GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 1.3 150 medium-grained plutonic rock from NW Italy with an initial porosity of 0.72%, were triaxially de- formed at strain rates of 3.6mm/hr under dry conditions until dynamic failure at confining pres- sures of 5, 10, 20 and 40 MPa. Each sample was positioned inside an engineered rubber jacket fitted with ports where an array of twelve 1 MHz single-component Piezo-Electric Transducers were embedded. Source mechanisms in terms of dilatation, shear and compression as well as AE rates with relation to incremental strain highlight distinct phases of deformation and fracture development, i.e. elasticity, fractures enucleation and propagation, strain localization and failure. Scattering and seismic velocity measurements provide a quantitative indication of the evolving mechanical conditions of the medium under stress (Fig. 1). There is significant variability in the data which makes it difficult for the model to learn the key attributes. Some physical parameters are better for forecasting strain, whilst others are better at stress. Normalisation across confining pressures will provide homogeneous training parameters to this aim. Advances would exploit 3D tomography as a tool to identify key pre-failure mechanisms in the lead up to coalescence. Corresponding author: sergiocarmelo.vinciguerra@unito.it