Rock-Mass Deformation Modulus Testing of Lithophysal Stratigraphic Units at the Yucca Mountain Project

摘要

Two pressurized slot tests have been conducted to make in situ measurements of deformation moduli and rock-mass strength in the rib of the Exploratory Studies Facility (ESF) at the Yucca Mountain Project. Each test employed two hydraulically inflated flat jacks sandwiched between platens. The jacks were located in two parallel slots in the rib. In the first test, conducted in a highly fractured lithophysal rock mass (RMR = 63 and Q = 6.7), the measured modulus was approximately 0.48GPa and the rock ceased to resist flat jack pressure at about 5.70MPa. The second test was conducted in a more competent zone of rock with fewer fractures and lithophysae (RMR = 64,Q = 2.5). The measured deformation modulus under ambient temperature was approximately 2.3GPa and at ～90°Cwas 1.15GPa. The rock at this location failed at ～10.7MPa.