ABSTRACT
The realization of M5 metro line in Bucarest has foreseen the underpass of the existing semi-shallow Eroilor1 station at a distance of about 1 m from the bottom slab. The excavation was carried out using two TBMs-EPB departing from the new station Eroilor 2. The most critical aspects were the demolition of the concrete DW for the part below the existing station bottom slab and the extreme excavation conditions due to a 20 m hydraulic head in presence of sand. It was necessary to realize preventive soil improvement under the foundation slab of the existing Eroilor1 station with vertical and horizontal injection using both cement and chemical grouting. All activities were carried out in presence of a dewatering system, lowering the water level more than 20 m. An automatic monitoring system of the hydraulic and tenso-deformative state of the area allowed the continous check of safety conditions during the excavation.
