2022, Articolo in rivista, ENG
Francesco Bucci(1), Michele Santangelo(1), Lorenzo Fongo(2), Massimiliano Alvioli(1), Mauro Cardinali(1), Laura Melelli(2), Ivan Marchesini(1)
Lithological maps contain information about the different lithotypes cropping out in an area. At variance with geological maps, portraying geological formations, lithological maps may differ as a function of their purpose. Here, we describe the preparation of a lithological map of Italy at the 1:100 000 scale, obtained from classification of a comprehensive digital database and aimed at describing geomechanical properties. We first obtained the full database, containing about 300 000 georeferenced polygons, from the Italian Geological Survey. We grouped polygons according to a lithological classification by expert analysis of the 5456 original unique descriptions of polygons, following compositional and geomechanical criteria. The procedure resulted in a lithological map with a legend including 19 classes, and it is linked to a database allowing ready interpretation of the classes in geomechanical properties and is amenable to further improvement. The map is mainly intended for statistical and physically based modelling of slope stability assessment and geomorphological and geohydrological modelling. Other possible applications include geoenvironmental studies, evaluation of river chemical composition, and estimation of raw material resources. The dataset is publicly available at https://doi.org/10.1594/PANGAEA.935673 (Bucci et al., 2021).
2022, Abstract in atti di convegno, ENG
Evelina Volpe 1, Stefano Luigi Gariano 1, Francesca Ardizzone 1, Federica Fiorucci 1, and Diana Salciarini 2
Shallow landslides induced by rainfall are very common movements that occur in hilly and mountainous areas causing losses of human life, ecological and environmental impacts and considerable economical costs. The predisposing factors for shallow landslides are represented by morphology, lithology, soil type, land cover, and land use, and their changes. Land use is constantly evolving because it is linked to human activities; the increase of population pressure and economic development forced more people to use all areas available. A lot of scientific contributions analyzed the positive effects of vegetation cover on slope stability, focusing on the mechanical effects of vegetation (both vegetation cover and roots) in terms of providing additional mechanical root reinforcement. Conversely, the effects of agricultural practices on slope stability conditions are poorly investigated. Indeed, while agriculture contributes positively to the landscape, biodiversity, climate and fires, on the other hand, improper agricultural practices and soil uses can modify the mechanical properties of the involved soils leading to a possible increase of instability phenomena. To evaluate the effect of agricultural practices on the slope stability conditions, we present an application of a probabilistic, physically-based model for the triggering of rainfall-induced landslides (PG_TRIGRS - a probabilistic, geostatistic-based extension of the TRIGRS model) to the Collazzone area, a cultivated area located in Umbria, central Italy, characterized by a high susceptibility to landslides, which is studied and periodically monitored through systematic image analysis and on-site surveys. The method applied in this research included the comparison between landslides observed in situ and the spatial distribution of the probability of failure derived from the application of PG_TRIGRS model, which models the study area in a GIS grid and treats each cell as an infinite slope. More in detail, a heuristic approach was adopted: after a first run of the model with unbiased parameters, the slope stability analysis has been carried out assuming several percentages of reduction of the effective soil cohesion (c') to mimic an increasing impact of agricultural practices on the strength conditions. A back-analysis methodology, with the support of sensitivity indices, was adopted to provide a preliminary quantitative evaluation of the effect induced by agricultural practices on the mechanical properties of the soil. To test the reliability of the method, standard contingency matrix and skill scores were adopted and the best compromise between correct and incorrect model outcomes was obtained considering a reduction of c' between 20% and 30%. In conclusion, we could estimate that in the analyzed area the agricultural practices can cause a 20 to 30% reduction in soil.
2021, Articolo in rivista, ENG
T.V. Tran(1), M. Alvioli(2), V.H. Hong(1)
The mechanical processes involved in movements of earth or rock masses under the effect of gravity - a landslide - may include several phases where the failure of one portion of terrain can lead to the instability of the surrounding parts. An earlier landslide might have follow-up landslides until the landscape finds the equilibrium state. Soon thereafter, recurring landslides are often recorded in landslide inventories but are seldom exploited in physical landslide modeling. Here, we study the landslide mechanism using Scoops3D - a three-dimensional, physically based landslide model. The program employs the three-dimensional column limit equilibrium and a digital elevation model to perform a slope stability analysis. Scoops3D evaluates the stability of rotational, spherical slip surfaces encompassing many grid cells, producing the least-stable sliding surface throughout the entire digital landscape. The program creates two important outputs, namely a factor of safety map and a terrain map showing the new topographical conditions of the site with unstable areas removed. To define the final predicted landslide boundary, we have run Scoops3D repeatedly to assess the site's stability using a newly produced terrain profile until the model predicts as stable all of the grid cells within the entire landscape. We compared the method's prediction with the actual sliding scar that took place on August 05th, 2019, following a historical rainstorm in Sapa - Vietnam. Results for modified success rate, a performance metric, show that with reliable input data, the approach can predict the evolution of landslides with improved results compared to the traditional method using Scoops3D.
2021, Articolo in rivista, ENG
J. López-Vinielles(1,2,3), J.A. Fernández-Merodo(1,4), P. Ezquerro(1,2), J.C. García-Davalillo(1), R. Sarro(1), C. Reyes-Carmona(1), A. Barra(5), J.A. Navarro(5), V. Krishnakumar(5), M. Alvioli(6), G. Herrera(1,7)
Slope failures pose a substantial threat to mining activity due to their destructive potential and high probability of occurrence on steep slopes close to limit equilibrium conditions, which are often found both in open pits and in waste and tailing disposal facilities. The development of slope monitoring and modeling programs usually entails the exploitation of in situ and remote sensing data, together with the application of numerical modeling, and it plays an important role in the definition of prevention and mitigation measures aimed at minimizing the impact of slope failures in mining areas. In this paper, a new methodology is presented; one that combines satellite radar interferometry and 2D finite element modeling for slope stability analysis at a regional scale, and applied within slope unit polygons. Although the literature includes many studies applying radar interferometry and modeling for slope stability analysis, the addition of slope units as input data for radar interferometry and modeling purposes has, to our knowledge, not previously been reported. A former mining area in southeast Spain was studied, and the method proved useful for detecting and characterizing a large number of unstable slopes. Out of the 1959 slope units used for the spatial analysis of the radar interferometry data, 43 were unstable, with varying values of safety factor and landslide size. Out of the 43 active slope units, 21 exhibited line of sight velocities greater than the maximum error obtained through validation analysis (2.5 cm/year). Finally, this work discusses the possibility of using the results of the proposed approach to devise a proxy for landslide hazard. The proposed methodology can help to provide non-expert final users with intelligible, clear, and easily comparable information to analyze slope instabilities in different settings, and not limited to mining areas.
2019, Contributo in atti di convegno, ENG
Cavallaro A.; Abate G.; Ferraro A.; Giannone A.; Grasso S.
During the 2010, due to intense meteoric events, some municipalities in Sicily were affected by rainfall-induced landslides. These events caused considerable damage to structures so it was necessary to realize some stabilization works. The aim of this paper is to present the dynamic stability analysis of a hill on top of which there are three multi-storey residential buildings. An accurate geotechnical characterisation was carried out, which involved the execution of boreholes and piezometers, Down-Hole and MASW tests, inclinometer measurements and laboratory tests. It was also carried out a laser scanner survey, in order to allow an accurate reconstruction of the post-event orography. The stabilization works for the landslide risk mitigation, were realized with bulkhead micropiles anchors on multiple rows. Results of the slope stability analyses obtained by finite element codes Quake/ W and Slope/W are presented, using some synthetic seismograms, related to the Messina earthquake of December 28, 1908.
2019, Articolo in rivista, ENG
Guillem Domènech(1), Massimiliano Alvioli(2), Jordi Corominas (1)
In this work, we present a novel quantitative geographical information system-based procedure to obtain the magnitude (area) and frequency of medium to large first-time shallow slope failures. The procedure has been set up at the Barcedana Valley, in the Tremp Basin (Eastern Pyrenees). First, pixel-based susceptibility classes were defined using a slope stability index obtained with the physically based model SINMAP. The frequency calculated from the number of first-time failures recorded during the last 60 years was then assigned to each susceptibility class. We devised a procedure to estimate the size of potential failures by means of the aggregation of pixels within the boundaries of morphological slope units, optimized for the purpose. Finally, the landslide hazard was prepared using the magnitude-frequency matrix. Results show that a proper pixel clustering has been carried which avoids the generation of small groups of pixels with different susceptibility degrees within the same slope unit. For a given hill slope, the area of the cluster of pixels depends on the size of the slope unit, which is not unique as it depends on the criterion used to delineate them. Therefore, the latter is a key factor in the final results. In this study, we validated our results with the size distribution of the observed landslides. The methodology presented in this work can be applied using any susceptibility assessment method with a pixel-based output.
2019, Articolo in rivista, ENG
Madonia, P.; Cangemi, M.; Olivares, L.; Oliveri, Y.; Speziale, S.; Tommasi, P.
Several shallow landslides occurred at La Fossa cone (Vulcano Island, Aeolian Archipelago, Italy) in the last 30years, during both unrests and periods of quiet volcanic activity. The main event occurred in 1988, during a volcanic unrest, when a landslide collapsed into the sea from the NE flank of La Fossa cone, producing a small tsunami. Hydrothermal activity has been suggested as a potential trigger for landslide generation in this area. However, no specific investigations were carried out to test this hypothesis. With the aim of filling this gap, we studied the mineralogy and hydraulic conductivity of La Fossa cone deposits, the relationships between shallow hydrothermal circulation and rainfall dynamics and their role in triggering slope failures. We also measured rainfall rate, volumetric soil moisture content and soil suction at two automated stations installed in areas with and without active hydrothermal circulation. We found that hydrothermally altered low-conductivity materials show higher background water contents and lower soil suctions than pristine deposits, and their water content is modulated by impulsive increments following rainfalls. This behaviour is due to the combination of lower permeability and direct condensation of hydrothermal vapour. We conclude that shallow hydrothermal circulation produces conditions for slope failures following transients in soil moisture content caused by rainfall infiltration. These considerations allow to identify the areas immediately NW and SE of the 1988 landslide as the most prone to future mass movements.
2019, Articolo in rivista, ENG
Fazio N.L.; Perrotti M.; Andriani G.F.; Mancini F.; Rossi P.; Castagnetti C.; Lollino P.
This paper aims to present a new methodological approach for the stability assessment of coastal cliffs constituted of discontinuous rock masses. The method entails in situ specific geostructural and geomechanical surveys, three-dimensional UAV-based Photogrammetric structural models, laboratory geotechnical tests and, two- and three-dimensional finite element analysis (FEM). The application of the method to a case study is then presented and discussed; it regards a 600m long sea rocky cliff located at Sant'Andrea (Melendugno, South of Apulia, SE Italy) and faced to the southern Adriatic Sea. Here the cliff is made up of an about 15 m-thick sequence of laminate calcisiltites alternate with bioturbated calcarenites belonging to the Uggiano la Chiesa Fm. (Middle-Upper Pliocene). The structural discontinuities detected with photogrammetry techniques were compared and validated with those derived from conventional in situ survey methods. Later on, the paper discusses assumptions and results of two- and three-dimensional finite element models developed to investigate the potential failure mechanisms of the sea cliff accounting for pre-existing weak planes or discontinuities with unfavourable orientation. The failure mechanisms obtained by both FEM analysis agree well with those typically observed in the study area.
2018, Contributo in atti di convegno, ENG
Giulia Bossi, Gianluca Marcato
In most developed countries the budget devoted to structural risk mitigation of natural hazards such as floods and landslide is reducing. On top of that, mitigation structures constructed decades ago require some maintenance that it is seldom guaranteed since they are widespread in all the territory and inspections are infrequent. In some cases, the cost correlated with the engineering activities could be compensated through the association of works that provide economic return on the long term. The case study consists of a slope instability phenomenon crossed by a National Road that connects the Veneto and Friuli Venezia Giulia regions. Due to the risk conditions the phenomenon has been investigated and monitored for more than 15 years. The landslide is crossed by a torrent and near the crown of the instability phenomenon some springs are present. The opportunity to use the water removed from the slope to produce energy through a small hydropower plant could help sustain economically the remediation project.
2017, Contributo in volume, ENG
M. Alvioli
Riassunto della lezione telematica tenuta per il corso Diplomazia2
2016, Key note o lezione magistrale, ENG
Tommasi P.; Rotonda T.; Verrucci L.; Graziani A.; Boldini D.
The paper initially reviews major issues of slope instability at active volcanoes on the basis of geotechnical and engineering geology literature. A detailed discussion is then provided with reference to two case studies on Italian insular active volcanoes: Stromboli and La Fossa (Vulcano Island). At Stromboli, the role of magma intrusion in initiating the instability phenomena associated to major eruptions and the particular mechanical behaviour of the volcaniclastic deposits in controlling the 2002 submarine failure are investigated by means of numerical and conceptual models based on an extensive geotechnical characterization. At La Fossa, the influence of flank erosion, hydrothermal alteration, and anomalous pore pressures produced by hydrothermal activity on the evolution of the NE sector of the volcanic edifice are described with the aid of numerical analyses based on laboratory and in situ investigations.
2016, Contributo in volume, ENG
Picarelli L., Comegna L., Gariano S.L., Guzzetti F., Mercogliano P., Rianna G., Santini M., Tommasi P.
Changes in the main weather features are becoming perceivable in Italy. In the last years, the average temperature and the intensity of rainstorms are increasing. Such phenomena could lead to changes in the earth-atmosphere interaction. Accounting for the high vulnerability of the Italian territory, an obvious consequence would concern the effects on the hydro-geological hazards, including landslides and floods. As a matter of fact, the higher frequency of high magnitude flood and landslide events represent an alarm bell. It is necessary to explore with all available instruments the consequences of the potential climate changes. Since quantitative predictions are not possible, the only way to run is depicting rational scenarios for the most vulnerable contexts adopting a multidisciplinary approach. Based on projections of potential climate changes in the 21st century, the report examines their potential impact in the context of the Italian peninsula. After a general overview about typical slope responses to weather changes, some quantitative scenarios have been depicted for representative geomorphological contexts. The last part of the paper examines changes in the expected risk, based on the characteristics of the Italian territory and its vulnerability, looking at the initiatives to undertake for its mitigation.
2014, Articolo in rivista, ENG
Cotecchia F.; Santaloia F.; Lollino P.; Vitone C.; Pedone G.; Bottiglieri O.
The diagnosis of landsliding at the slope scale resulted from synergic geohydromechanical analyses of the slope factors, which should represent the first step to assess landslide hazard. According to the methodological approach discussed in the paper, the landslide hazard analysis should start from a phenomenological interpretation of the slope behaviour, including the definition of the slope factors, getting then to a quantitative prediction of the slope evolution with time. This quantitative evaluation should result from limit equilibrium analyses and numerical modelling, both of them performed considering the outcomes of the phenomenological reconstruction. Therefore, the understanding of the slope factors and of the landslide mechanism at the slope scale should drive the landslide hazard assessment, through analyses performed for different levels of diagnosis (phenomenological, analytical and numerical). Some landslides, representative for chain slopes in the Italian peninsula, are discussed in the paper in order to show the maturity of the geohydromechanical diagnosis of landslide hazard and, hence, to properly design the mitigation actions. A methodology for intermediate to regional landslide hazard assessment, based on geomechanical interpretations, is finally proposed.
2013, Contributo in volume, ENG
P. Tommasi, M. Sciotti, T. Rotonda, L. Verrucci, D. Boldini
Orvieto rises on top of a mesa formed by a slab of weak pyroclastic rocks overlying an overconsolidated clay formation. The particular geotechnical conditions of the site enhanced the erosive process that isolated the mesa and in turn favoured human settlement. These geotechnical conditions include the stiffness contrast between the slab and the clay, the low strength of the pyroclastics, and the susceptibility to degradation of the clay formation. These conditions have been found to be the source of a complex and time-dependent interaction between landslides and urbanization. In this paper the anthropic changes to the natural evolution of the landscape are reconstructed through archival and historic documents over the last eight centuries and interpreted from a geotechnical point of view. The types and characteristics of failures that occurred in the past are described by means of aerial photo analysis, field surveys and archival research, whilst geometry and kinematics of active movements are illustrated using present-day monitoring results. Based on a detailed interpretation of displacement and pore pressure monitoring in the clay slope and the results of numerical analysis of the erosional process and selected failures, a conceptual model of the instability mechanism of the hill is proposed. Finally, protection policies from the Renaissance period until the XX century, when comprehensive preservation projects started, are illustrated and their impact on the instability mechanism discussed.
2010, Rapporto tecnico
Borselli L.
2009, Articolo in rivista, ENG
A. Milia; A. Raspini; M.M. Torrente
The interpretation of high-resolution seismic profiles acquired close the eastern coast of the Bay of Naples offshore Somma-Vesuvius volcano, and calibrated by borehole data, allowed us to recognize a reflection-free seismic facies consisting of a volcaniclastic debris avalanche overlain by pyroclastic density current deposits. Both are associated with the 3.5 ka 'Avellino eruption' and are in turn overlain by a marine succession. The top of the volcaniclastic unit corresponds to a deep erosional surface covered by a coarse-grained bioclastic layer with rounded pumice. We argue that these features are related to a tsunami that was triggered by the sudden entrance into the sea of the gigantic (>1km3) volcaniclastic unit. The onshore-offshore correlation and mapping of this volcaniclastic unit have allowed us to evaluate its distribution west of Somma-Vesuvius. The pyroclastic density current deposits terminate seaward at 40 m water depth; at the same depth the debris avalanche is affected by a gravitational instability. Over the last 3.5 ka the slump has been in constant movement, as documented by the angular unconformities at the top of the chaotic seismic unit and within the overlying marine deposits. © The Geological Society of London 2009.
2008, Abstract in atti di convegno, ENG
Cherubini C., Pagliarulo R., Trizzino R
2008, Articolo in rivista, ENG
Perrone A; Vassallo R; Lapenna V; Di Maio C
Slope stability is influenced by many factors, among which are subsoil structure and pore water pressure distribution. This paper presents a multi-disciplinary approach for the determination of these two factors and for the construction of a reliable model of the subsoil for the slope stability analysis. The case of a clay slope located in the Southern Apennines ( Italy) is presented and discussed. Geophysical imaging (2D electrical resistivity tomography-ERT), in situ geotechnical monitoring ( measurements of pore pressures and horizontal displacements) and laboratory geotechnical tests ( for the determination of index, hydraulic and mechanical properties of soils) have been carried out. The comparison and the integration between ERT images and direct observations of the material extracted from boreholes have allowed us to reconstruct the subsoil stratigraphy with continuity. Thus, a reliable 2D model of the subsoil has been obtained, with well-defined boundaries on which it has been possible to apply appropriate hydraulic conditions. This geotechnical model has been used for studying the pore water pressure distribution and for analysing how the hydraulic boundary conditions-among which rain events - influence the slope stability. Our findings demonstrate the powerful skill of the ERT, if integrated with borehole data, to generate an accurate subsoil model. It is also evident that geophysical imaging can be a source of ambiguity and misjudgement if interpreted without a comparison with geotechnical data.
2006, Contributo in atti di convegno, ENG
Iovine G., Petrucci O., Rizzo V. & Tansi C.
In the early morning of March 7th 2005, after a period of prolonged rainfall (645 mm in 90 days, about 72% of mean annual precipitation) and snowfall, the hamlet of Cavallerizzo was severely damaged by a vast complex debris slide-earth flow. In total, thirty buildings were severely damaged or destroyed by the landslide, and the main road connecting Cavallerizzo with the villages of Cerzeto and Mongrassano was disrupted. About 310 inhabitants had to be evacuated to nearby villages. Several superimposed tectonic units, made of metamorphic rocks (Palaeozoic-Mesozoic) overlain by clastic terrains (Cenozoic-Neozoic), crop out in the vicinity of the study area. The main scarp of the slide developed at the eastern tectonic boundary of the Coastal Chain, marked by the "San Fili-Cerzeto-San Marco Argentano" recent (presumably active) N-S trending normal fault; its crown is mainly located within the cataclastic zone associated with such master fault. In the lower part of the landslide, two main earth-flows extended eastward along minor valleys, that merged down slope along the S. Nicola torrent. The sector affected by the landslide belongs to a wider large-scale slope movement, which extends westwards up to about 800 m a.s.l. The 2005 event is only the last paroxysmal episode of a long history of deformation recorded in the area of Cavallerizzo since the XVIII century. The area has been kept under control by the CNR-IRPI, by means of desultory field measurements (essentially, deep and superficial displacements, and piezometric levels) since 1999. Velocities, recorded at superficial benchmarks along opening cracks, pointed out "anomalous" conditions in the weeks preceding the collapse: pre-rupture velocities ranged from 0.8 to 5-6 cm/day. Despite its emergency character, the monitoring carried out helped to support civil-protection activities, and allowed all inhabitants to be saved.
2003, Contributo in atti di convegno, ENG
Tommasi P., Consorti C., Campedel P., Ribacchi R.