Hazard assessment of a potential rock avalanche in South Tyrol, Italy: 3D modeling and risk scenarios. (original) (raw)
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Formation, Characterisation and Modeling of the Val Pola Rock-Avalanche Dam (Italy)
Lecture Notes in Earth Sciences, 2010
Landslide dams (i.e., the natural blockage of river channels by hillslope-derived mass movements ) are common natural phenomena with great relevance for geomorphological conditions and for the safety of people living close to them. Landslide dams can induce significant geomorphic hazards in the adjacent areas. Flooding by impounded water can create large lakes in the upstream areas, causing damages to human activities. Catastrophic outburst floods and/or debris flows can be triggered by a rapid dam failure with exceptional rates of sediment erosion and deposition along the downstream part of the valley.
Site investigation and modelling at "La Maina" landslide (Carnian Alps, Italy
Natural Hazards and Earth System Science, 2006
The Sauris reservoir is a hydroelectric basin closed downstream by a 136 m high, double arc concrete dam. The dam is firmly anchored to a consistent rock (Dolomia dello Schlern), but the Lower Triassic clayey formations, cropping out especially in the lower part of the slopes, have made the whole catchment basin increasingly prone to landslides. In recent years, the "La Maina landslide" has opened up several joints over a surface of about 100 000 m 2 , displacing about 1 500 000 m 3 of material. Particular attention is now being given to the evolution of the instability area, as the reservoir is located at the foot of the landslide. Under the commission of the Regional Authority for Civil Protection a numerical modelling simulation in a pseudo-time condition of the slope was developed, in order to understand the risk for transport infrastructures, for some houses and for the reservoir and to take urgent mesaures to stabilize the slope. A monitoring system consisting of four inclinometers, three wire extensometers and ten GPS bench-mark pillars was immediately set up to check on surface and deep displacements. The data collected and the geological and geomorphological evidences was used to carry out a numerical simulation. The reliability of the results was checked by comparing the model with the morphological evidence of the movement. The mitigation measures were designed and realised following the indications provided by the model.
Instabilityplanning …, 2002
UPC contribution UPC intends to use the Finite Element Method to analyse the sites in this project. The computer software that will be used is DRAC, a powerful code specifically developed at UPC to perform finite element analysis of Rock Mechanics engineering problems in two and three dimensions. The package includes several types of finite elements in two and three dimensions, joint elements to model rock discontinuities, linear elements to represent rock bolts, facilities to simulate excavation and construction, a new procedure to introduce an equilibrium initial stress state, advanced numerical features for non-linear analysis and a great variety of constitutive models for the continuum, joint and linear elements. The same computer package includes a post-processor specially designed to handle output of the main program in two and three dimensions, and a parallel code to analyse flow problems.
Interpretation of landslide mechanisms based on numerical modelling: two case-histories
European Journal of Environmental and Civil Engineering, 2014
Numerical modelling represents a powerful technique to develop a quantitative assessment of the stress-strain mechanisms leading to either first-time slope failures or evolution of slopes already failed in the past. In this perspective, a valid interpretation of the landslide behaviour and an adequate strategy of risk mitigation can be achieved from a numerical validation of both the causative factors and the evolution mechanism that have been previously assumed according to detailed phenomenological or simple analytical approaches. This paper presents two case histories of slow landslides in clay slopes, both located in Puglia (Southern Italy), for which detailed phenomenological studies have been firstly carried out to infer assumptions on the slope failure mechanisms that have been later on verified by means of numerical analyses accounting for soil mechanical behaviour and slope hydraulic processes. The first case study concerns the first-time failure of a stiff clay slope in Lucera, which has been induced by the slow dissipation of negative excess pore water pressures generated by previous quarry excavation at the slope toe. The second case history is represented by the analysis of the stress-strain evolution of the ancient Volturino landslide, which is observed to reactivate mainly in wet seasons.
Techniques issues and advances in numerical modelling of landslide hazard
Bulletin de la Societe Geologique de France, 2007
Slope movements (e.g. landslides) are dynamic systems that are complex in time and space and closely linked to both inherited and current preparatory and triggering controls. It is not yet possible to assess in all cases conditions for failure, reactivation and rapid surges and successfully simulate their transient and multi-dimensional behaviour and development, although considerable progress has been made in isolating many of the key variables and elementary mechanisms and to include them in physically-based models for landslide hazard assessments. Therefore, the objective of this paper is to review the state-of-the-art in the understanding of landslide processes and to identify some pressing challenges for the development of our modelling capabilities in the forthcoming years for hazard assessment. This paper focuses on the special nature of slope movements and the difficulties related to simulating their complex time-dependent behaviour in mathematical, physicallybased, models. It analyses successively the research frontiers in the recognition of first-time failures (pre-failure and failure stages), reactivation and the catastrophic transition to rapid gravitational processes (post-failure stage). Subsequently, the paper discusses avenues to transfer local knowledge on landslide activity to landslide hazard forecasts on regional scales and ends with an outline how geomorphological investigations and supporting monitoring techniques could be applied to improve the theoretical concepts and the modelling performance of physically-based landslide models at different spatial and temporal scales. Techniques, état de l'art et avancées dans la modélisation numérique de l'aléa 'Glissement de Terrain'. Mots clés.-Glissement de terrain, Evaluation de l'aléa, Modélisation, Pré-rupture, Rupture, Postrupture, Directions de recherche Résumé.-Les mouvements de versant (i.e. glissements de terrain) sont des phénomènes dynamiques, au comportement complexe dans le temps et dans l'espace et contrôlés par des facteurs (hérités et actuels) de prédisposition et de déclenchement. A l'heure actuelle, il n'est ni possible d'évaluer les conditions qui conduisent à la rupture du versant, à la réactivation d'un glissement déclaré ou à une accélération forte, ni de simuler leur comportement transitoire et multidimensionnel, bien que des avancées considérables sur l'identification des variables de contrôle et des mécanismes élémentaires, et sur le développement de modèles à base physique aient été effectuées. Ainsi, l'objectif de ce manuscrit est d'effectuer un état de l'art critique sur la connaissance des processus 'glissement de View publication stats View publication stats
Introduction to the special issue “Landslides: forecasting, hazard evaluation, and risk mitigation”
Natural Hazards, 2012
The papers collected in this special issue of Natural Hazards were originally presented as oral or poster contributions in the sessions ''Innovative approaches for evaluation of the landslide hazard and mitigation of the landslide risk'' and ''Landslide forecasting'', which were part of the scientific program of the Geoitalia 2009 meeting, the 7th Italian Forum of the Earth Sciences, held in Rimini, Italy, from 9 to 11 September 2009. The eighteen papers comprising the special issue of Natural Hazards discuss topics related to techniques, tools, and methods for landslide identification, forecasting, hazard evaluation, and the mitigation of landslide risk. The issue opens with the two keynote lectures invited in the sessions: in the first keynote, Jaboyedoff and co-workers review the application of light detection and ranging (LIDAR) technology for landslide investigation, including the study of slides, rockfalls, and debris flows. The authors discuss critically the application of LIDAR very-high-resolution terrain elevation data for the detection and characterization of landslides, for hazard assessment and susceptibility modeling, and for landslide monitoring and modeling. In the second keynote, Günther and co-workers, discuss a GIS-based deterministic approach for the spatial evaluation of the geometrical and kinematical properties of rock slopes. Based on spatially distributed directional information on planar geological fabrics, and DEM-derived topographic attributes, the internal geometry of the rock slopes is characterized. The obtained information, in combination with hydraulic and strength data on the geological discontinuities, can be used to prepare scenario-based rock-slope stability evaluations, at different geographical scales.
Engineering Geology, 2012
The Moscardo Torrent basin (Eastern Italian Alps) is a high-risk site, since a large roto-translational landslide might dam the torrent, with the consequence of increasing the possibility of large debris flow events, creating a threat for the infrastructures and the socio-economic activities of the villages that dot the valley below. The landslide, whose volume is estimated 2 million m 3 , has been monitored since 2006 with inclinometers, electric piezometers and a GPS network. The velocity, along the entire body of the landslide, averages 1.0-1.5 cm per month. The shear surface develops at depths varying from 9 to 10 m to 55-62 m, while the groundwater table is almost constant throughout the year, despite a cumulative rainfall of the area that usually reaches 2000 mm/year. The movements were simulated in a numerical model, in order to estimate the stabilization effect obtained by different types of possible countermeasures. The simulation was carried out using FLAC 2D, with creep modelling. Visco-elasto-plastic model of the medium in the sliding zone was assumed, allowing to determine the relation between time and displacement. A 10-year displacement trend, starting from the initial situation of 2006 was simulated. Moreover, seismic conditions were taken into consideration with a quasi-static approach, by applying a horizontal acceleration. The numerical model was built and validated on the basis of the data retrieved from geological investigations, as well as from inclinometric and GPS measurements. The results show that an accurate and well-planned multidisciplinary approach can help the decision makers in the choice of the most effective engineering solution for the mitigation of landslide hazard and risk.