Full scale structural testing on extruded Fibre Reinforced Concrete tunnel segments

Automation in construction industry has been gaining great potential and momen-tum due to the necessity of enhancing the productivity and innovation uptake of the sector and making it more and more aligned with the evolving needs of the society. In this framework, this paper presents the validation through full scale tests, of a slip-forming methodology for the refur-bishment of existing tunnels which employs extrudable steel fibre reinforced concrete (SFRC). This method provides an innovative framework for the maintenance interventions of highways and railways tunnels. Four real scale mock-ups replicating a motorway tunnel lining have been produced employing the aforesaid technology and tested in load configurations mimicking the relevant combination of actions for tunnel linings in the intended scenarios. Both a symmetric and a skew symmetric load combinations have been tested, in one case also in sequence to assess of accumulated damage on the residual bearing capacity. The structural tests have been performed at the ELSA laboratory of the European Commission Joint Research Centre in Ispra in the frame-work of the OPENLAB ETRL project and are meant as a preliminary validation of the employed design criteria as well as of the effectiveness and structural soundness of the proposed technology. A design-wise assessment of the full-scale test results has been also performed using as input design parameters those fed by material testing, performed in the framework of the fib Model Code 2010 design approach for FRC structures..