F. Cafaro - Academia.edu (original) (raw)
Papers by F. Cafaro
Studia Geotechnica et Mechanica, 2019
Water infiltration through coal stocks exposed to weather elements represents a key issue for man... more Water infiltration through coal stocks exposed to weather elements represents a key issue for many old mining sites and coal-fired power plants from the environmental point of view, considering the negative impact on human health of the deriving groundwater, soil and air pollution. Within this context, the paper investigates the hydraulic behaviour of a self-weight compacted unsaturated coal mass and its impact on the numerical prediction of infiltration induced by rainfall events. In particular, the work focuses on the experimental investigation carried out at different representative scales, from the grain scale to physical modelling. The material, when starting from uncompacted conditions, seems to be characterized by metastable structure, which tends to collapse under imbibition. In addition, direct numerical predictions of the seepage regime through a partially saturated coal mass have been performed. As the compaction of the coal stock induced by dozers has not been taken into...
Granular Matter, 2021
A correction to this paper has been published: https://doi.org/10.1007/s10035-021-01117-2
Granular Matter, 2020
The study of processes characterized by impulsive nature (i.e. impacts) can be considered of grea... more The study of processes characterized by impulsive nature (i.e. impacts) can be considered of great interest in both physics and engineering disciplines: in the geotechnical field, for instance, their effect on the interaction between soil and structures need to be investigated. The present work aims at the validation, by means of two-dimensional finite element simulations, of a methodology of force calibration which uses results obtained from three-dimensional discrete element analysis for predicting the stress at the base of a granular bed, retained by a movable wall, arising when the system is hit by a projectile. To approach this problem, the low-velocity impact has been modeled as a punctual impulsive force on a granular packing.
Proceedings of the Second International Workshop on Characterisation and Engineering Properties of Natural Soils, Singapore, 29 November-1 December 2006, 2006
ABSTRACT The paper presents the geotechnical characterisation of a site in the Daunia region (sou... more ABSTRACT The paper presents the geotechnical characterisation of a site in the Daunia region (southern Italy), Santa Croce di Magliano, which is located within the East-side border of the Apennines chain. The soils outcropping in the site form the so-called Daunia unit. They are mainly allochthonous finegrained soils, which were originally deposited elsewhere and were moved and largely deformed during the Apennines orogenesis. Therefore, they are severely disturbed and fissured. The paper first discusses briefly the geological setting of Daunia and, in particular, of Santa Croce di Magliano. Thereafter, it presents the main results of a research about the mechanical properties of two of the four main soilcomplexes assembled in the Daunia Unit: the scaly clays and the fissured bentonite part of the Red Flysch, which are excessively and intensely fissured respectively. Their mechanical characterisation results in the definition of a framework of mechanical behaviour for both the soils, representing the main features of the influence of highly intense fissuring on the mechanical behaviour of clays.
Studia Geotechnica et Mechanica
The present paper focuses on the shear strength exhibited by rocks and soils when sliding along d... more The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.
Journal of Aerospace Engineering, 2019
Understanding the mechanical behaviour of lunar regolith is of great importance to address the bu... more Understanding the mechanical behaviour of lunar regolith is of great importance to address the building of structures on the Moon, as well as for predicting the response of some equipments or facilities interacting with the lunar soil (i.e. rovers). Since the amount of lunar regolith samples on Earth is quite low due to the difficulties to bring it back during space missions, in the last decades researchers started to develop similar materials, usually named lunar regolith simulants. This paper reports the geotechnical characterization of DNA "De NoArtri" lunar simulant carried out in the laboratory. Compositional analyses and mechanical tests have been carried out to characterize this simulant: particle-size distribution analysis, chemical analysis, scanning electron microscope (SEM) analysis have been performed, to identify the DNA-1A from a compositional point of view, as well as triaxial compression tests, direct shear tests and oedometer tests for depicting its mechanical behaviour, with some comparison with the original lunar soil and other simulants.
Scientific Reports
The paper presents the results of the analysis of the geo-chemo-mechanical data gathered through ... more The paper presents the results of the analysis of the geo-chemo-mechanical data gathered through an innovative multidisciplinary investigation campaign in the Mar Piccolo basin, a heavily polluted marine bay aside the town of Taranto (Southern Italy). The basin is part of an area declared at high environmental risk by the Italian government. The cutting-edge approach to the environmental characterization of the site was promoted by the Special Commissioner for urgent measures of reclamation, environmental improvements and redevelopment of Taranto and involved experts from several research fields, who cooperated to gather a new insight into the origin, distribution, mobility and fate of the contaminants within the basin. The investigation campaign was designed to implement advanced research methodologies and testing strategies. Differently from traditional investigation campaigns, aimed solely at the assessment of the contamination state within sediments lying in the top layers, the ...
Géotechnique Letters
The letter describes an investigation of the microstructural features of a high-plasticity clay, ... more The letter describes an investigation of the microstructural features of a high-plasticity clay, in both its natural conditions and reconstituted in the laboratory. Scanning electron microscopy is used here to characterise the fabric at different magnification, while image processing of the micrographs delivers a quantitative assessment of the fabric orientation. Results of Energy dispersive X-ray spectroscopy and swelling tests, as reported in previous work by the authors, are used to characterise the bonding nature and strength, as well as mercury intrusion porosimetry to investigate the clay porosimetry. Despite their identical composition, the natural and the reconstituted clay have experienced different deposition and loading history, generating different microstructural features that are shown to underlie their differences in state. For both clays, 1D compression to medium-high pressures is seen to determine a well oriented medium magnification fabric. However, larger scale observations and the corresponding image processing results reveal non-uniform local fabric features, hence making fabric characterisation dependent on the scale of analysis and bringing about the issue of identifying the clay micro-scale representative element volume relating to the clay macro-behaviour. The micro-REV is identified for the clays under study and its connection with the macro-behaviour characterized. The microstructural evolution induced by 1D compression to very high pressures is shown to concern mainly the clay porosity and porosimetry, the fabric orientation being steady, thus explaining the isotropic hardening observed in laboratory tests.
Journal of Geophysical Research: Solid Earth
In this study, the micromechanical interparticle contact behavior of "De NoArtri" (DNA-1A) grains... more In this study, the micromechanical interparticle contact behavior of "De NoArtri" (DNA-1A) grains is investigated, which is a lunar regolith simulant, using a custom-built micromechanical loading apparatus, and the results on the DNA-1A are compared with Ottawa sand which is a standard quartz soil. Material characterization is performed through several techniques. Based on microhardness intender and surface profiler analyses, it was found that the DNA-1A grains had lower values of hardness and higher values of surface roughness compared to Ottawa sand grains. In normal contact micromechanical tests, the results showed that the DNA-1A had softer behavior compared with Ottawa sand grains and that cumulative plastic displacements were observed for the DNA-1A simulant during cyclic compression, whereas for Ottawa sand grains elastic displacements were dominant in the cyclic sequences. In tangential contact micromechanical tests, it was shown that the interparticle friction values of DNA-1A were much greater than that of Ottawa sand grains, which was attributed to the softer contact response and greater roughness of the DNA-1A grains. Widely used theoretical models both in normal and tangential directions were fitted to the experimental data to obtain representative parameters, which can be useful as input in numerical analyses which use the discrete element method. Plain Language Summary Lunar regolith simulants comprise natural soils found on Earth or artificially created materials which mimic the properties of the real lunar surface soil. Understanding the behavior of these simulants can help researchers to prepare for further explorations and settling of facilities on the Moon. In this study, an attempt is made to examine in the laboratory the behavior of the lunar regolith simulant "De NoArtri" (DNA-1A), and the results are compared with a standard soil of quartz grains to understand the differences and obtain insights into the properties of the lunar simulant. The behavior of regolith simulant is compared with Ottawa sand grains to understand the differences between these two materials in terms of material properties as well as micromechanical behavior. This micromechanical behavior gives a fundamental understanding of the mechanical response of the material and can provide important parameters to be further utilized in computer simulations so that settling of facilities on the Moon surface can be designed safely.
Journal of Materials in Civil Engineering
Reduction of pore water pressures is a useful strategy to improve the stability of slopes. Deep d... more Reduction of pore water pressures is a useful strategy to improve the stability of slopes. Deep draining trenches can be used for this scope. For the realisation of deep trenches, the usual conventional construction techniques are not adequate and the use of adjacent vertical panels, built by means of the methods well established for diaphragm walls, is necessary. However, unbonded materials (i.e. gravels) cannot be used, since the excavation of a panel adjacent to already built ones will cause instability. For this scope a bonded material such as the pervious concrete can be used. It must have high permeability, filtering capacity in order to prevent the internal erosion of the soil in which the trench drain is installed, sufficient shear strength after a short curing time avoiding the instability of adjacent previously built panels. This paper reports the hydraulic characterization of two mixtures of pervious concrete carried out in the laboratory. The hydraulic conductivity has been measured in saturated conditions. Then, the water retention functions of the mixtures have been experimentally deduced, by investigating different calculation options, and their impact on the simulation of seepage processes through an unsaturated soil mass, in which an ideal trench is located, has been studied.
Bulletin of Engineering Geology and the Environment, 2016
Landslide hazard maps are often defined as reliable a posteriori, in accordance with the real lan... more Landslide hazard maps are often defined as reliable a posteriori, in accordance with the real landslides occurring from the time of the map production. However, to be useful for planning, a reliability judgment concerning the hazard mapping should be a priori, based on data uncertainty characterization, and must be driven by the knowledge of the slope instability mechanisms. The landslide hazard assessment, when based on the deterministic diagnosis of the processes, may really lead to really providing clues about how and why the slope could fail (landslide susceptibility) and, possibly, when (landslide hazard). Such deterministic assessment can be pursued only through the interpretation and the geo-hydro-mechanical modelling of the slope equilibrium. In practice, though, the landslide hazard assessment is still seldom dealt with slope modelling, in particular when it addresses intermediate to regional zoning. The paper firstly offers an overview of the key steps of a methodology called the multiscalar method for landslide mitigation, MMLM, which that is a methodological approach for the intermediate to regional landslide hazard assessment using the hydro-mechanical diagnoses of landsliding. The validation of the MMLM to the geologically complex outer sectors of the Southern Apennines (Daunia-Lucanian mountains; Italy) is also delineated, together with a practical approach to incorporate a reliability judgment in the landslide susceptibility/hazard mapping.
Procedia Engineering, 2016
Peer-review under the responsibility of the organizing and scientific committees of CNRIG2016
Procedia Engineering, 2016
Peer-review under the responsibility of the organizing and scientific committees of CNRIG2016
Rivista Italiana di Geotecnica
Studia Geotechnica et Mechanica, 2019
Water infiltration through coal stocks exposed to weather elements represents a key issue for man... more Water infiltration through coal stocks exposed to weather elements represents a key issue for many old mining sites and coal-fired power plants from the environmental point of view, considering the negative impact on human health of the deriving groundwater, soil and air pollution. Within this context, the paper investigates the hydraulic behaviour of a self-weight compacted unsaturated coal mass and its impact on the numerical prediction of infiltration induced by rainfall events. In particular, the work focuses on the experimental investigation carried out at different representative scales, from the grain scale to physical modelling. The material, when starting from uncompacted conditions, seems to be characterized by metastable structure, which tends to collapse under imbibition. In addition, direct numerical predictions of the seepage regime through a partially saturated coal mass have been performed. As the compaction of the coal stock induced by dozers has not been taken into...
Granular Matter, 2021
A correction to this paper has been published: https://doi.org/10.1007/s10035-021-01117-2
Granular Matter, 2020
The study of processes characterized by impulsive nature (i.e. impacts) can be considered of grea... more The study of processes characterized by impulsive nature (i.e. impacts) can be considered of great interest in both physics and engineering disciplines: in the geotechnical field, for instance, their effect on the interaction between soil and structures need to be investigated. The present work aims at the validation, by means of two-dimensional finite element simulations, of a methodology of force calibration which uses results obtained from three-dimensional discrete element analysis for predicting the stress at the base of a granular bed, retained by a movable wall, arising when the system is hit by a projectile. To approach this problem, the low-velocity impact has been modeled as a punctual impulsive force on a granular packing.
Proceedings of the Second International Workshop on Characterisation and Engineering Properties of Natural Soils, Singapore, 29 November-1 December 2006, 2006
ABSTRACT The paper presents the geotechnical characterisation of a site in the Daunia region (sou... more ABSTRACT The paper presents the geotechnical characterisation of a site in the Daunia region (southern Italy), Santa Croce di Magliano, which is located within the East-side border of the Apennines chain. The soils outcropping in the site form the so-called Daunia unit. They are mainly allochthonous finegrained soils, which were originally deposited elsewhere and were moved and largely deformed during the Apennines orogenesis. Therefore, they are severely disturbed and fissured. The paper first discusses briefly the geological setting of Daunia and, in particular, of Santa Croce di Magliano. Thereafter, it presents the main results of a research about the mechanical properties of two of the four main soilcomplexes assembled in the Daunia Unit: the scaly clays and the fissured bentonite part of the Red Flysch, which are excessively and intensely fissured respectively. Their mechanical characterisation results in the definition of a framework of mechanical behaviour for both the soils, representing the main features of the influence of highly intense fissuring on the mechanical behaviour of clays.
Studia Geotechnica et Mechanica
The present paper focuses on the shear strength exhibited by rocks and soils when sliding along d... more The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.
Journal of Aerospace Engineering, 2019
Understanding the mechanical behaviour of lunar regolith is of great importance to address the bu... more Understanding the mechanical behaviour of lunar regolith is of great importance to address the building of structures on the Moon, as well as for predicting the response of some equipments or facilities interacting with the lunar soil (i.e. rovers). Since the amount of lunar regolith samples on Earth is quite low due to the difficulties to bring it back during space missions, in the last decades researchers started to develop similar materials, usually named lunar regolith simulants. This paper reports the geotechnical characterization of DNA "De NoArtri" lunar simulant carried out in the laboratory. Compositional analyses and mechanical tests have been carried out to characterize this simulant: particle-size distribution analysis, chemical analysis, scanning electron microscope (SEM) analysis have been performed, to identify the DNA-1A from a compositional point of view, as well as triaxial compression tests, direct shear tests and oedometer tests for depicting its mechanical behaviour, with some comparison with the original lunar soil and other simulants.
Scientific Reports
The paper presents the results of the analysis of the geo-chemo-mechanical data gathered through ... more The paper presents the results of the analysis of the geo-chemo-mechanical data gathered through an innovative multidisciplinary investigation campaign in the Mar Piccolo basin, a heavily polluted marine bay aside the town of Taranto (Southern Italy). The basin is part of an area declared at high environmental risk by the Italian government. The cutting-edge approach to the environmental characterization of the site was promoted by the Special Commissioner for urgent measures of reclamation, environmental improvements and redevelopment of Taranto and involved experts from several research fields, who cooperated to gather a new insight into the origin, distribution, mobility and fate of the contaminants within the basin. The investigation campaign was designed to implement advanced research methodologies and testing strategies. Differently from traditional investigation campaigns, aimed solely at the assessment of the contamination state within sediments lying in the top layers, the ...
Géotechnique Letters
The letter describes an investigation of the microstructural features of a high-plasticity clay, ... more The letter describes an investigation of the microstructural features of a high-plasticity clay, in both its natural conditions and reconstituted in the laboratory. Scanning electron microscopy is used here to characterise the fabric at different magnification, while image processing of the micrographs delivers a quantitative assessment of the fabric orientation. Results of Energy dispersive X-ray spectroscopy and swelling tests, as reported in previous work by the authors, are used to characterise the bonding nature and strength, as well as mercury intrusion porosimetry to investigate the clay porosimetry. Despite their identical composition, the natural and the reconstituted clay have experienced different deposition and loading history, generating different microstructural features that are shown to underlie their differences in state. For both clays, 1D compression to medium-high pressures is seen to determine a well oriented medium magnification fabric. However, larger scale observations and the corresponding image processing results reveal non-uniform local fabric features, hence making fabric characterisation dependent on the scale of analysis and bringing about the issue of identifying the clay micro-scale representative element volume relating to the clay macro-behaviour. The micro-REV is identified for the clays under study and its connection with the macro-behaviour characterized. The microstructural evolution induced by 1D compression to very high pressures is shown to concern mainly the clay porosity and porosimetry, the fabric orientation being steady, thus explaining the isotropic hardening observed in laboratory tests.
Journal of Geophysical Research: Solid Earth
In this study, the micromechanical interparticle contact behavior of "De NoArtri" (DNA-1A) grains... more In this study, the micromechanical interparticle contact behavior of "De NoArtri" (DNA-1A) grains is investigated, which is a lunar regolith simulant, using a custom-built micromechanical loading apparatus, and the results on the DNA-1A are compared with Ottawa sand which is a standard quartz soil. Material characterization is performed through several techniques. Based on microhardness intender and surface profiler analyses, it was found that the DNA-1A grains had lower values of hardness and higher values of surface roughness compared to Ottawa sand grains. In normal contact micromechanical tests, the results showed that the DNA-1A had softer behavior compared with Ottawa sand grains and that cumulative plastic displacements were observed for the DNA-1A simulant during cyclic compression, whereas for Ottawa sand grains elastic displacements were dominant in the cyclic sequences. In tangential contact micromechanical tests, it was shown that the interparticle friction values of DNA-1A were much greater than that of Ottawa sand grains, which was attributed to the softer contact response and greater roughness of the DNA-1A grains. Widely used theoretical models both in normal and tangential directions were fitted to the experimental data to obtain representative parameters, which can be useful as input in numerical analyses which use the discrete element method. Plain Language Summary Lunar regolith simulants comprise natural soils found on Earth or artificially created materials which mimic the properties of the real lunar surface soil. Understanding the behavior of these simulants can help researchers to prepare for further explorations and settling of facilities on the Moon. In this study, an attempt is made to examine in the laboratory the behavior of the lunar regolith simulant "De NoArtri" (DNA-1A), and the results are compared with a standard soil of quartz grains to understand the differences and obtain insights into the properties of the lunar simulant. The behavior of regolith simulant is compared with Ottawa sand grains to understand the differences between these two materials in terms of material properties as well as micromechanical behavior. This micromechanical behavior gives a fundamental understanding of the mechanical response of the material and can provide important parameters to be further utilized in computer simulations so that settling of facilities on the Moon surface can be designed safely.
Journal of Materials in Civil Engineering
Reduction of pore water pressures is a useful strategy to improve the stability of slopes. Deep d... more Reduction of pore water pressures is a useful strategy to improve the stability of slopes. Deep draining trenches can be used for this scope. For the realisation of deep trenches, the usual conventional construction techniques are not adequate and the use of adjacent vertical panels, built by means of the methods well established for diaphragm walls, is necessary. However, unbonded materials (i.e. gravels) cannot be used, since the excavation of a panel adjacent to already built ones will cause instability. For this scope a bonded material such as the pervious concrete can be used. It must have high permeability, filtering capacity in order to prevent the internal erosion of the soil in which the trench drain is installed, sufficient shear strength after a short curing time avoiding the instability of adjacent previously built panels. This paper reports the hydraulic characterization of two mixtures of pervious concrete carried out in the laboratory. The hydraulic conductivity has been measured in saturated conditions. Then, the water retention functions of the mixtures have been experimentally deduced, by investigating different calculation options, and their impact on the simulation of seepage processes through an unsaturated soil mass, in which an ideal trench is located, has been studied.
Bulletin of Engineering Geology and the Environment, 2016
Landslide hazard maps are often defined as reliable a posteriori, in accordance with the real lan... more Landslide hazard maps are often defined as reliable a posteriori, in accordance with the real landslides occurring from the time of the map production. However, to be useful for planning, a reliability judgment concerning the hazard mapping should be a priori, based on data uncertainty characterization, and must be driven by the knowledge of the slope instability mechanisms. The landslide hazard assessment, when based on the deterministic diagnosis of the processes, may really lead to really providing clues about how and why the slope could fail (landslide susceptibility) and, possibly, when (landslide hazard). Such deterministic assessment can be pursued only through the interpretation and the geo-hydro-mechanical modelling of the slope equilibrium. In practice, though, the landslide hazard assessment is still seldom dealt with slope modelling, in particular when it addresses intermediate to regional zoning. The paper firstly offers an overview of the key steps of a methodology called the multiscalar method for landslide mitigation, MMLM, which that is a methodological approach for the intermediate to regional landslide hazard assessment using the hydro-mechanical diagnoses of landsliding. The validation of the MMLM to the geologically complex outer sectors of the Southern Apennines (Daunia-Lucanian mountains; Italy) is also delineated, together with a practical approach to incorporate a reliability judgment in the landslide susceptibility/hazard mapping.
Procedia Engineering, 2016
Peer-review under the responsibility of the organizing and scientific committees of CNRIG2016
Procedia Engineering, 2016
Peer-review under the responsibility of the organizing and scientific committees of CNRIG2016
Rivista Italiana di Geotecnica