Vortrag der Masterarbeit von Leonie Soltek am 5. Dezember


Liquefaction in sediments underneath Landslides – a transient pore pressure analysis

Plexiglas Box Urheberrecht: © LIH

Landslides from catastrophic rock slope failure can entail a whole cascade of hazards. Different studies investigated excess pore pressure that may evolve during the run-out of debris flows and could show their importance on run-out characteristics. In my master thesis, I investigate excess pore pressures induced by a rock avalanche impact on runout path sediments and its time-dependent dissipation to understand the influence of this underlaying sediment layer on overall rock avalanche behavior. Specially to find out under which conditions the valley fill sediments are at a risk of liquefaction.

Therefore, an experimental setup consisting of a Plexiglas box was designed, representing a column of pass material. Pressure sensors at different height of the column were used to capture the transient pore pressure response. The box is half filled with fully saturated sediments of typical grain size distribution for an Alpine valley. The rock avalanche impact loading is simulated by dropping debris onto the saturated material. The results indicate that pore pressures in the underlying sediments mainly rise after the material has been loaded, leading to a hypothesis of a propagating pressure “wave” in an attempt to equilibrate pore pressure. The threshold of liquefaction is not reached under the used conditions, but the experiments imply that the likelihood for the path sediment to liquefy is highest in the bottom of the valley fill layer and in around 10 cm to 15 cm depth.