Mechanical investigation of tunnels: risk analysis and notation system

The current mechanical investigation strategy applied to RATP (Regie Autonome des Transpots Parisiens) tunnels is mainly based on visual inspection. All the works are inspected and every apparent fault is located and reported in inspection reports. However, this type of inspection detects only apparent faults without linking them to their causes. A new methodology of mechanical investigation is proposed in the framework of the ANR project MEDITOSS (Methodologie de Diagnostic des Tunnels et Ouvrages Souterrains en Service), consisting in integrating mechanical investigation tools to better characterise the geometrical and mechanical state of the tunnel. This new strategy combines four techniques (ground penetrating radar, light dynamic penetrometer, endoscopy and geo-mechanical impedance). These techniques are applied to panels to obtain a ‘panel score’. This paper presents a risk analysis of the system studied (network of corridors and tunnels), by applying the bow-tie method in order to obtain informatio...