1,720,969 research outputs found
Anisotropia della rigidezza a taglio mediante misure di bender elements in cella triassiale
No full textMultidirectional bender element measurements in the triaxial cell: equipment set-up and signal interpretation
No full textThe paper presents a description of the arrangements of the vertical and horizontal bender elements and their implementation
in stress-path triaxial cells, together with the comparison among three of the most commonly used interpretation
methods of the bender elements signals to identify the travel time of the input wave to the receiver. The methods are
the first arrival time, travel time between the characteristic points, cross-correlation method and π-point phase comparison
method. For the material tested in this research and the test boundary conditions, the signals from bender elements demonstrate
that the travel time should be taken as the time corresponding to that obtained by the first arrival method based
on the visual identification of the wave arrival to the receiver. The horizontal and vertical bender elements implemented
in stress-path triaxial cells have been used to investigate the evolution of shear moduli G(ij) of reconstituted specimens of
Lucera clay (Southern Italy) under both isotropic and anisotropic stress states up to pressures higher than those usually
achieved in similar studies. In this way the influence of long anisotropic stress paths on the clay stiffness will be highlighted.
It is deduced that the different plastic straining resulting from the imposition of different virgin radial paths tends to modify
the original pattern of
Progetto strategico per la valutazione del rischio da frana nell’appennino pugliese dauno: approccio metodologico e risultati preliminari
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
A research project for deterministic landslide risk assessment in Southern Italy: methodological approach and preliminary results
No full textNew peptidyl-anthraquinones: Synthesis and DNA binding
No full textAminoiacyl-hydroxy-anthraquinones bearing glicyl, valyl, lysyl and tryptophanyl residues in the side-chain were synthesized as new potential DNA-directed drugs
Progetto strategico per la valutazione del rischio da frana nell’appennino pugliese dauno: ulteriori sviluppi della ricerca
No full textExperimental investigation of the evolution of elastic stiffness anisotropy in a clayey soil
No full textThe paper presents the main results of a research study into the very small strain shear stiffness of a clayey soil, as measured in vertical and horizontal directions, G(hv) and G(hh), respectively, by means of T-shaped horizontal bender elements fitted in a stress-controlled triaxial system. The testing programme was designed to investigate the evolution of the anisotropy ratio G(hh)/G(hv) along isotropic (eta = 0) and anisotropic (eta not equal 0) virgin radial paths. In particular, a reconstituted clay has been chosen as tested material in order to unequivocally relate the observed evolution of its stiffness anisotropy to the specific stress-strain histories imposed in laboratory. The results show that the small strain stiffness anisotropy smoothly adapts itself to the imposed strain history, achieving different constant values ranging from 1 to 1.2 for eta ranging from 0 to 0.8. The experiments 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. In this context, the variation of the fabric orientation has been quantified through a specific digital image processing
Meccanismi di frana in pendii in argille dell’Italia Meridionale ed effetti delle precipitazioni meteoriche
No full textDeterministic landslide hazard assessment at regional scale
No full textThe paper presents a new methodology for the deterministic assessment of landslide hazard at the regional scale in geologically complex chain areas. The methodology entails site specific geo-mechanical studies, as background of any hazard prediction application, and the creation of a Regional Landslide Manual portraying the geo-mechanical knowledge about the slope conditions across the region. The search in the regional manual of the landslide mechanisms which may correspond to the combination of landslide factors recorded at the local scale results in the hazard prediction. The testing of the methodology in the Daunia Apennines is discussed. © 2010 ASCE
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