Research into shallow-buried near-field blast has been accelerated over the last decade and has been driven by the need to develop more effective protection systems for both mobile as well as fixed assets. This research focus has been justified as the shallow buried threat delivers a focused blast effect that is extremely efficient and effective thus requiring less explosive content to defeat protection systems than unconstrained explosive charges [1, 2]. Although a blast load is over within a few milliseconds when quasi-constrained it is not a single peak event but appears phased over time [3]. This implies that a shallow-buried near-field blast load is made up of different components each contributing to the total load at different times within the blast event.
Within published research [4,5] the components of a shallow buried blast load have been broadly defined as shock (incident as well as reflected), soil cap and blast wind. In some cases the blast wind can be further split into initial detonation gas release and later occurring secondary burn. In general this body of work indicates that the impulse contribution of the shock from a shallow buried blast load is negligible with the main portion of the impulse attributed to the blast wind and ejecta. Computational modelling results using flat cylindrically shaped charges predict the shock contribution a more substantial contribution of between 5-10% of the total coupled impulse, while attributing around 18% and 70 % respectively to the soil cap and blast wind [5].
To enhance protection systems it is important to confirm the components of a blast load and to quantify the load contribution of each of these components. This paper presents a scaled research method that uses a purpose designed test rig [6] to investigate and to delineate a shallow-buried blast-load’s phases. These data are also used to quantify the component’s blast load contribution using the force-time and impulsive load response of flat steel near-field target with side-on pressure and high speed imaging measurements. The initial scaled results, using 20 grams of PE4 with a D:H ratio of 3:1 and a scaled distance ≈0.3 m/kg3 indicate that the load contribution of the initial shock impact is considerably higher than predicted.
[1] Tremblay JE, Impulse from Blast Deflectors from a Landmine Explosion, DREV-TM-9814, September 1998;
[2] Swisadk MM, Explosion Effects and Properties Part I – Explosion Effects in air, October 1976;
[3] Smith PD and Hetherington JG, Blast and Ballistic Loading of Structures, Routledge 1994;
[4] Ramasamy A. et al: Blast Mines: Physics, Injury Mechanisms And Vehicle Protection. JR Army Med Corps 155(4): 258-264
[5] Fourney, W. L., et al: `Mechanism of loading on plates due to explosive detonation, Fragblast, 9:4, 205 -217;
[6] Snyman IM, Blast-loading Partitioning and Quantification: Report and Updated Strategy. GLBL-AG900-09-004 Rev 1, November 2009;
[7] Reinecke JD, Horsfall I and Snyman I, Development of a Scaled Shallow-Buried Near-Field Blast Load Test Rig, 85th Shock and Vibration Symposium, Reston USA, October 2014;
