Experimental challenges of modelling structure response to tunnelling

This paper discusses centrifuge modelling challenges when exploring the response of surface structures to tunnelling in sand. The model tunnel employed consists of an interior brass cylinder surrounded by water inside a sealed flexible latex lining. Prior to extracting water to simulate tunnelling volume loss, soil displacements obtained during centrifuge acceleration indicate that this flexible tunnel can lead to differential settlements during spin-up. These ground movements are triggered by a change of the tunnel shape due to a stress imbalance between the tunnel and the surrounding soil. Additionally, it was found that surface structures interact with the model tunnel during the spin-up, and thus can change the amount of differential surface settlements, depending on the structure location. As a consequence, some differential settlements may be imposed on the structures as the g-level increases. Results indicate the necessity to consider these effects when interpreting the results of the subsequent tunnelling simulation.