Anisotropic yielding of rocks at high temperatures and pressures: Technical progress report No. 2, 16 December 1987--15 December 1988

Technical Report · Sun Jan 01 04:00:00 EST 1989

DOI:https://doi.org/10.2172/6769579· OSTI ID:6769579

Kronenberg, A K; Russell, J E; Carter, N L; Handin, C J; Gottschalk, R R; Shea, W T

Progress has been made towards the quantitative determination of anisotropic yield criteria for several foliated and lineated rocks, towards developing models for their mechanical properties based upon interactions between deformation mechanisms and preexisting fabric elements, and towards the characterization of fabrics resulting from diapiric emplacement of magma bodies within shallow portion of the earth's crust. The suite of extension and compression experiments on Four-mile gneiss is nearly complete. Samples cored along six different orientations have been tested at temperatures ranging from 25/degree/ to 800/degree/C and confining pressures of 0 to 400 MPa at a strain rate of 10/sup /minus/5//s, and we are currently investigating the influence of strain rate on yield strength over the range 10/sup /minus/4/less than or equal to/dot /var epsilon//less than or equal to10/sup /minus/6//s. We have examined deformation microstructures of deformed gneiss samples and identified those processes at the grain scale which are associated with its inelastic response. The orthorhombic anisotropy of fracture strength exhibited by the gneiss may be explained by a simple model involving localized slip within micas and microcracking within the stronger, surrounding framework silicates. Micas appear to interact in much the same way as do Mode II shear cracks, and their density, distribution, and preferred orientation affect the nucleation of microcracks which ultimately lead to failure. Ten material parameters of a generalized anisotropic yield function for Four-mile gneiss at room temperature have been determined using nonlinear fitting methods applied to the completed room temperature data. 45 refs.

• Research Organization: Texas A and M Univ., College Station (USA). Center for Tectonophysics
• DOE Contract Number: FG05-87ER13711
• OSTI ID: 6769579
• Report Number(s): DOE/ER/13711-2; ON: DE89006616
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
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ANISOTROPY
DEFORMATION
DOCUMENT TYPES
ENERGY
ENERGY SOURCES
FIELD TESTS
FORECASTING
GEOTHERMAL ENERGY
GNEISSES
Geothermal Legacy
MECHANICS
METAMORPHIC ROCKS
PETROGRAPHY
PROGRESS REPORT
RENEWABLE ENERGY SOURCES
ROCK MECHANICS
ROCKS
TEMPERATURE DEPENDENCE
TESTING