Challenges of Tunnelling in Volcanic Rock Masses

Abstract Volcanic rock masses exhibit temporal and spatial variability, even at the scale duration of engineering projects. processes are dynamic, resulting in ranging from high-porosity, clay-rich, fractured, soil-like to low-porosity, high-strength, brittle, massive. Based on a number studies variety geological settings, such as active fossil geothermal systems, surface volcanoes up 3000 m below surface, work presented this article shows relationship between characteristics mechanical parameters volcanic rocks. These then linked resultant challenges tunnelling associated with behaviour rocks masses, ductile failure squeezing swelling dynamic spalling rockburst. This highlights some key that should be incorporated site laboratory investigations build representative ground models masses. Rock mass characterisation needs address highly variable anisotropic nature rocks, millimetre decametre scale. Ground must include not only properties, strength stiffness, typical lab investigations, but also petrophysical porosity, conditions, alteration. Geomechanical these requires an understanding select appropriate field, design tools. In perhaps more than any other types, geology is critical characterising response tunnelling.