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":null,"pages":null},"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":null,"pages":null},"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}
Assessing the risk of slope failures of earth structures comprising loose, saturated soils has seen increased focus recently owing to a series of prominent tailings and water dam failures. The potential for the triggering of slope instability by a rising phreatic surface – commonly referred to as the constant shear drained (CSD) stress path – has been well documented over the past few decades for sands and sandy soils under a wide range of loading modes. Alternatively, there has been limited CSD element testing of more clayey soils, with the available data rather showing a dilative tendency through the CSD stress path and mobilised strengths greater than the critical friction ratio, even for specimens commencing CSD shearing from an initially loose state. The current paper expands on the CSD data of clayey soils by testing an iron ore tailings (IOT) and kaolin clay in both triaxial and direct simple shear (DSS) devices, with an emphasis on the DSS. Owing to the tendency for the CSD stress path to result in an overconsolidated condition (i.e. unloading) the tests in the current study were interpreted in the SHANSEP framework given its frequent use to analyse clay behaviour. The results indicated that the SHANSEP framework can reasonably characterise some aspects of CSD behaviour of clays in DSS loading, with some caveats.
{"title":"A SHANSEP approach to quantifying the behaviour of clayey soils on a constant shear drained stress path","authors":"David Reid, Riccardo Fanni, Andy Fourie","doi":"10.1139/cgj-2022-0473","DOIUrl":"https://doi.org/10.1139/cgj-2022-0473","url":null,"abstract":"Assessing the risk of slope failures of earth structures comprising loose, saturated soils has seen increased focus recently owing to a series of prominent tailings and water dam failures. The potential for the triggering of slope instability by a rising phreatic surface – commonly referred to as the constant shear drained (CSD) stress path – has been well documented over the past few decades for sands and sandy soils under a wide range of loading modes. Alternatively, there has been limited CSD element testing of more clayey soils, with the available data rather showing a dilative tendency through the CSD stress path and mobilised strengths greater than the critical friction ratio, even for specimens commencing CSD shearing from an initially loose state. The current paper expands on the CSD data of clayey soils by testing an iron ore tailings (IOT) and kaolin clay in both triaxial and direct simple shear (DSS) devices, with an emphasis on the DSS. Owing to the tendency for the CSD stress path to result in an overconsolidated condition (i.e. unloading) the tests in the current study were interpreted in the SHANSEP framework given its frequent use to analyse clay behaviour. The results indicated that the SHANSEP framework can reasonably characterise some aspects of CSD behaviour of clays in DSS loading, with some caveats.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947351","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}
Ali Dadashiserej, Amalesh Jana, Zhongze Xu, Armin W. Stuedlein, T. Matthew Evans, Kenneth H. Stokoe II, Brady R. Cox
This study compares the in-situ dynamic response of a low plasticity silt deposit subjected to multidirectional loading from vibroseis shaking and controlled blasting to a suite of element-scale, cyclic laboratory test specimens. The agreement between excess pore pressures and simple shear strain relationships over a wide range in strains is remarkable. Slightly larger excess pore pressures observed in-situ are attributed to three-dimensional loading and pore pressure migration/ redistribution in the shallower portions of the deposit. Noted differences in shear modulus, G, are attributed to strain rate effects, spatial variability in the in-situ stiffness, and hydraulic boundary conditions. The variation in in-situ G/Gmax follows the trend from torsional shear specimens up to 0.4% shear strain; larger strains in the silt deposit imposed by controlled blasting yielded a stiffer response than that from cyclic torsional shear and direct simple shear specimens due in part to field drainage for deeper portions of the deposit. The in-situ cyclic resistance ratio for the deeper portion of the deposit in which plane body waves could be assumed and for the selected excess pore pressure ratio criterion was larger than that of stress-controlled CDSS test specimens, despite the detrimental effect of multidirectional shaking in the field. The effect of strain history, spatial variability, and drainage boundary conditions to drive differences between the in-situ and laboratory test specimens is identified.
{"title":"Dynamic Response of a Low Plasticity Silt Deposit: Comparison of In-situ and Laboratory Responses","authors":"Ali Dadashiserej, Amalesh Jana, Zhongze Xu, Armin W. Stuedlein, T. Matthew Evans, Kenneth H. Stokoe II, Brady R. Cox","doi":"10.1139/cgj-2022-0579","DOIUrl":"https://doi.org/10.1139/cgj-2022-0579","url":null,"abstract":"This study compares the in-situ dynamic response of a low plasticity silt deposit subjected to multidirectional loading from vibroseis shaking and controlled blasting to a suite of element-scale, cyclic laboratory test specimens. The agreement between excess pore pressures and simple shear strain relationships over a wide range in strains is remarkable. Slightly larger excess pore pressures observed in-situ are attributed to three-dimensional loading and pore pressure migration/ redistribution in the shallower portions of the deposit. Noted differences in shear modulus, G, are attributed to strain rate effects, spatial variability in the in-situ stiffness, and hydraulic boundary conditions. The variation in in-situ G/Gmax follows the trend from torsional shear specimens up to 0.4% shear strain; larger strains in the silt deposit imposed by controlled blasting yielded a stiffer response than that from cyclic torsional shear and direct simple shear specimens due in part to field drainage for deeper portions of the deposit. The in-situ cyclic resistance ratio for the deeper portion of the deposit in which plane body waves could be assumed and for the selected excess pore pressure ratio criterion was larger than that of stress-controlled CDSS test specimens, despite the detrimental effect of multidirectional shaking in the field. The effect of strain history, spatial variability, and drainage boundary conditions to drive differences between the in-situ and laboratory test specimens is identified.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135482610","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}
This study addresses the microfabric evolution of coral sand during earthquake-induced liquefaction using the joint tests of macroscopic shaking table and microscopic X-ray computed tomography (μCT). Based on the non-destructive scanning and image reconstruction in 3D, the change in the grain-pore structure of sands under earthquakes is discussed. Furthermore, the special microstructural evolution of coral sand is studied by the contrast tests with Fujian sand. The results show that the coordination number of coral sand is larger than that of Fujian sand after liquefaction, which is consistent with that the reduction in acceleration of coral sand is smaller than that of the Fujian sand, and the coral sand foundation still has a larger shear strength due to the smaller excess pore pressure accumulation. Moreover, the contact index of Fujian sand and Reigate sand fluctuates in a similar range with the change of void ratio and coordination number compared with coral sand. This is due to the fact that the Fujian sand and Reigate sand are both general terrigenous sands (quartz sand), while coral sand has irregular particle shapes and larger surface friction caused by marine biogenesis. The test results deepen the understanding of the liquefaction mechanism of coral sand.
{"title":"Joint analysis of macroscopic response and microfabric evolution of coral sand during earthquake-induced liquefaction","authors":"Qi Wu, Xuanming Ding, Yanling Zhang","doi":"10.1139/cgj-2022-0512","DOIUrl":"https://doi.org/10.1139/cgj-2022-0512","url":null,"abstract":"This study addresses the microfabric evolution of coral sand during earthquake-induced liquefaction using the joint tests of macroscopic shaking table and microscopic X-ray computed tomography (μCT). Based on the non-destructive scanning and image reconstruction in 3D, the change in the grain-pore structure of sands under earthquakes is discussed. Furthermore, the special microstructural evolution of coral sand is studied by the contrast tests with Fujian sand. The results show that the coordination number of coral sand is larger than that of Fujian sand after liquefaction, which is consistent with that the reduction in acceleration of coral sand is smaller than that of the Fujian sand, and the coral sand foundation still has a larger shear strength due to the smaller excess pore pressure accumulation. Moreover, the contact index of Fujian sand and Reigate sand fluctuates in a similar range with the change of void ratio and coordination number compared with coral sand. This is due to the fact that the Fujian sand and Reigate sand are both general terrigenous sands (quartz sand), while coral sand has irregular particle shapes and larger surface friction caused by marine biogenesis. The test results deepen the understanding of the liquefaction mechanism of coral sand.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135549012","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}
Luke Morgan Weidner, Alex Ferrier, Megan van Veen, Matthew J Lato
Topographic change detection is increasingly being used to identify and monitor landslides and other geohazards in support of risk-informed decision making. Expanding change detection from site-specific to regional scales enables increasingly proactive asset management and contributes to improving the resilience of infrastructure to extreme events. It is widely known that change detection precision can be improved by applying three-dimensional (3D) algorithms, such as iterative closest point (ICP) and M3C2, directly to raw point clouds. However, this also increases the computational requirements compared to alternatives such as digital elevation model (DEM) differencing (DoD). This study presents a novel graphics processing unit (GPU) based implementation of the ICP-M3C2 workflow to address this limitation. In the proposed algorithm, point cloud data segments are automatically queued and served to the working GPU, which efficiently performs point cloud processing operations, while the central processing unit (CPU) performs data management operations in parallel. The developed method is estimated to be up to 54 times faster than CPU-based versions of the same algorithm. In this paper, we present how the workflow has been applied to six regional-scale landslide identification and monitoring case studies, in which landslides are causing the disruption of pipelines, highways, and rail corridors. Overall, in 2021 and 2022, over 17,500 linear kms of change detection were processed using the demonstrated method.
{"title":"Rapid 3D lidar change detection for geohazard identification using GPU-based alignment and M3C2 algorithms","authors":"Luke Morgan Weidner, Alex Ferrier, Megan van Veen, Matthew J Lato","doi":"10.1139/cgj-2023-0073","DOIUrl":"https://doi.org/10.1139/cgj-2023-0073","url":null,"abstract":"Topographic change detection is increasingly being used to identify and monitor landslides and other geohazards in support of risk-informed decision making. Expanding change detection from site-specific to regional scales enables increasingly proactive asset management and contributes to improving the resilience of infrastructure to extreme events. It is widely known that change detection precision can be improved by applying three-dimensional (3D) algorithms, such as iterative closest point (ICP) and M3C2, directly to raw point clouds. However, this also increases the computational requirements compared to alternatives such as digital elevation model (DEM) differencing (DoD). This study presents a novel graphics processing unit (GPU) based implementation of the ICP-M3C2 workflow to address this limitation. In the proposed algorithm, point cloud data segments are automatically queued and served to the working GPU, which efficiently performs point cloud processing operations, while the central processing unit (CPU) performs data management operations in parallel. The developed method is estimated to be up to 54 times faster than CPU-based versions of the same algorithm. In this paper, we present how the workflow has been applied to six regional-scale landslide identification and monitoring case studies, in which landslides are causing the disruption of pipelines, highways, and rail corridors. Overall, in 2021 and 2022, over 17,500 linear kms of change detection were processed using the demonstrated method.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135549147","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}
Jean-Marc LeBlanc, Richard W.I. Brachman, Arian Zarpeima
Modular polymer stormwater structures are a relatively new class of buried structure with two horizonal platens supported by vertical columns. While structural demand at design truck loads has been quantified, the ultimate limit state to design tuck loading is unknown. Full-scale physical experiments were conducted to quantify the applied load and identify the mode(s) of failure at the ultimate limit state of three types of modular structures when buried (with 0.6 m soil cover) and subject to static design truck loading. All three module types tested reached an ultimate limit state at applied loads around 3 times the nominal design load, but had different modes of failure. The ultimate resistance for the module with columns having the lowest moment of inertia relative to length squared was caused by column buckling and top platen rupture, while the two modules with nearly twice the moment of inertia relative to length squared failed by top platen rupture and their column forces at most were 70% to 75% of their short-term single column buckling resistance. The results provide new data to allow independent load rating of the buried structure, support continued assessment of column buckling, and identify the need to limit platen bending deflections.
{"title":"Design-truck ultimate limit states of buried modular polymer stormwater collection structures","authors":"Jean-Marc LeBlanc, Richard W.I. Brachman, Arian Zarpeima","doi":"10.1139/cgj-2023-0055","DOIUrl":"https://doi.org/10.1139/cgj-2023-0055","url":null,"abstract":"Modular polymer stormwater structures are a relatively new class of buried structure with two horizonal platens supported by vertical columns. While structural demand at design truck loads has been quantified, the ultimate limit state to design tuck loading is unknown. Full-scale physical experiments were conducted to quantify the applied load and identify the mode(s) of failure at the ultimate limit state of three types of modular structures when buried (with 0.6 m soil cover) and subject to static design truck loading. All three module types tested reached an ultimate limit state at applied loads around 3 times the nominal design load, but had different modes of failure. The ultimate resistance for the module with columns having the lowest moment of inertia relative to length squared was caused by column buckling and top platen rupture, while the two modules with nearly twice the moment of inertia relative to length squared failed by top platen rupture and their column forces at most were 70% to 75% of their short-term single column buckling resistance. The results provide new data to allow independent load rating of the buried structure, support continued assessment of column buckling, and identify the need to limit platen bending deflections.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135549023","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}
Soumyaranjan Mishra, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Trung Ngo
The most common railway ballast is produced by quarrying, and its mechanical characteristics are crucial for both stability and drainage for safer and faster rail operations. Ballasted tracks have certain drawbacks, primarily because ballast starts to degrade over time. In this regard, reducing the rate of ballast degradation is vital to enhance track longevity and minimise maintenance costs. This paper demonstrates how segments of waste rubber tyres (e.g. 3m in diameter) from the mining industry can improve stability of tracks, while contributing to reduced ballast deformation and degradation. By placing arched segments along the track shoulders beyond the edge of sleepers, the in-situ lateral confining pressure can be increased from 20-25 kPa (standard track) to 40-50 kPa. This novel idea of Confined-Caterpillar Track (CCT) was tested at a prototype physical model (1:1 scale) at the National Facility for the Heavy-haul Railroad Testing (NFHRT), and the experimental outcomes compared to the performance of a conventional track. Apart from constributing to at least 25% saving of quarried aggregates, the test results prove that the CCT concept can curtail the lateral displacement and settlement of the ballast layer, while reducing particle breakage and effecting significant stress reduction in the underlying substructure layers.
{"title":"Use of recycled tyre segments to enhance the stability of ballasted track by increased confinement","authors":"Soumyaranjan Mishra, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Trung Ngo","doi":"10.1139/cgj-2022-0666","DOIUrl":"https://doi.org/10.1139/cgj-2022-0666","url":null,"abstract":"The most common railway ballast is produced by quarrying, and its mechanical characteristics are crucial for both stability and drainage for safer and faster rail operations. Ballasted tracks have certain drawbacks, primarily because ballast starts to degrade over time. In this regard, reducing the rate of ballast degradation is vital to enhance track longevity and minimise maintenance costs. This paper demonstrates how segments of waste rubber tyres (e.g. 3m in diameter) from the mining industry can improve stability of tracks, while contributing to reduced ballast deformation and degradation. By placing arched segments along the track shoulders beyond the edge of sleepers, the in-situ lateral confining pressure can be increased from 20-25 kPa (standard track) to 40-50 kPa. This novel idea of Confined-Caterpillar Track (CCT) was tested at a prototype physical model (1:1 scale) at the National Facility for the Heavy-haul Railroad Testing (NFHRT), and the experimental outcomes compared to the performance of a conventional track. Apart from constributing to at least 25% saving of quarried aggregates, the test results prove that the CCT concept can curtail the lateral displacement and settlement of the ballast layer, while reducing particle breakage and effecting significant stress reduction in the underlying substructure layers.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135549213","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}
Jonathan D. Aubertin, Michel Aubertin, Abtin Jahanbakhshzadeh
Résumé Le comportement géomécanique du sel gemme a été largement étudié au fil des ans. Les différentes études expérimentales ont permis d'identifier des caractéristiques distinctives associées à une réponse inélastique non-linéaire qui est fonction du temps et de l'historique de chargement. Ces caractéristiques doivent être reproduites par les équations constitutives utilisées pour analyser la réponse du sel gemme autour des ouvertures souterraines. Dans cet article, un modèle constitutif relativement simple est introduit dans le code numérique FLAC et appliqué pour analyser le comportement différé d'excavations dans des mines de sel. Le modèle unifié en fluage et plasticité comprend une variable d“état interne avec une loi d”évolution qui induit un écrouissage progressif jusqu'à ce qu“un état stationnaire soit atteint. Des analyses numériques sont effectuées avec le modèle ISV-SH pour évaluer les paramètres du matériau et simuler la réponse d”une ouverture circulaire et d'excavations minières rectangulaires créées séquentiellement. Les résultats sont présentés et comparés à ceux obtenus avec l“équation bien connue de la loi de puissance de Norton, couramment utilisée dans l”ingénierie des mines de sel. Les résultats des calculs, présentés en termes de l’évolution des contraintes, des déformations et de vitesses de déformation, illustrent certains des aspects clés du comportement du sel gemme et ils mettent en évidence l“influence majeure de la loi de comportement utilisée pour les analyses numériques. L”approche de simulation proposée ici constitue une alternative pratique et flexible aux outils de modélisation basés sur le fluage stationnaire, souvent utilisés pour l“analyse des ouvertures souterraines dans les opérations d”extraction de sel gemme. 1 Ceci est une traduction fournie par l'auteur du résumé en anglais.
{"title":"Correction: numerical implementation and application of an internal state variable model to analyze the time-dependent behavior of mining excavations in rock salt","authors":"Jonathan D. Aubertin, Michel Aubertin, Abtin Jahanbakhshzadeh","doi":"10.1139/cgj-2023-0442","DOIUrl":"https://doi.org/10.1139/cgj-2023-0442","url":null,"abstract":"Résumé Le comportement géomécanique du sel gemme a été largement étudié au fil des ans. Les différentes études expérimentales ont permis d'identifier des caractéristiques distinctives associées à une réponse inélastique non-linéaire qui est fonction du temps et de l'historique de chargement. Ces caractéristiques doivent être reproduites par les équations constitutives utilisées pour analyser la réponse du sel gemme autour des ouvertures souterraines. Dans cet article, un modèle constitutif relativement simple est introduit dans le code numérique FLAC et appliqué pour analyser le comportement différé d'excavations dans des mines de sel. Le modèle unifié en fluage et plasticité comprend une variable d“état interne avec une loi d”évolution qui induit un écrouissage progressif jusqu'à ce qu“un état stationnaire soit atteint. Des analyses numériques sont effectuées avec le modèle ISV-SH pour évaluer les paramètres du matériau et simuler la réponse d”une ouverture circulaire et d'excavations minières rectangulaires créées séquentiellement. Les résultats sont présentés et comparés à ceux obtenus avec l“équation bien connue de la loi de puissance de Norton, couramment utilisée dans l”ingénierie des mines de sel. Les résultats des calculs, présentés en termes de l’évolution des contraintes, des déformations et de vitesses de déformation, illustrent certains des aspects clés du comportement du sel gemme et ils mettent en évidence l“influence majeure de la loi de comportement utilisée pour les analyses numériques. L”approche de simulation proposée ici constitue une alternative pratique et flexible aux outils de modélisation basés sur le fluage stationnaire, souvent utilisés pour l“analyse des ouvertures souterraines dans les opérations d”extraction de sel gemme. 1 Ceci est une traduction fournie par l'auteur du résumé en anglais.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136235359","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}
Deepak Patwa, Anant Aishwarya Dubey, K Ravi, Sreedeep Sekharan
Thermally active structures (TAS) such as crude oil pipelines and high-power voltage cables are usually embedded within local soils for their sub-structural stability. Based on site requirements, soils are amended with synthetic cementitious materials to improve their strength. However, synthetic binders such as cementation, geo-polymerization, and bio-cementation undermine thermal insulation while improving strength. Moreover, commonly used synthetic binders such as cement and lime are extremely harmful to the geoenvironment due to their hyper-alkalinity and high carbon footprint. Therefore, this study proposes a novel backfill composite consisting of clay loam, biochar, and biopolymer for superior thermal insulation and strength characteristics. Local soil containing high clay content was chosen due to its low thermal conductivity and potential to form stable hydrogen bonding with the biopolymer. The clay loam is amended with 2.5% to 7.5% (w/w) biochar and 0.5% to 1.5% (w/w) of biopolymer and their various combinations. Out of nine soil-biochar-biopolymer composites devised in the current study, six composites exhibited superior strength and lowered thermal conductivity than the plain soil in both conditions, i.e., optimum moisture state and upon drying. The findings of this study establish the synergistic attributes of biopolymer and biochar amendment for developing a high-strength thermal-insulating soil composite.
{"title":"Investigation of Thermal and Strength Characteristics of a Natural Backfill Composite Inspired by Synergistic Biochar-Biopolymer Amendment of Clay Loam","authors":"Deepak Patwa, Anant Aishwarya Dubey, K Ravi, Sreedeep Sekharan","doi":"10.1139/cgj-2022-0528","DOIUrl":"https://doi.org/10.1139/cgj-2022-0528","url":null,"abstract":"Thermally active structures (TAS) such as crude oil pipelines and high-power voltage cables are usually embedded within local soils for their sub-structural stability. Based on site requirements, soils are amended with synthetic cementitious materials to improve their strength. However, synthetic binders such as cementation, geo-polymerization, and bio-cementation undermine thermal insulation while improving strength. Moreover, commonly used synthetic binders such as cement and lime are extremely harmful to the geoenvironment due to their hyper-alkalinity and high carbon footprint. Therefore, this study proposes a novel backfill composite consisting of clay loam, biochar, and biopolymer for superior thermal insulation and strength characteristics. Local soil containing high clay content was chosen due to its low thermal conductivity and potential to form stable hydrogen bonding with the biopolymer. The clay loam is amended with 2.5% to 7.5% (w/w) biochar and 0.5% to 1.5% (w/w) of biopolymer and their various combinations. Out of nine soil-biochar-biopolymer composites devised in the current study, six composites exhibited superior strength and lowered thermal conductivity than the plain soil in both conditions, i.e., optimum moisture state and upon drying. The findings of this study establish the synergistic attributes of biopolymer and biochar amendment for developing a high-strength thermal-insulating soil composite.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136102038","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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