Tweet Share

• Send by email

  Send by email

  

  Monitoring the San Mamés tunnel, a NATM tunnel in an urban area: lessons learned

  The San Mamés tunnel was excavated in Bilbao (Bizkaia, the Basque Country), to improve the traffic management of the Spanish A8 motorway - named Autovia del Cantabrico- the main road in Northern Spain. The tunnel is placed under the city’s neighbourhood of Altamira.This tunnel is about 0.5 Km long with an operational section of 59.2m2, while the excavated section is 99,93m2. The geotechnical investigation during the design phase highlighted a rock mass made of marls, limestones and consolidated gravels with a median RMR around 60 and eluvial soils. For this reason, two main types of excavation-support operations were designed: a first one with topheading, benching and invert for the soil sections with heavy support including lattice girders and micropiles as a pre-support and a second one, an excavation with top-heading and benching with a lighter support with rock bolts and shotcrete for the rock sections.In view of this geological context, the operator company appointed by the Regional Government (Diputación Foral de Bizkaia) put in place a precise monitoring program for keeping the project under close surveillance and minimizing its impact in the area. The monitoring campaign started during the design phase with the use of InSAR technology that allowed the designer to understand the history of the surface deformation and to improve the design of the excavation phase to minimize settlement. During construction, a combination of real time monitoring with geotechnical classical approach and high resolution InSAR data was used achieving a full spatial and temporal coverage of the ground displacements. This monitoring approach resulted in an improved excavation of the tunnel in a project with challenging geotechnical conditions. Monitoring, NATM, Urban, InSAR, accuracy, historical study.

  Recipient :

  Name ^* :

  E-mail address ^* :

  ^* Required fields

  Send   or  Cancel

• Print