The question of the proper scaling of crater dimensions resulting from buried explosions is investigated. Dimensional analyses are performed from which four different scaling rules are derived. Data are reviewed in an attempt to distinguish which scaling rules are fundamental to cratering. Inability to perform cratering experiments with similitude apparently is one reason for lack of an unambiguous answer to the scaling question. Influences of possible sources of similarity violation are qualitatively examined, and some experiments are suggested which may provide more direct information about the correct scaling of crater dimensions.

Atmospheric-lithostatic pressure ratio effects on explosive crater dimensions in dry soil.

A theory of the important cratering mechanisms, which has been evolved on the basis of these data and data from other sources, is outlined.

One hundred twenty-one model tests of explosion induced craters in dry sand were conducted using small charges of PETN detonated at accelerations between 1g and 101g; ninety-six were found to be useful in analysis. Extrapolation to prototype dimensions indicates that for half-buried charges, crater volume, V, is a function of explosive weight, W to the 0.84 power, and crater radius and depth are functions of W to the 0.28 power. There were no detectable acceleration related scale effects from 31g to 101g. This confirms the value of the geotechnical centrifuge in modelling explosion induced craters at less than 100 g provided attention is paid to certain test conditions and scale effects. These include soil particle size, and angularity and soil strength which appear to strongly affect model crater volume and shape. Crater volume is also very sensitive to the unit weight of dry sand and to a lesser degree to charge location, geometry and orientation. Boundary effects arising from model dimensions and the centrifuge enclosure were examined. Keywords: Cratering, Model test extrapolation, Half buried high explosives. (EDC).

Field work, supplemented by laboratory studies, is a cornerstone for the geological sciences. This volume provides an introduction to general field work through selected topics that illustrate specific techniques and methodologies. One hundred and twenty-three main entries prepared by leading authorities from around the world deal with aspects of exploration surveys, geotechnical engineering, environmental management. field techniques, mapping, prospecting, and mining. Special efforts were made to include topics that consider aspects of environmental geology in particular those subjects that involve field inspections related to, for example, the placement of artificial fills, sediment control in canals and waterways, the geologic effects of cities, or the importance of expansive soils to environmental management and engineering. In addition, some widely ranging topics dealing with legal affairs, geological methodology, the scope and organization of geology, report writing, and other concepts, such as those related to plate tectonics and continental drift, provide a necessary perspective to the arena of field geology.