Geotechnical and hydrological characterization of hillslope deposits for regional landslide prediction modeling

We attempt a characterization of the geotechnical and hydrological properties of hillslope deposits, with the final aim of providing reliable data to distributed catchment-scale numerical models for shallow landslide initiation. The analysis is based on a dataset built up by means of both field tests and laboratory experiments over 100 sites across Tuscany (Italy). The first specific goal is to determine the ranges of variation of the geotechnical and hydrological parameters that control shallow landslide-triggering mechanisms for the main soil classes. The parameters determined in the deposits are: grain size distribution, Atterberg limits, porosity, unit weight, in situ saturated hydraulic conductivity and shear strength parameters. In addition, mineral phases recognition via X-ray powder diffraction has been performed on the different soil types. The deposits mainly consist of well-sorted silty sands with low plastic behavior and extremely variable gravel and clay contents. Statistical analyses carried on these geotechnical and hydrological parameters highlighted that it is not possible to define a typical range of values only with relation to the main mapped lithologies, because soil characteristics are not simply dependent on the bedrock type from which the deposits originated. A second goal is to explore the relationship between soil type (in terms of grain size distribution) and selected morphometric parameters (slope angle, profile curvature, planar curvature and peak distance). The results show that the highest correlation between soil grain size classes and morphometric attributes is with slope curvature, both profile and planar

Application of a physically based model to forecast shallow landslides at a regional scale

<p>In this work, we apply a physically based model, namely the HIRESSS (HIgh REsolution Slope Stability Simulator) model, to forecast the occurrence of shallow landslides at the regional scale. HIRESSS is a physically based distributed slope stability simulator for analyzing shallow landslide triggering conditions during a rainfall event. The modeling software is made up of two parts: hydrological and geotechnical. The hydrological model is based on an analytical solution from an approximated form of the Richards equation, while the geotechnical stability model is based on an infinite slope model that takes the unsaturated soil condition into account. The test area is a portion of the Aosta Valley region, located in the northwest of the Alpine mountain chain. The geomorphology of the region is characterized by steep slopes with elevations ranging from 400 m a.s.l. on the Dora Baltea River's floodplain to 4810 m a.s.l. at Mont Blanc. In the study area, the mean annual precipitation is about 800–900 mm. These features make the territory very prone to landslides, mainly shallow rapid landslides and rockfalls. In order to apply the model and to increase its reliability, an in-depth study of the geotechnical and hydrological properties of hillslopes controlling shallow landslide formation was conducted. In particular, two campaigns of on site measurements and laboratory experiments were performed using 12 survey points. The data collected contributed to the generation of an input map of parameters for the HIRESSS model. In order to consider the effect of vegetation on slope stability, the soil reinforcement due to the presence of roots was also taken into account; this was done based on vegetation maps and literature values of root cohesion. The model was applied using back analysis for two past events that affected the Aosta Valley region between 2008 and 2009, triggering several fast shallow landslides. The validation of the results, carried out using a database of past landslides, provided good results and a good prediction accuracy for the HIRESSS model from both a temporal and spatial point of view.</p

Effectiveness of aquicludes media as hydraulic barriers in respect to DNAPLs: an experimental study

Some experimental results of the hydrodynamic and geotechnical effects induced on a compacted fine grained porous medium by DNAPLs are presente

Caratterizzazione geotecnica e valutazione delle condizioni di stabilità delle coperture detritiche nell'area archeologica di Macchu Picchu (Perù)

Since 1997 the Machu Picchu area has been in the spotlight for its slope instability, when Carreno & Bonnard described the general geological and geomorphological condition, and the further studies of Sassa et alii contributed to define the interpretation of the structures, as the result of the existence of a main deep slow slide involving the archaeological area. However, the attention of these studies focused on the condition of the entire slope, with a lesser consideration for the shallow landslides, even if debris flows often occur and cause damages (like in 1995-1996, along the access road to the site) and real catastrophes (such as the one in 2004, when the day after Easter a channelized debris flow produced eleven casualties in Aguas Calientes, the close tourist town). A more general approach to the instability conditions of the site was undertaken in 2002, with the start of an international project, coordinated by K. Sassa and carried out in the framework of the activity of the International Consortium on Landslides. As constituent of this project, an integrate study of the instability condition of the debris was established: in this work the results of the field survey and the geotechnical analysis are shown. In particular, starting from the field data of the Carretera Hiram Bingham slope, two aspects has been handled: the interpretation of the distribution of debris thickness and the assessment of the working order of the runoff drainage system. Both the topics and the potentiality of their integration were approached in this work and the results constitute the first step for an exhaustive debris flow hazard assessment in this area, where the interactions between slope instability and land use can produce some very critical conditions

Valutazione del rischio di inquinamento in una limitata zona ad alto impatto antropico del Valdarno Inferiore

Si tratta della valutazione del rischio di inquinamento, secondo una metodologia parametrica di valutazione, sul territorio interessato dal comune di Fucecchio (FI) e dai comuni di Santa Croce sull'Arno e San Miniato (PI)

Caratterizzazione geotecnica e valutazione delle condizioni di stabilità delle coperture detritiche nell’area archeologica di Machu Picchu (Perù)

Caratterizzazione geotecnica e valutazione delle condizioni di stabilità delle coperture detritiche nell’area archeologica di Machu Picchu (Perù

Investigations on debris sheets for the analysis of slope instability conditions in the Machu Picchu area

Since 1997 the Machu Picchu area has been in the spotlight for its slope instability, when Carreno & Bonnard described the general geological and geomorphological condition, and the further studies of Sassa et alii (2001, 2002) contributed to define the interpretation of the structures, as the result of the existence of a main deep slow slide involving the archaeological area. However, the attention of these studies focused on the condition of the entire slope, with a lesser consideration for the shallow rainfall induced landslides, even if debris flows often occur and cause damages (like in 1995- 1996, along the access road to the site) and real catastrophes (such as the one in 2004, when the day after Easter a channelized debris flow produced eleven casualties in Machu Picchu Pueblo, the close tourist town). A more general approach to the instability conditions of the site was undertaken in 2002, with the start of an international project, coordinated by K. Sassa and carried out in the framework of the activity of the International Consortium on Landslides. As constituent of this project, an integrate study of the instability condition of the debris was established: in this work the results of the field survey and the geotechnical investigation and of a slope stability analysis are shown. In particular, starting from the field data of the Carretera Hiram Bingham slope, two aspects has been handled: the interpretation of the distribution of debris thickness and the assessment of the working order of the runoff drainage system. Both the topics and the potentiality of their integration were approached in this work: the data deriving from these studies, combined with the results of the geotechnical tests, allowed the realisation of a slope stability analysis with a distributed model. The results constitute the first step for an exhaustive debris flow hazard assessment in this area, where the interactions between slope instability and land use can produce some very critical conditions