ABSTRACT
This experimental study was conducted to investigate the effects of pressure variations on sediment entrainment. A quasi-saturated fine sand sample was examined. In a closed-conduit, it was subjected to stream flow causing weak sediment movement. Full-scale waves were simulated by applying absolute pressure fluctuations at the sediment surface. The results prove that pressure variations cause vertical seepage in the bed. An absolute pressure reduction causes upward seepage. Image analysis of the bed surface reveals an increase of sediment mobility during pressure reduction. Data evaluation shows that this increase is mainly triggered by the upward seepage force acting on the particles.
