| 摘要 |
<p>The bearing plate assembly for a rock bolt has a hemispherical or similarly domed bearing plate (15) having a rim providing a reduced contact area with rock face (21) and a circular opening sized so that the rock bolt (3) can assume a range of angles to the rock face. A washer (17) is provided having a radius matching that of plate (15). A keyblock (19) is inserted in the hole of the washer and surrounding the rock bolt. Its presence increases resistance by preventing deformation of the washer (17) into the hole thereof when the assembly is subjected to excessive stress. The keyblock (19) may be of metal or plastics and formed integrally with tightening nut (13) or with the rock bolt if desired.</p> |
