AN EVALUATION OF THE DESIGN AND APPLICATIONS OF YIELDABLE ROCK BOLTS

This is a compilation of develomental, design, and the data for three types of yieldable rock bolts which have been developed and tested. The three types of bolts (termed herein the South African, Bureau of Mines, and Omaha District rock bolts) represent the major thrusts in rock bolt developmental work to date. The rock bolts evaluated in this study were of two basic types: the "die-thread" type (the South African and Bureau of Mines bolts) and the "plug-tubing" type (the Omaha District bolt). With both types of yielding mechanisms the physical shape or configuration of the component parts was shown to be of critical importance. For the two yieldable rock bolts the sensitivity of yield loads to construction methods appears to be comparable. The cost, however, is expected to be somewhat higher for the Omaha District mechanism. All yielding mechanisms performed in accordance with design criteria under static and quasistatic loading conditions, but the Omaha District bolt has a quicker reaction time than either of the other two bolts. Under dynamic loading conditions both types of yielding mechanisms exhibited rate effects. Increases in displacement velocity of the bolts gave higher yield loads for the Bureau of Mines bolts, whereas measurements for the Omaha District bolts indicated the opposite trend, with slight decreases in yield load with increases in velocity. The types of resistance provided by each bolt tested were similar. Each was shown to provide about one-third of the resistance in the form of frictional resistance. Both types of yieldable rock bolts are recommended for use in locations of incipient or suspected movements and displacements. The final recommendation for future testing is a full-scale field test in which the performance of the two basic types of yieldable rock bolts would be evaluated under dynamically loaded conditions.

  • Corporate Authors:

    U.S. Army Waterways Experiment Station

    3909 Halls Ferry Road
    Vicksburg, MS  USA  39180-6199
  • Authors:
    • Miller, W O
  • Publication Date: 1976-11

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 77 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00148396
  • Record Type: Publication
  • Report/Paper Numbers: Techn Rept. S-76-14 Final Rpt.
  • Files: TRIS, ATRI
  • Created Date: Mar 30 1977 12:00AM