Development of a predictive capability for oil shale rubblization: Result of recent cratering experiments

Sandia National Laboratories conducted two heavily instrumented single borehole cratering tests during 1983 at the Anvil Points Mine. These tests, one stemmed and one unstemmed, were executed expressly to provide baseline data for correlation with existing rock fragmentation models, to provide input for the development and verification of rock motion models, and to investigate the effect of minimum gas pressure on rubblization. An extensive array of embedded sensors was employed to obtain diagnostic and response measurements. Photometric coverage with high speed framing cameras, monitoring anchored target movement, provided independent measurements of rock motion. Rubble excavation and screening provided data on crater volumes and shapes, void percent, and fragment size distribution. Diagnostic measurements verified satisfactory and repeatable explosive and stemming performance. Crater depths and volumes were less than predicted and nearly equal for the stemmed and unstemmed tests. The particle size distributions were almost identical. The detonation-induced stress wave amplitudes and initial velocity changes were essentially the same. Rock motion measurements from sensor and photometric data compared favorably. Post-test calculations, using a finite element program, DYNA2D, compared well with early-time response measurements. Later-time rock motion data are being used in the development of discrete element programs, BLOCKS and BUMP. Use ofmore » the experimental data in the development of these models is discussed, along with comparisons of BLOCK model calculations with experimental results. These comparisons indicate that the BLOCKS model simulates later-time rock motion adequately. 16 references, 31 figures.« less