An Experimental Investigation on the Progressive Failure of Unsaturated Granular Slopes

Abstract

Slope failure is a complex process which depends on several factors concerning nature and properties of soil, slope morphology and structure, past stress history, groundwater regime, boundary conditions, and their changes. As a consequence, the mechanism of slope failure is typically characterized by the development of a highly non-uniform strain field, which does not allow an easy prediction of the failure conditions. Usually, the process which will bring the slope to final collapse starts with local soil failure, which then leads to formation and propagation of a shear zone, and finally to general slope failure. This mechanical process is called progressive failure. However, in spite of the progresses in the knowledge of the slope behavior, a complete framework about the progressive failure is still missing; in particular, information about the response of granular unsaturated sloping soils is very poor. This paper reports the results of a couple of small-scale experiments on slopes reconstituted with unsaturated pyroclastic soils and subjected to continuous rainfall. The use of miniaturized sensors and optical fibers provided useful data to read some aspects of the mechanics of failure.

The Undrained Behaviour of an Air-Fall Volcanic Ash

“…In a landslide soil mass, depending on the selected point along the slope, type of movement, interaction between soil mass and constraint (bedrock, etc. ), the stress paths to failure can be very different from each other and can significantly differ from those applied in compression triaxial tests [24]. This should be kept in mind when analyzing problems of failure in undrained conditions, not trusting exclusively in the value that is provided by "ordinary" triaxial compression tests if the shear strength in extension is lower than in compression.…”

Recent advancements of landslide hydrology

“…In the first case, the laboratory experiments are performed in an artificial environment under controlled conditions, which are aimed at investigating the deformation and triggering mechanism of landslides (e.g., Darban et al, 2019;Lora et al, 2016;Weng et al, 2018) and debris flows (Hu et al, 2016(Hu et al, , 2018. Other experiments focused on the infiltration process in layered sloping deposits, focusing on the possible formation of capillary barriers and flow diversion, which may affect the triggering mechanism of shallow landslides (Capparelli et al, 2020;Damiano, 2019;Damiano et al, 2017;Reder et al, 2017).…”

Distributed Optical Fiber Sensor Applications in Geotechnical Monitoring

“…The distributed optical fiber sensor was used in experimental tests aimed at investigating the deformation process up to failure of small-scale volcanic slopes subjected to artificial rainfall [16]. The soil used in the experiments was taken from the Cervinara site (North-East of Naples), an area affected by a catastrophic debris avalanche in 1999.…”