Abstract:
The transformation of soil from a plastic state into a VISCOUS liquid state is
primarily caused by changing the water content of the soil mass. As the water content
increases, the soil mass gradually starts to behave like a viscous liquid. In spite of
viscosity being a key parameter to the behavior of mudflows, there have no datasets of
soil viscosity changes successfully measured continuously as they move from plastic to
viscous liquid states. The aim of the current research "is to design a new device to
overcome this difficulty. Based on the trap door principle formulated by Terzaghi
(1943) and the Bingham model, a new device called the Flow Box was designed. The
governing equation of the Flow Box was derived in this research in order to obtain the
relationship between initial viscosity and liquidity index. In this study, the viscosities in
both plastic and viscous liquid states were clearly defined by the Flow Box Test. The
expected decrease in initial viscosity was followed by an increase in liquidity index,
which corroborated with the test results. The initial viscosity readings with the results of
other similar research and the case study of the Maokong mudflow was also validated.
