ABSTRACT
Rainfall-induced landslide hazards are a serious and continual problem in Hong Kong. There are, on average, about 300 landslides reported every year (Ho & Lau 2007). Landslide motion ranges from a few centimeters per year to many meters per second, depending on the relative time scale between pore water pressure generation and dissipation (Iverson 2005). If the soil mass of a slope is in a loose state prior to failure, it is plausible to expect that soil contraction during failure will generate positive excess pore water pressures, which, under a relative slower drainage rate, may cause soil liquefaction and rapid flow landslides ( Iverson et al. 2000; Major & Iverson 1999; Wang & Sassa 2003) If the soil mass is in a dense state, the undrained shearing during slope failure will induce negative excess pore water pressure due to soil dilation and therefore increase the effective stress and the shear resistance. This in turn will retard the landslide motion.
