Hydrogeological interferences in tunneling - A comprehensive study (Am03024)

The interference of groundwater with tunneling is both an environmental and an engineering problem. In fractured rocks, the prediction of tunnel water inflows is of primary importance, but unfortunatelyit is very complex, even impossible without the development of a well-founded Conceptual Hydrogeological Model (CHM). For this purpose, a comprehensive study is ongoing in the region of Monte Ceneri close to Lugano (Ticino, Switzerland), where a tunnel of 16 km in length is under construction in metamorphic rocks (gneiss and amphibolites). In particular, we are integrating the structural geological informations, commonly used for tunnel design, with geophysical surveys (VLF electromagnetic and resistivity) and physico-chemical data (discharge, temperature, electric conductivity, pH, ionic and stable isotope composition) of water collected at the surface and within the tunnel actually in construction. The theoretical frameworks and the preliminary results of the research are presented.