Laboratory Particle Velocity Experiments on (JVE) Analog Rock
Final rept. 24 Aug 1988-30 Nov 1990
SRI INTERNATIONAL MENLO PARK CA
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This project was performed in support of a DARPA program to calibrate a Soviet nuclear test site be generating spherical waves in granite obtained from a borehole drilled adjacent to the site of the JVE. Objectives were to determine effects of pore condition and effective stress on spherical wave propagation and attenuation and to investigate coupling and attenuation properties in different low porosity hard rocks to find a suitable analog to the JVE rock and determine if attenuation is independent of the hard rock constituents. Particle velocity histories in cores of Sierra White granite and rocks obtained from a site on Mt. Katahdin, Maine, were measured in laboratory spherical wave experiments. Effects of initial porosity on attenuation were determined by comparing results from low porosity Katahdin limestone. The effects of pore condition on attenuation were determined by laboratory tests on Sierra White granite with three initial conditions dry, saturated with zero effective stress, and saturated with 11.7 MPa initial effective stress. Coupling and attenuation properties in different low porosity hard rocks were determined by experiments on Katahdin coarse-and fine-grained granite and Katahdin limestone. Experimental results showed that 1 pore condition i.e., dry versus saturated and initial effective stress conditions had little if any, effect on velocity and displacement attenuation in low porosity Sierra White granite and 2 attenuation of peak displacements in Sierra White granite, Katahdin coarse- and fine-granite, and Katahdin limestone was the same within the scatter of the experimental data. Comparisons of high porosity Indiana limestone and low porosity Katahdin limestone showed a substantial effect of initial porosity on attenuation.
- Geology, Geochemistry and Mineralogy
- Seismic Detection and Detectors
- Nuclear Weapons