Rock Mass Characterization of Phyllites for Tunnelling (II)

Mineralogical and microstructural studies of phyllites by means of optical microscope, scanning electron microscope and X-ray diffraction analysis. The results are correlated with mechanical properties and will be utilised to explain the typical deformation of phyllites in tunneling. Tunneling in alpine regions pose many problems to the tunneling engineer. Large deformations associated with squeezing rock mass behavior are frequently observed in a variety of rock masses and stress conditions. This proposal presents a coherent multi-disciplinary approach to study these phenomena. Principles from structural geology will be applied to characterize the microstructure (mineralogy, crystal orientation, microcrack characteristics). The relationship between the initial microstructure and the deformation pattern induced by additional load during laboratory testing will be evaluated. A laboratory testing programme will be performed to study the mechanical behavior using modern rock mechanic testing procedures and interpretation. This information will be combined with geological documentation and monitored tunnel excavation performance to systematically evaluate the relationship between laboratory results, the tunnel behavior and the observed geology. Tunnels for analyses in different geologic environments are necessary so the influence of different geologic structures and stress conditions can be considered.