ABSTRACT
The Mularroya hydraulic tunnel, located in Zaragoza, Spain, is a 13.3 km long, 2.9 m internal diameter conduit excavated using a Single Shield TBM. Delivered by UTE MULARROYA, an ACCIONA-SACYR Joint Venture, the excavation phase has been completed. To tackle the anticipated geological and geotechnical challenges, the TBM, originally a Double Shield manufactured by HERRENKNECHT, was refurbished and converted into a Single Shield by ACCIONA ‘s in-house workshops in Toledo, Spain. Bespoke logistical solutions were implemented to accommodate the tunnel’s length and small diameter, including a pioneering tunnel conveyor belt for tunnels under 3 meters in diameter, deployed for the first time in Europe on a long drive exceeding 4 km. This paper also describes the risk management strategies to overcome challenging geological conditions, including successfully resolving a TBM entrapment incident while crossing the Datos Fault.
