Simulation of the EPB-shield TBM in model tests with foam as additive

Model tests have been performed to investigate the behaviour of a sand-water-foam mixture. A TBM with an earth pressure balance shield was simulated. Saturated sand was mixed with foam and the sand-water-foam mixture was removed with a screw conveyor. The properties of the mixture in the ‘mixing chamber’ and in the screw conveyor have been studied. Two different sands where tested with a d₅₀ of 135 μm and 300 μm respectively and two different foams. Changing the sand had a significant influence on the result. The influence of the type of foam was less.