Nicola Moraci - Academia.edu (original) (raw)
Papers by Nicola Moraci
ACTA SCIENTIARUM POLONORUM - Architectura Budownictwo
The interface friction between geosynthetics has previously been extensively studied with referen... more The interface friction between geosynthetics has previously been extensively studied with reference to medium-high contact stresses. The interface strength at low contact stress is a less investigated chapter whose importance, however, is evident for the stability of geosynthetic landfill barriers during the construction stage and of the covering systems. The inclined plane is the most used laboratory test for measuring the geosynthetic interface friction at normal stresses as low as 5 kPa. This type of test, however, is not free from criticalities, due to the non-uniformity of the contact stresses induced by the inclination of the plane. Alternatively, it is possible to extrapolate the results of the classic direct shear test, which, however, generally cannot be performed at such low contact stress values. The paper compares data results provided by inclined plane tests and an experimental apparatus capable of performing horizontal shear tests at a vertical stress of 5 kPa. The pec...
International Journal of Geosynthetics and Ground Engineering, Oct 23, 2023
A relevant issue in the development of disaster risk reduction strategies is played by design of ... more A relevant issue in the development of disaster risk reduction strategies is played by design of mitigation measures aimed at reducing risk to acceptable values. For rapid landslides, such as debris flows, sheltering structures are very common mitigation measures realized in exposed areas that allow to protect elements at risk and to stop flowing mass. For the design of these works, the debris flow-structure interaction mechanism is very important. The paper focuses on the evaluation of debris flow-structure interaction mechanism in earth reinforced embankments based on an uncoupled analysis of the interaction in two flow cases (dominant static and dynamic). In particular, a novel approach to evaluate the horizontal stress distribution at different time of the impact phenomenon along the upstream face height of deformable sheltering structures considering the dominant flow component has been proposed. First, impact force over the time against structure is calculated. Subsequently, assuming that debris flow is completely stopped by embankment according to a scheme of accumulation of material behind the obstacle, the deformative response of different geometrical types of embankment is obtained by FEM numerical analysis for considered flow cases. The results of numerical analyses are discussed in terms of horizontal displacements in different control points in sheltering structures. The analysis showed that the deformative response of two geometries of embankments depends on dominant static or dynamic components of impact force.
Le frane superficiali di tipo flusso indotte da pioggia coinvolgono diverse tipologie di terreno ... more Le frane superficiali di tipo flusso indotte da pioggia coinvolgono diverse tipologie di terreno e spesso causano perdita di vite umane e ingenti disastri socio-economici. Tale circostanza è connessa alla limitata presenza di segnali premonitori nella fase di pre-rottura (soprattutto in assenza di efficienti sistemi di monitoraggio), alle alte velocità raggiunte dalla colata nella fase di propagazione ed all’aumento del volume di detrito coinvolto, a causa dell’erosione del terreno lungo il percorso. Per via delle loro caratteristiche e delle conseguenze che possono causare, la valutazione della suscettibilità di questi fenomeni franosi diventa un aspetto da indagare in dettaglio soprattutto nell’ottica di una corretta pianificazione territoriale e di una virtuosa gestione del territorio. Il presente contributo intende fornire una valutazione preliminare della suscettibilità all’innesco di frane superficiali di tipo flusso detritico attraverso l’implementazione di un modello fisicamente basato (TRIGRS). Il modello è stato testato e validato in un’area studio del Sud Italia da tempo interessata da questa tipologia di fenomeni franosi. I risultati ottenuti sono soddisfacenti, se confrontati con l’evento franoso che ha interessato l’area di studio nel 2001, sia in termini di localizzazione delle aree di innesco sia in termini di individuazione delle aree potenzialmente instabili.
Abstract The hydraulic properties of geotextiles are fundamental parameters in the design and cho... more Abstract The hydraulic properties of geotextiles are fundamental parameters in the design and choice of a geotextile for filtration and drainage applications. In these applications, hydraulic requirements must be met. These requirements are typically the retention, clogging, and hydraulic conductivity performance of filters and the transmissivity of drains, in addition to other specific requirements of the project. This chapter deals with the relevant hydraulic properties of geotextiles and subsequent test methods used to obtain them. In some cases, additional inquiry and research are recommended. The main groups of referred standard are the American Society for Testing and Materials and the International Organization for Standardization together with the European Committee for Standardization.
Procedia Engineering, 2016
Peer-review under the responsibility of the organizing and scientific committees of CNRIG2016
![Research paper thumbnail of Corrigendum to “A simple method to evaluate the pullout resistance of extruded geogrids embedded in a compacted granular soil”[Geotextiles and Geomembranes 24 (2006) 116–128]](https://attachments.academia-assets.com/112774542/thumbnails/1.jpg)
](Geotextiles and Geomembranes, Jun 1, 2006
Geotextiles and Geomembranes, Aug 1, 2019
The knowledge of soil-geosynthetic interface behaviour is a key point in the design of geosynthet... more The knowledge of soil-geosynthetic interface behaviour is a key point in the design of geosynthetic-reinforced soil structures. The pullout ultimate limit state can be reproduced conveniently by means of pullout tests performed with large-size laboratory apparatuses, which allow studying the interaction mechanisms that develop in the anchorage zone. During the service life of geosynthetic-reinforced soil structures, reinforcements may be subjected to long-term cyclic vehicular loads or short-term seismic loads in addition to dead loadings, such as the structure's self-weight and other sustained loads. In order to study the influence of a cyclic loading history (a sinusoidal function with fixed amplitude A, number of cycles N and frequency f) on the post-cyclic peak pullout resistance, the writers carried out a series of multi-stage pullout tests on a high density polyethylene extruded uniaxial geogrid embedded in a compacted granular soil for different vertical effective stress σ′ v values. Moreover, the stability of the soil-geosynthetic interface from a point of view linked to the cyclic loading application has also been investigated. Test results showed that the design pullout resistance parameters are affected by the applied cyclic loading history for specific combined conditions (A, N and σ′ v) and it should be taken into account for designing geosynthetic reinforced soil structures.
Landslides, Oct 6, 2018
Landslide susceptibility assessment over large areas is considered a preliminary step for the pla... more Landslide susceptibility assessment over large areas is considered a preliminary step for the planning or design of the most appropriate risk mitigation measures. The use of physically based models is considered a useful tool for landslide susceptibility assessment. Sometimes, using the available geotechnical input data, physically based models can be used to assess landslide susceptibility to obtain a susceptibility map which allows the expert to identify areas where detailed in situ investigations and laboratory tests should be carried out. In this context, the paper proposes a methodology based on the use of TRIGRS to assess landslide susceptibility in an area of about 1 km 2 frequently affected by shallow phenomena in weathered gneiss. Owing to the fact that these materials are extremely complex to characterize from a mechanical and hydraulic point of view, the methodology starts with the collection and analysis of the geotechnical data available for weathered gneiss outcropping in the study area. These data are combined with the data provided by scientific literature on soils similar, for genesis and stress history, to those of the studied area. Through the application of TRIGRS, the data are combined in order to obtain the values of parameters that better analyze shallow landslide source areas. Subsequently, using the abovementioned values, several susceptibility maps are obtained. Finally, the most representative shallow landslide susceptibility map for the area is chosen by means of the error index (EI), the true positive fraction (TPF), and the forecasting index (FI). The success of the best map is confirmed by the high value of the area under the receiver operator characteristic curve (AUC) that demonstrates a good level of forecasting ability.
Water
Permeable reactive barriers (PRBs) based on the use of zero valent iron (ZVI) represent an effici... more Permeable reactive barriers (PRBs) based on the use of zero valent iron (ZVI) represent an efficient technology for the remediation of contaminated groundwater, but the literature evidences “failures”, often linked to the difficulty of fully understanding the long-term performance of ZVI-based PRBs in terms of their hydraulic behavior. The aim of this paper is to provide an overview of the long-term hydraulic behavior of PRBs composed of ZVI mixed with other reactive or inert materials. The literature on the hydraulic performance of ZVI-based PRBs in full-scale applications, on long-term laboratory testing and on related mathematical modeling was thoroughly analyzed. The outcomes of this review include an in-depth analysis of factors influencing the long-term behavior of ZVI-based PRBs (i.e., reactive medium, contamination and the geotechnical, geochemical and hydrogeological characteristics of the aquifer) and a critical revision of the laboratory procedures aimed at investigating ...
Nel presente studio si riportano i risultati di prove d’interazione in colonna condotte al fine d... more Nel presente studio si riportano i risultati di prove d’interazione in colonna condotte al fine di valutare l’efficienza di barriere permeabili reattive (BPR) costituite da Fe 0 e da miscele granulari Fe 0 /pomice e Fe 0 /lapillo per la bonifica di acque di falda contaminate da metalli pesanti, in particolare nichel e zinco, ad una concentrazione iniziale di 50 mg/l. La necessita di miscelare il Fe 0 con la pomice o il lapillo, nasce dall’intento di migliorare il comportamento idraulico di una barriera costituita da solo Fe 0 . Infatti, la conducibilita idraulica di una BPR di solo Fe 0 puo diminuire nel tempo, a causa di differenti fattori, con conseguente inefficacia del processo di bonifica. Le prove in colonna hanno evidenziato le migliori prestazioni delle miscele, rispetto al solo Fe 0 , in termini di rimozione dei contaminanti (con particolare riferimento a soluzioni contaminate da nichel), e di mantenimento nel tempo della conducibilita idraulica (con particolare riferimento...
SYNOPSIS The study ~ttempts to determine the in situ shear strength parameters of a stiff clay fr... more SYNOPSIS The study ~ttempts to determine the in situ shear strength parameters of a stiff clay from a back analys1s of a well documented landslide. The relatively small extension of the instability, as well as the homogeneity of the clay formation and the defined slip surface, allows a consistent evaluation of shear strength parameters. The study is also supported by ring shear tests, and microscopic analysis performed on undisturbed thin sections , by means of scanning electron microscopy. The results of back analysis are in good agreement with laboratory tests and microscopy observations.
Canadian Geotechnical Journal, 2016
Studying the shear strength of a naturally weathered clay is important to understand rain-induced... more Studying the shear strength of a naturally weathered clay is important to understand rain-induced slope failures in weathered soils. However, experimental studies on naturally weathered soils are limited. The paper focuses on the laboratory experimental investigation carried out to analyse the shear strength of a naturally weathered stiff clay that can be found in unsaturated conditions in situ. This has an important practical relevance in the evaluation of the stability conditions of natural slopes at clay outcrops. Different experimental techniques of suction measurement were used to obtain the soil-water retention curve of the clay over a wide range of suctions. Scanning electronic microscope (SEM) observations and results of mercury intrusion porosimetry (MIP) tests are also presented to highlight the considerable fabric arrangement modifications at the microstructural level induced by wetting–drying processes. Moreover, isotropic consolidated drained triaxial compression tests ...
Geosynthetics' 99 Conference …, 1999
A vertical retaining wall, 4m high and 10m long, was constructed by reinforcing the backfill with... more A vertical retaining wall, 4m high and 10m long, was constructed by reinforcing the backfill with geogrids. The reinforcing layers were instrumented with strain gauges, tensile geogrid load transducers and horizontal displacement sensors. In addition, total soil pressure transducers were installed inside the structure to monitor the internal state of stress of the reinforced wall. The aim of this research is to better understand the behavior of reinforced structures. In particular, the development of slip surfaces and the tensile forces acting in the reinforcements were investigated. By this analysis it was possible to assess current design approaches and related safety factors in terms of either long term tensile failure, pullout, direct sliding or compound failures. Data related to reinforcement tensile strains and loads, applied vertical pressures, rainfall and construction sequences were collected for two different geogrids over a period exceeding 10,000 hours.
Geosynthetics International, Feb 1, 2017
Residual deformations due to sustained and cyclic loading, acting on full-scale reinforced soil-r... more Residual deformations due to sustained and cyclic loading, acting on full-scale reinforced soil-retaining walls, could lead to an unacceptable serviceability limit state. In the present study, the writers carried out an extensive experimental programme comprising several monotonic and multistage tensile tests on a high-density polyethylene (HDPE) uniaxial extruded geogrid. Based on analysis of the test results, a combined empirical model has been developed that can predict the tensile behaviour of a specific HDPE geogrid subject to cyclic tensile loading. The paper presents the results and analyses of the effect of cyclic tensile loading histories (varying pre-stress tensile load, frequency, amplitude and number of cycles) on those parameters that are characteristic of hysteresis loops (i.e. the maximum and residual strains cumulated during each cyclic loading, tensile stiffness and area of the hysteresis loops). The results show that the average strain rate and the loading time affect the material's tensile response, as well as the combination of pre-stress tensile load and loading amplitude. The writers also investigated the difference between the load-strain relations for the monotonic test and those for the multistage tests, and concluded that the effects of cyclic loading histories are not due to material degradation.
A crucial role in the conception of landslide risk mitigation strategies is played by the design ... more A crucial role in the conception of landslide risk mitigation strategies is played by the design of mitigation measures aimed at reducing risk to acceptable levels. In the case of extremely rapid landslides, such as debris flows, artificial obstacles are very common mitigation measures, designed either to stop or to deviate the flowing mass. In the design of these types of sheltering structures, crucial is the evaluation of the impact forces exerted by the flowing mass on the structure, commonly accepted, this latter, to be a function of many variables, such as structure location, structure geometry, local topographic profile, flowing mass height, velocity and so on. Protection structures dissipate the flowing mass energy either partially or totally and, for this purpose, they are set along the potential flowing path where the debris is transported and, more prevalently, deposited. This paper focuses on a procedure for simply evaluating the impact forces transmitted with time to quasi-rigid protection structures. The approach is based on the hypotheses of (i) employing a numerical code capable of describing the propagation of the rapid landslide in its downhill path and (ii) adding, in the evaluation of the impact force, the hydrodynamic and the quasi-static terms. Despite its simplicity, the proposed procedure takes into account most of the engineering factors governing the problem, synthetized by the authors by using geometrical non-dimensional ratios. To clarify the proposed procedure, the results of numerical analyses are discussed and the influence of the above mentioned factors critically analysed
(*) Mediterranea University of Reggio Calabria Dep. DICEAM via Graziella Loc. Feo di Vito 89060 R... more (*) Mediterranea University of Reggio Calabria Dep. DICEAM via Graziella Loc. Feo di Vito 89060 Reggio Calabria, Italy. nicola.moraci@unirc.it (**)ETS de Ingenieros de Caminos Universidad Politécnica de Madrid Ciudad Universitaria, s/n 28040 Madrid, Spain (***)University of Padua Dep. ICEA via Ognissanti, 39 35129 Padova, Italy ANALYSES AND DESIGN PROCEDURE OF A NEW PHYSICAL MODEL FOR DEBRIS FLOWS: RESULTS OF NUMERICAL SIMULATIONS BY MEANS OF LABORATORY TESTS
Landslide susceptibility analysis allows drawing the susceptibility maps of anarea, where the pre... more Landslide susceptibility analysis allows drawing the susceptibility maps of anarea, where the predicted areas involved by rapid landslides are drafted. The paper shows the susceptibility zoning of debris flows performed in an area in the Province of Reggio Calabria (Italy), regularly and historically involved by rapid flow-like landslide events.In particular, the source areas of landslides have been predicted using an empirical/heuristic method based on observed phenomena and on geological/geomorphological setting of the area (detailed and validated in field thematic maps). Then, propagation phase of debris flows has been analysed by advanced methods (numerical model) to assess the path, the travel distance and velocity of flowing mass. The obtained results represent a preliminary level of zoning of the area, developed on the base of nowadays available data, on which more sophisticated studies can be developed
ACTA SCIENTIARUM POLONORUM - Architectura Budownictwo
The interface friction between geosynthetics has previously been extensively studied with referen... more The interface friction between geosynthetics has previously been extensively studied with reference to medium-high contact stresses. The interface strength at low contact stress is a less investigated chapter whose importance, however, is evident for the stability of geosynthetic landfill barriers during the construction stage and of the covering systems. The inclined plane is the most used laboratory test for measuring the geosynthetic interface friction at normal stresses as low as 5 kPa. This type of test, however, is not free from criticalities, due to the non-uniformity of the contact stresses induced by the inclination of the plane. Alternatively, it is possible to extrapolate the results of the classic direct shear test, which, however, generally cannot be performed at such low contact stress values. The paper compares data results provided by inclined plane tests and an experimental apparatus capable of performing horizontal shear tests at a vertical stress of 5 kPa. The pec...
International Journal of Geosynthetics and Ground Engineering, Oct 23, 2023
A relevant issue in the development of disaster risk reduction strategies is played by design of ... more A relevant issue in the development of disaster risk reduction strategies is played by design of mitigation measures aimed at reducing risk to acceptable values. For rapid landslides, such as debris flows, sheltering structures are very common mitigation measures realized in exposed areas that allow to protect elements at risk and to stop flowing mass. For the design of these works, the debris flow-structure interaction mechanism is very important. The paper focuses on the evaluation of debris flow-structure interaction mechanism in earth reinforced embankments based on an uncoupled analysis of the interaction in two flow cases (dominant static and dynamic). In particular, a novel approach to evaluate the horizontal stress distribution at different time of the impact phenomenon along the upstream face height of deformable sheltering structures considering the dominant flow component has been proposed. First, impact force over the time against structure is calculated. Subsequently, assuming that debris flow is completely stopped by embankment according to a scheme of accumulation of material behind the obstacle, the deformative response of different geometrical types of embankment is obtained by FEM numerical analysis for considered flow cases. The results of numerical analyses are discussed in terms of horizontal displacements in different control points in sheltering structures. The analysis showed that the deformative response of two geometries of embankments depends on dominant static or dynamic components of impact force.
Le frane superficiali di tipo flusso indotte da pioggia coinvolgono diverse tipologie di terreno ... more Le frane superficiali di tipo flusso indotte da pioggia coinvolgono diverse tipologie di terreno e spesso causano perdita di vite umane e ingenti disastri socio-economici. Tale circostanza è connessa alla limitata presenza di segnali premonitori nella fase di pre-rottura (soprattutto in assenza di efficienti sistemi di monitoraggio), alle alte velocità raggiunte dalla colata nella fase di propagazione ed all’aumento del volume di detrito coinvolto, a causa dell’erosione del terreno lungo il percorso. Per via delle loro caratteristiche e delle conseguenze che possono causare, la valutazione della suscettibilità di questi fenomeni franosi diventa un aspetto da indagare in dettaglio soprattutto nell’ottica di una corretta pianificazione territoriale e di una virtuosa gestione del territorio. Il presente contributo intende fornire una valutazione preliminare della suscettibilità all’innesco di frane superficiali di tipo flusso detritico attraverso l’implementazione di un modello fisicamente basato (TRIGRS). Il modello è stato testato e validato in un’area studio del Sud Italia da tempo interessata da questa tipologia di fenomeni franosi. I risultati ottenuti sono soddisfacenti, se confrontati con l’evento franoso che ha interessato l’area di studio nel 2001, sia in termini di localizzazione delle aree di innesco sia in termini di individuazione delle aree potenzialmente instabili.
Abstract The hydraulic properties of geotextiles are fundamental parameters in the design and cho... more Abstract The hydraulic properties of geotextiles are fundamental parameters in the design and choice of a geotextile for filtration and drainage applications. In these applications, hydraulic requirements must be met. These requirements are typically the retention, clogging, and hydraulic conductivity performance of filters and the transmissivity of drains, in addition to other specific requirements of the project. This chapter deals with the relevant hydraulic properties of geotextiles and subsequent test methods used to obtain them. In some cases, additional inquiry and research are recommended. The main groups of referred standard are the American Society for Testing and Materials and the International Organization for Standardization together with the European Committee for Standardization.
Procedia Engineering, 2016
Peer-review under the responsibility of the organizing and scientific committees of CNRIG2016
Geotextiles and Geomembranes, Jun 1, 2006
Geotextiles and Geomembranes, Aug 1, 2019
The knowledge of soil-geosynthetic interface behaviour is a key point in the design of geosynthet... more The knowledge of soil-geosynthetic interface behaviour is a key point in the design of geosynthetic-reinforced soil structures. The pullout ultimate limit state can be reproduced conveniently by means of pullout tests performed with large-size laboratory apparatuses, which allow studying the interaction mechanisms that develop in the anchorage zone. During the service life of geosynthetic-reinforced soil structures, reinforcements may be subjected to long-term cyclic vehicular loads or short-term seismic loads in addition to dead loadings, such as the structure's self-weight and other sustained loads. In order to study the influence of a cyclic loading history (a sinusoidal function with fixed amplitude A, number of cycles N and frequency f) on the post-cyclic peak pullout resistance, the writers carried out a series of multi-stage pullout tests on a high density polyethylene extruded uniaxial geogrid embedded in a compacted granular soil for different vertical effective stress σ′ v values. Moreover, the stability of the soil-geosynthetic interface from a point of view linked to the cyclic loading application has also been investigated. Test results showed that the design pullout resistance parameters are affected by the applied cyclic loading history for specific combined conditions (A, N and σ′ v) and it should be taken into account for designing geosynthetic reinforced soil structures.
Landslides, Oct 6, 2018
Landslide susceptibility assessment over large areas is considered a preliminary step for the pla... more Landslide susceptibility assessment over large areas is considered a preliminary step for the planning or design of the most appropriate risk mitigation measures. The use of physically based models is considered a useful tool for landslide susceptibility assessment. Sometimes, using the available geotechnical input data, physically based models can be used to assess landslide susceptibility to obtain a susceptibility map which allows the expert to identify areas where detailed in situ investigations and laboratory tests should be carried out. In this context, the paper proposes a methodology based on the use of TRIGRS to assess landslide susceptibility in an area of about 1 km 2 frequently affected by shallow phenomena in weathered gneiss. Owing to the fact that these materials are extremely complex to characterize from a mechanical and hydraulic point of view, the methodology starts with the collection and analysis of the geotechnical data available for weathered gneiss outcropping in the study area. These data are combined with the data provided by scientific literature on soils similar, for genesis and stress history, to those of the studied area. Through the application of TRIGRS, the data are combined in order to obtain the values of parameters that better analyze shallow landslide source areas. Subsequently, using the abovementioned values, several susceptibility maps are obtained. Finally, the most representative shallow landslide susceptibility map for the area is chosen by means of the error index (EI), the true positive fraction (TPF), and the forecasting index (FI). The success of the best map is confirmed by the high value of the area under the receiver operator characteristic curve (AUC) that demonstrates a good level of forecasting ability.
Water
Permeable reactive barriers (PRBs) based on the use of zero valent iron (ZVI) represent an effici... more Permeable reactive barriers (PRBs) based on the use of zero valent iron (ZVI) represent an efficient technology for the remediation of contaminated groundwater, but the literature evidences “failures”, often linked to the difficulty of fully understanding the long-term performance of ZVI-based PRBs in terms of their hydraulic behavior. The aim of this paper is to provide an overview of the long-term hydraulic behavior of PRBs composed of ZVI mixed with other reactive or inert materials. The literature on the hydraulic performance of ZVI-based PRBs in full-scale applications, on long-term laboratory testing and on related mathematical modeling was thoroughly analyzed. The outcomes of this review include an in-depth analysis of factors influencing the long-term behavior of ZVI-based PRBs (i.e., reactive medium, contamination and the geotechnical, geochemical and hydrogeological characteristics of the aquifer) and a critical revision of the laboratory procedures aimed at investigating ...
Nel presente studio si riportano i risultati di prove d’interazione in colonna condotte al fine d... more Nel presente studio si riportano i risultati di prove d’interazione in colonna condotte al fine di valutare l’efficienza di barriere permeabili reattive (BPR) costituite da Fe 0 e da miscele granulari Fe 0 /pomice e Fe 0 /lapillo per la bonifica di acque di falda contaminate da metalli pesanti, in particolare nichel e zinco, ad una concentrazione iniziale di 50 mg/l. La necessita di miscelare il Fe 0 con la pomice o il lapillo, nasce dall’intento di migliorare il comportamento idraulico di una barriera costituita da solo Fe 0 . Infatti, la conducibilita idraulica di una BPR di solo Fe 0 puo diminuire nel tempo, a causa di differenti fattori, con conseguente inefficacia del processo di bonifica. Le prove in colonna hanno evidenziato le migliori prestazioni delle miscele, rispetto al solo Fe 0 , in termini di rimozione dei contaminanti (con particolare riferimento a soluzioni contaminate da nichel), e di mantenimento nel tempo della conducibilita idraulica (con particolare riferimento...
SYNOPSIS The study ~ttempts to determine the in situ shear strength parameters of a stiff clay fr... more SYNOPSIS The study ~ttempts to determine the in situ shear strength parameters of a stiff clay from a back analys1s of a well documented landslide. The relatively small extension of the instability, as well as the homogeneity of the clay formation and the defined slip surface, allows a consistent evaluation of shear strength parameters. The study is also supported by ring shear tests, and microscopic analysis performed on undisturbed thin sections , by means of scanning electron microscopy. The results of back analysis are in good agreement with laboratory tests and microscopy observations.
Canadian Geotechnical Journal, 2016
Studying the shear strength of a naturally weathered clay is important to understand rain-induced... more Studying the shear strength of a naturally weathered clay is important to understand rain-induced slope failures in weathered soils. However, experimental studies on naturally weathered soils are limited. The paper focuses on the laboratory experimental investigation carried out to analyse the shear strength of a naturally weathered stiff clay that can be found in unsaturated conditions in situ. This has an important practical relevance in the evaluation of the stability conditions of natural slopes at clay outcrops. Different experimental techniques of suction measurement were used to obtain the soil-water retention curve of the clay over a wide range of suctions. Scanning electronic microscope (SEM) observations and results of mercury intrusion porosimetry (MIP) tests are also presented to highlight the considerable fabric arrangement modifications at the microstructural level induced by wetting–drying processes. Moreover, isotropic consolidated drained triaxial compression tests ...
Geosynthetics' 99 Conference …, 1999
A vertical retaining wall, 4m high and 10m long, was constructed by reinforcing the backfill with... more A vertical retaining wall, 4m high and 10m long, was constructed by reinforcing the backfill with geogrids. The reinforcing layers were instrumented with strain gauges, tensile geogrid load transducers and horizontal displacement sensors. In addition, total soil pressure transducers were installed inside the structure to monitor the internal state of stress of the reinforced wall. The aim of this research is to better understand the behavior of reinforced structures. In particular, the development of slip surfaces and the tensile forces acting in the reinforcements were investigated. By this analysis it was possible to assess current design approaches and related safety factors in terms of either long term tensile failure, pullout, direct sliding or compound failures. Data related to reinforcement tensile strains and loads, applied vertical pressures, rainfall and construction sequences were collected for two different geogrids over a period exceeding 10,000 hours.
Geosynthetics International, Feb 1, 2017
Residual deformations due to sustained and cyclic loading, acting on full-scale reinforced soil-r... more Residual deformations due to sustained and cyclic loading, acting on full-scale reinforced soil-retaining walls, could lead to an unacceptable serviceability limit state. In the present study, the writers carried out an extensive experimental programme comprising several monotonic and multistage tensile tests on a high-density polyethylene (HDPE) uniaxial extruded geogrid. Based on analysis of the test results, a combined empirical model has been developed that can predict the tensile behaviour of a specific HDPE geogrid subject to cyclic tensile loading. The paper presents the results and analyses of the effect of cyclic tensile loading histories (varying pre-stress tensile load, frequency, amplitude and number of cycles) on those parameters that are characteristic of hysteresis loops (i.e. the maximum and residual strains cumulated during each cyclic loading, tensile stiffness and area of the hysteresis loops). The results show that the average strain rate and the loading time affect the material's tensile response, as well as the combination of pre-stress tensile load and loading amplitude. The writers also investigated the difference between the load-strain relations for the monotonic test and those for the multistage tests, and concluded that the effects of cyclic loading histories are not due to material degradation.
A crucial role in the conception of landslide risk mitigation strategies is played by the design ... more A crucial role in the conception of landslide risk mitigation strategies is played by the design of mitigation measures aimed at reducing risk to acceptable levels. In the case of extremely rapid landslides, such as debris flows, artificial obstacles are very common mitigation measures, designed either to stop or to deviate the flowing mass. In the design of these types of sheltering structures, crucial is the evaluation of the impact forces exerted by the flowing mass on the structure, commonly accepted, this latter, to be a function of many variables, such as structure location, structure geometry, local topographic profile, flowing mass height, velocity and so on. Protection structures dissipate the flowing mass energy either partially or totally and, for this purpose, they are set along the potential flowing path where the debris is transported and, more prevalently, deposited. This paper focuses on a procedure for simply evaluating the impact forces transmitted with time to quasi-rigid protection structures. The approach is based on the hypotheses of (i) employing a numerical code capable of describing the propagation of the rapid landslide in its downhill path and (ii) adding, in the evaluation of the impact force, the hydrodynamic and the quasi-static terms. Despite its simplicity, the proposed procedure takes into account most of the engineering factors governing the problem, synthetized by the authors by using geometrical non-dimensional ratios. To clarify the proposed procedure, the results of numerical analyses are discussed and the influence of the above mentioned factors critically analysed
(*) Mediterranea University of Reggio Calabria Dep. DICEAM via Graziella Loc. Feo di Vito 89060 R... more (*) Mediterranea University of Reggio Calabria Dep. DICEAM via Graziella Loc. Feo di Vito 89060 Reggio Calabria, Italy. nicola.moraci@unirc.it (**)ETS de Ingenieros de Caminos Universidad Politécnica de Madrid Ciudad Universitaria, s/n 28040 Madrid, Spain (***)University of Padua Dep. ICEA via Ognissanti, 39 35129 Padova, Italy ANALYSES AND DESIGN PROCEDURE OF A NEW PHYSICAL MODEL FOR DEBRIS FLOWS: RESULTS OF NUMERICAL SIMULATIONS BY MEANS OF LABORATORY TESTS
Landslide susceptibility analysis allows drawing the susceptibility maps of anarea, where the pre... more Landslide susceptibility analysis allows drawing the susceptibility maps of anarea, where the predicted areas involved by rapid landslides are drafted. The paper shows the susceptibility zoning of debris flows performed in an area in the Province of Reggio Calabria (Italy), regularly and historically involved by rapid flow-like landslide events.In particular, the source areas of landslides have been predicted using an empirical/heuristic method based on observed phenomena and on geological/geomorphological setting of the area (detailed and validated in field thematic maps). Then, propagation phase of debris flows has been analysed by advanced methods (numerical model) to assess the path, the travel distance and velocity of flowing mass. The obtained results represent a preliminary level of zoning of the area, developed on the base of nowadays available data, on which more sophisticated studies can be developed