Groundwater table might significantly fluctuate due to seasonal rainfall. In order to investigate the effect of the moving water table on the screening performance of multiple open trench barriers

a finite element model is developed to describe wave propagation in a layered ground

which is modeled as a dry layer resting on a saturated substratum. The effect of infiltrated water in trenches is considered in this model

and the vibration isolation efficiencies of multi-trench barriers with equal and unequal trench depth

multi-trench barriers with inclined trench wall and continuous undulating terrain barriers at different water levels are analyzed as comparable cases. Comparing with the corresponding single-phase elastic foundation

the numerical results show that a low permeability coefficient of the saturated substratum might have a significantly adverse effect on the vibration isolation efficiency for most of water tables. A triple trench barrier with a depth of 0.3LR (LR is Rayleigh wavelength) usually can achieve a satisfactory screening efficiency (i.e. 75% reduction)

while the depth should be at least 0.6LR at the critical water table

where the worst isolation efficiency occurs. A multiple trench barrier with decremental depth can effectively reduce the adverse effect of the resonance. The larger sloping sides are

the better isolation effect of a barrier is for the shallow trenches

while it is not important for deep ones. Moreover

a rolling terrain landscape can be an environment-friendly isolation measure

which would achieve a great vibration isolation efficiency.