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2. The shear strength of rock and rock joints
3. shear strength of intact rock at high stress, which involved F.E. analysis, 4th Rapid Excavation and Tunnelling Conference,
4. the Mohr strength envelope. This condition was shown or sug-W.A. Hustrulid (Eds), American Inst. of Min. & Metall, & Petroleum Engineers, Inc. New York, New York, 1979.