Physical modelling and PIV analyses of an underground tunnel heading

摘要

Predicting surface and sub-surface movement upon tunnel heading failure is essential for safetyrnand contingency planning. This paper presents the results of a 2D physical modelling experiment of tunnelrnheading failure in cohesionless soil. By modelling six overburden to diameter ratios, the research seeks torninvestigate the behaviour, magnitude and failure mechanism of a tunnel heading. The physical model usesrndisplacement control to simulate tunnel heading movement. The use of transparent faced modelling containersrnallows video capture of the soil movement as the tunnel heading is displaced. From the captured video, ParticlernImage Velocimetry (PIV) was then utilised to analyse soil movement. PIV examines and monitors groups ofrnpixels based on colour variability, thus small amounts of coloured sand were added to ensure accurate tracking.rnThis then allowed close monitoring of the soil movement, which allows verification of settlement results andrnexamination of failure behaviour. It is concluded that the current experimental procedures produce qualitativernresults that can be used to compare with results obtained from numerical experiments. FLAC modelling withrnFISH programing is recommended for this purpose in the future.