Tunneling and karst systems: a review

Karst is a common geo-morphological feature widespread all over the world and develops in presence of well-defined lithological and environmental conditions. In the last decades, tunnels are becoming longer and longer and with higher overburden (base-tunnels), and usually exe-cuted by means of a TBM. This executive choice requires a full knowledge of the geologi-cal/geomechanical setting already in the first stages of a project. Failing careful well-addressed preliminary investigations can result into unexpected incidents, with delay of the timing, in-crease of the costs and also possible injuries and casualties. The paper outline karst principles and on the base of field experiences gives some suggestions for addressing this hazard.