tube 102″ is attached to a proximal tube 102′, a connection 200 may be made between the tubes, such as between a first end 103 of a proximal tube 102′ and a second end 105 of a distal tube 102″.

[0076] The series of interlocking tubes may be facilitated from a launch pit 113, from which new interlocking tubes may be carried within and through previously installed interlocking tubes 102 toward the bottomhole 116 for installation as the borehole 115 is advanced and secured. The series of interlocking tubes 102, having been connected and joined at respective ends of tubes, create a wholly and structural tunnel. The series of previously installed interlocking tubes 102 are shown being installed in place in respect to a top of ground 114 orientation, similarly found in tunnel and microtunnel installations, this orientation may be of any slope without departing from the spirit of the invention.

[0077] FIGS. 4A and 4B illustrate at least one manner of connecting consecutive tubes within a borehole. For example, a tube 102 may be provided with a male end 126 and a female end 127. The female end 127 of a proximal tube 102′ may be adapted for receiving a male end 126 of a distal tube 102″. In one aspect, the female end 127 may be provided with a connecting strip 125, which may at least partially overhand the female end 127. The connecting strip 125 may comprise a weld backing strip. Upon insertion of the male end 126 of a distal tube 102″ into the female end 127 of a proximal tube 102′, the connecting strip 125 may be used to weld or otherwise attach the distal tube 102″ to the proximal tube 102′. As illustrated in FIG. 4B, the first section 100 and the second section 101 of the tube 102 may each include a portion of the respective male and female ends 126, 127 of the tube.

[0078] Turning to FIGS. 5A-5F, there are shown a series of diagrams of the installation process to install new distal tube 102″ within and through previously set proximal tubes 102′. In one aspect, a radius gage 109 or other radius measuring tool may be used as shown and described.

[0079] Turning to FIG. 5A, a previously installed, proximal interlocking tube 102′ is illustrated, having a first end 103 and a second end 105. Through this proximal tube 102′, a second section 101, in a collapsed configuration, may be passed. The collapsed configuration of the second section 101 may be maintained by contraction of the expansion and contraction device 112 during transport of the second section 101 through the proximal tube 102′.

[0080] As shown in FIG. 5B, the second section 101 may be progressed to a point within the borehole such that the second end 105 of the second section 101 is aligned with the first end 103 of the proximal tube 102′. The expansion and contraction device 112 may be actuated to expand the second section 101 until the second end 105 of the second section 101 engages the first end 103 of the proximal tube 102′. In one aspect, the second end 105 of the second section 101 may comprise a profile that is a mirror image of a profile of the first end 103 of the proximal tube 102′. In another aspect, the second end 105 of the second section 101 may comprise a male profile adapted to engage a female profile of the first end 103 of the proximal tube 102′.

[0081] Once the second section 101 is expanded, the diameter of the second section 101 may be the same as the diameter of the proximal tube 102′. Expansion of the second section 101 may be measured or controlled by the radius gage 109. The radius gage 109 may include a biasing device, such as a spring for biasing the diameter of the second section 101 radially inward or radially outward. In another aspect, the radius gage 109 may comprise a stop, such as a set screw, a limited tongue and groove, a spring within a groove including a stop wall, or other means of limiting the expansion and contraction of the second section 101. The stop may allow the tube to be expanded to a predetermined diameter, rather than expanding to engage a sidewall of the borehole, a profiled ridge, edge, or other feature of the borehole.

[0082] Turning to FIGS. 5C-5D, once the second section 101 has been expanded, the first section 100 may be transferred through the proximal tube 102′. The first section 100 may be inserted through the proximal tube 102′, such as by a carrier 111 and brought into longitudinal alignment with the second section 101. As shown in FIGS. 5E-5F, the first section 100 may then be attached to the second section 101, such as by way of reinforcing strips 117, thus creating a fully formed distal tube 102″. The carrier 111 may then be removed for use in a similar installation of a subsequent interlocking tube.

[0083] The proximal tube 102′ and the distal tube 102″ may be connected by forming a connection 200 therebetween. The connection 200 may comprise a connecting strip 125 and/or male and female corresponding profiles as described herein. The male and female corresponding profiles may be non-threaded in nature.

[0084] FIGS. 6A-6C show a profile view of a collapsible and expandable second section 101 and first section 100 which may be used to create an assembled configuration of a distal interlocking tube 102″, connected to a proximal tube 102′, from the downhole perspective within the borehole. As can be seen in FIG. 6A, the expansion and contraction device 112 may be used to reduce the diameter of the second section 101 to an installation diameter for insertion through the proximal tube 102′. This installation diameter of second section 101 is smaller than a diameter of the previously installed proximal tube 102′.

[0085] As illustrated in FIG. 6B, once the second section 101 is positioned in the appropriate longitudinal position with respect to the proximal tube 102′, the expansion and contraction device 112 may be actuated to expand the second section 101 to the assembled diameter, which may be equal to the final diameter of the proximal tube 102′ and the assembled, distal tube 102″. FIG. 6C illustrates the installation of the first section 100, which may be joined to the second section 101 to form the distal tube 102″ as described herein.

[0086] The radius gage 109, which may be installed at a location adjacent the first end 103 of the second section 101, may include a biasing member 130, such as a spring or telescoping rod. The biasing member 130 may slide with respect to a track or guide 132. In use, one of the biasing member 130 and the track or guide 132 may include a stop, such as a set screw or a wall beyond which the biasing member may no longer travel or expand. This stop may limit diameter to which the second section 101 may expand, such as to a predetermined assembled diameter.

[0087] Turning to FIG. 7 there is shown an enlarged schematic view of connection 200 between a previously installed proximal tube 102′ and a subsequently installed distal tube 102″. The proximal tube 102′ may include a first connector 203, which may be positioned on a first end 103 of the proximal tube 102′. The distal tube 102″ may include a second connector 205, which may be positioned on a second end 105 of the distal tube 102″. As illustrated, the second connector 205 is radially inward from the first connector 203.

[0088] In profile, the first connector 203 may include a first connector wall 213, and the second connector 205 may include a second connector wall 215. Each of the first connector wall 213 and the second connector wall 215 may extend in a generally longitudinal direction. The first connector wall 213 may face radially inward, and the second connector wall 215 may face radially outward within the connection. Thus, as illustrated, the first connector 203 may be a female connector and the second connector 205 may be a male connector, as the second connector 205 is adapted to be received radially within the first connector 203. The first connector wall 213 and the second connector wall 215 may comprise complementary profiles that may include one or more extensions and receivers for fitting together and inhibiting relative longitudinal movement between the proximal tube 102′ and the distal tube 102″.

[0089] In one aspect, the connection 200 may include one or more gaps 118 therein. The gap 118 may extend in a longitudinal direction between at least a portion of the first connector 203 and the second connector 205. The gap 118 may be 1%, 3%, 10%, or greater than an overall length of the connection 200. In some instances, a plurality of gaps 118 may be provided, such as between profile features of the first connector wall 213 and the second connector wall 215. Thus, the complementary profiles of the first connector wall 213 and the second connector wall 215 may be adapted to allow a longitudinal space therebetween, such as within the connection 200. The one or more gaps 118 may allow for a defined amount of angular deflection between the proximal tube 102′ and the distal tube 102″, once the connection 200 is formed therebetween. The shape or spacing of the gaps 118 may be adapted to provide for angular deflection in a horizontal direction, a vertical direction, or both.

[0090] In a further aspect, a shim 107 may be provided for use in association with the connection 200. The shim 107 may be adapted for placement within a gap 118, thus forcing a relative angular position between the proximal tube 102′ and the distal tube 102″. The shim 107 may be of a shape adapted to hold a specific predetermined relative angular position between the proximal tube 102′ and the distal tube 102″. For example, the shim 107 may comprise a predetermined shape, which may extend at least partially in a circumferential direction around the annular connection 200. In one aspect, the shim 107 may extend around the entire circumference of the connection 200, while in other aspects, the shim 107 may extend only partially around the circumference of the connection 200. The shim 107 may vary in shape and/or thickness along its profile.

[0091] For example, as illustrated in FIG. 8, the shim 107 may be crescent shaped. Such a configuration may allow for the shim to hold the proximal tube 102′ and the distal tube 102″ farther apart at a portion of the circumference of the connection 200 in which the shim 107 is thickest, while allowing the proximal tube 102′ and the distal tube 102″ to be closer together along portions of the circumference of the connection 200 in which the shim 107 is thinner or not present within the gap 118, thus maintaining the angular deflection between consecutive tubes. The application of a shim 107 may allow for curved tunnels or microtunnels, horizontal directional drilling, and U-shaped, Y-shaped, and heel and toe drilling operations. As further illustrated in FIG. 8, the shim may be installed during the process of installation of the distal tube 102″, such as at the time of expanding the second section 101 to engage the first end 103 of the proximal tube 102′. Accordingly, the shim 107 may be captured within the connection 200 at the time of forming said connection 200.

[0092] Turning to FIGS. 9A-9B, a further embodiment of connection 200 between a previously installed proximal tube 102′ and a subsequently installed distal tube 102″ is illustrated. At least one of the first connector wall 213 or the second connector wall 215 may include profile that trends radially inward (i.e. at an incline) or radially outward (i.e. at a decline) in a direction from a proximal end to a distal end with respect to the longitudinal axis. This incline or decline may be linear. The incline or decline may define an angle of deflection of 1, 3, 5, or 10 degrees or greater. This incline or decline may allow for deflection within the connection 200, and therefore relative angular deflection between the proximal tube 102′ and distal tube 102″.

[0093] A deflection plane 220 may exist within the connection 200, which may define a plane beyond which the profile of a first or second connector wall 213, 215 may extend from a proximal to a distal direction in a linear incline or decline profile with respect to the longitudinal axis. In FIG. 9A, the deflection plane 220 is located on a proximal end of the second connector wall 215, such that the profile of the second connector wall 215 extends, from the proximal to the distal direction, at an incline with respect to the longitudinal axis. As illustrated in FIG. 9B, the deflection plane 220 may be located at a distal end of the second connector wall 215, such that the second connector wall 215 includes a profile defining a decline from its proximal end to its distal end. In one aspect, the inclined or declined profile of a connector wall may be constant around a circumference of the annular connection 200.

[0094] In another aspect, the incline or decline of the profile of the connector wall may change around a circumference of the annular connection 200. For example, at a first position on the circumference of the connection 200, the profile of the connection may be as illustrated in FIG. 9A. As the profile transitions in a circumferential direction around the connection 200, the profile may gradually and continuously shift from the profile of FIG. 9B, such as at a position 180 degrees apart from the location of the profile of FIG. 9A on the circumference of connection 200. Thus, the deflection plane 220 may shift from a proximal end of the second connector wall 215 to a distal end of the second connector wall 215. This transition of the profile of the connection may further facilitate relative angular deflection between adjacent tubes.

[0095] While FIGS. 9A-9B illustrate an incline associated with only the second connector wall 215, with the first connector wall 213 extending generally in the longitudinal direction, it is understood that either or both of the connector walls 213, 215 may include an incline or a decline as described. It is further understood that while either or both of the connector walls 213, 215 may include a linear incline or a decline, said connector wall(s) may also include projections and/or recesses adapted to engage the corresponding connector wall along that inclined or declined profile.

[0096] FIGS. 10A-10C illustrate that the deflection plane 200 may be located at a position other than at a proximal or distal end of the first or second connecting wall 213, 215. For example, the deflection plane 220 may be located at a position between a proximal end of the second connector wall 215 and the distal end of the second connector wall 215. FIG. 10A illustrates the deflection plane 220 at an intermediate point along the second connector wall 215, but closer to a proximal end. On a proximal side of the deflection plane 220, the second connector wall 215 includes a profile defining a linear decline with respect to the longitudinal axis, while on the distal side of the deflection plane 220, the second connector wall 215 includes a profile defining a linear incline with respect to the longitudinal axis. In FIG. 10B, the deflection plane 220 is located at an intermediate point along the second connector wall 215, but closer to a distal end. And in FIG. 10C, the deflection plane 220 is located at a midpoint along the second connector wall 215. In each instance, the incline or decline of the connector wall may define an angle of deflection of 1, 3, 5, or 10 degrees or greater.

[0097] As with FIGS. 9A-9B, the embodiment of any of FIGS. 10A-10C may remain constant around the circumference of annular connection 200, or the profile may transition from one to another of the illustrated profiles at different points around the circumference of annular connection 200. For example, the profile of connection 200 may appear as that of FIG. 10A at a first point on the circumference of the connection 200, then the deflection plane 220 may gradually and continuously transition to the location illustrated in FIG. 10C at an adjacent position along the circumference of the connection 200, and then further gradually and continuously transition to the location illustrated in FIG. 10B at a further position along the circumference.

[0098] Turning to FIGS. 11A-11C, the profile of a given connector wall around a deflection plane 220 may be non-linear from a proximal to a distal end. FIG. 11A illustrates a deflection plane 220 closer to a proximal end of second connector wall 215. The profile of that second connector wall 215 on a proximal side of the deflection plane 220 may define a non-linear decline, such as a parabolic or other curvilinear trend radially outward in a direction from the proximal end to the distal end. On a distal side of the deflection plane 220, the profile may define a non-linear incline, such as a parabolic or other curvilinear trend radially inward in a direction from the proximal end to the distal end. FIG. 11B illustrates the deflection plane 220 located at a midpoint of the second connector wall 215, while FIG. 11C illustrates the deflection plane 220 located closer to a distal end of the second connector wall 215.

[0099] As with the previous embodiments, the embodiment of any of FIGS. 11A-11C may remain constant around the circumference of annular connection 200, or the profile may transition from one to another of the illustrated profiles at different points around the circumference of annular connection 200. For example, the profile of connection 200 may appear as that of FIG. 11A at a first point on the circumference of the connection 200, then the deflection plane 220 may gradually and continuously transition to the location illustrated in FIG. 11B at an adjacent position along the circumference of the connection 200, and then further gradually and continuously transition to the location illustrated in FIG. 11C at a further position along the circumference.

[0100] In another embodiment, as shown in FIGS. 12A-12B, the connection 200 may include both first connector wall 213 and second connector wall 215 defining corresponding curvilinear profiles. In each of these embodiments, no projections or recesses are illustrated within the profile of the first and second connector walls 213, 215, though such projections and recesses may be present, as described in other embodiments. The deflection plane 220 may define a point at which the profile of a connector wall transitions from an incline curve to a decline curve. For example, FIG. 12A shows that first connector wall 213 may comprise a concave profile, while second connector wall 215 may comprise a convex profile. Similarly, FIG. 12B shows that first connector wall 213 may comprise a convex profile, while second connector wall 215 may comprise a concave profile. Thus, the coordination of first and second connector walls 213, 215 may form a ball and socket joint therebetween. In one aspect, a radius of curvature of the concave and convex profile of the first and second connector walls 213, 215 may be half of the diameter of the annular connection 200.

[0101] A ball and socket connection, such as that of FIGS. 12A-12B, may provide an interlocking joint due to the curvature of the radius being of sufficient size to prevent or limit relative longitudinal movement between adjacent tubes. The end joint may be machined from a thicker piece of steel casing than the tube itself to be able to cut a radius and provide the required strength for the designed tunnel. Once second connector 205 of the second section 101 is opened against the first connector 203 of a proximal tube 102′, welding along a seam between the second connector 205 of the first section 101 and the first connector 203 of the proximal tube 102′ may produce a pool of molten weld melt into the first connector 203 of the proximal tube 102′, such as because of a v-groove weld preparation. Therefore, a socket formed by the first connector 203 of the proximal tube 102′ may act as the weld back strip. Hence, a ball and socket, especially in the context of a metal pipe, may provide substantial pull-apart resistance compared to a bell and spigot on a concrete pipe.

[0102] The interlocking tubes 102 of the present invention are not limited to horizontal boring operations. For example, as illustrated in FIGS. 13A-13B, installation of consecutive tubes 102 is shown in a vertical drilling operation. As can be seen, a vertical drilling shaft 119 is used to drive a vertical drill bit 140 in order to progress a borehole 115. The vertical drill bit 140 may be applied at the bottomhole 116, thus progressing a length of the borehole 115 downward.

[0103] As shown in FIG. 13A, a first interlocking tube 302 has been installed near the level of the ground 114. A second interlocking tube 302′ is installed and has been connected to the first interlocking tube 302, such as by way of a connection 200 described herein. A second section 101 of third interlocking tube 302″ may be inserted through the previously-installed tubes, such as by way of vertical rigging 121. As described herein, the second end 105 of the second section 101 may be aligned with the first end 103 of the previously-installed second tube 302′. A first section 101 may be introduced through the first and second tube 301, 301′, to be joined with the first section 101. As shown in FIG. 13B, the third tube 302″ may be formed from the first and second sections 100, 101, and the assembled third tube 302″ may be connected to the second tube 302′, such as by way of a connection 200. Thus the tubing lining the vertical borehole 115 may be further extended, much as with the horizontal examples illustrated herein.

[0104] While the invention has been described with reference to specific examples, it will be understood that numerous variations, modifications and additional embodiments are possible, and all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention. Also, the drawings, while illustrating the inventive concepts, are not to scale, and should not be limited to any particular sizes or dimensions. Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.