PERMFILE56525

• Permit No: C1984065
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: App. 4.3-1 Initial Geotech Study
• Section_Exhibit Name: APPENDIX 4.3-1 INITIAL GEOTECHNICAL STUDY LOGGING & TESTING EVALUATION
• Media Type: D
• Archive: No

6
• Triaxiat Strength. The uniaxial strength of a rock core
is increased if a confining stress is subjected to the circum-
ferential area of the sample. Rock cores tested under a confin-
ing stress are said to be tested under triaxial conditions. By
conducting several tests under different confining stresses, a
Mohr's envelope may be developed. The Mohr's envelope is defined
as a straight line as follows:
t ~ On Tan ~' + C [3]
where '[ ~ shearing stress
on ~ normal stress
~' ~ angle of internal friction
C ~ cohesion
•
In terms of the principal stresses, al, and a~, the normal stress,
an is:
an ~ al 2 a3 + of 2 a3 Cos 2a [4]
where al ~ major principal stress (failure stress)
a3 ~ minor principal stress(confining stress)
a ~ angle of failure plane to horizontal
and the shearing stress, T is:
T ~ O1 2 0~ Cos 2a [5]

One procedure used to obtain the two characteristic properties,
Q' and C, is to conduct several triaxial tests and graphically
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