In this study, a hypoplastic model is developed to describe the mechanical behaviors of cemented sand under both monotonic and cyclic loading conditions. A state variable is proposed to qualify the bonding strength. This variable is incorporated into the model to reflect the influence of cementation on the strength, stiffness, and dilatancy of sand. Bonding degradation is considered by allowing the state variable to evolve during deformation. A simple evolution is used with vanishing bonding strength for large deformation. The void ratio and friction angle in the critical state are related to the initial cementation. The model is subsequently extended to account for cyclic loading by incorporating the intergranular strain, fabric change effect, and semifluidized state. The capability of the model is demonstrated by simulating the behavior of cemented sand under both monotonic and cyclic loading conditions.
{"title":"A hypoplastic model for cemented sand under monotonic and cyclic loading","authors":"Dong Liao, Zhongxuan Yang, Shun Wang, Wei Wu","doi":"10.1139/cgj-2023-0079","DOIUrl":"https://doi.org/10.1139/cgj-2023-0079","url":null,"abstract":"In this study, a hypoplastic model is developed to describe the mechanical behaviors of cemented sand under both monotonic and cyclic loading conditions. A state variable is proposed to qualify the bonding strength. This variable is incorporated into the model to reflect the influence of cementation on the strength, stiffness, and dilatancy of sand. Bonding degradation is considered by allowing the state variable to evolve during deformation. A simple evolution is used with vanishing bonding strength for large deformation. The void ratio and friction angle in the critical state are related to the initial cementation. The model is subsequently extended to account for cyclic loading by incorporating the intergranular strain, fabric change effect, and semifluidized state. The capability of the model is demonstrated by simulating the behavior of cemented sand under both monotonic and cyclic loading conditions.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"53 1-2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135265837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aria Tingxian Zhang, Jeff G. Bain, Adrienne Schmall, Carol J. Ptacek, David Blowes
This study presents the field performance of a five-layer composite cover to mitigate acid mine drainage in legacy sulfide tailings in northern Ontario, Canada. Installed in 2008, this cover comprised sand, clay, geosynthetic clay liner, sand, and waste rock layers. To evaluate the effectiveness of the cover in reducing water and oxygen ingress, groundwater and vadose zone hydrological characterization, stable water isotope analysis, pore-gas measurements, oxygen flux calculations, and variably saturated flow modelling were conducted. Results indicate that the clay layer stayed nearly saturated in the spring, fall, and winter, but temporary desiccation occurred during the summer. Compared to uncovered tailings, the cover significantly lowered diffusive oxygen flux. In the summer, fall, and winter, the capillary barrier effect of the cover functioned effectively and inhibited percolation. Atmospheric pore-gas oxygen concentrations at one out of three monitoring locations indicate potential cover imperfections that enabled oxygen transport into the tailings. In the spring and early summer, snowmelt infiltration resulted in percolation that compromised the capillary barrier effect, as well as lateral drainage. The resulting increase in water saturation in the cover limited oxygen transport. Despite potential cover imperfections, this composite cover reduced oxygen and water ingress a decade after installation.
{"title":"Seasonal hydrology and gas transport in a composite cover on sulfide tailings","authors":"Aria Tingxian Zhang, Jeff G. Bain, Adrienne Schmall, Carol J. Ptacek, David Blowes","doi":"10.1139/cgj-2022-0606","DOIUrl":"https://doi.org/10.1139/cgj-2022-0606","url":null,"abstract":"This study presents the field performance of a five-layer composite cover to mitigate acid mine drainage in legacy sulfide tailings in northern Ontario, Canada. Installed in 2008, this cover comprised sand, clay, geosynthetic clay liner, sand, and waste rock layers. To evaluate the effectiveness of the cover in reducing water and oxygen ingress, groundwater and vadose zone hydrological characterization, stable water isotope analysis, pore-gas measurements, oxygen flux calculations, and variably saturated flow modelling were conducted. Results indicate that the clay layer stayed nearly saturated in the spring, fall, and winter, but temporary desiccation occurred during the summer. Compared to uncovered tailings, the cover significantly lowered diffusive oxygen flux. In the summer, fall, and winter, the capillary barrier effect of the cover functioned effectively and inhibited percolation. Atmospheric pore-gas oxygen concentrations at one out of three monitoring locations indicate potential cover imperfections that enabled oxygen transport into the tailings. In the spring and early summer, snowmelt infiltration resulted in percolation that compromised the capillary barrier effect, as well as lateral drainage. The resulting increase in water saturation in the cover limited oxygen transport. Despite potential cover imperfections, this composite cover reduced oxygen and water ingress a decade after installation.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135219376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nripojyoti Biswas, Anand J Puppala, Sayantan Chakraborty, Dallas Little
The addition of calcium-based stabilizers to sulfate-rich expansive soils is associated with the formation of ettringite, a deleterious reactant that can cause moderate-to-severe swell-related damage to overlying lightweight infrastructures. This research study was conducted to understand the effects of combining nanosilica admixtures with a traditional Ca-based stabilizer to treat high-sulfate soils with the intent to suppress ettringite formation. Engineering and microstructural studies were thus performed to gain a comprehensive understanding of the behavior of sulfate-bearing soils treated with lime in the presence of amorphous nanosilica. Engineering studies included strength tests before and after capillary soaking, free swell strain, and resilient moduli to study and understand the macrostructural behavior of these soils at different curing periods. Supplemental studies using scanning electron microscope and energy dispersive X-ray spectroscopy, thermal analyses using differential scanning calorimetry, and X-ray diffraction studies were also conducted to determine the microstructural changes that occur within these sulfate-rich soils. The results showed that additional silica phases furnished from nanosilica suppressed the precipitation of ettringite and correspondingly increased the formation of cementitious phases. This study also provided ample evidence that the application of siliceous nanomaterials positively impacts chemical treatments and reduces the precipitation of ettringite, thus enhancing their engineering performance.
{"title":"Micro-Mechanical Behavior of Nanosilica-Treated High-Sulfate Soils","authors":"Nripojyoti Biswas, Anand J Puppala, Sayantan Chakraborty, Dallas Little","doi":"10.1139/cgj-2023-0051","DOIUrl":"https://doi.org/10.1139/cgj-2023-0051","url":null,"abstract":"The addition of calcium-based stabilizers to sulfate-rich expansive soils is associated with the formation of ettringite, a deleterious reactant that can cause moderate-to-severe swell-related damage to overlying lightweight infrastructures. This research study was conducted to understand the effects of combining nanosilica admixtures with a traditional Ca-based stabilizer to treat high-sulfate soils with the intent to suppress ettringite formation. Engineering and microstructural studies were thus performed to gain a comprehensive understanding of the behavior of sulfate-bearing soils treated with lime in the presence of amorphous nanosilica. Engineering studies included strength tests before and after capillary soaking, free swell strain, and resilient moduli to study and understand the macrostructural behavior of these soils at different curing periods. Supplemental studies using scanning electron microscope and energy dispersive X-ray spectroscopy, thermal analyses using differential scanning calorimetry, and X-ray diffraction studies were also conducted to determine the microstructural changes that occur within these sulfate-rich soils. The results showed that additional silica phases furnished from nanosilica suppressed the precipitation of ettringite and correspondingly increased the formation of cementitious phases. This study also provided ample evidence that the application of siliceous nanomaterials positively impacts chemical treatments and reduces the precipitation of ettringite, thus enhancing their engineering performance.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"277 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135729228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A profile of geotechnical properties is often needed for geotechnical design and analysis. However, site-specific data might be characterized as MUSIC-X (i.e., Multivariate, Uncertain and Unique, Sparse, Incomplete, and potentially Corrupted with “X” denoting the spatial/temporal variability), posing a significant challenge in accurately interpreting geotechnical property profiles. Different sources, or types, of data are commonly available from a specific site investigation program, and they are usually cross-correlated, and thus can provide complementary information. This leads to an important question in geotechnical site investigation: how to integrate multiple sources of sparse data for enhancing the profiling of different geotechnical properties. To address this issue, this study proposes a novel method, called fusion Bayesian compressive sampling (Fusion-BCS), for integrating sparse and non-co-located geotechnical data. In the proposed method, the auto- and cross-correlation structures of different sources of data are exploited in a data-driven manner through a joint sparse representation. Then, profiles of different geotechnical properties are jointly reconstructed from all measurements under a framework of compressive sampling/sensing. The proposed method is illustrated using simulated and real geotechnical data. The results indicate that accuracy of the interpreted geotechnical property profiles may be significantly improved by integrating multiple sources of site investigation data.
{"title":"Fusion of Sparse Non-co-located Measurements from Multiple Sources for Geotechnical Site Investigation","authors":"Zheng Guan, Yu Wang, Kok-Kwang Phoon","doi":"10.1139/cgj-2023-0289","DOIUrl":"https://doi.org/10.1139/cgj-2023-0289","url":null,"abstract":"A profile of geotechnical properties is often needed for geotechnical design and analysis. However, site-specific data might be characterized as MUSIC-X (i.e., Multivariate, Uncertain and Unique, Sparse, Incomplete, and potentially Corrupted with “X” denoting the spatial/temporal variability), posing a significant challenge in accurately interpreting geotechnical property profiles. Different sources, or types, of data are commonly available from a specific site investigation program, and they are usually cross-correlated, and thus can provide complementary information. This leads to an important question in geotechnical site investigation: how to integrate multiple sources of sparse data for enhancing the profiling of different geotechnical properties. To address this issue, this study proposes a novel method, called fusion Bayesian compressive sampling (Fusion-BCS), for integrating sparse and non-co-located geotechnical data. In the proposed method, the auto- and cross-correlation structures of different sources of data are exploited in a data-driven manner through a joint sparse representation. Then, profiles of different geotechnical properties are jointly reconstructed from all measurements under a framework of compressive sampling/sensing. The proposed method is illustrated using simulated and real geotechnical data. The results indicate that accuracy of the interpreted geotechnical property profiles may be significantly improved by integrating multiple sources of site investigation data.
","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compared to the traditional drainage consolidation measures for soft ground improvement, the siphon-vacuum drainage method (SVD) offers more advantages, e.g., improved drainage efficiency, lower maintenance costs, lower demand for energy and materials, and less environmental impact. Hence, it is expected to be widely applied in soft ground improvement. However, the mechanism of vacuum formation in the system remains unclear. In this work, the vacuum formation mechanism of SVD is investigated based on the theoretical deduction of the variations of the water level and air pressures during the siphon drainage and seepage processes. A theoretical model is developed to describe the vacuum formation, allowing the estimation of the varying air pressure, water level, seepage rate, and discharge rate in the system. Moreover, a field investigation was carried out in Zhoushan, Zhejiang Province, to further validate the correctness of the developed model. This work also provides further insights and suggestions into the field application of SVD for soft ground improvement.
{"title":"Theoretical and field investigation into the vacuum formation in the siphon-vacuum drainage system for soft ground improvement","authors":"Junwei Shu, Hongyue Sun, Ni An","doi":"10.1139/cgj-2023-0174","DOIUrl":"https://doi.org/10.1139/cgj-2023-0174","url":null,"abstract":"Compared to the traditional drainage consolidation measures for soft ground improvement, the siphon-vacuum drainage method (SVD) offers more advantages, e.g., improved drainage efficiency, lower maintenance costs, lower demand for energy and materials, and less environmental impact. Hence, it is expected to be widely applied in soft ground improvement. However, the mechanism of vacuum formation in the system remains unclear. In this work, the vacuum formation mechanism of SVD is investigated based on the theoretical deduction of the variations of the water level and air pressures during the siphon drainage and seepage processes. A theoretical model is developed to describe the vacuum formation, allowing the estimation of the varying air pressure, water level, seepage rate, and discharge rate in the system. Moreover, a field investigation was carried out in Zhoushan, Zhejiang Province, to further validate the correctness of the developed model. This work also provides further insights and suggestions into the field application of SVD for soft ground improvement.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135825520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extreme rainfall occurred in July 1996 over the Saguenay Region, some 200 km north of Quebec City. With about 1000 landslides, seven damaged dams, one dike failure, washed out road sections, tens of bridges damaged or destroyed, 1700 properties destroyed or damaged and several casualties, this event was one of the most important natural disasters in Canada. Detailed geotechnical investigations permitted better understanding of the soils involved, mainly sensitive clays and their superficial crust, including their behaviour in landslides, the erosion processes, impacts on infrastructure and sediment deposition.
{"title":"The July 1996 Saguenay Flood: geotechnical aspects","authors":"Serge Leroueil, Régis Bouchard, Denis Demers, Didier Perret","doi":"10.1139/cgj-2022-0692","DOIUrl":"https://doi.org/10.1139/cgj-2022-0692","url":null,"abstract":"Extreme rainfall occurred in July 1996 over the Saguenay Region, some 200 km north of Quebec City. With about 1000 landslides, seven damaged dams, one dike failure, washed out road sections, tens of bridges damaged or destroyed, 1700 properties destroyed or damaged and several casualties, this event was one of the most important natural disasters in Canada. Detailed geotechnical investigations permitted better understanding of the soils involved, mainly sensitive clays and their superficial crust, including their behaviour in landslides, the erosion processes, impacts on infrastructure and sediment deposition.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135883450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enhancing the complexity of the hydraulic fractures to provide a wide channel for the injection of the agent is crucial for remediating low-permeability contaminated sites. This study involved a physical simulation experiment of large-scale true triaxial hydraulic fracturing in undisturbed soil, as well as field fracturing tests, to investigate fracture initiation mechanisms and the influence of different factors on fracture propagation. The study revealed a unique failure mode for low-permeability soils characterized by impact splitting, involving simultaneous tensile and shear failure. Three typical fracture propagation patterns emerged: (1) horizontal fracture, (2) parallel fracture, and (3) complex fracture. Silty clay predominantly exhibited horizontal fractures, while mucky clay facilitated the formation of complex fractures dominated by multiple transverse fractures. As the vertical stress difference coefficient increased from 1.0 to 1.5, the pressure on the fracture surface enhanced the connection between hydraulic fractures and natural fractures. Hydraulic fracturing in low-permeability soils necessitated large displacements and high-viscosity fracturing fluids to sustain fracture propagation. The field fracturing test results underscored that soil type and in-situ stress were the primary factors governing hydraulic fracture initiation and propagation. Identifying the optimal fracturing location was critical for achieving the maximum stimulated formation volume (SFV).
{"title":"Enhancing Hydraulic Fracturing for In-Situ Remediation in Low-Permeability Soils: A Comprehensive Investigation of Fracture Propagation","authors":"Zhuang Cui, Bing Hou","doi":"10.1139/cgj-2023-0219","DOIUrl":"https://doi.org/10.1139/cgj-2023-0219","url":null,"abstract":"Enhancing the complexity of the hydraulic fractures to provide a wide channel for the injection of the agent is crucial for remediating low-permeability contaminated sites. This study involved a physical simulation experiment of large-scale true triaxial hydraulic fracturing in undisturbed soil, as well as field fracturing tests, to investigate fracture initiation mechanisms and the influence of different factors on fracture propagation. The study revealed a unique failure mode for low-permeability soils characterized by impact splitting, involving simultaneous tensile and shear failure. Three typical fracture propagation patterns emerged: (1) horizontal fracture, (2) parallel fracture, and (3) complex fracture. Silty clay predominantly exhibited horizontal fractures, while mucky clay facilitated the formation of complex fractures dominated by multiple transverse fractures. As the vertical stress difference coefficient increased from 1.0 to 1.5, the pressure on the fracture surface enhanced the connection between hydraulic fractures and natural fractures. Hydraulic fracturing in low-permeability soils necessitated large displacements and high-viscosity fracturing fluids to sustain fracture propagation. The field fracturing test results underscored that soil type and in-situ stress were the primary factors governing hydraulic fracture initiation and propagation. Identifying the optimal fracturing location was critical for achieving the maximum stimulated formation volume (SFV).","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carlos Andrés Contreras, Samuel Yniesta, Abtin Jahanbakhshzadeh, Michel Aubertin
Résumé Une campagne d“essais en laboratoire et sur le terrain a été réalisée pour caractériser le comportement des résidus miniers de roche dure. Des essais cycliques triaxiaux, de cisaillement direct simple et de cisaillement simple triaxial ont montré que les résidus contractants sont susceptibles de se liquéfier et que leur comportement est similaire à un sable lâche malgré leur pourcentage de fines plus élevé. Afin de modéliser le comportement des parcs à résidus dans des simulations dynamiques, la loi de comportement PM4Sand est calibré à partir de l”ensemble de données présenté ici. Certains des paramètres du modèle sont définis sur la base d“essais de consolidation et de compression, tandis que la ligne d”état critique est définie sur la base des résultats d“essais de cisaillement direct et triaxial monotones. La ligne d”état critique est plus basse pour les résidus que pour la plupart des sables naturels, ce qui est cohérent avec les études précédentes. Le modèle calibré peut reproduire de manière raisonnable le comportement monotone, et fournit un excellent ajustement des courbes de résistance cyclique mesurées en laboratoire à différentes pressions de confinement et indices de densité. Les résultats présentés dans l'article indiquent que la loi de comportement PM4Sand peut être utilisée pour simuler le comportement cyclique des résidus de mines en roches dures de faible plasticité. La procédure proposée fournie aussi des lignes directives générales pour calibrer le modèle pour d'autres types de résidus miniers. 1 Ceci est une traduction fournie par l'auteur du résumé en anglais.
{"title":"Correction: calibration of the PM4Sand model for hard-rock mine tailings based on laboratory and field testing results","authors":"Carlos Andrés Contreras, Samuel Yniesta, Abtin Jahanbakhshzadeh, Michel Aubertin","doi":"10.1139/cgj-2023-0509","DOIUrl":"https://doi.org/10.1139/cgj-2023-0509","url":null,"abstract":"Résumé Une campagne d“essais en laboratoire et sur le terrain a été réalisée pour caractériser le comportement des résidus miniers de roche dure. Des essais cycliques triaxiaux, de cisaillement direct simple et de cisaillement simple triaxial ont montré que les résidus contractants sont susceptibles de se liquéfier et que leur comportement est similaire à un sable lâche malgré leur pourcentage de fines plus élevé. Afin de modéliser le comportement des parcs à résidus dans des simulations dynamiques, la loi de comportement PM4Sand est calibré à partir de l”ensemble de données présenté ici. Certains des paramètres du modèle sont définis sur la base d“essais de consolidation et de compression, tandis que la ligne d”état critique est définie sur la base des résultats d“essais de cisaillement direct et triaxial monotones. La ligne d”état critique est plus basse pour les résidus que pour la plupart des sables naturels, ce qui est cohérent avec les études précédentes. Le modèle calibré peut reproduire de manière raisonnable le comportement monotone, et fournit un excellent ajustement des courbes de résistance cyclique mesurées en laboratoire à différentes pressions de confinement et indices de densité. Les résultats présentés dans l'article indiquent que la loi de comportement PM4Sand peut être utilisée pour simuler le comportement cyclique des résidus de mines en roches dures de faible plasticité. La procédure proposée fournie aussi des lignes directives générales pour calibrer le modèle pour d'autres types de résidus miniers. 1 Ceci est une traduction fournie par l'auteur du résumé en anglais.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shui-Hua Jiang, Xian Liu, Guotao Ma, Mohammad Rezania
Rainfall infiltration analysis has a great significance to the mitigation and risk assessment of rainfall-induced landslides. The original Green-Ampt (GA) model ignored the fact that a transitional layer exists in infiltration regions of soils under the rainfall permeation, therefore it cannot effectively analyze the rainfall-infiltrated heterogeneous slope considering the spatial variability of saturated hydraulic conductivity (ks). In this paper, an improved GA model is proposed for the rainfall-infiltration analysis of heterogeneous slopes. Four common slope cases are investigated to validate the effectiveness of the proposed model. An infinite slope model is taken as an illustrative example to investigate the distributions of volumetric water content and slope stability under the rainfall infiltration. The results show that the distributions of volumetric water content and factors of safety (Fs) obtained from the proposed model are in very good agreement with the numerical results of Richards equation. In contrast, the modified GA model obtains biased distributions of volumetric water content and smaller Fs for the same cases. The results show that the proposed GA model can accurately identify the location of critical slip surface of the slope, and as such it provides an efficient method for risk control analysis of slopes susceptible to landslide.
{"title":"Stability analysis of heterogeneous infinite slopes under rainfall-infiltration by means of an improved Green-Ampt model","authors":"Shui-Hua Jiang, Xian Liu, Guotao Ma, Mohammad Rezania","doi":"10.1139/cgj-2023-0203","DOIUrl":"https://doi.org/10.1139/cgj-2023-0203","url":null,"abstract":"Rainfall infiltration analysis has a great significance to the mitigation and risk assessment of rainfall-induced landslides. The original Green-Ampt (GA) model ignored the fact that a transitional layer exists in infiltration regions of soils under the rainfall permeation, therefore it cannot effectively analyze the rainfall-infiltrated heterogeneous slope considering the spatial variability of saturated hydraulic conductivity (ks). In this paper, an improved GA model is proposed for the rainfall-infiltration analysis of heterogeneous slopes. Four common slope cases are investigated to validate the effectiveness of the proposed model. An infinite slope model is taken as an illustrative example to investigate the distributions of volumetric water content and slope stability under the rainfall infiltration. The results show that the distributions of volumetric water content and factors of safety (Fs) obtained from the proposed model are in very good agreement with the numerical results of Richards equation. In contrast, the modified GA model obtains biased distributions of volumetric water content and smaller Fs for the same cases. The results show that the proposed GA model can accurately identify the location of critical slip surface of the slope, and as such it provides an efficient method for risk control analysis of slopes susceptible to landslide.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135968198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adrian Robert Mifsud, Federica Cotecchia, Francesca Santaloia, Francesco Cafaro
Three soft rock facies of the Middle Globigerina Limestone (MGL) from Malta, of mineralogical composition and index properties similar to some medium-high density Chalk facies, are disaggregated through prolonged agitation in water, to create reconstituted samples. The significant activity of their clay-sized calcite grains can impart a medium-high plasticity. SEM analyses of natural and reconstituted samples show the natural bonding as interlock, possibly induced by cohesive clay-sized calcite grains during the sediment compaction. Micro-analyses and compression test data also show that local calcite crystal over-growth under burial has reduced further the soft rock porosity, making it lower than that of the reconstituted material one-dimensionally compressed to the geological preconsolidation pressure. Nonetheless, the low stress sensitivity of natural MGL suggests that this interlock bonding does not strengthen much the material with respect to the highly compressed reconstituted soil. The natural MGL is of very low permeability, which reduces further with compression. Concurrently, the soft rock creep coefficient increases, reaching values far above those typical for clays. The microstructural features and the mechanical properties of the different MGL facies are shown to be sensitive to clay mineral content.
{"title":"Medium-high density soft micrites: Impact of microstructural features on state and compressibility","authors":"Adrian Robert Mifsud, Federica Cotecchia, Francesca Santaloia, Francesco Cafaro","doi":"10.1139/cgj-2023-0190","DOIUrl":"https://doi.org/10.1139/cgj-2023-0190","url":null,"abstract":"Three soft rock facies of the Middle Globigerina Limestone (MGL) from Malta, of mineralogical composition and index properties similar to some medium-high density Chalk facies, are disaggregated through prolonged agitation in water, to create reconstituted samples. The significant activity of their clay-sized calcite grains can impart a medium-high plasticity. SEM analyses of natural and reconstituted samples show the natural bonding as interlock, possibly induced by cohesive clay-sized calcite grains during the sediment compaction. Micro-analyses and compression test data also show that local calcite crystal over-growth under burial has reduced further the soft rock porosity, making it lower than that of the reconstituted material one-dimensionally compressed to the geological preconsolidation pressure. Nonetheless, the low stress sensitivity of natural MGL suggests that this interlock bonding does not strengthen much the material with respect to the highly compressed reconstituted soil. The natural MGL is of very low permeability, which reduces further with compression. Concurrently, the soft rock creep coefficient increases, reaching values far above those typical for clays. The microstructural features and the mechanical properties of the different MGL facies are shown to be sensitive to clay mineral content.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136293506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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