Analysis of the rock mechanics properties of volcanic tuff units from Yucca Mountain, Nevada Test Site

Abstract

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Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project; Yucca Mountain Site Characterization Project

“…However, two uniaxial and three triaxial test results for the TCw unit were reported by Price (1983); a uniaxial compressive strength of 7 MPa and triaxial compressive strength of 895 MPa with 20 MPa confineme_t was reported. The range of the test results suggests the potential for large variation of the intact strength of the TCw unit.…”

“…These data are obtained from the following sources: RIB, Version 4.4 (DOE, 1991); Site Characterization Plan, Conceptual Design Report o (SCP-CDR) (SNL, 1987); a report on rock fracture analysis and RQD estimation (Lin et al, 1992); and reports on intact rock laboratory test data Price, 1983). The mechanical properties for the intact rock, such as uniaxial compressive strength, elastic modulus, Poisson's " ratio, cohesion, and angle of internal friction, are listed in the intact rock properties subsection.…”

“…The 31 sets of triaxial data for the TSw2 unit listed in Appendix C and the uniaxial compressive strength data listed in Appendix B were used to obtain the parameters c_cand N of Equation 3-1 for the welded tuff units. The 19 sets of triaxial data in Appendix C and the uniaxial compressive streng.th data in Price (1983) for the CHnl unit were used to obtain the parameters ac and N of Equation 3-1 for the nonwelded tuff units. Cohesion and angle of internal friction for both the welded and nonwelded tuff units were then calculated using Equations 3-3 and 3-4.…”

“…The triaxial data listed in Appendix C and the uniaxial compressive strength data listed in Price (1983) for the CHnl unit were used to curve fit Equation 2-3 to obtain the material constants B and cz for the nonwelded tuff units. Using a least-square technique, a good fit of the data was obtained.…”

Mechanical properties of tuffaceous rocks under triaxial conditions

“…In all previous studies performed on dry and saturated tuffs from the Nevada Test Site, saturation has decreased the compressive strength of the specimens tested (Price, 1983 andTillerson andNimick, 1984) …”