Re-examination of peak stress and scaled distance due to ground shock

Ground motions associated with the passage of blast transients are important in two respects. Firstly, they develop as a result of the dynamic pressure pulse and are integrally related to the strains suffered by the soils. Secondly, ground motions subject nearby structures, buried or aboveground, to possible damaging vibrations. An accurate assessment of ground shock parameters, especially peak stresses, is thus essential for a reliable design against blast loading. Reliable ground shock parameters can be obtained from full-scale tests or small-scale tests complemented by numerical analyses. The US Army Corps of Engineers TM5-855-1 manual is widely used for estimates of ground shock parameters. This paper examines the TM5-855-1 estimation of the peak stresses in the light of small-scale field explosion tests in Singapore residual soils. The TM5-855-1 equations for ground shock predictions are not dimensionally consistent and become cumbersome when the need for units conversion arises. To overcome this problem, dimensionless parameters are proposed. A better understanding of the peak pressure–scaled distance plot in TM5-855-1 is provided using the dimensionless parameters.