Rock Mass Characterization of Phyllites for Tunnelling

Research project P 14767 Rock Mass Characterization of Phyllites for Tunnelling Wulf SCHUBERT 27.11.2000 Tunneling in alpine regions poses 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. Phyllites are associated with many of these case histories. There has not been a systematic study linking the observed behavior of phyllites during excavation to the rock mass geometry, the rock structure, and the mechanical properties determined in the laboratory. This proposal presents `a coherent multi-disciplinary approach to study these phenomenons. 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 program will be performed to study the mechanical behavior using modem rock mechanic testing procedures and interpretation. This inforination. 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. Two specific tunnel projects have been chosen for this study, the pilot tunnel for the Sernmering Basis Tunnel and the S-6 Spital bypass tunnel. Other projects will be included depending on the timely coincidence with the research. Tunnels for analyses in different geologic environinents are necessary so the influence of different geologic structures and stress conditions can be considered. This variability allows for a more complete picture of the rock mass behavior than by performing the analyses at a single site where conditions are unique. This procedure will establish the UPSCALING relationship of phyllites related to engineering characterization and performance.