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The principal investigator at CRT was M. H. Wagner. Technical advice and guidance were contributed by K. N. Kreyenhagen. W. S. Goerke performed the computer programming and code development work. C. C. Fulton and G. E. Eggum provided valuable assistance in formulation of the material models and data reduction, and in the computer production runs, respectively. The penetrator specifications, site profile, and material properties were provided by WES. The Contracting Officer's Representative was D. K. Butler of WES. The contract was monitored and coordinated with the overall DNA penetration program under DNA Subtask SB211, Work Unit 03, "Contract Support Studies of Projectile Penetration and Impact". A. J. Breithaupt was the Contracting Officer and Col. G. H. Hilt was the Director of WES during this contract investigation.

The results show only minor differences between waveforms and peak stresses for the three cases. Peak stresses attenuated approximately as the square of the depth, i.e., ma x a D-2 (similar to attenuation observed in hard rock). Layering in media above the bedrock (Case 1) reduce stresses in the bedrock by only 10-15% (as compared with the homogenized media in Case 2). In the three cases, stresses above 1.5 kb were experienced to depths between about 3200 and 3800 ft. It is concluded that the effects of typical layering in saturated sedimentary soft rock layers will not substantially reduce peak stresses beneath near-surface bursts. Deep base facilities in such geologies would probably need to be placed at depths equivalent to those required in hard rock.

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