Numerical analysis of the partial collapse of a twin-tubes tunnel

On the 1st of January 2014, the left tunnel of the twin-tube situated in the eastern part of the East-West Algerian highway, still under construction, was affected by a partial collapse, which induced significant damages over a distance of 120 m. In this paper, a 3D numerical simulation was used to investigate the loading state and deformation pattern governing the structure during the partial collapse. The results shows that the failure was mainly triggered by a large displacements of the primary lining which was applied to the left tunnel without final reinforcements, and was insufficient to counteract the applied stresses. Practical recommendations that could be drawn from this case are suggested.