Investigation of The Vertical Retreating Flow Slide

Confirmation seminar presented by Hossein Khoshgou

Breaching flow slide is a special type of slope failure which occurs in clean densely packed sand. The term "flow slide" is derived from sediment falling down the slope, transported not as a sediment mass but as a mixture of sediment and water. Breaching flow slide accompanied by the generation of turbidity currents. Turbidity currents are characterized as sediment-laden gravity-driven underflows, where particles are predominantly or entirely suspended due to fluid turbulence. Turbidity currents are crucial in sediment transport, facilitating sediment movement from continental shelves to the deep sea or on a small scale, transporting beach sand into the near tidal channels as can be seen at Amity Point. The mechanism of breaching is associated with the creation of negative pore pressures that impede rapid erosion processes caused by flow or, in the case of a steep slope, by gravity. The negative pore pressure generates effective stresses, which enhance the deposit's strength, leading to a stable and steep (Vertical) retrograding failure surface. This research focused on the physical process of turbidity current as a phenomenon which accelerates the slope failure and the importance of retreating velocity and sediment entrainment. Breaching flow slide can be started by a small scrape on subaqueous vertical face and the height of its become greater as its retreat. However, the termination point of flow slide and flow regime is missing in the literature. This research suggests investigating the flow regime in the large-scale flume under different scenarios, Investigating the sediment entrainment from the vertical sand deposit and its effect on turbidity current, and developing a numerical model verified by experimental data to investigate the effect of different parameters on the breaching flow slide.