FRICTION OF ROCKS AND STABILITY OF ROCK SLOPES

THE SIMILARITIES AND DIFFERENCES BETWEEN SOIL AND ROCK MECHANICS ARE DISCUSSED WITH PARTICULAR REFERENCE TO THE STABILITY OF SLOPES. THE EFFECTS OF CONSTRAINTS AND OF THE STIFFNESS OF THE SYSTEM APPLYING STRESS ARE OF GREATER IMPOTANCE IN ROCK MECHANICS. THE CRITERIA FOR FAILURE OF ROCKS ARE MOSTLY EMPIRICAL AND LEAD TO LINEAR OR POWER LAWS. SIMILAR LAWS MIGHT BE EXPECTED TO HOLD FOR FRICTON. WHILE THE COULOMB LAW IS IN GENERAL ADEQUATE FOR SOILS, IT APPEARS THAT THE FRICTIONAL BEHAVIOR OF ROCKS IS DESCRIBED BETTER BY A NON-LINEEAR LAW AND IF A COULOMB LAW IS USED FACTORS OF SAFETY ARE SENSITIVE TO THE VALUE ADOPTED FOR THE COHESION. THE VARIOUS METHODS FOR MEASURING FRICTION ARE DESCRIBED AND THEIR LIMITATIONS DISCUSSED. THE PROCESS OF WEAR AND THE AREA OF CONTACT BETWEEN SLIDING SURFACES ARE CONSIDERED. IT APPEARS THAT IN SOME CASES RESIDUAL VALUES OF FRICTION ARE ATTAINED AFTER SMALL AMOUNT OF SLIDING. GOUGE IS BUILT UP DURING SLIDING AND ITS BEHAVIOR APPEARS TO BE TIME-DEPENDENT. AT PRESENT, NUMERICAL VALUES FOR FRICTION AND OTHER PARAMETERS OF JOINTED SYSTEMS ARE UNCERTAIN AND SO SIMPLE FORMULAE ARE STILL USEFUL. A NUMBER OF FORMULAE FOR FACTORS OF SAFETY FOR SLIDING ON ONE OR TWO PLANE SURFACES ARE GIVEN. FOR THE CASE OF ROCK WITH CLOSELY SPACED JOINTS THE USE OF SOIL MECHANICS THEORY FOR CIRCULAR AND OTHER SURFACES OF SLIDING IS REASONABLE. IN THIS CASE, VALUES OF FRICTION OBTAINED FROM SINGLE JOINT SURFACES OR CRUSED ROCK ARE CONSERVATIVE SINCE THE INTERLOCKING OF ROCK ELEMENTS MAY CAUSE A SUBSTANTIAL INCREASE IN STRENGTH. /TRRL/

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 97-134
  • Serial:
    • GEOTECHNIQUE
    • Volume: 21
    • Issue Number: 2
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00235221
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: TRIS
  • Created Date: Jun 11 1972 12:00AM