Dynamic fault damage

Experimental dynamic damage device

We propose to set up a new experimental device to test the dynamic damage of rocks near active faults. The objective of this study is to understand the mechanical behaviour of rocks at high deformation rates (around 102/s). This is the approach we followed to understand the sprayed rocks near the San Andreas fault (Doan and Gary, Nature Geoscience, 2009). More generally, there is the problem of dynamic damage near the faults.

We are currently mounting Hopkinson bars (SHPB : Split Hopkinson Pressure Bars, Figure 1). This device consists of two long metal bars enclosing a sample. An impactor dynamically loads the system. Deformation gauges in the middle of the bars allow the created waves to be tracked. The 1D geometry of the system allows the waves to be backpropelled to the ends of the bars in contact with the sample, and then to infer the stresses and strains experienced by the sample at deformation rates greater than 10/s.

Bibliography

Doan, M.L., Gary, G., 2009, Rock pulverization at high strain rate near the San Andreas Fault, Nature Geoscience, 2:709-712.

Doan, M.L., Billi, A., 2011, High strain rate damage of Carrara marble, Geophys. Res. Lett., 38, L19302, doi:10.1029/2011GL049169.

Doan, M.L. et d’Hour V. Effect of initial damage on rock pulverization along faults, in review at J. Struc.Geol.