Reinforcement design and control of rock slopes above tunnel portals in Northern Italy

The stability features of slopes located above the portals of tunnels along important roads are here presented, together with two examples for reinforcement and protection works. The investigation phase and the reinforcement works have considered also the purpose of avoiding the interruption of the traffic when this would cause unacceptable consequences. The first case refers about the construction of a portal along a narrow and steep valley in a volcanick rock formation. The control of the vibration of the blasting action has been carried out for the period of the excavation in order to foresee the occurrence of potential dangerous situations. The second is the case of the portal of the East access to the Highway n.10. Even though the adits are protected by two portals, the occurrence of rock and debris falls from the upper part of the mountain could create a dangerous situation. Above the portals the morphology of the slope is characterized by two subvertical rock slopes, which are separated by an intermediate zone of debris material.