The University of Sheffield
Department of Civil and Structural Engineering

Shock Transmission Through Geological Materials

Supervisor: Dr Sam Clarke

It is known that the properties of a soil/rock medium influence the propagation of shock, compaction, and elastic waves. The Blast and Impact Dynamics research group at the University of Sheffield has a long track record in researching buried explosive events, and have demonstrated the influence that geotechnical parameters have on the loading generated from shallow buried explosives. It is posited that the primary reason for the differences in loading is due to wave propagation in the geological material. Shock waves tend to be highly localised and propagate over only short distances, whereas elastic waves are lower in magnitude compared to compaction waves. It is important, therefore, to better understand the propagation of compaction waves through such materials. The problem is made more complex when inhomogeneities, e.g. layers of materials and the presence of geological faults, are present. This studentship is aimed at addressing key research questions in the area of compaction wave propagation through complex granular/geological media.

The aim of the PhD will be to investigate the 3 zone model below. It is expected that zones 1 and 3 will be of lesser interest and zone 2 is where the work will be focussed.
Zone 1: Cratering- total compaction of the layer with the material being ejected. This is assuming that the initial source is buried. For an above ground burst it is highly likely that cratering will not occur. It is proposed that this is covered by a focussed literature review.
Zone 2: Dynamic compaction and shock propagation using the Split-Hopkinson Pressure Bar (Kolsky Bar) apparatus.
Zone 3: Elastic shock propagation - traditional earthquake mechanics, soils can and have previously been quantified using "bender" element tests. It is proposed that this is covered by a focussed literature review.

This project is NOT FUNDED, although Departmental/University scholarships are available for applicants who can demonstrate strong evidence of research potential.

Pre-requisite qualification

Suitable for candidates holding or anticipating an award of Distinction at MSc level, or 1st at undergraduate degree in an engineering or numerical/physical sciences discipline. Some experience in blast/dynamic analysis is preferred, as is experience in the design and running of experimental trials.