ABSTRACT: Over a number of years, the Fracture and Shock physics group has engaged with the blast mining industry to investigate the physics of geological materials. This has encompassed a wide variety of materials including a number of sandstones, gneiss, schist, granite and iron ore. Efforts have mainly focused on loading the materials using a gas gun in a one dimensional strain configuration to measure high strain rate properties in compression, tension and shear. Progress has been made towards generalizing these results to provide predictive methodologies for other materials. In addition, a methodology has been developed to examine, using a variety of time resolved and post experimental diagnostics, the fragmentation of small geological samples under explosive loading. Results from a variety of experiments will be presented, along with a discussion of future directions and challenges in the field. 1 INTRODUCTION Geological materials are the source of a significant amount of the resources that are relied on to ensure that the modern world continues to function. The vast majority of these materials are obtained through the process of blast mining, which subjects the materials to a high rate, high amplitude loading regime. As more material is mined, yields tend to fall, and this has meant that optimizing the process of blast mining has become increasingly important to mining companies. Much of the effort has focused on developing computational modelling tools (Onederra 2013), however there is a requirement for these models to be underpinned by experimental data, and a thorough understanding of the underlying scientific processes that govern the material behavior.

ABSTRACT: An experimental investigation was carried out on the Hawkesbury sandstone to study effects of loading rate on the peak strength and deformability during uniaxial monotonic compressive testing. Axial load and axial and lateral deformations were measured precisely from start of loading until post-peak state. To predict properties of anisotropic Hawkesbury sandstone samples, a methodology to conduct monotonic testing was devised including the development of an innovative peak strength prediction method. The strength of the sandstone was increased with an increase in loading rate. The Tangent Young's modulus was found to increase slightly with increase of loading rate. Poisson's ratio of samples were also affected by loading rate, however, no conclusive trend was observed. A preliminary model was developed to predict variations of the Hawkesbury sandstone peak strength under different loading rates.