Patent Publication Number: US-9840913-B1

Title: Device, system and method for reinforcing a tunnel

Description:
BACKGROUND 
     1. Technical Field 
     This disclosure relates generally to tunnel drilling and more particularly, but not exclusively, to reinforcing a tunnel during drilling thereof. 
     2. Background Art 
     Computing and communication networks have been expanding worldwide into an increasing number and variety of environments. One factor driving the proliferation of network infrastructure is the increase in speed and capacity that is provided by new generations of fiber optic network hardware. Another factor is the increasing number and variety of devices that can avail of a given access point coupled at an end of a network link. Still another factor is the lower cost, in terms of both materials and labor, which comes with more affordable technology and economies of scale. 
     Although networks are increasingly available in a wider range of environments, it is still typically preferable or even necessary to route at least some network cabling underground. As successive generations of technologies continue to trend toward fast, high capacity and affordable network solutions adaptable to a wider range of environments, there is expected to be increasing demand for incremental improvements in techniques to perform tunneling that facilitate the construction of underground network infrastructure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which: 
         FIG. 1  is a hybrid perspective view and functional block diagram illustrating elements of a system to reinforce a tunnel according to an embodiment. 
         FIG. 2  is a flow diagram illustrating elements of a method for reinforcing a tunnel according to an embodiment. 
         FIG. 3  is a functional block diagram illustrating elements of a device to drill and reinforce a tunnel according to an embodiment. 
         FIG. 4  is a functional block diagram illustrating elements of a device to condition soil for reinforcing a tunnel according to an embodiment. 
         FIG. 5  is a functional block diagram illustrating elements of a hardware platform according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of a device, system and method for reinforcing a tunnel are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     In an embodiment, a device that is configured to drill a tunnel includes mechanisms operable to form a structure (referred to herein as a reinforcement structure) comprising material through which the device has previously drilled. The reinforcement structure—e.g., a casing—may be formed by conditioning and compacting the drill material, which is subsequently extruded or otherwise ejected from a back end of the device. The drill device may thus deposit any of a variety of structures to reinforce a tunnel that is formed in its wake. For brevity, the term “capsule” is used herein to refer to such a device. 
     A capsule according to one embodiment may include a drill head to drill through soil, sand and/or other aggregate material and utilize at least a portion of the drilled material as a feedstock for processing to form a casing or other reinforcement structure that is built in a wake of the capsule&#39;s path. Unless otherwise indicated, “dirt” is used herein to refer to such drilled material, where other terms (“earth,” “soil,” “ground” etc.) variously refer to undrilled material from which dirt is obtained. Feedstock dirt may be compacted in the capsule and subsequently eliminated from the capsule under pressure to form a reinforcement structure that is to function as a supporting floor, ceiling and/or sidewall structure within the tunnel. Material eliminated to form a reinforcement structure is referred to herein as casing material. 
     In some embodiments, a compound may be mixed with at least some dirt to aid in formation of the casing material. The compound may include an epoxy or other material that is suitable to function as a binder for chemically and/or mechanically improving structural integrity that is to be provided with the compacted dirt. In some applications, a capsule functions to further lay conductive, fiberoptic and/or other cable in the tunnel. For example, the capsule may contain a spool to pay out cable during tunneling, where the capsule forms a casing material that is to jacket the cable and/or the tunnel as the capsule moves through the ground. 
       FIG. 1  illustrates elements of a system  100  to form a reinforcement structure in a tunnel according to an embodiment. System  100  may include a capsule  130  to drill a tunnel  124  at least partially through ground  120 , where other resources  110  of system  100  (or alternatively, coupled to system  100 ) are variously disposed, for example, on or above a surface  122  of ground  120 . During drilling in ground  120 , capsule  130  may form a reinforcement structure to reinforce tunnel  124 . One example of such reinforcement structure according to an embodiment is represented by the illustrative casing  126 , which is shown partially in cross-section. Casing  126  may be comprised at least in part of dirt that is received into capsule  130  as a result of the drilling in ground  120 . 
     For example, a drill head  132  of capsule  130  may encounter a volume  128  of ground  120  including soil or other such material. During drilling, dirt may be received into capsule  130  from volume  128 . In one embodiment, capsule  130  includes one or more intakes (not shown) disposed in or around drill head  132 —e.g., where the one or more intakes are selectively controllable or otherwise configured to receive from outside of capsule  130  dirt that is loosened by the drilling with dill head  132 . 
     At least a portion of such dirt may be conditioned and/or otherwise processed by structures in capsule  130  (such as the illustrative reinforcement unit  136 ) to form a casing material that is subsequently eliminated from capsule  130  to form a portion of casing  126  or another reinforcement structure distinct from casing  126 . Processing by reinforcement unit  136  may include, for example, shaking or otherwise breaking up dirt, sifting or otherwise separating dirt by size and/or mixing dirt with one or both of water and a binder. Alternatively or in addition, reinforcement unit  136  may compress casing material and extrude or otherwise eliminate such casing material from capsule  130  to provide reinforcement of tunnel  124 . In some embodiments, reinforcement unit  136  (or another component of capsule  130 ) may cure the casing material at least in part. The casing material may be exposed to heat, light (e.g., ultraviolet light), pressure, air and/or other such conditions to promote such curing. 
     In an illustrative scenario according to one embodiment, other resources  110 —variously included in or coupled to system  100 —may include a control sub-system (SS)  112  comprising logic (e.g., hardware and/or software) to exchange control communications with capsule  130 . Such communications may facilitate control sub-system  112  sensing, controlling or otherwise determining direction, depth, speed or other characteristics of drilling in ground  120  by capsule  130 . Control sub-system  112  may be configured to further control, or otherwise operate with, one or more other ones of resources  110 . By way of illustration and not limitation, resources  110  may further comprise a power sub-system  114  that is to provide electrical power to capsule  130 , a fluid sub-system  116  that is to provide one or more fluids to capsule  130  and/or a cable sub-system  118  to facilitate the laying of one or more cables in tunnel  124 . Control sub-system  112  may be coupled to control or otherwise communicate with some or all such power sub-system  114 , fluid sub-system  116 , cable sub-system  118  and/or any of a variety of other mechanisms that might be additionally or alternatively included in or coupled to resources  110 . In other embodiments, some or all of resources  110  are distinct from system  100 , and are instead to variously couple to and operate with system  100 . 
     One or more cables, hoses and or other connections—e.g., including the illustrative connection  134 —may variously couple capsule  130  to some or all of resources  110 . In an illustrative scenario according to one embodiment, one or more connections coupled between capsule  130  and resources  110  include a communication cable to facilitate communication between capsule  130  and control sub-system  112 . Alternatively or in addition, such one or more connections may include a power cable to deliver power from power sub-system  114  for operation of reinforcement unit  136 , drill head  132  and/or one or more other components of capsule  130 . In some embodiments, the one or more connections include a tube or tubes each to exchange a respective one of pneumatics, hydraulics, water and/or any of a variety of other fluids. Pneumatics or hydraulics may be drive operation of one or more pumps, actuators or other mechanisms of capsule  130 . Water may be provided via a supply line to capsule  130  for mixing with dirt to aid in formation of a casing material. A return fluid line may send from capsule  130  an effluent, slurry of other waste that comprises, for example, a mixture of water and other dirt that is not to be used to reinforce tunnel  124 . A connection may include a fiber optic or other cable that is paid out from capsule  130  or, for example, from cable subsystem  118 . In some embodiments, a connection provides capsule  130  with a liquid epoxy or other binder material to be mixed with dirt—e.g., in addition to or instead of water—to aid in formation of a casing material. Although certain embodiments are not limited in this regard, such a binder may instead be a dry material and/or may be stored locally in capsule  130 . 
       FIG. 2  illustrates elements of a method  200  to reinforce a tunnel according to an embodiment. Method  200  may be performed with a device or system including some or all of the features of capsule  130 , for example. In an embodiment, method  200  includes, at  210 , collecting dirt received in a capsule during drilling at a first end of the capsule. The drilling may form a tunnel that, for example, is to accommodate a communication line, power line and/or other connection. Collecting the dirt at  210  may include receiving the dirt through one or more intakes that are formed in or near a drill head of the capsule. 
     Method  200  may further comprise, at  220 , conditioning a first portion of the dirt in the capsule, including mixing the first portion with a binder to form a casing material. As used herein with respect dirt received in a drilling device, “conditioning” refers to processing of such dirt in aid of preparing the dirt for inclusion in a casing material. Such conditioning may include mixing the dirt with other material such as water and/or a binder. Alternatively or in addition, such conditioning may change an integrity (e.g., particle size), temperature, dryness or other characteristic of the dirt, or of a mixture that includes such dirt. 
     In an embodiment, method  200  further includes, at  230 , extruding the casing material from a second end of the capsule (e.g., opposite the first end) to form a reinforcement structure disposed along a side of the tunnel. The reinforcement structure may extend around a periphery of the tunnel. In some embodiments, another portion of the dirt collected at  210  is prevented from being included in any reinforcement structure that is to reinforce the tunnel. For example, the other dirt portion may be deposited directly into the tunnel, where the other dirt portion is outside of, but surrounded by, the reinforcement structure. Alternatively or in addition, another dirt portion may be transported, via a hose extending from the capsule, as part of a slurry, effluent or other waste to be removed from the tunnel. 
       FIG. 3  shows elements of a capsule  300  to provide a tunnel reinforcement structure according to an embodiment. Capsule  300  may include one or more features of capsule  130 —e.g., where mechanisms of capsule  300  provide some or all of the functionality of reinforcement unit  136 . In an embodiment, operation of capsule  300  is according to method  200 . 
     Capsule  300  may comprise a drill head  312  and a housing  314  in which is disposed mechanisms to operate drill head  312  for drilling of a tunnel into (e.g., through) soil, sand and/or other such material. In an illustrative scenario according to one embodiment, operation of capsule  300  may drill into ground  305  with drill head  312  and form in a wake of capsule  300  a casing  372  that is to reinforce a tunnel  370  created by such drilling. Drill head  312  may include structures comprising metal, carbon fiber and/or other suitable material—for example, including stainless steel coated with hardened carbon steel—the structures configured to rotate and, in some embodiments, to further oscillate back and forth in a linear motion. Drill mechanics  320  to operate drill head  312  may include, for example, an electric, pneumatic or other motor, such as the illustrative motor  322 , to drive rotation or other motion of drill head  312 . For example, a pneumatic pump may cause liquefaction as it pushes drill head  312  back and forth, vibrating an adjoining portion of ground  305  to allow drill head  312  to spin through more pliable material. In some embodiments, drill mechanics  320  further comprises a steering unit  324  to selectively change an angle of drill head  312  relative to housing  314 , which in turn may facilitate changing a direction of drilling by capsule  300 . In one illustrative embodiment, steering unit  324  includes a cable actuator to provide at least 2-axis (up/down and left/right) directional steering of drill head  312 . However, drill head  312  and drill mechanics  320  may include any of a variety of additional or alternative components to aid in drilling in ground  305 —e.g., where such components include mechanisms adapted from conventional drilling techniques. 
     Mechanisms for providing locomotion of capsule  300  (represented by the illustrative locomotion  326 ) may include one or more movable slats, wheels, pistons, treads, paddles or other such mechanisms to provide pushing, rolling and/or other means for moving capsule  300  along tunnel  370  during drilling. Such motion may result from selective application of force at an oblique angle against sidewalls of tunnel  370  that adjoin housing  314 . Locomotion  326  may be powered, for example, with pneumatics or hydraulics provided by one or more lines—represented by the illustrative connection  374 —coupling capsule  300  to resources (e.g., fluid subsystem  116 ) above ground  305 . Certain embodiments are not limited with respect to a particular mechanism by which capsule  300  provides for locomotion through tunnel  370 . 
     Motion of drill head  312  may break down a portion of ground  305 , resulting in dirt being pushed into, or otherwise collected by, one or more intakes  316  that are formed in or proximate to drill head  312 . Such dirt may be received by a dirt conditioning unit  350  that is to use at least a portion of the dirt as feedstock for the formation of casing  372 . Dirt conditioning unit  350  may perform sifting, separating, hydrating, mixing and/or other operations to create a casing material that includes dirt received via one or more intakes  316 . Production of the casing material may include dirt conditioning unit  350  mixing dirt with one or more fluids—e.g., water and/or a binder—that, for example, are provided to capsule  300  via one or more tubes  352  of connection  374  (or other such connections to above-ground resources). In some embodiments, dirt conditioning unit  350  is further coupled to send from capsule  300  waste material that is not to be included in the casing material. For example, one or more return lines  354  may send out through tunnel  370  a slurry, effluent or other mixture of water and waste dirt. The casing material produced with dirt conditioning unit  350  may be provided to a compactor  360  of capsule  360 . Compactor  360  may include an annular (or other) die  364 —shown in cross-section in  FIG. 3 —through which the casing material is extruded to form a casing  372  and/or other such reinforcement structure in (e.g., along a side of) tunnel  370 . In some embodiments, capsule  300  further comprises a component—e.g., in compactor  360 —to provide at least partial curing of the casing material before or during elimination via die  364 . Such curing may include exposing the casing material to heat and/or light (e.g., UV light) to activate a binder material. Although certain embodiments are not limited in this regard, capsule  300  may eliminate at least some waste material (for example, stones too large for die  364 ) through the channel  362  for deposition directly into tunnel  370 . 
     Connection  374  is merely one example of one or more hoses, cables, wires and/or other hardware that links capsule  300  to resources above ground  305 . In an embodiment, compactor  360  and/or die  364  extend radially around a channel  362  that is configured to receive such connection hardware for coupling with capsule  300 . Channel  362  may accommodate various exchanges between capsule  300  and above ground resources via one or more tubes  352 , one or more return lines  354  and/or any of the variety of additional or alternative links. In the example embodiment of capsule  300 , control  330  represents mechanisms to direct or otherwise control other components of capsule  300  during drilling with drill head  312 . One or more sensors  332  represents mechanisms to sense conditions during such drilling. Power  334  represents mechanisms to store and/or distribute power in capsule  300  during drilling with drill head  312 . In such an embodiment, some of all of control  330 , one or more sensors  332  and power  334  may variously participate in respective exchanges with above-ground resources—e.g., via channel  362  and connection  374 . 
     For example, power  334  may include one or more batteries to receive power that is delivered to capsule  300  via connection  374  and through channel  362 . Such power may may be variously distributed for operation of drill mechanics  320 , one or more sensors  332 , dirt conditioning unit  350 , compactor  360  and/or the like. Alternatively or in addition, circuitry of control  330  may exchange control signals with other components of capsule  300  and/or may exchange signals via channel  362  with above-ground resources (not shown). In some embodiments, one or more sensors  332  comprise, for example, any of the variety of sensors to monitor operation of drill head  312  and/or other machinery within housing  314 . Channel  362  may facilitate a communication of sensor information from one or more sensors  332  to above ground resources—e.g., via connection  374 . One or more sensors  332  may include any of the variety of one or more heat sensors, pressure sensors or other mechanisms to sense operational characteristics of dirt conditioning unit  350  or other components of capsule  300 . Alternatively for in addition, one or more sensors  332  may sense hardness, moisture and/or other characteristics of dirt that is processed by dirt conditioning unit  350 . In some embodiments, one or more sensors  332  perform spectroscopic or other analysis of dirt received via one or more inputs  316 . Such analysis may be used to facilitate determining a direction of drilling for capsule  300 . 
     One or more sensors  332  may include a receiver and/or a transmitter to participate in signal exchanges (e.g., with control  330  and/or with above-ground resources) that facilitate positioning of capsule  300  in a coordinate system. Such signal exchanges may take place between capsule  300  and one or more beacons located above ground  305 . In some embodiments, ultrasonic or other echolocation signals may be variously received from such beacons through ground  305 . Alternatively or in addition, one or more sensors  332  may analyze the strength of a radio signal received via tunnel  370 . Based on signal exchanges with such beacons and, for example, a predetermined map information, capsule  300  may be steered through ground  305  toward a destination. Certain embodiments are not limited to particular mechanisms by which control signals, sensor signals and/or power is communicated between components of capsule  300 . 
     In some embodiments, drilling by capsule  300  is to aid in laying a cable or other link in tunnel  370 . By way of illustration and not limitation, housing  314  may accommodate a spool  340  for a cable  342  including optical fibers, conductive wire or other communication link structures. As tunnel  370  is drilled and capsule  300  moves through tunnel  370 , cable  342  may pay out from spool  340 , and through channel  362 , into tunnel  342 . In another embodiment, spool  340  is instead located above ground  305 , where an end of cable  342  is tethered or otherwise anchored to capsule  300 , and where movement of capsule  300  through tunnel  370  pulls cable  342  into tunnel  370 . 
       FIG. 4  illustrates elements of a device  400  to reinforce a tunnel according to an embodiment. Device  400  may include some or all of the features of one of capsules  130 ,  300 , for example. In an embodiment, operation of device  400  is performed according to method  200 . 
     Device  400  is one example of an embodiment that provides functionality such as that of dirt conditioning unit  350  and compactor  360 . In an embodiment, one or more mixers of device  400 —e.g., including the illustrative mixers,  420 ,  430 ,  440 —are variously configured to process respective portions of dirt  405  that is received by device  400  during drilling of a tunnel. Although some embodiments are not limited in this regard, dirt  405  may be disintegrated (e.g., crushed), sifted or otherwise conditioned by other mechanisms (not shown) of device  400  prior to, and in preparation for, mixing at mixer  420 . In an embodiment, device  400  receives dirt through intakes that are disposed within or near a drill head (not shown) that is included in or coupled to device  400 . Such dirt may be drawn into device  400  by a vacuum applied from within device  400  and/or by a positive pressure differential from outside of device  400 . Device  400  may include a sieve that rotates in order to pass dirt  405  through pores using centripetal motion. The sieve may pass dirt  405  through one or more screens that, for example, each include pores of respective sizes. Dirt  405  may be broken up into particles of sizes (less than 0.3 mm, for example) that are small enough for extrusion from device  400 . In one embodiment, at least a portion of relatively small dirt particles may be directed for inclusion in casing material, where other dirt is directed for removal out of the tunnel or for deposition as waste material within the tunnel. 
     Device  400  may be coupled to exchange any of one or more materials via respective hoses that extend through the tunnel and couple device  400  to external resources (e.g., including resources  110 ). Such materials may include one or more of supply water  412 , effluent  442  and binder  410 . Although certain embodiments are not limited in this regard, some or all such materials may be exchanged via a channel  452  that extends through a compactor  450  of device  400 . 
     In an illustrative scenario according to one embodiment, mixer  420  may receive, and form a mixture of, dirt  405  and a portion of supply water  420 . Different portions of the mixture may be variously directed for inclusion in a reinforcement structure or, alternatively, for removal via the tunnel to an above-ground location. For example, a first portion  422  of the mixture may be sent to mixer  430 , where another portion  424  of the mixture is provided to mixer  440 . Mixer  440  may further dilute the portion  424  with additional supply water  412  to from a slurry of other fluid that, for example, is output from device  400  as an effluent  442 . 
     Mixer  430  may provide for further mixing of portion  422  with binder  410  to form a casing material  432 . In an embodiment, binder  410  includes one or both components of a two-part epoxy to act as an adhesive or sealant that, for example, begins to cure when exposed to one or more of water, heat, UV light, pressure and/or other such conditions. Binder  410  may function at least in part as a solvent, for example, that breaks down organic material of soil and/or other material. In one embodiment, binder  410  includes any of a variety of quick-setting cement materials—where at least a portion of dirt  405  is to function as aggregate within the cement to create a concrete tube. Binder  410  may be housed in a chamber (not shown) of device  400 , from which binder  410  may be dripped, spayed or otherwise disposed into mixer  430 —e.g., by a small direct current pump and solenoid operable to open to allow one or more components of binder  410  into mixer  430  at a specific rate. Deposition of binder  410  into mixer  430  may be at a rate that, for example, is based on a detected hardness (or other condition) of the ground through which device  400  drills. 
     A pump  434  may convey casing material  432  from mixer  430  to a compactor  450  (e.g., compactor  360 ) that extrudes or otherwise shapes casing material  432  to form a reinforcement structure. Any of a variety of means may be used for conveying dirt (or a mixture including dirt) into, through or from device  400 , according to various embodiments. For example, pump  434  and other such conveyance means or compacting means of device  400 —e.g., including compactor  450 —may comprise a peristaltic pump, a screw pump or the like. The shaped casing material  432  may be eliminated from an annular output  460  of compactor  460  (shown in cross-section). Extrusion of the casing material from output  460  may push device  400  in an opposite direction to advance drilling of the tunnel. In some embodiments, a cure unit  454  included in or proximate to compactor  450  may provide for at least partial curing of casing material  432  prior to or during shaping thereof by compactor  450 . For example, cure unit  454  may expose casing material  432  to heat, light and/or other conditions to promote curing by binder  430 . 
       FIG. 5  is an illustration of components of a device to utilize an embodiment of the disclosure. Platform  500  may be used for controlling the formation of reinforcement structures by a drill device as described herein. For example, platform  500  may be such a drill device, or a component thereof. Alternatively, platform  500  may be operable to communicate with such a drill device—e.g., where resources  100  include platform  500 . Platform  500  as illustrated includes bus or other internal communication means  515  for communicating information, and processor  510  coupled to bus  515  for processing information. The platform further comprises random access memory (RAM) or other volatile storage device  550  (alternatively referred to herein as main memory), coupled to bus  515  for storing information and instructions to be executed by processor  510 . Main memory  550  also may be used for storing temporary variables or other intermediate information during execution of instructions by processor  510 . Platform  500  also comprises read only memory (ROM) and/or static storage device  520  coupled to bus  515  for storing static information and instructions for processor  510 , and data storage device  525  such as a magnetic disk, optical disk and its corresponding disk drive, or a portable storage device (e.g., a universal serial bus (USB) flash drive, a Secure Digital (SD) card). Data storage device  525  is coupled to bus  515  for storing information and instructions. 
     Platform  500  may further be coupled to display device  570 , such as a cathode ray tube (CRT) or an LCD coupled to bus  515  through bus  565  for displaying information to a computer user. Alphanumeric input device  575 , including alphanumeric and other keys, may also be coupled to bus  515  through bus  565  (e.g., via infrared (IR) or radio frequency (RF) signals) for communicating information and command selections to processor  510 . An additional user input device is cursor control device  580 , such as a mouse, a trackball, stylus, or cursor direction keys coupled to bus  515  through bus  565  for communicating direction information and command selections to processor  510 , and for controlling cursor movement on display device  570 . In embodiments utilizing a touch-screen interface, it is understood that display  570 , input device  575  and cursor control device  580  may all be integrated into a touch-screen unit. 
     Another device, which may optionally be coupled to platform  500 , is a communication device  590  for accessing other nodes of a distributed system via a network. Communication device  590  may include any of a number of commercially available networking peripheral devices such as those used for coupling to an Ethernet, token ring, Internet, or wide area network. Communication device  590  may further be a null-modem connection, or any other mechanism that provides connectivity between computer system  500  and the outside world. Note that any or all of the components of this system illustrated in  FIG. 5  and associated hardware may be used in various embodiments of the disclosure. 
     It will be appreciated by those of ordinary skill in the art that any configuration of the system illustrated in  FIG. 5  may be used for various purposes according to the particular implementation. The control logic or software implementing embodiments of the disclosure can be stored in main memory  550 , mass storage device  525 , or other storage medium locally or remotely accessible to processor  510 . 
     It will be apparent to those of ordinary skill in the art that any system, method, and process to capture media data as described herein can be implemented as software stored in main memory  550  or read only memory  520  and executed by processor  510 . This control logic or software may also be resident on an article of manufacture comprising a computer readable storage medium having computer readable program code embodied therein and being readable the mass storage device  525  and for causing processor  510  to operate in accordance with the methods and teachings herein. 
     Embodiments of the disclosure may also be embodied in a handheld or portable device containing a subset of the computer hardware components described above. For example, the handheld device may be configured to contain only the bus  515 , the processor  510 , and memory  550  and/or  525 . The handheld device may also be configured to include a set of buttons or input signaling components with which a user may select from a set of available options. The handheld device may also be configured to include an output apparatus such as a LCD or display element matrix for displaying information to a user of the handheld device. Conventional methods may be used to implement such a handheld device. The implementation of the disclosure for such a device would be apparent to one of ordinary skill in the art given the disclosure as provided herein. 
     Embodiments of the disclosure may also be embodied in a special purpose appliance including a subset of the computer hardware components described above. For example, the appliance may include processor  510 , data storage device  525 , bus  515 , and memory  550 , and only rudimentary communications mechanisms, such as a small touch-screen that permits the user to communicate in a basic manner with the device. In general, the more special-purpose the device is, the fewer of the elements need be present for the device to function. 
     Techniques and architectures for reinforcing a tunnel are described herein. In the above description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of certain embodiments. It will be apparent, however, to one skilled in the art that certain embodiments can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to avoid obscuring the description. 
     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     Some portions of the detailed description herein are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the computing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of steps leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the discussion herein, it is appreciated that throughout the description, discussions utilizing terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
     Certain embodiments also relate to apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs) such as dynamic RAM (DRAM), EPROMs, EEPROMs, magnetic or optical cards, or any type of media suitable for storing electronic instructions, and coupled to a computer system bus. 
     The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will appear from the description herein. In addition, certain embodiments are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of such embodiments as described herein. 
     Besides what is described herein, various modifications may be made to the disclosed embodiments and implementations thereof without departing from their scope. Therefore, the illustrations and examples herein should be construed in an illustrative, and not a restrictive sense. The scope of the invention should be measured solely by reference to the claims that follow.