233 research outputs found
Dissesto di abitati situati su piastroni lapidei giacenti su argille tettonizzate: il caso di Santa Croce di Magliano
No full textPlastic strain-induced small strain stiffness anisotropy. A multi-scale experimental evidence
No full textThe paper summarises the main results of a research into the very small strain shear stiffness of a clayey soil, as measured in vertical and horizontal directions, Ghv and Ghh respectively, by means of T-shape horizontal bender elements fitted in a stress-controlled triaxial system.
The testing programme, carried out on a reconstituted clay, was designed to investigate the evolution of the anisotropy ratio Ghh/Ghv along isotropic (η = 0) and anisotropic (η 0) virgin radial paths. The results show that the small strain stiffness anisotropy smoothly adapts itself to the imposed strain history. The experiments also show that the complete modification of the directional elastic properties of the soil requires the virgin radial compression path to be extended along a new direction up a stress level at least four times larger than that experienced previously. Finally, the variations in the clay elastic anisotropy have been related to the changes in clay fabric as investigated by means of scanning electron microscopy (SEM). In this context, the variation of the fabric orientation has been quantified through a specific digital image processing
PROGETTO STRATEGICO PER LA VALUTAZIONE DE RISCHIO DA FRANA NELL'APPENNINO PUGLIESE DAUNO: APPROCCIO METODOLOGICO E RISULTATI PRELIMINARI
No full textInterventi di stabilizzazione nei pendii dell’Appennino Dauno:analisi dello stato esistente e proposta di criteri innovativi
No full textApplicazione del metodo multi-scalare per la valutazione della pericolosità da frana nell’Appennino Dauno-Lucano.
No full textInterpretation of landslide mechanisms based on numerical modelling: two case-histories
No full textNumerical 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
Analysis of landslide reactivation mechanisms in Daunia by means of limit equilibrium and FEM methods
No full textThe paper presents the analysis of the mechanism of reactivation of a deep landslide process which involves the western slope of Volturino in the Daunia Apennines (Southern Italy), where tectonized and fissured soils of poor mechanical properties outcrop. The reactivation, which is monitored by piezometers and inclinometers, takes place when the water table is approximately at the ground surface, i.e. during winter. Limit equilibrium back-analyses of the current landslide process, with a pore pressure distribution consistent with the field data, were performed to assess the in situ mobilised strengths and the depth of the sliding body. Drained finite element analyses were then carried out to simulate the reactivation mechanism by modelling the presence of a band of softened material within the slope along with the seasonal variation in seepage conditions. The results of the different analyses tend to confirm the higher instability of deep sliding bodies in the slop
Applicazione dei metodi avanzati al fronte appenninico apulo-lucano: analisi di II livello della metodologia multiscalare
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