The use of high viscous pore fluid has been widely established to match the rate of excess
pore pressure generation and subsequent dissipation in dynamic centrifuge tests. The appropriate viscosity
is linked to the geometric and gravity scaling factors which corresponds to the use of pore fluid of ‘N’
cSt in a ‘N’g centrifuge test. The use of either water (1 cSt) or pore fluid lower than ‘N’ cSt can influence
the behaviour of soil liquefaction in a centrifuge test. In this paper, the floatation of a tunnel following
soil liquefaction is investigated using pore fluids with two different viscosities. The results show that the
uplift displacement of the tunnel is significantly affected by the pore fluid viscosity.