"PROPERTIES OF ROCK DISCONTINUITIES"

ROCK MASSES ARE THE HOST MEDIA FOR ENGINEERING VENTURES OF MAJOR ECONOMIC AND DEFENSE SIGNIFICANCE. THE PERFORMANCE OFA ROCK MASS UNDER ENGINEERING CONDITIONS IS USUALLY DOMINATED BY THE DISCONTINUOUS NATURE OF THE MEDIUM. HOWEVER, THE TECHNIQUES OF DESCRIBING THE TOPOGRAPHY OF DISCONTINUITIES OR JOINTS, WHICH STRONGLY INFLUENCE THEIR PROPERTIES, AND OF EXPERIMENTALLY MEASURING THEIR MECHANICALPROPERTIES, ARE STILL RATHER ELEMENTARY. THE PROPOSED RESEARCH IDENTIFIES AN APPROACH FOR DETERMININGJOINT STIFFNESS AND STRENGTH PROPERTIES UNDER A TESTING CONDITION OF CONTROLLED NORMAL STIFFNESS, WHICH IS COMPLETELY ANALOGOUS TO THE STATE OF LOADING WHICH A JOINT EXPERIENCES IN SITU. A STIFFNESS-CONTROLLED SYSTEM IS PROPOSED FOR JOINT TESTING WHICH CAN YIELD JOINT STIFFNESS AND STRENGTH PROPERTIES IN ONE-DIRECTIONAL DIRECT SHEAR AND AFTER LOAD REVERSAL. THE SAME SYSTEM MAY BE USED TO DETERMINE JOINT TORSIONAL RESISTANCE PROPERTIES, WHICH ARE IMPORTANT IN THE THREE-DIMENSIONAL ANALYSIS OF BLOCK-JOINTEDMEDIA. THE ULTIMATE PURPOSE OF THE RESEARCH IS TO RELATE JOINT MECHANICAL PROPERTIES TO ROCK MATERIAL PROPERTIES AND JOINT TOPOGRAPHY. THE FRACTAL DIMENSION OF THE JOINT SURFACE IS SUGGESTED AS A PARAMETER WHICH MAY AVOID CURRENT PROBLEMS INDESCRIBING THE ROUGH STATE OF A JOINT SURFACE.