| Description |
x, 101 leaves : illustrations ; 29 cm |
| Summary |
"Underground facilities are finding increasing use due to space restrictions, environmental considerations, and economic reasons. Protection of these facilities from surface and subsurface explosions is a concern. Full scale tests arc hazardous and uneconomical, however, small scale models can be used to simulate full scale tests with the use of the artificial gravitational field produced in a centrifuge. The purpose of this research is to develop an artificially cemented sand model for a study of blast response over underground openings. Other studies have shown that artificially cemented sands can be used to simulate the behavior of naturally cemented sands. Artificially cemented sands have the additional benefit of allowing control over the degree of cementation, density of the final product, and size of the test specimens. Material type, strength parameter development, and evaluation of blast response in one g tests are examined. In all, 27 static, undrained triaxial tests, 75 unconfined compression tests, 70 density tests, and nine blast response tests were conducted. All specimens were prepared with a sliding weight compaction hammer and compacted to a relative density of 80 to 84 percent with three, five, and seven percent cement by weight. Variables considered were cement content, curing period, moisture content, effective confining pressure, and opening depth and geometry. Test results indicate that unconfined compressive strength, shear strength, and initial tangent modulus increase considerably with cementation. Cementation had little or no effect on the friction angle. Blast induced crater volume and spalling characteristics were also influenced by the level of cementation"--Abstract, leaf iii. |
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