Dynamic behavior of geomaterials

Understanding the dynamic behaviors of geomaterials (i.e., rocks or rock-like materials) is crucial for evaluating the safety and stability of structures in rock engineering. The exposure to environmental conditionings (e.g., thermal treatment, microwave irradiation, and freeze-thaw cycles) has a distinct influence on both the microstructures and the mechanical properties of geomaterials and therefore may contribute to failures of these geomaterial structures. Furthermore, these structures may be under high in situ stresses (e.g., prestress, hydrostatic pressure, and triaxial stress) in deep underground constructions and spaces. Moreover, these geomaterials in the underground structures are prone to experience impact loads caused by gas explosions, operational blasting, earthquakes, and terrorist attacks. It is therefore important to understand the dynamic failure mechanisms and behaviors of geomaterials after exposure to environmental conditionings and under in situ stresses. In this chapter, the dynamic mechanical properties including the dynamic compressive strength, the dynamic tensile strength, the dynamic flexural tensile strength, and the mode I and II fracture properties of geomaterials under various environmental conditionings and in situ stress states are systematically explored using recent literature where the split Hopkinson pressure bar device has been used for characterizing the behavior of the rocks and rock-like materials under various conditions. This chapter also presents the principles and unique features of experimental approaches and techniques for characterizing the dynamic behaviors of deep rocks.