Understanding protection from buried threats in different operating environments

The blast generated by shallow buried charges is known to be heavily affected by the soil surrounding the charge itself. Recent, well controlled full-, half- and quarter-scale physical experiments have developed a large dataset which show how measured impulse varies for different geotechnical conditions, and also how the distribution of the loading is a product of the soil type and geotechnical conditions. While this is a large and valuable resource it only represents a small sample of the range of different soil types and conditions which may be encountered in the field. Two examples, which have been identified by Dstl as having specific operational relevance are explosives buried in frozen ground (such as in arctic and sub-arctic regions) and in littoral environments (where the water table may be relatively close to the ground surface).

Assessing the ability of protective structures to resist the blast from buried charges, and thereby determining their safety in different operational environments, is most effectively done via numerical modelling. This process relies heavily on a) the physical data to validate the numerical models, and b) having constitutive models which are able to fully describe the material behaviour. The principal scientific challenge here is being able to predict the soil behaviour based on its fundamental characteristics and in-situ conditions rather than having to conduct an ever increasing array of tests to validate numerical models for different permeations of soil type & conditions.

What is crucially missing is knowledge of what physics drive the variations seen and crucially whether this information can be used to predict the output from charges buried in new areas/soils.

This work requires an excellent knowledge of which geotechnical parameters govern the loading, which is currently being developed at the University of Sheffield. There is also an ever-increasing dataset in the open literature which will be used to increase the quantity of data available in the proposed study. This project will complement the existing work by UoS/Dstl in the areas of rate dependent soil characterisation, buried charge testing, characterisation of blast loading and applique performance giving a dedicated, fundamental numerical understanding of the problems currently being investigated.