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Generation of Rayleigh waves by underground of nuclear explosions: an examination of the effect of spall impact and site configuration

Description: Thesis. The effect of spall impact, site configuration, and the material properties of rocks at the blast site on the generation of Rayleigh waves by underground nuclear explosions was examined by experimental and computational methods. The hypothesis was that the impact of earth and rock, i.e., spall, falling back after being kicked up by the initial shock wave of an explosion is a source of surface waves observed from explosions. A comparison of amplitudes derived from spall momentum with observed Rayleigh amplitudes at ranges of from 50 to 500 km showed that the spall has sufficient impulse to account for these waves. In the site configuration studies it was found that the strongest signal was produced by a horizontally distributed source placed beneath a mountain, and the weakest signal was produced by a concentrated source placed beneath a flat plain. The horizontal dimension of the source had the biggest effect on the Rayleigh amplitude. Based on laboratory measurements of the mechanical properties of rocks in drill cores from the Boxcar and Gasbuggy sites, calculations were made of the spall impulse and surface displacement profiles from these explosions. The numerically obtained profiles were in reasonable agreement with values inferred from accelerometer data obtained at the sites. (LCL)
Date: July 1, 1973
Creator: Viecelli, J.A.
Partner: UNT Libraries Government Documents Department

Instrument evaluation, calibration, and installation for the heater experiments at Stripa

Description: Borehole instrumentation for the measurement of temperature, displacement, and stress was evaluated, modified, calibrated, and installed in an underground site at Stripa, Sweden where experiments are currently underway to investigate the suitability of granite as a storage medium for nuclear waste. Three arrays of borehole instrumentation measure the thermomechanical effects caused by electrical heaters which simulate the thermal output of canisters of radioactive waste. Because most rock mechanics investigations are carried out at modest temperatures, a sustained operating temperature as high as 200/sup 0/C was an unusual and most important criterion governing the instrumentation program. Extensive laboratory experiments were conducted to determine the effect of high temperature on instrument behavior and also to develop calibration and data-reduction procedures. The rod extensometers were tested for anchor creep, the selection of a suitable high-temperature pressurizing fluid, and the thermal stability of the grout. Four temperature corrections are incorporated into the data reduction of the USBM borehole deformation measurement: the bridge voltage offset correction, the change in calibration factor induced by temperature, and the thermal expansion of the gage and of the rock. The vibrating wire gages were calibrated in the laboratory by loading gages installed in a granite block at pressures up to 13 MPa and at temperatures ranging from 20/sup 0/ to 200/sup 0/C. Both the slope and offset of the response equation are corrected for temperature effects. Most thermocouples were calibrated in an oven at the field site. Thermocouples were emplaced with individual gages and into holes backfilled with sand or grout.
Date: December 1, 1979
Creator: Schrauf, T.; Pratt, H.; Simonson, E.; Hustrulid, W.; Nelson, P.; DuBois, A. et al.
Partner: UNT Libraries Government Documents Department