REFRACTION SEISMIC AND ELECTRICAL RESISTIVITY STUDIES OF ENGINEERING GEOLOGIC PROBLEMS AT MOUNTAIN TUNNEL SITES

TUNNEL CONSTRUCTION IN MOUNTAINOUS TERRAIN SUFFERS FROM INADEQUATE KNOWLEDGE ABOUT THE ENGINEERING PROPERTIES OF THE ROCKS AND GEOLOGIC DISCONTINUITIES, SUCH AS SHEAR ZONES, THAT WILL BE ENCOUNTERED DURING CONSTRUCTION. THE REFRACTION SEISMIC METHOD IS UNIQUE IN THAT IT PROVIDES VELOCITY DATA WHICH ARE A FUNCTION OF THE ENGINEERING PROPERTIES OF THE ROCK MASS. SHOCK WAVE RECEPTION IS AFFECTED BY CHANGES IN ROCK TYPE AS WELL AS THE OCCURRENCE OF SHEAR ZONES AND OTHER TROUBLESOME STRUCTURAL FEATURES. THE PAPER SUMMARIZED THE USEFULNESS OF THE METHOD IN DETERMINING THSES FACTORS, AS WELL AS SERIOUS LIMITATIONS TO ANY PRACTICAL SOLUTION TO THE IMMEDIATE PROBLEM, I.E., PREDICTION OF AT-DEPTH CONDITIONS IN COMPLEX GEOLOGIC AREAS. THOUGH INSENSITIVE TO THE ELASTIC PROPERTIES OF ROCK, THE ELECTRICAL EARTH RESISTIVITY METHOD RESPONDS TO CHANGES IN RESISTANCE TO CURRENT FLOW CAUSED BY DIFFERENT ROCK TYPES AND BY ROCK ALTERATION EITHER OF MASSIVE HYDROTHERMAL ORIGIN OR THAT WHICH HAS OCCURRED ALONG FEATURES SUCH AS SHEAR ZONES. THE FIELD RESULTS AND THE PROBLEMS INHERENT IN THE METHOD'S STANDARD FIELD USE ARE REVIEWED, AS WELL AS THE INTERPRETIVE AMBIGUITIES WHICH PRECLUDE EFFECTIVE USE OF THE METHOD FOR TUNNEL DESIGN. BOTH METHODS PROVED SUCCESSFUL IN DEFINING PREVIOUSLY MAPPED GEOLOGIC FEATURES. IN ADDITION, DATA FROM BOTH METHODS INDICATED THE PRESENCE OF PREVIOUSLY UNMAPPED FEATURES AS WELL AS EXTENSIVE MODIFICATION OF SURFACE-MAPPED ROCK QUALITIES. THE COMPLEMENTARY FEATURES OF THE TWO METHODS OVER THE SAME TRAVERSE ARE ILLUSTRATED. THE PROBLEMS AND PROMISE OF USING GEOPHYSICS FOR THE SOLUTION OF THE IMPORTANT PROBLEM OF PREDICITING TUNNEL CONSTRUCTION CONDITIONS ARE SUMMARIZED. /AUTHOR/

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  • Serial:
    • Issue Number: 0

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Filing Info

  • Accession Number: 00229890
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 26 1971 12:00AM