Pub Date : 2023-07-21DOI: 10.3390/geotechnics3030037
José Maria dos Santos Rodrigues Neto, N. Bhandary, Y. Fujita
The rainfall-induced landslide disasters in July 2018 in Southwestern Japan yet again exemplified the severity of slope failure-related damage and the need for improvement of early warning systems. The Japanese Meteorological Agency (JMA) uses a method based on a threshold value of soil water index (SWI), a conceptual measurement that represents saturation of slope soil. The current SWI early warning system uses 60-min rainfall data on a 5-km2 mesh and does not take into consideration other landslide conditioning factors such as slope angle and geology. This study calculates SWI values during the July 2018 disasters in Kure City (Hiroshima Prefecture) using 1-min XRAIN rainfall data in a 250-m mesh to investigate the relationship between SWI and landslide occurrence. It was found that the SWI threshold of 124 mm used in the JMA early warning system for the area was surpassed in all cells. A new SWI threshold calculation method taking slope angle and geology into consideration and produced with machine learning is proposed, comprising power lines for different geological units at a two-dimensional graph where points located above the threshold line represent landslide risk. It is judged that this method would provide a more accurate early warning system for landslide disasters.
2018年7月在日本西南部发生的降雨引发的滑坡灾害再次证明了边坡破坏相关损害的严重性以及改进预警系统的必要性。日本气象厅(JMA)使用了一种基于土壤水指数(SWI)阈值的方法，这是一种代表斜坡土壤饱和度的概念性测量。目前的SWI预警系统采用的是5平方公里网格上60分钟的降雨数据，没有考虑坡角、地质等其他滑坡调节因素。本研究利用250米网1分钟XRAIN降雨数据，计算了2018年7月广岛县Kure市灾害期间的SWI值，探讨了SWI与滑坡发生的关系。结果发现，所有小区均超过了气象厅预警系统中使用的124 mm SWI阈值。提出了一种考虑坡角和地质因素并利用机器学习生成的新的SWI阈值计算方法，该方法在二维图中包含不同地质单元的电力线，位于阈值线上的点代表滑坡风险。该方法可为滑坡灾害提供更为准确的预警系统。
{"title":"An Analytical Study on Soil Water Index (SWI), Landslide Prediction and Other Related Factors Using XRAIN Data during the July 2018 Heavy Rain Disasters in Hiroshima, Japan","authors":"José Maria dos Santos Rodrigues Neto, N. Bhandary, Y. Fujita","doi":"10.3390/geotechnics3030037","DOIUrl":"https://doi.org/10.3390/geotechnics3030037","url":null,"abstract":"The rainfall-induced landslide disasters in July 2018 in Southwestern Japan yet again exemplified the severity of slope failure-related damage and the need for improvement of early warning systems. The Japanese Meteorological Agency (JMA) uses a method based on a threshold value of soil water index (SWI), a conceptual measurement that represents saturation of slope soil. The current SWI early warning system uses 60-min rainfall data on a 5-km2 mesh and does not take into consideration other landslide conditioning factors such as slope angle and geology. This study calculates SWI values during the July 2018 disasters in Kure City (Hiroshima Prefecture) using 1-min XRAIN rainfall data in a 250-m mesh to investigate the relationship between SWI and landslide occurrence. It was found that the SWI threshold of 124 mm used in the JMA early warning system for the area was surpassed in all cells. A new SWI threshold calculation method taking slope angle and geology into consideration and produced with machine learning is proposed, comprising power lines for different geological units at a two-dimensional graph where points located above the threshold line represent landslide risk. It is judged that this method would provide a more accurate early warning system for landslide disasters.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"27 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82864758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-19DOI: 10.3390/geotechnics3030036
Jude Zeitouny, W. Lieske, Arash Alimardani Lavasan, Eva Heinz, M. Wichern, T. Wichtmann
Microbially induced calcite precipitation (MICP) is a green bio-inspired soil solidification technique that depends on the ability of urease-producing bacteria to form calcium carbonate that bonds soil grains and, consequently, improves soil mechanical properties. Meanwhile, different treatment methods have been adopted to tackle the key challenges in achieving effective MICP treatment. This paper proposes the combined method as a new MICP treatment approach, aiming to develop the efficiency of MICP treatment methods and simulate naturally cemented soil. This method combines the premixing, percolation, and submerging MICP methods. The strength outcomes of Portland-cemented and MICP-cemented sand using the percolation and combined methods were compared. For Portland-cemented sand, the UCS values varied from 0.6 MPa to 17.2 MPa, corresponding to cementation levels ranging from 5% to 30%. For MICP-cemented sand, the percolation method yielded UCS values ranging from 0.5 to 0.9 MPa, while the combined method achieved 3.7 MPa. The strength obtained by the combined method is around 3.7 times higher than that of the percolation method. The stiffness of bio-cemented samples varied between 20 and 470 MPa, while for Portland-cemented sand, it ranged from 130 to 1200 MPa. In terms of calcium carbonate distribution, the percolation method exhibited higher concentration at the top of the sample, while the combined method exhibited more precipitation at the top and perimeter, with less concentration in the central bottom region, equivalent to 10% of a half section’s area.
{"title":"Impact of New Combined Treatment Method on the Mechanical Properties and Microstructure of MICP-Improved Sand","authors":"Jude Zeitouny, W. Lieske, Arash Alimardani Lavasan, Eva Heinz, M. Wichern, T. Wichtmann","doi":"10.3390/geotechnics3030036","DOIUrl":"https://doi.org/10.3390/geotechnics3030036","url":null,"abstract":"Microbially induced calcite precipitation (MICP) is a green bio-inspired soil solidification technique that depends on the ability of urease-producing bacteria to form calcium carbonate that bonds soil grains and, consequently, improves soil mechanical properties. Meanwhile, different treatment methods have been adopted to tackle the key challenges in achieving effective MICP treatment. This paper proposes the combined method as a new MICP treatment approach, aiming to develop the efficiency of MICP treatment methods and simulate naturally cemented soil. This method combines the premixing, percolation, and submerging MICP methods. The strength outcomes of Portland-cemented and MICP-cemented sand using the percolation and combined methods were compared. For Portland-cemented sand, the UCS values varied from 0.6 MPa to 17.2 MPa, corresponding to cementation levels ranging from 5% to 30%. For MICP-cemented sand, the percolation method yielded UCS values ranging from 0.5 to 0.9 MPa, while the combined method achieved 3.7 MPa. The strength obtained by the combined method is around 3.7 times higher than that of the percolation method. The stiffness of bio-cemented samples varied between 20 and 470 MPa, while for Portland-cemented sand, it ranged from 130 to 1200 MPa. In terms of calcium carbonate distribution, the percolation method exhibited higher concentration at the top of the sample, while the combined method exhibited more precipitation at the top and perimeter, with less concentration in the central bottom region, equivalent to 10% of a half section’s area.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"6 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81371128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.3390/geotechnics3030035
Abolfazl Baghbani, H. Abuel-Naga, Danial Shirkavand
The thermal conductivity of materials is a crucial property with diverse applications, particularly in engineering. Understanding soil thermal conductivity is crucial for designing efficient geothermal systems, predicting soil temperatures, and assessing soil contamination. This paper aimed to predict quartz sand thermal conductivity by using four mathematical models: multiple linear regression (MLR), artificial neural network (ANN), classification and regression random forest (CRRF), and genetic programming (GP). A grey-box AI method, GP, was used for the first time in this topic. Seven inputs affecting thermal conductivity were evaluated in the study, including sand porosity, degree of saturation, coefficient of uniformity, coefficient of curvature, mean particle size, and minimum and maximum void ratios. In predicting thermal conductivity, the MLR model performed poorly, with a coefficient of determination R2 = 0.737 and a mean absolute error MAE = 0.300. Both ANN models using the Levenberg–Marquardt algorithm and the Bayesian Regularization (BR) algorithm outperformed the MLR model with an accuracy of R2 = 0.916 and an error of MAE = 0.151. In addition, the CRRF model had the best accuracy of R2 = 0.993 and MAE = 0.045. In addition, GP showed acceptable performance in predicting sand thermal conductivity. The R2 and MAE values of GP were 0.986 and 0.063, respectively. This paper presents the best GP equation for evaluating other databases. Additionally, the porosity and saturation of the sand were found to have the greatest impact on the model results, while coefficients of curvature and uniformity had the least influence. Overall, the results of this study demonstrate that grey-box artificial intelligence models can be used to accurately predict quartz sand thermal conductivity.
{"title":"Accurately Predicting Quartz Sand Thermal Conductivity Using Machine Learning and Grey-Box AI Models","authors":"Abolfazl Baghbani, H. Abuel-Naga, Danial Shirkavand","doi":"10.3390/geotechnics3030035","DOIUrl":"https://doi.org/10.3390/geotechnics3030035","url":null,"abstract":"The thermal conductivity of materials is a crucial property with diverse applications, particularly in engineering. Understanding soil thermal conductivity is crucial for designing efficient geothermal systems, predicting soil temperatures, and assessing soil contamination. This paper aimed to predict quartz sand thermal conductivity by using four mathematical models: multiple linear regression (MLR), artificial neural network (ANN), classification and regression random forest (CRRF), and genetic programming (GP). A grey-box AI method, GP, was used for the first time in this topic. Seven inputs affecting thermal conductivity were evaluated in the study, including sand porosity, degree of saturation, coefficient of uniformity, coefficient of curvature, mean particle size, and minimum and maximum void ratios. In predicting thermal conductivity, the MLR model performed poorly, with a coefficient of determination R2 = 0.737 and a mean absolute error MAE = 0.300. Both ANN models using the Levenberg–Marquardt algorithm and the Bayesian Regularization (BR) algorithm outperformed the MLR model with an accuracy of R2 = 0.916 and an error of MAE = 0.151. In addition, the CRRF model had the best accuracy of R2 = 0.993 and MAE = 0.045. In addition, GP showed acceptable performance in predicting sand thermal conductivity. The R2 and MAE values of GP were 0.986 and 0.063, respectively. This paper presents the best GP equation for evaluating other databases. Additionally, the porosity and saturation of the sand were found to have the greatest impact on the model results, while coefficients of curvature and uniformity had the least influence. Overall, the results of this study demonstrate that grey-box artificial intelligence models can be used to accurately predict quartz sand thermal conductivity.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74317929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.3390/geotechnics3030034
Yun K Huang, Weichen Sun, Hongyi You, Kai Wu
This study employs a 3D discrete element method (DEM) to simulate cone penetration tests (CPTs) in granular soils, taking into account the effect of temperature. A coupled thermal mechanical model is developed to allow for heat transfer and storage in the granular materials. The CPT simulations are conducted on granular samples prepared at various temperatures, with the specific heat and velocity of thermal conductivity being identified as two critical factors that influence sample heating time. Additionally, the thermal expansion coefficient is a crucial parameter that is closely related to the porosity of the sample. As the sample temperature increases, the particles expand, resulting in an increase in cone resistance.
{"title":"Influence of Temperature Effects on CPT in Granular Soils by Discrete Element Modeling in 3D","authors":"Yun K Huang, Weichen Sun, Hongyi You, Kai Wu","doi":"10.3390/geotechnics3030034","DOIUrl":"https://doi.org/10.3390/geotechnics3030034","url":null,"abstract":"This study employs a 3D discrete element method (DEM) to simulate cone penetration tests (CPTs) in granular soils, taking into account the effect of temperature. A coupled thermal mechanical model is developed to allow for heat transfer and storage in the granular materials. The CPT simulations are conducted on granular samples prepared at various temperatures, with the specific heat and velocity of thermal conductivity being identified as two critical factors that influence sample heating time. Additionally, the thermal expansion coefficient is a crucial parameter that is closely related to the porosity of the sample. As the sample temperature increases, the particles expand, resulting in an increase in cone resistance.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"23 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87771048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-04DOI: 10.3390/geotechnics3030033
Ophélie Rohmer, Maria Paola Santisi d’Avila, E. Bertrand, J. Regnier
This research investigates the convenience of structural identification tools to detect the rocking motion tendency, using as input the structural response to ambient vibrations. The rocking ratio and rocking spectrum are proposed as original tools to highlight the rocking motion and its frequency content. The proposed procedure allows the detection and quantification of rocking using only building vertical motion records in both cases of ambient vibration and earthquake. First, three-dimensional finite element models of reinforced concrete buildings are adopted to simulate the structural response to white noise vibration. Different low- and high-rise buildings are studied, having framed structure and frame–wall system, regular and irregular structure, shallow foundation and underground floors. The structural response obtained numerically is analyzed using different signal processing tools to obtain the dynamic features of buildings, and the rocking motion tendency is identified by comparison with a reference fixed base condition. Then, the reliability of the proposed methodology to detect rocking motion attitude, using only the structural motion, is verified and quantified using the proposed tools. Finally, the same approach is applied to real structural motion records of a high-rise reinforced concrete building.
{"title":"Rocking Motion Analysis Using Structural Identification Tools","authors":"Ophélie Rohmer, Maria Paola Santisi d’Avila, E. Bertrand, J. Regnier","doi":"10.3390/geotechnics3030033","DOIUrl":"https://doi.org/10.3390/geotechnics3030033","url":null,"abstract":"This research investigates the convenience of structural identification tools to detect the rocking motion tendency, using as input the structural response to ambient vibrations. The rocking ratio and rocking spectrum are proposed as original tools to highlight the rocking motion and its frequency content. The proposed procedure allows the detection and quantification of rocking using only building vertical motion records in both cases of ambient vibration and earthquake. First, three-dimensional finite element models of reinforced concrete buildings are adopted to simulate the structural response to white noise vibration. Different low- and high-rise buildings are studied, having framed structure and frame–wall system, regular and irregular structure, shallow foundation and underground floors. The structural response obtained numerically is analyzed using different signal processing tools to obtain the dynamic features of buildings, and the rocking motion tendency is identified by comparison with a reference fixed base condition. Then, the reliability of the proposed methodology to detect rocking motion attitude, using only the structural motion, is verified and quantified using the proposed tools. Finally, the same approach is applied to real structural motion records of a high-rise reinforced concrete building.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"31 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89587809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-01DOI: 10.3390/geotechnics3030032
Miltiadis Kontogeorgos, C. Fuggini
The current study investigates the capacity of the proposed meta-material layout for the blast protection of above-ground steel pipes against explosions. The philosophy of the meta-material layout’s design is described adequately, and the 1D periodic structures’ theory is adopted for the analytical prediction of the layout’s band-gaps. The special characteristics of the blast loading are explained, and specific time-related parameters are calculated. The layout is tested numerically for nine explosion scenarios of various magnitude via the finite element program ABAQUS, and the CONWEP model is selected for the simulation of the explosions. The results demonstrate a significant reduction in the maximum displacements developed on the pipe’s spring line and crown within a blast loading. This study composes an extension of the author’s previous research on buried steel pipes and surface explosion, advancing now the applicability of the meta-material layouts for the cases of above-ground steel pipes towards explosions and blast hazards. The outer goal is the investigation and the further spreading of the beneficial exploitation of meta-materials concepts for the scope of the pipelines’ effective blast protection, readdressing that this way is a major hazard for this type of structure and a gap in the current literature.
{"title":"Meta-Material Layout for the Blast Protection of Above-Ground Steel Pipes","authors":"Miltiadis Kontogeorgos, C. Fuggini","doi":"10.3390/geotechnics3030032","DOIUrl":"https://doi.org/10.3390/geotechnics3030032","url":null,"abstract":"The current study investigates the capacity of the proposed meta-material layout for the blast protection of above-ground steel pipes against explosions. The philosophy of the meta-material layout’s design is described adequately, and the 1D periodic structures’ theory is adopted for the analytical prediction of the layout’s band-gaps. The special characteristics of the blast loading are explained, and specific time-related parameters are calculated. The layout is tested numerically for nine explosion scenarios of various magnitude via the finite element program ABAQUS, and the CONWEP model is selected for the simulation of the explosions. The results demonstrate a significant reduction in the maximum displacements developed on the pipe’s spring line and crown within a blast loading. This study composes an extension of the author’s previous research on buried steel pipes and surface explosion, advancing now the applicability of the meta-material layouts for the cases of above-ground steel pipes towards explosions and blast hazards. The outer goal is the investigation and the further spreading of the beneficial exploitation of meta-materials concepts for the scope of the pipelines’ effective blast protection, readdressing that this way is a major hazard for this type of structure and a gap in the current literature.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"184 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80687883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.3390/geotechnics3030031
Arvin M. Farid, Holly Gunderson, Rakesh Acharya, J. Browning
Electromagnetic (EM) waves, traditionally used for purposes such as geophysical characterization, impact properties to be measured. This paper describes the effects of radio frequency (RF) waves on the hydraulic conductivity of glass beads and natural sand. A series of tests was conducted using a customized, rigid-wall, cylindrical permeameter inside a resonant cavity made of Plexiglas covered with electrically conductive transparent films. Constant-head ASTM-D2434 tests were performed to measure the samples’ hydraulic conductivity. RF stimulation was performed using a magnetically coupled loop antenna at various frequencies and input RF-power levels. The hydraulic conductivity of both natural sand and glass-bead samples increased with RF stimulation. Furthermore, the measurement of the electric field component of RF waves was also performed to illustrate the pattern of the electric field, as well as evaluate RF’s impact on the hydraulic conductivity tests. The electric field was numerically simulated and validated against experimentally measured electric fields. A finite-difference numerical model was developed in MATLAB to analyze the seepage flow, which was then validated against the experimental results. An optimization scheme was then used to develop a governing equation for RF’s impact on hydraulic conductivity.
{"title":"Electromagnetic Waves’ Impact on Hydraulic Conductivity of Granular Soils","authors":"Arvin M. Farid, Holly Gunderson, Rakesh Acharya, J. Browning","doi":"10.3390/geotechnics3030031","DOIUrl":"https://doi.org/10.3390/geotechnics3030031","url":null,"abstract":"Electromagnetic (EM) waves, traditionally used for purposes such as geophysical characterization, impact properties to be measured. This paper describes the effects of radio frequency (RF) waves on the hydraulic conductivity of glass beads and natural sand. A series of tests was conducted using a customized, rigid-wall, cylindrical permeameter inside a resonant cavity made of Plexiglas covered with electrically conductive transparent films. Constant-head ASTM-D2434 tests were performed to measure the samples’ hydraulic conductivity. RF stimulation was performed using a magnetically coupled loop antenna at various frequencies and input RF-power levels. The hydraulic conductivity of both natural sand and glass-bead samples increased with RF stimulation. Furthermore, the measurement of the electric field component of RF waves was also performed to illustrate the pattern of the electric field, as well as evaluate RF’s impact on the hydraulic conductivity tests. The electric field was numerically simulated and validated against experimentally measured electric fields. A finite-difference numerical model was developed in MATLAB to analyze the seepage flow, which was then validated against the experimental results. An optimization scheme was then used to develop a governing equation for RF’s impact on hydraulic conductivity.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"87 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73516532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Guida, Vincenzo Sergio Vespo, G. Musso, G. Della Vecchia
Evaporation from geological formations results from the interaction between the geomaterial and the atmosphere. Geotechnical engineering issues, such as slope stability, pollution containment and soil heave/shrinkage, require a deep understanding of the soil–atmosphere interaction ruled by evaporation. Evaporation is a multiphase thermo-hydraulic phenomenon that includes liquid water, vapour and heat fluxes. It is generally modelled considering the thermal energy and water mass balance equations of unsaturated soils. This paper presents a numerical model for reproducing evaporation processes under controlled environmental conditions. The model was implemented in the Comsol Multiphysics finite-element software and first validated against experimental data from the literature. Then, it was used to investigate the role of hydraulic and thermal properties in the evaporative response. The numerical results revealed differences in the evolution of the water content profiles over time due to the interplay between hydraulic conductivity and retention properties. Hydraulic conductivity mainly impacts the shape of water content isochrones: fast drying of superficial layers and slow desaturation of deeper layers occur with decreasing hydraulic conductivity values. On the other hand, the moisture capacity primarily impacts the thickness of the desaturating layer, which decreases for higher values of the moisture capacity.
{"title":"The role of hydraulic and thermal properties of soil in evaporation: a numerical insight","authors":"G. Guida, Vincenzo Sergio Vespo, G. Musso, G. Della Vecchia","doi":"10.1680/jenge.22.00132","DOIUrl":"https://doi.org/10.1680/jenge.22.00132","url":null,"abstract":"Evaporation from geological formations results from the interaction between the geomaterial and the atmosphere. Geotechnical engineering issues, such as slope stability, pollution containment and soil heave/shrinkage, require a deep understanding of the soil–atmosphere interaction ruled by evaporation. Evaporation is a multiphase thermo-hydraulic phenomenon that includes liquid water, vapour and heat fluxes. It is generally modelled considering the thermal energy and water mass balance equations of unsaturated soils. This paper presents a numerical model for reproducing evaporation processes under controlled environmental conditions. The model was implemented in the Comsol Multiphysics finite-element software and first validated against experimental data from the literature. Then, it was used to investigate the role of hydraulic and thermal properties in the evaporative response. The numerical results revealed differences in the evolution of the water content profiles over time due to the interplay between hydraulic conductivity and retention properties. Hydraulic conductivity mainly impacts the shape of water content isochrones: fast drying of superficial layers and slow desaturation of deeper layers occur with decreasing hydraulic conductivity values. On the other hand, the moisture capacity primarily impacts the thickness of the desaturating layer, which decreases for higher values of the moisture capacity.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49257472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Construction and demolition waste is one of the most impactful waste streams worldwide, so efforts should be made to find applications that promote its recovery. The use of recycled aggregates from construction and demolition waste as filling materials in geotechnical works, where they may come into contact with geosynthetics, is one of those applications. This work evaluates the mechanical damage induced to five geotextiles with different structures (non-woven and woven) by three recycled aggregates from construction and demolition waste. The damage suffered by the geotextiles was evaluated qualitatively by visual inspection and quantitatively by monitoring changes in their tensile and static puncture behaviour. The results showed that in some cases, the recycled aggregates from construction and demolition waste induced damage to the geotextiles, affecting their properties. The impact of the aggregates depended on (a) their particle characteristics and (b) the physical properties of the geotextiles. For both non-woven and woven geotextiles, the increase in mass per unit area and thickness resulted in better resistance to degradation. The damage caused by the recycled aggregates to 251 and 495 g/m2 non-woven geotextiles was small to negligible. Corundum (standard aggregate) had a more harmful impact on the geotextiles than the recycled aggregates.
{"title":"Mechanical damage of geotextiles induced by recycled construction and demolition waste","authors":"J. Carneiro, F. Almeida, M. Lopes","doi":"10.1680/jenge.22.00116","DOIUrl":"https://doi.org/10.1680/jenge.22.00116","url":null,"abstract":"Construction and demolition waste is one of the most impactful waste streams worldwide, so efforts should be made to find applications that promote its recovery. The use of recycled aggregates from construction and demolition waste as filling materials in geotechnical works, where they may come into contact with geosynthetics, is one of those applications. This work evaluates the mechanical damage induced to five geotextiles with different structures (non-woven and woven) by three recycled aggregates from construction and demolition waste. The damage suffered by the geotextiles was evaluated qualitatively by visual inspection and quantitatively by monitoring changes in their tensile and static puncture behaviour. The results showed that in some cases, the recycled aggregates from construction and demolition waste induced damage to the geotextiles, affecting their properties. The impact of the aggregates depended on (a) their particle characteristics and (b) the physical properties of the geotextiles. For both non-woven and woven geotextiles, the increase in mass per unit area and thickness resulted in better resistance to degradation. The damage caused by the recycled aggregates to 251 and 495 g/m2 non-woven geotextiles was small to negligible. Corundum (standard aggregate) had a more harmful impact on the geotextiles than the recycled aggregates.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47810609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avishek Adhikary, Tapabrata Chakraborty, Pradyumna Konar, S. Pal, Sudipta Ghosh
Erythromycin (ERY) is environmentally resilient because of its aromatic nature, which hinders degradation. In the present study, silty–sandy soil, with a saturated hydraulic conductivity (K) value of 1.66 × 10−7 m/s, was studied for its potential to remove aqueous ERY using a laboratory-scale constructed wetland. With a dose of 10 g/l, a concentration of 25 mg/l and a contact time of 30 min, the maximum adsorption reached 89.79 ± 1.5%, as found from batch experiments. The Freundlich isotherm (R 2 = 0.983, n = 0.575, K f = 0.04 mg/g) was the best fitting among different user models. In the kinetic study, the pseudo-second-order model (q e = 1.297 mg/g, K 2 = 0.182 g/(mg min)) had the best fit with experimental data. A one-dimensional vertical column study exhibited an exhaustion time of 2.7 days for a 40 mm deep soil bed to remove ERY. A laboratory-scale constructed wetland model composed of silty–sandy soil showed a reduction of ERY of 92.44%. Finally, the results were validated with the CW2D wetland model of the Hydrus software, which corroborated the experimental results. The outcome exhorts that constructed wetlands with silty–sandy soil may be an effective technique for the reduction of ERY present in waste water, which has profound importance from a social health perspective.
红霉素(ERY)具有环境适应性，因为它的芳香性阻碍了降解。在本研究中，我们利用实验室规模的人工湿地，研究了饱和水力传导性(K)值为1.66 × 10−7 m/s的粉砂质土壤去除水中ERY的潜力。当剂量为10 g/l，浓度为25 mg/l，接触时间为30 min时，最大吸附量为89.79±1.5%。Freundlich等温线(r2 = 0.983, n = 0.575, K f = 0.04 mg/g)在不同用户模型中拟合最佳。在动力学研究中，拟二阶模型(q e = 1.297 mg/g, K 2 = 0.182 g/(mg min))与实验数据拟合最好。一项一维垂直柱研究表明，40毫米深的土床需要2.7天的耗尽时间才能去除ERY。粉砂质土壤组成的实验室尺度人工湿地模型的ERY降低率为92.44%。最后，利用Hydrus软件的CW2D湿地模型对结果进行验证，验证了实验结果。结果表明，粉砂质土壤人工湿地可能是一种减少废水中ERY的有效技术，从社会健康的角度来看，这具有深远的意义。
{"title":"Attenuation of erythromycin-laden waste water using the constructed wetland technique","authors":"Avishek Adhikary, Tapabrata Chakraborty, Pradyumna Konar, S. Pal, Sudipta Ghosh","doi":"10.1680/jenge.22.00082","DOIUrl":"https://doi.org/10.1680/jenge.22.00082","url":null,"abstract":"Erythromycin (ERY) is environmentally resilient because of its aromatic nature, which hinders degradation. In the present study, silty–sandy soil, with a saturated hydraulic conductivity (K) value of 1.66 × 10−7 m/s, was studied for its potential to remove aqueous ERY using a laboratory-scale constructed wetland. With a dose of 10 g/l, a concentration of 25 mg/l and a contact time of 30 min, the maximum adsorption reached 89.79 ± 1.5%, as found from batch experiments. The Freundlich isotherm (R 2 = 0.983, n = 0.575, K f = 0.04 mg/g) was the best fitting among different user models. In the kinetic study, the pseudo-second-order model (q e = 1.297 mg/g, K 2 = 0.182 g/(mg min)) had the best fit with experimental data. A one-dimensional vertical column study exhibited an exhaustion time of 2.7 days for a 40 mm deep soil bed to remove ERY. A laboratory-scale constructed wetland model composed of silty–sandy soil showed a reduction of ERY of 92.44%. Finally, the results were validated with the CW2D wetland model of the Hydrus software, which corroborated the experimental results. The outcome exhorts that constructed wetlands with silty–sandy soil may be an effective technique for the reduction of ERY present in waste water, which has profound importance from a social health perspective.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44043279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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