Abstract:
A tensile-testing apparatus ( 10 ) comprises a platen ( 40 ) for situating a tendon-type support system in manner mimicking its expected installation condition. A force-imposing device ( 20 ) imposes installation-expected forces and sensors ( 61, 71 ) sense displacement in the force-imposing direction. A station ( 80 ) collects force and displacement data and a station ( 90 ) outputs the collected data in format allowing system analysis.

Description:
BACKGROUND 
     A tendon type support system, such as a mechanical rock bolt system, can be used to stabilize rock in a tunnel or mine. Such a bolt system supports the rock that makes up the immediate roof structure by supporting it from a stronger or more stable rock structure that lies above. 
     SUMMARY 
     An apparatus is provided for tensile testing of a tendon-type support system that simultaneously tests the total system, subsystems, and individual components. Additionally or alternatively, the testing apparatus allows the system&#39;s tendon element to be anchored to a platen part in the same way as it is anchored in a field installation. 
    
    
     
       DRAWINGS 
         FIG. 1  shows an apparatus for tensile testing of a tendon-type support system. 
         FIG. 2  shows output features of the apparatus. 
         FIG. 3  shows tendon-type support systems in an installation condition. 
         FIGS. 4-5  show a tendon-type support system before and after forces are imposed. 
         FIG. 6  shows the tendon-type support system mounted in the apparatus for testing. 
         FIG. 7  shows the tendon-type support system being tested by the apparatus. 
         FIGS. 8A-8H  show some comprehensive output formats that can be provided by the apparatus. 
     
    
    
     DESCRIPTION 
     Referring now to the drawings, and initially to  FIG. 1 , tensile testing apparatus  10  is shown. The apparatus  10  can be made more compact, light weight and portable than commercially available equipment whereby it can be easily broken down, transported by hand, and quickly reassembled to conduct tests at different locations as needed. The apparatus  10  can be constructed, for example, with a footprint of less than 10 square feet (e.g., about 3 feet by 3 feet) and/or with a weight less than 1000 pounds (e.g., around 500 pounds). Additionally or alternatively, the apparatus  10  can be adapted to test much longer specimens than conventional equipment and thus is useful in analyzing long specimens in their entirety. 
     The testing apparatus  10  comprises a force-imposing device  20  designed to impose force on the tendon-type support system in a manner duplicating that which it will encounter in its installation setting. The illustrated device  20  comprises a cylinder  21  having a central bore  22  and an annular fluid chamber  23  therearound. A ram  24  is slidably mounted within the chamber  23  so as to move vertically in response to fluid contained therein. The ram  24  has a central bore  25  aligned with the central bore  22  of the cylinder  21 . A fluid source  26  (e.g., a pump) can be connected to the chamber  23  via hose  27  or other suitable conduit. 
     The cylinder-ram components of the force-imposing device  20  can be mounted on a table  30  having a horizontal platform  31  and vertical legs  32 . The cylinder  21  extends partially through an opening  33  in the platform  31  and is held in place by a bracket  34 . 
     The tensile testing apparatus  10  additionally comprises a platen  40  adapted to pose a tendon-type support system in a way representative of its installation setting. The platen  40  is fixed to the top of the cylinder  21  and has a central bore  41  aligned with those of the force-imposing device  20 . An upper surface  42  surrounds the central bore  41  and includes a counterbore  43 . 
     The tensile testing apparatus  10  further comprises an assembly  50  for fixturing the to-be-tested support system to the force-imposing device  20 . In the illustrated apparatus  10 , the fixturing assembly  50  includes a pipe  51 , a washer  52 , and locking elements  53 . The pipe  51  has a central bore  54  and the washer  52  has a central opening  52  which are alignable with the ram&#39;s central bore  25 . 
     Sensing equipment  60  can be situated to sense changes above the platen  40  and sensing equipment  70  can be situated to sense changes below the pipe  51  (or at least below the ram  24 ). This equipment can include electronic position sensors  61  and  71  linked to determine vertical displacement. Cameras  62  and  72  can be placed near the sensors  61  and  71  to visually record changes and video document a test from start to finish. A microphone  63  can also be strategically located to record relevant sounds associated with the testing. These sounds can include, for example, the “pops”, “pings”, “kings”, “rings”, and “booms” which occur as components deform, fail, and redistribute load to other components. 
     A data-collecting station  80  can collect data from the force-imposing device  20  and the sensing equipment  60 - 70 . As shown in  FIG. 2 , the data collecting station  80  can convey data to an output station  90  which outputs the data in visual formats  91 - 92 , a graphical format  93 , and/or graphical format  93 . The output station  90  can be incorporated into a conventional laptop computer. 
     The apparatus  10  can be used to tensile test a tendon-type support system, such as the mechanical rock bolt systems  100  depicted in  FIG. 3 . The illustrated support systems  100  are shown in a mine or tunnel  110 . Each system  100  supports the rock that makes up the immediate roof structure  111  by supporting it from a stronger or more stable rock structure  112  that lies above. 
     The tendon-type support system  100  can involve a cylindrical borehole  101 , drilled through the to-be-supported rock structure  111  and into the support-providing rock structure  112 . As is best seen by referring to  FIG. 4 , the system  100  can comprise a roof bolt  120 , an anchor  130 , a roof plate  140 , and a washer  150 . 
     The rock bolt  120  constitutes the “tendon” element of the support system  100 . It can comprise a cylindrical body  121  having an upper threaded portion  122  and a lower end  123 . A circular flange  124  and a square bolt head  124  are located on the body&#39;s lower end  123 . The anchor  130  is situated in an upper region of the borehole  101  and includes a wedge part  131  and a leaf part  132 . 
     The upper threaded portion  122  of the bolt  120  is in contact with the anchor&#39;s wedge part  131 . The wedge part  131  acts upon the leaf part  132  when the bolt  120  is pulled in a downward direction. The roof plate  140  has an upper face in contact with the roof rock structure  111  and a lower face adjacent an upper face of the washer  150 . 
     In  FIG. 4 , a tendon-type support system  100  is shown immediately after installation, prior to any force being applied. In  FIG. 5 , a system  100  is shown as it might exist after a typical Force F is applied. This Force F is transferred from the supported rock structure  111  to the bearing plate  140  to the washer  150 , to the bolt flange  124  and then to the bolt head  125 . From the bolt head  125 , the Force F is transferred to the bolt body  121  to the threaded upper portion  122 , into the anchor  130 , and then into the stable rock structure  112 . 
     In most installations, some or all of the components (i.e., the bolt  120 , the anchor  130 , the plate  140 , and the washer  150 ) of the system  100  are deformed as a result of the Force F. And the rock structure  111  and the rock structure  112  will sometimes separate by a distance M T . 
     To test the support system  100 , it is mounted on the test apparatus  10  as shown in  FIG. 6  in a manner resembling its installation, except up-side-down in orientation. Specifically, for example, the plate  140  and the washer  150  are placed on the platen  40 . The bolt  120  is lowered through the aligned bores and through the fixturing pipe  51 . The washer  52  and the wedge elements  53  are assembled onto the bolt&#39;s end portion  122  to secure it to the pipe  51 . 
     Once the support system  100  is mounted, fluid can be supplied (e.g., pumped) to the cylinder  21  from the source  26 . This force simulates that experienced by the system  100  in its installation setting and thus it displaces in a corresponding manner. As force is applied, the sensor  61  monitors upper displacement (e.g., the combined displacement of the bolt flange  124 , the bolt head  125 , the plate  140  and the washer  150 ) and the sensor  71  monitors total displacement (e.g., the upper displacement seen by sensor  61  and displacement caused by lower bolt portions). At the same time, the camera  62  visually records changes in the upper-displacement components, the camera  72  visually records changes in the bolt body  121 , and the microphone  63  audibly records relevant sounds. This data is conveyed to the collection station  80  and to the output station  90 , for compilation into an easily understandable format. 
     As shown in  FIGS. 8A-8H , test data can be output in video formats, graphical formats, and/or audio formats. The combination of some or all of these formats may often provide the meaningful analysis. For example, visual images corresponding to plotted points correlate component deformation with force curves to fully appreciate failure sequences during testing.