Pore-pressure development near tunnel due to underwater explosion from centrifuge tests Available to Purchase

An instrumented 1:70 scale model underground tunnel, located below a free water body, was subjected to explosions in centrifuge model tests. Utilising centrifuge scaling relations, each test at 70g modelled the effects of an explosion due to approximately 0.9 t of trinitrotoluene equivalent. The explosives were located at the ground surface, above the tunnel centreline. The effect of water level on the extent of damage was of primary interest in this study. Instrumentation in each test included pore-water pressure (PWP) transducers and strain gauges. PWP and strain measurements showed instantaneous increase due to the explosion, followed by gradual dissipation. The magnitude of peak pore pressure and strain increased with increase in water level. PWP ratios, calculated based on measured PWPs during the centrifuge tests, indicate that liquefaction occurred near the ground surface, close to the crown of the tunnel in all cases and at the bottom, near the endspan, only when the water level was high. The measured pore-pressure ratios and strains, induced due to the explosion, are useful in understanding the effects of explosion on an underground tunnel below a water body.