On How to Look Inside Geo-Materials

The observation of structural changes inside geo-materials during testing is still uncommon in geotechnical engineering. New developments in imaging techniques and improved analysis methods allow us for the first time to observe structural changes inside geo-materials and to provide us with the required information for developing new knowledge and constitutive relationships. The presented paper introduces three approaches for observing structural changes in porous media: (1) Particle Imaging Velocimetry (PIV) in combination with transparent hydro-gel beads, (2) Spatial Time Domain Reflectometry (Spatial TDR) for observing porosity distributions during contact erosion testing, and (3) Ultra High Speed Camera (UHSC) imaging in combination with a brittle, low strength rock like material for investigating hydraulic fracturing