Debris flow monitoring and early warning systems in the Eastern Alps of Italy

( Matteo Berti ) 대한지질공학회 2016 대한지질공학회 학술발표회논문집 Vol.2016 No.0

Back-analysis of a Large Landslide in a Heterogeneous Rock Mass

( Matteo Berti ),( Anna Rita Bernardi ),( Giuseppe Caputo ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Flysch is a sedimentary rock consisting of a rhythmic alternation of hard (limestone, sandstone, siltstone) and weak (marl, mudstone, claystone) layers. Because of the presence of layers with different physical properties the mechanical characterization of heterogeneous rock masses such as flysch is a real challenge. Different methods have been proposed in the literature to characterize flysch, combining empirical classification indexes with laboratory tests. Most of these methods, however, were specifically designed for tunneling and underground excavations and their applicability to slope stability problems is not yet fully investigated. In this study, we analyze a large landslide in a cretaceous flysch rock in order to compare the mobilized strength at failure with those predicted by the modified GSI method (Marinos and Hoek, 2001). The landslide occurred in the Savena River basin (Northern Apennines of Italy) on April 6, 2013 with a volume of about 3 million cubic meters. Soon after the failure, geological, geotechnical, and geophysical investigations were carried out to detect the failure mechanism and define the landslide geometry. Back-analyses of the failed slope were performed using both limit equilibrium and finite difference methods to estimate the in situ strength of the flysch. The results show that the mobilized rock mass cohesion is very low and that the GSI method can predict the in situ strength only assuming a very high disturbance factor. Moreover, the analysis shows that the linearization criteria proposed in literature to compute the equivalent Mohr-Coulomb parameters remarkably overestimate the rock mass strength.

International Symposium of Landslide Prediction and Early Warning : Hydrologic response to rainfall of unstable clay slopes

( M Berti ),( A Simoni ) 대한지질공학회 2014 대한지질공학회 학술발표회논문집 Vol.2014 No.-

Slip line model for forces estimation in the radial-axial ring rolling process

Quagliato, Luca,Berti, Guido A.,Kim, Dongwook,Kim, Naksoo Elsevier 2018 International journal of mechanical sciences Vol.138 No.-

<P><B>Abstract</B></P> <P>In the research presented in this paper, a slip line-based model is proposed for the estimation of both radial and axial force in the radial-axial ring rolling (RARR) process. Based on the shape of the contact arcs between ring and tools in the two deformation gaps present in the ring rolling process, a recursive algorithm for the calculation of the two slip line fields starting from the two pairs of opposite tools is derived and implemented in a commercial spreadsheet software (MS Excel). By considering the stress boundary conditions applied to the portion of material undergoing the deformation, both for the radial and axial deformation gaps, the pressure factors those make the two slip line fields starting from the two opposite tools to intersect are calculated and utilized for the estimation of radial and axial forces, for each round of the process. The developed model has been validated by cross-comparing its results with those of laboratory experiment and numerical simulation. For the validation study case, the average deviations, in comparison to the experimental results, are calculated in 1.86% and 4.55% for the slip line force model whereas in 6.86% and 0.88% for the numerical simulation, for the radial and axial forces respectively. The proposed slip line model has been also utilized for the estimation of radial and axial forming forces of nine different study cases of flat rings having the outer diameter ranging from 800 mm to 2000 mm, observing a maximum deviation, in comparison to the relevant FEM simulation, of 4.92% (radial force) and 5.88% (axial force). The developed slip line force model allows estimating almost in real time and with a reasonable accuracy the process forces and, for this reason, it may be of interest for both industrial and academic researchers dealing with the set-up and control of the radial-axial ring rolling process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of analytical slip line field construction algorithm. </LI> <LI> Slip line algorithm implementation and boundary conditions calculation procedure. </LI> <LI> Radial and axial force calculation in the ring rolling process. </LI> <LI> Model validation by comparison with experimental and numerical results. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Contact geometry estimation and precise radial force prediction for the radial-axial ring rolling process

Quagliato, Luca,Berti, Guido A.,Kim, Dongwook,Kim, Naksoo Springer-Verlag 2018 International journal of material forming Vol.11 No.6

Towards the development of a custom talus prosthesis produced by SLM: design rules and verification

Francesca Danielli,Francesca Berti,Adelaide Nespoli,Martina Colombo,Tomaso Villa,Luigi La Barbera,Lorenza Petrini 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

Additive manufacturing (AM) is a promising technology for the personalized medicine industry, especially in the orthopedic field. It allows the production of prostheses that can fit complex anatomical sites and mimic bone morphology, featuring an external solid shell and an inner trabecular core. The new medical device regulation has recently outlined the need for safety assessment of these particular implants: to the best of the authors' knowledge, there are no defined methodologies to assess the quality of a custom product since each device is intended for single-time use. The goal of the current work is to propose a well-structured pipeline for designing and verifying an AM custom prosthesis: the exemplified case is that for the ankle joint treatment (i.e. talus resurfacing), whose standard solutions are affected by significant failure rates. A comprehensive characterization of the unique features of AM orthopedic implants will be presented, integrating finite element analyses and experiments.

Hydrotropic effect and thermodynamic analysis on the solubility and mass transfer coefficient enhancement of ethylbenzene

Nagarajan Nagendra Gandhi,Antony Bertie Morais,Chinnakannu Jayakumar 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.4

Concentrated aqueous solutions of a large number of hydrotropic agents, urea, nicotinamide, and sodium salicylate, have been employed to enhance the aqueous solubilities of poorly water soluble organic compounds. The influence of a wide range of hydrotrope concentrations (0-3.0mol·L−1) and different system temperatures (303-333 K)on the solubility of ethylbenzene has been studied. The solubility of ethylbenzene increases with increase in hydrotrope concentration and also with system temperature. Consequent to the increase in the solubility of ethylbenzene, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass transfer coefficient of ethylbenzene. The Setschenow constant, Ks, a measure of the effectiveness of a hydrotrope,was determined for each case. To ascertain the hydrotropic aggregation behavior of ethylbenzene, thermodynamic parameters such as Gibb’s free energy, enthalpy, and entropy of ethylbenzene were determined.

Pre-failure Landslide Deformation Measured by Satellite Radar Interferometry in the Northern Apennines of Italy

( Alessandro Simoni ),( Benedikt Bayer ),( Matteo Berti ),( Silvia Franceschini ),( Gabriela Squarzoni ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

In this work we back-analyze two landslide failures that occurred in the Northern Apennines of Italy, in terms of surface movements and their relation with rainfalls. The two landslides have some similarities in that they are historical earthflows characterized by relatively long period of slow-moving stable sliding that can be interrupted by rapid acceleration and catastrophic failure. In both cases, the catastrophic failures were sudden and unexpected, causing problems to infrastructures (roads and railways) located at the toe of the landslides. We process interferograms of SAR images acquired by Sentinel 1 A/B with time spans ranging from 6 to 24 days, removing those having low coherence by manual inspection. The conventional 2-pass technique allowed us to obtain measurements of surface displacement despite the fact that no infrastructures nor major reflectors are present on landslide bodies. Our interferograms show that surface displacements are well visible since 2015. They display nearly continuous downslope motion with seasonal velocity changes. Time series between 2015 and 2018 shows that surface displacements can be appreciated throughout most part of the year with snow cover and summer peak of vegetation being the most notable exceptions. Distinct accelerations can be detected in space and time during the weeks and months preceding the catastrophic failures. We compare time-dependent deformations to precipitation patterns to explore interactions between precipitation and landslide kinematics and to document the transition from stable to unstable sliding. Our work indicate that InSAR interferometry can be successfully used to anticipate catastrophic failure.

Landslide prediction, monitoring and early warning: a concise review of state-of-the-art

채병곤,박혁진,Filippo Catani,Alessandro Simoni,Matteo Berti 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.6

Landslide is one of the repeated geological hazards during rainy season, which causes fatalities, damage to property and economic losses in Korea. Landslides are responsible for at least 17% of all fatalities from natural hazards worldwide, and nearly 25% of annual casualties caused by natural hazards in Korea. Due to global climate change, the frequency of landslide occurrence has been increased and subsequently, the losses and damages associated with landslides also have been increased. Therefore, accurate prediction of landslide occurrence, and monitoring and early warning for ground movements are very important tasks to reduce the damages and losses caused by landslides. Various studies on landslide prediction and reduction in landslide damage have been performed and consequently, much of the recent progress has been in these areas. In particular, the application of information and geospatial technologies such as remote sensing and geographic information systems (GIS) has greatly contributed to landslide hazard assessment studies over recent years. In this paper, the recent advances and the state-of-the-art in the essential components of the landslide hazard assessment, such as landslide susceptibility analysis, runout modeling, landslide monitoring and early warning, were reviewed. Especially, this paper focused on the evaluation of the landslide susceptibility using probabilistic approach and physically based method, runout evaluation using volume based model and dynamic model, in situ ground based monitoring techniques, remote sensing techniques for landslide monitoring, and landslide early warning using rainfall and physical thresholds.

Development of a Concept to Optimize the Energy Efficiency in Forging Process Chains

Berend Denkena,박홍석,Bernd-Arno Behrens,Jan Henjes,Sebastian Bertys,Prakash Dahal,Ingo Lüken,Andreas Klassen 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

In the industrial production, approaches for the optimization of process chains mainly focus on criteria like quality, costs and time. Normally the energy consumption of process chains is not considered, although the variation of process parameters is an important possibility to reduce the consumption significantly. Besides that, the investigated processes are often optimized locally without considering the interaction between the different process elements of the whole process chain. Based on this background the developed concept realizes the optimization of the energy consumption of a forging process chain by adaptation of its energetic relevant parameters. Therefore, the concept defines at first variation intervals for the energetic most significant parameters of a forging process chain. After that, the resulting technical/technological modifications are evaluated energetically. To enable a holistic optimization of the process chain, the approach includes the use of a simulation model. The application of the concept has been approved with a simulation model of a 4-cylinder-crankshaft process chain. With the parameter variations “reduction of the forging temperature”,“reduction of the raw part volume” and “reduction of the forging time” three possibilities to reduce the energy consumption were identified successfully.