Mechanical and fluid-dynamic behaviour of debris and hyper-concentrated flows: overview and challenges

Abstract

Debris and hyper-concentrated flows are among the most destructive of all water-related disasters. They mainly affect mountain areas in a wide range of morphoclimatic environments and in recent years have attracted more and more attention from the scientific and professional communities and concern from public awareness, due to the increasing frequency with which they occur and the death toll they claim. In this context, achieving a set of debris and hyper-concentrated flow constitutive equations is a task that has been given particular attention by scientists during the second half of the last century.In relation to these issues, this paper reviews the most updated and effective geotechnical and fluid-dynamic procedures nowadays available, suitable to predict the triggering and mobilising processes of these phenomena, and proposes a mathematical model that is able to assess the depth of the wave and the velocities of the liquid and solid phases of both non-stratified (mature) and stratified (immature) flows following flash-floods and dam-break events in one and two dimensional cases.Different experimental cases of dam-break situations in a square section channel were considered for the purpose of comparing results.These tools will allow, on one hand, to better focus on what to observe in the field and, on the other hand, to improve both mitigation measures and hazard mapping procedures. Keywords: debris flow, rheological behaviour of the mixture, slope failure, numerical models, laboratory and field tests.

A Systematic Review of the Relationship between Geotechnics and Disasters

“…The geotechnical engineering cluster is linked to research on risk assessment on slope stability [248,249], geographic information systems in geotechnical engineering [250], liquefaction during earthquakes [251], the interaction between anti-slip piles and landslides [252], site investigation for disaster reconstruction [253] and the performance of soft soil under the action of thunderstorms [254]. Cluster 2, called "disaster", presents 12 nodes with themes related to debris flow disasters [255][256][257], geotechnical damage caused by earthquakes [258,259], damage to geostructures and slopes caused by heavy rains [258,260], erosion control and disaster prevention [261], debris flow drainage channels with energy dissipation structures in mountainous areas [262], volcanic mountain area disasters caused by an earthquake [263], prediction and assessment of slope-failure hazard based on GIS [232], satellite radar interferometry to delineate burn areas and detect sediment accumulation [260], and mechanical and fluid-dynamic behavior of debris and hyperconcentrated flows [264]. Cluster 3, called "earthquake", with 62 occurrences and 23 nodes, is related to research on landslides caused by earthquakes and rains [265,266], seismic site effects in a coastal urban area [267], and GIS-based liquefaction susceptibility [146].…”

Improvement on Numerical Solution of 1-D Flow With Hyper-Concentrated Sediment

“…The hyper-concentrated flow under this definition is classified as mudflow, mud flood and debris flow, each of them has its own features or characteristics. Debris and hyper-concentrated flows are among the most destructive of all water-related disasters [11]. Debris flows would be more potential to occur when the heavy rainfall takes place; this is due to the condition that the slope materials become saturated with rainwater resulting in slope failures and mass movement.…”