DISTRIBUTION OF THIS DOlfltyHfl |£|\IWIITEDAs part of a Laboratory program (Seismic Evasion) dealing with the detec tion of underground nuclear explosions, we have measured the physical properties of various materials selected to represent a wide range of possible responses to stress pulses. The physical properties so determined are then used in conjunction with small-scale explosion and shock-wave measurements to define the behavior of the material over a wide range of stresses, strains and strain rates. This informa tion is then used to develop numerical techniques which seek to model stresswave propagation. Factors such as water content and porosity, and related physical and a large pressure derivative of the shear modulus at low pressure are believed to be due to an abundance of cracks with low aspect ratios.The initial effective shear modulus of about 55 koar increases rapidly with the closing of cracks. At 1 kbar confining pressure, a shear modulus of about 120 kbar is determined in both uniaxial stress and uniaxial strain experiments The rock has an ultimate strength compa rable to granite (1.2 kbj.r unconfincd) and exhibits brittle behavior at failure to the highest mean prassur« studied (14 kbar). Failure is preceded by dilatant behaviox.properties such as moduli and strength. are well known to have a large effect on stress-wave propagation.In this report we present the result of high-pressure, mechanical properties measurements on one material, the Nugget sandstone, from Utah. This i sandstone is composed primarily of ; detrital quartz with siliceous cementing materials. Based on a reported quartz i. content of 99%.' the rock may be classi-2 fied as orthoquartzite or a quartz arenite by the more recent scheme of q Fettijohn et al. The average density of the material used in this study is -3 2.56 g-cm with a variation between
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Mechanical properties measurements for desert alluvium from borehole Ue3-ct, Nevada Test Site, have been made as a function of pressure up to 30 kDar. Pressure-volume relations, compressive shear strength, shear response during uniaxial strain, and ultrasonic compressional velocity are reported. Data include results for large (10-15 cm diam by about 20 cm) samples prepared from intact re covered cores. Compressions of ~ 30% occur under quasihydrostatic pressures of 30 kbar, with 65% of this deformation taking place in the first 2 kbar. Shear strengths (T) vary with water content for samples fabricated from the same alluvium; r -600 bars for the air dry material and 2 bars when the material is water saturated (mean pressure = 2 kbar).The uniaxial strain loading path (strain ~ -5 rate = 10 /sec) approaches the failure envelope in deviatoric stress /mean stress space at T = 100 bars and P m = 365 bars.
Thermal conductivity, thermal diffusivity, and thermal linear expansion were measured on two samples of Avery Island rock salt up to simultaneous temperatures and pressures of 573 K and 50 HPa. Thermal conductivity at room temperature measured 6.3 ± 0.6 W/aS and decreased monotonically to 3.3 ± 0.4 W/mK at 573 K. Thermal diffusivity decreased from 3.0 £ 0.8-6 2-6 2 x 10 m /s at room temperature to 1.4 + 0.5 x 10 m /s at 573 K. Thermal linear expansivity increased from 4.8 + 0.3 x 10 K~ at room temperature to 5.6 + 0.3 x 10~ K at 573 K. The thermal properties showed no measurable 1+5*) dependence on confining pressure from 0-50 MPa for any temperature tested. The thermal conductivity values were not distinguishable (+5%) from intrinsic (single crystal) values measured by others. Diffusivity fell about 20* below intrinsic values, and linear expansivity about 20% above intrinsic values. Thermal conductivity values for Avery Island salt measured recently by Morgan are as much as 50* lower than values measured here and were probably strongly affected by sample handling prior to measurement. The pressure independence of th° thermal properties measured in our stud;r suggests that thermally-induced microfracturing is nearly nonexistent. This lack of thermal cracking is consistent with the high (cubic) symmetry of halite.
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