1,721,004 research outputs found
Monitoring Of Temperature-Induced Deformations in High Mountain Huts
No full textGlobal warming is affecting a lot ofhuman activities and has a relevant environmental impact. This is particularly evidentin the Alps, where the recorded temperature increases are larger than average. This trend has direct consequences onthe stability of high mountain slopes, as it provokes the upward receding of permafrost and triggers a series of rockfall events. Although it is difficult to pinpoint the direct cause-effectrelationship for any recorded event, two general facts emerge: failures are becoming more and more frequent, especially during particularly hot summer seasons; failures tend to concentrate within the altitude range affected by permafrost receding.In this paper,we discuss the structuralmonitoring at Capanna Margherita hut (Punta Gnifetti 4554m a.s.l., Monte Rosa massif), which is the highest mountain hut in the Alps and Europe in general. Geomechanicalmonitoring was activated there in 2023 and it is now complemented by the installation of sensors onthe hut structurein 2024. Afull set of data is continuously being recorded, including inclinometric, thermometric and accelerometric data.The paperanalysisis based on the data recorded by thesensors and the air temperature at Capanna Margherita hut, includingthe relationship between the temperatures and displacements, and the dynamic characteristics of structural vibrations
Dry granular masses impacting on rigid obstacles: numerical analysis and theoretical modelling
Full text linkThe assessment of the time evolution of the impact force exerted by dry flowing masses on rigid obstacles is mandatory for the dynamic design of sheltering structures and the evaluation of the vulnerability of existing structures. In this paper, the results of an extensive numerical campaign performed by employing a discrete element method (DEM) code are presented and the role of different geometrical factors (flow length, height and front inclination) and state parameters (porosity and velocity) on the impact force–time evolution is investigated. The impact process is studied to correlate local information with the macroscopic response and a physically based force–time function, generalising the formula already introduced by the authors for the assessment of maximum impact force, in which each parameter is correlated with the previously mentioned factors, is proposed
DEM Modelling of Ice Filled Rock Joints
No full textThe research we present in this paper is part of a wider project about the modelling of climate change effects on the degradation of permafrost, with particular attention for the stability of rock masses. The presence of ice and/or mixtures of ice and granular materials in rock joints has a big impact on the shear resistance of joints and on the evolution of joint persistence. In previous research we modelled the mechanical behavior of ice and frozen soils with a Distinct Element model and compared the evolution of the resistance with ice content with experimental data available in the literature. In this paper, we are focusing on rock joints and we are modelling both fill material (ice and frozen soil mixtures) and rock as collections of Distinct Elements, taking advantage of the previous experience in terms of calibration of the parameters. In particular, in this preliminary study, we will focus on the shear resistance of joints as a function of the composition of the fill material. The purpose of this research is to study the mechanical behavior of joints and derive the corresponding force-displacement relationship to be assigned to the interfaces between blocks in a full scale model of rock masses
Analisi agli elementi discreti del comportamento di una fondazione modello su pendio
No full textIn questo intervento si presentano i risultati di alcune analisi numeriche agli elementi discreti volte a simulare una prova di collasso eseguita su modello fisico caricando una fondazione posta alla sommità di un pendio modello in terreno granulare. Il confronto è condotto considerando sia la curva carico-spostamento della piastra che il campo degli spostamenti nel terreno costituente il pendio, spostamenti che sono stati rilevati mediante la tecnica PIV (Particle Image Velocimetry)
Modellazione micromeccanica dell'effetto dell'evaporazione sulla stabilità di un pendio granulare
No full textL’analisi di stabilità dei pendii granulari si concentra spesso sui terreni più superficiali, così da essere necessariamente legata alle dinamiche di infiltrazione, filtrazione ed evaporazione. In questo contesto la distribuzione spaziale e temporale della suzione riveste un ruolo fondamentale: per esempio, è ben noto l’effetto stabilizzante dato dalla presenza di piccole quantità d’acqua all’interno di un terreno
granulare. Da un punto di vista micromeccanico, in condizioni di umidità bassissima (regime pendolare) l’acqua forma dei ponti capillari tra le particelle di terreno che determinano l’insorgenza di forze di attrazione la cui intensità è proporzionale alla granulometria e al volume d’acqua condiviso. Questo articolo presenta un metodo per determinare l’entità di queste forze all’interno di un aggregato ideale di particelle sferiche e mostra come esso può essere incorporato all’interno di un modello agli elementi discreti per studiare l’effetto sulla resistenza e sull’erodibilità di un pendio
Analisi dell’installazione di pali a spostamento di terreno con il metodo agli elementi discreti
No full textDrying and Stability of a Granular Slope Experimental and Numerical Dem Analysis
No full textThis paper analyses the mechanical behaviour of granular soils in pendular state using a discrete element approach with a contact model modified for taking into account the interparticle capillary forces. The role of water content at different confinement stresses is investigated using some numerical triaxial tests. The capability of the improved DEM is tested simulating the evaporation process occurred in a slope composed by glass spheres
An assessment of plasticity theories formodelling the incrementally nonlinear behavior of granular soils
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