Impact behaviour of tunnel lining assembled from non-planar interlocking steel fibre reinforced concrete bricks

In this study, a new design of tunnel lining assembled from non-planar interlocking segments was developed and tested. The new tunnel segment is made of steel fibre reinforced concrete (SFRC), and it has six symmetrical side surfaces with a concave-convex topology, which can prevent the movement of each element in the interlocked tunnel. A series of lab-scale drop weight tests were conducted to investigate the performance of the interlocking SFRC tunnel specimen under impact. A special aluminium mould was designed to cast the developed tunnel segments, and a novel testing frame was developed to allow the drop hammer to hit on the inner surface of the tunnel specimen. The peak impact force, the displacement of the drop hammer and the failure pattern of the interlocking SFRC brick were measured and analysed, considering the influences of hammer dropping height and confining load on the dynamic behaviour of the interlocking SFRC tunnel specimen.