Αn online questionnaire was developed to find out (i) whether geotechnical engineering instructors have available a variety of satisfactory educational material and (ii) the types of educational material they desire. The title of the questionnaire was phrased as “What Geotechnical Engineering Educational Material can we dream of?”, in order to convey that the main purpose of the survey project reported herein is to learn about these desired educational materials. In doing so, the survey also aims to assemble information on related issues, such as: existing educational materials, where do instructors search for them and how satisfied they are with available material. The questionnaire has 12 close-ended (four yes/no and eight multiple choice) and four open-ended questions. From the 94 completed questionnaires received, 63 were deemed to be conscientious attempts to answer its questions and were analyzed in detail. The most revealing findings from the close-ended questions include the following. The majority of the instructors (52%) are not adequately satisfied with the material they use. Likewise, whereas a significant percentage has searched for additional material, a little less than half of them (45%) are not satisfied with material found. Respondents need materials for their lectures, materials to engage students outside lecture time and, to a lesser extent, materials to assess students. In terms of topics of interest, case studies and laboratory-related educational materials are the most popular. The online supplement of the paper includes broad-stroke and fine-stroke descriptions of desirable educational materials that provide directions for developing them.
{"title":"What kinds of educational material are useful for and desired by university instructors? The case of Geotechnical Engineering","authors":"Marina Pantazidou, Michele Calvello","doi":"10.28927/sr.2024.003623","DOIUrl":"https://doi.org/10.28927/sr.2024.003623","url":null,"abstract":"Αn online questionnaire was developed to find out (i) whether geotechnical engineering instructors have available a variety of satisfactory educational material and (ii) the types of educational material they desire. The title of the questionnaire was phrased as “What Geotechnical Engineering Educational Material can we dream of?”, in order to convey that the main purpose of the survey project reported herein is to learn about these desired educational materials. In doing so, the survey also aims to assemble information on related issues, such as: existing educational materials, where do instructors search for them and how satisfied they are with available material. The questionnaire has 12 close-ended (four yes/no and eight multiple choice) and four open-ended questions. From the 94 completed questionnaires received, 63 were deemed to be conscientious attempts to answer its questions and were analyzed in detail. The most revealing findings from the close-ended questions include the following. The majority of the instructors (52%) are not adequately satisfied with the material they use. Likewise, whereas a significant percentage has searched for additional material, a little less than half of them (45%) are not satisfied with material found. Respondents need materials for their lectures, materials to engage students outside lecture time and, to a lesser extent, materials to assess students. In terms of topics of interest, case studies and laboratory-related educational materials are the most popular. The online supplement of the paper includes broad-stroke and fine-stroke descriptions of desirable educational materials that provide directions for developing them.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"21 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":"135666757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maria Almeida, Jorge Zornberg, Ennio Palmeira, Nathalie Touze
An international educational initiative to facilitate the exposure of geosynthetics to undergraduate civil engineering students has been conducted by the International Geosynthetics Society (IGS) for over a decade. Geosynthetics is a comparatively new topic within geotechnical engineering and, consequently, has only been sporadically introduced into undergraduate Civil Engineering curricula. In particular, geotechnical engineering professors themselves may have not been exposed to the basics of geosynthetics to be able to comfortably transfer such knowledge to their students. As part of this educational program, civil engineering professors are invited to take a course on geosynthetics, for which they receive fellowships covering their expenses. The course also includes complementary components such as a workshop consisting of practical demonstrations, pedagogical material, and technical documents. Implementation of the program involves multiple parties, including the IGS, its national chapters, and geosynthetics industry, who are allotted the responsibilities of supporting the program instructors, offering practical project-oriented input. This paper describes the course structure, the educational tools employed, the impact on the program caused by the pandemic, and results from feedback surveys that assessed how the knowledge on geosynthetics acquired by the participants was transferred to their students in terms of new courses on geosynthetics, inclusion of geosynthetics topics in existing undergraduate disciplines, etc. Emphasis is given on the experience of the Brazilian Chapter of IGS, which has already conducted programs. The educational outcomes of the programs currently offered are being evaluated and they suggest excellent acceptance of the course by participants and undergraduate students at the universities.
{"title":"An international initiative on geosynthetic education","authors":"Maria Almeida, Jorge Zornberg, Ennio Palmeira, Nathalie Touze","doi":"10.28927/sr.2024.003823","DOIUrl":"https://doi.org/10.28927/sr.2024.003823","url":null,"abstract":"An international educational initiative to facilitate the exposure of geosynthetics to undergraduate civil engineering students has been conducted by the International Geosynthetics Society (IGS) for over a decade. Geosynthetics is a comparatively new topic within geotechnical engineering and, consequently, has only been sporadically introduced into undergraduate Civil Engineering curricula. In particular, geotechnical engineering professors themselves may have not been exposed to the basics of geosynthetics to be able to comfortably transfer such knowledge to their students. As part of this educational program, civil engineering professors are invited to take a course on geosynthetics, for which they receive fellowships covering their expenses. The course also includes complementary components such as a workshop consisting of practical demonstrations, pedagogical material, and technical documents. Implementation of the program involves multiple parties, including the IGS, its national chapters, and geosynthetics industry, who are allotted the responsibilities of supporting the program instructors, offering practical project-oriented input. This paper describes the course structure, the educational tools employed, the impact on the program caused by the pandemic, and results from feedback surveys that assessed how the knowledge on geosynthetics acquired by the participants was transferred to their students in terms of new courses on geosynthetics, inclusion of geosynthetics topics in existing undergraduate disciplines, etc. Emphasis is given on the experience of the Brazilian Chapter of IGS, which has already conducted programs. The educational outcomes of the programs currently offered are being evaluated and they suggest excellent acceptance of the course by participants and undergraduate students at the universities.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"23 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":"135667202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Márcia Mascarenha, José Camapum de Carvalho, Andrelisa Jesus, Lilian Rezende, Mauricio Sales, Marta Luz
The Federal University of Goiás (UFG) and the University of Brasília (UnB), in partnership with the company Eletrobras Furnas, have developed research and, based on this, extension projects aimed at education in a broad sense, in which they seek to disseminate and popularise technical-scientific knowledge. This paper aims to present and evaluate educational actions carried out in the area of soil science and geotechnics applied to engineering, geography, and the environment. To do so, the educational experiences developed within the scope of two extension projects are shared. Beside that, the relevance of publishing books and primer, with language adapted to lay society, within the scope of research projects, is analyzed. The results collected regarding the effectiveness of the extension actions as a tool for learning point to a positive evaluation by the students. Furthermore, social networks are an important tool for scientific dissemination and have the potential to disseminate knowledge more widely than in a classroom course. By comparing the number of citations in Google Scholar of the books and booklets with the papers arising from these projects, one can observe the reach of this type of publication, although its purpose is the popularisation of science, with reach in places not considered in the technical-scientific publication metrics. Finally, for effective scientific development, it is necessary to have public policies, effective interaction between universities, research centres and schools, and the participation of professional associations, funding and evaluation agencies, Education Departments and the Ministry of Education, Science, Technology and Innovation.
{"title":"Interaction of geotechnics with society through education","authors":"Márcia Mascarenha, José Camapum de Carvalho, Andrelisa Jesus, Lilian Rezende, Mauricio Sales, Marta Luz","doi":"10.28927/sr.2024.004023","DOIUrl":"https://doi.org/10.28927/sr.2024.004023","url":null,"abstract":"The Federal University of Goiás (UFG) and the University of Brasília (UnB), in partnership with the company Eletrobras Furnas, have developed research and, based on this, extension projects aimed at education in a broad sense, in which they seek to disseminate and popularise technical-scientific knowledge. This paper aims to present and evaluate educational actions carried out in the area of soil science and geotechnics applied to engineering, geography, and the environment. To do so, the educational experiences developed within the scope of two extension projects are shared. Beside that, the relevance of publishing books and primer, with language adapted to lay society, within the scope of research projects, is analyzed. The results collected regarding the effectiveness of the extension actions as a tool for learning point to a positive evaluation by the students. Furthermore, social networks are an important tool for scientific dissemination and have the potential to disseminate knowledge more widely than in a classroom course. By comparing the number of citations in Google Scholar of the books and booklets with the papers arising from these projects, one can observe the reach of this type of publication, although its purpose is the popularisation of science, with reach in places not considered in the technical-scientific publication metrics. Finally, for effective scientific development, it is necessary to have public policies, effective interaction between universities, research centres and schools, and the participation of professional associations, funding and evaluation agencies, Education Departments and the Ministry of Education, Science, Technology and Innovation.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"57 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":"135666919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammad Ghasvareh, Mohammad Shahabi, Mojtaba Shahid, Maryam Panjeh
As dams play a very important role in the optimum use of water resources, it is very important to keep them stable and the water stored in the reservoir. It is particularly important to investigate how water moves through rocks and the permeability and quality of the rock mass in structures like dams. Therefore, one of the issues considered in dam stability is monitoring the quantity of leaks. In this research, the engineering geological and geotechnical parameters of the rock mass for the construction of the Kurit Dam located in the city of Tabas in eastern Iran were evaluated. Initially, following the determination of geotechnical parameters, the engineering classification of the rock mass of the study area was carried out. In addition, in order to study and trace the water evacuation routes of the dam construction, two parameters of the RQD and Lugeon were studied and modelled. Analyses have been conducted to examine the permeability and rock quality index in three parts of the left and right abutment, the dam’s axis and reservoir with geostatistics and kriging methods. Three-dimensional model of the construction of the Kurit dam was presented and the results were analyzed. Based on the results, the quality of the rock mass in the right and left abutments is arguably better than the dam axis and reservoir. Additionally, as the depth increases, the permeability decreases and the permeability is higher at shallow depths. The highest level of permeability is located at the surface and near the BH4 borehole.
{"title":"Investigating the geomechanical properties and permeability of the rocks of the Kurit dam site using geostatistical methods","authors":"Mohammad Ghasvareh, Mohammad Shahabi, Mojtaba Shahid, Maryam Panjeh","doi":"10.28927/sr.2024.014622","DOIUrl":"https://doi.org/10.28927/sr.2024.014622","url":null,"abstract":"As dams play a very important role in the optimum use of water resources, it is very important to keep them stable and the water stored in the reservoir. It is particularly important to investigate how water moves through rocks and the permeability and quality of the rock mass in structures like dams. Therefore, one of the issues considered in dam stability is monitoring the quantity of leaks. In this research, the engineering geological and geotechnical parameters of the rock mass for the construction of the Kurit Dam located in the city of Tabas in eastern Iran were evaluated. Initially, following the determination of geotechnical parameters, the engineering classification of the rock mass of the study area was carried out. In addition, in order to study and trace the water evacuation routes of the dam construction, two parameters of the RQD and Lugeon were studied and modelled. Analyses have been conducted to examine the permeability and rock quality index in three parts of the left and right abutment, the dam’s axis and reservoir with geostatistics and kriging methods. Three-dimensional model of the construction of the Kurit dam was presented and the results were analyzed. Based on the results, the quality of the rock mass in the right and left abutments is arguably better than the dam axis and reservoir. Additionally, as the depth increases, the permeability decreases and the permeability is higher at shallow depths. The highest level of permeability is located at the surface and near the BH4 borehole.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"443 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135480734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Discussion of “Proposition of correlations for the dynamic parameters of carbonate sands”","authors":"Raphael Carneiro","doi":"10.28927/sr.2024.003423","DOIUrl":"https://doi.org/10.28927/sr.2024.003423","url":null,"abstract":"","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134974897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seismic bearing capacity of strip footings is a challenging task for geotechnical engineers due to its stochastic framework instigated by the natural uncertainties incorporated into geotechnical properties and earthquake parameters. Consequently, the introduction of the random field theory into reliability analysis may provide power tools to succor designers check how reliable their designs. This paper aims to assess the seismic bearing capacity of shallow strip footings resting on soils with randomly varying parameters. Bearing capacity formulas for purely cohesive and cohesive-frictional soils are considered. The influence of the type of the autocorrelation functions (ACFs), the scale of fluctuations (SOFs) and the coefficient of variation (COV) of the random parameters are investigated. Statistical moments, probability density function (PDF) and failure probability (Pf) of the seismic bearing capacity are computed. It is shown that the Single Exponential (SNE) ACF is the most appropriate function to characterize the spatial variability of the soil properties since it provides conservative results. On other hand, the results indicate that the increase in the coefficients of variation (COV) of the cohesion or the friction angle increases the variability of the seismic bearing capacity while this variability remains unaffected when the COV of the seismic coefficient increases. The results also highlight that the effect of the vertical SOF on the PDF and the failure probability is much more significant than that of the horizontal SOF. In addition, the mean seismic bearing capacity fluctuates slightly as the horizontal or vertical SOF increases so that the increment of variation is between 0.4% and 2% for the both two soil types.
{"title":"Reliability-based analysis of seismic bearing capacity of shallow strip footings resting on soils with randomly varying geotechnical and earthquake parameters","authors":"Faiçal Bendriss, Zamila Harichane","doi":"10.28927/sr.2024.078821","DOIUrl":"https://doi.org/10.28927/sr.2024.078821","url":null,"abstract":"Seismic bearing capacity of strip footings is a challenging task for geotechnical engineers due to its stochastic framework instigated by the natural uncertainties incorporated into geotechnical properties and earthquake parameters. Consequently, the introduction of the random field theory into reliability analysis may provide power tools to succor designers check how reliable their designs. This paper aims to assess the seismic bearing capacity of shallow strip footings resting on soils with randomly varying parameters. Bearing capacity formulas for purely cohesive and cohesive-frictional soils are considered. The influence of the type of the autocorrelation functions (ACFs), the scale of fluctuations (SOFs) and the coefficient of variation (COV) of the random parameters are investigated. Statistical moments, probability density function (PDF) and failure probability (Pf) of the seismic bearing capacity are computed. It is shown that the Single Exponential (SNE) ACF is the most appropriate function to characterize the spatial variability of the soil properties since it provides conservative results. On other hand, the results indicate that the increase in the coefficients of variation (COV) of the cohesion or the friction angle increases the variability of the seismic bearing capacity while this variability remains unaffected when the COV of the seismic coefficient increases. The results also highlight that the effect of the vertical SOF on the PDF and the failure probability is much more significant than that of the horizontal SOF. In addition, the mean seismic bearing capacity fluctuates slightly as the horizontal or vertical SOF increases so that the increment of variation is between 0.4% and 2% for the both two soil types.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135481070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Phenomena that do not obey Terzaghi’s principle of effective stress (PES) are related to strain rate and time effects. This issue led the author to refer to early articles in soil mechanics, which used to consider the shear resistance of clays as a combination of two components: a frictional and a viscous one. In these articles the viscous component was assigned to the distortion of highly viscous adsorbed water layer in the contact points between grains along the plane where shearing takes place. Assuming the shear resistance of plastic soils comprises frictional and viscous resistance components, a shear stress equation can be added to the PES. It is shown that Mohr’s circle of effective stress is the sum of two ellipses: the viscosity and the friction ellipses. The ordinates of the viscosity and the friction ellipses represent the viscous and the frictional components of shear resistance in different planes, respectively. This approach leads to a failure criterion considering strain rate, according to which failure takes place whenever the friction ellipse touches the strength envelope, which is the 'e φ sloped straight line passing through the origin, 'e φ being the Hvorslev’s true angle of friction. By adding such shear stress equation to the PES, a model that explains strain rate and time effects is developed. Predictions of the proposed model are compared to results from tests carried out on San Francisco Bay Mud specimens.
{"title":"The 8th Victor de Mello lecture: role played by viscosity on the undrained behaviour of normally consolidated clays","authors":"Ian Martins","doi":"10.28927/sr.2023.006123","DOIUrl":"https://doi.org/10.28927/sr.2023.006123","url":null,"abstract":"Phenomena that do not obey Terzaghi’s principle of effective stress (PES) are related to strain rate and time effects. This issue led the author to refer to early articles in soil mechanics, which used to consider the shear resistance of clays as a combination of two components: a frictional and a viscous one. In these articles the viscous component was assigned to the distortion of highly viscous adsorbed water layer in the contact points between grains along the plane where shearing takes place. Assuming the shear resistance of plastic soils comprises frictional and viscous resistance components, a shear stress equation can be added to the PES. It is shown that Mohr’s circle of effective stress is the sum of two ellipses: the viscosity and the friction ellipses. The ordinates of the viscosity and the friction ellipses represent the viscous and the frictional components of shear resistance in different planes, respectively. This approach leads to a failure criterion considering strain rate, according to which failure takes place whenever the friction ellipse touches the strength envelope, which is the 'e φ sloped straight line passing through the origin, 'e φ being the Hvorslev’s true angle of friction. By adding such shear stress equation to the PES, a model that explains strain rate and time effects is developed. Predictions of the proposed model are compared to results from tests carried out on San Francisco Bay Mud specimens.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135200027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alberto Ortigao, Paulo Dias, Hélio Brito, Marnio Camacho
This is an investigative work by the authors, all of them former students and employees at Tecnosolo Ltd, the company founded by our late Professor Costa Nunes, to find and photograph the first tieback wall designed and built in 1957 by Tecnoloso under Prof Costa Nunes’ guidance.
{"title":"A dig into the past: the first tieback wall","authors":"Alberto Ortigao, Paulo Dias, Hélio Brito, Marnio Camacho","doi":"10.28927/sr.2023.007423","DOIUrl":"https://doi.org/10.28927/sr.2023.007423","url":null,"abstract":"This is an investigative work by the authors, all of them former students and employees at Tecnosolo Ltd, the company founded by our late Professor Costa Nunes, to find and photograph the first tieback wall designed and built in 1957 by Tecnoloso under Prof Costa Nunes’ guidance.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48628049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The characterization of unsaturated soils using hydromechanical methods is an essential requirement in soil science. However, current laboratory techniques used to obtain soil water retention and unsaturated hydraulic conductivity curves are time-consuming. To address this issue, a method based on indirect measures (electrical resistivity/electrical conductivity) was developed to quantitatively characterize soils. A novel unsaturated semi-empirical hydrogeophysical model of soils was developed by incorporating the hydrodynamic, geophysical, and petrophysical characteristics of soils. The model assumes that the parameters influencing the variation in the volumetric water content with matric suction and electrical resistivity are the same. The electrical resistivity characteristic curve (ERCC) defines a function that correlates environmental variables, electrical resistivity, soil water status, matric suction, hydraulic and petrophysical parameters, and fluid electrical resistivity. Model validation confirmed that the proposed approach can estimate the soil water retention curve (SWRC) via the indirect measures, and the results agreed with the experimental data. This indicates that it is possible to determine the SWRC and unsaturated hydraulic conductivity function of soil using the described approach.
{"title":"Prediction of hydraulic and petrophysical parameters from indirect measurements of electrical resistivity to determine soil-water retention curve – studies in granular soils","authors":"M. Góis, K. Costa, André Cavalcante","doi":"10.28927/sr.2023.013822","DOIUrl":"https://doi.org/10.28927/sr.2023.013822","url":null,"abstract":"The characterization of unsaturated soils using hydromechanical methods is an essential requirement in soil science. However, current laboratory techniques used to obtain soil water retention and unsaturated hydraulic conductivity curves are time-consuming. To address this issue, a method based on indirect measures (electrical resistivity/electrical conductivity) was developed to quantitatively characterize soils. A novel unsaturated semi-empirical hydrogeophysical model of soils was developed by incorporating the hydrodynamic, geophysical, and petrophysical characteristics of soils. The model assumes that the parameters influencing the variation in the volumetric water content with matric suction and electrical resistivity are the same. The electrical resistivity characteristic curve (ERCC) defines a function that correlates environmental variables, electrical resistivity, soil water status, matric suction, hydraulic and petrophysical parameters, and fluid electrical resistivity. Model validation confirmed that the proposed approach can estimate the soil water retention curve (SWRC) via the indirect measures, and the results agreed with the experimental data. This indicates that it is possible to determine the SWRC and unsaturated hydraulic conductivity function of soil using the described approach.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43946374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maelckson Gomes, A. Guimarães, F. Nascimento, Juliana Santos
Across countries, associations and institutions publish technical standards for railway ballast, however it is observed that those norms have differences when compared to each other. Each one of them has its particularity, varying according to the stone materials available in their countries, axle load and climate. In that sense, it is still a challenge to establish specific guidelines for the properties of the ballast layer. Recently, several techniques for acquisition, image analysis and particle scanning have been developed, either in 2D or in 3D. Those techniques vary from the use of pachymeter to the use of sophisticated scanners. This research seeks to evaluate, through laboratory tests, the evolution of the particle shape parameters through 3D scanning and the level of degradation of the steel slag when subjected to stresses close to those experienced in freight transport railways. Based on the performed tests and the obtained results, the authors recommend for a railway pavement subjected to a load of 32.5 t/axle and composed of steel aggregates used as ballast, a granulometric distribution with uniformity coefficient 1.5 ≤ Cu ≤ 1.6 (AREMA n. 4) and particles with: 0.625 ≤ Elongation ≤ 0.999, 0.567 ≤ Flatness ≤ 0.995, 0.475 ≤ Aspect ≤ 0.969 and 0.825 ≤ Ellipsoidness ≤ 0.957. These specifications enable a good performance of the ballast layer. In addition, the results found contribute to the understanding of siderurgic aggregate behavior under cyclic loading conditions.
在各个国家，协会和机构发布了铁路镇流器的技术标准，但观察到这些规范在相互比较时存在差异。每一种都有其特殊性，根据各自国家可用的石材，轴载荷和气候而有所不同。从这个意义上说，为压载层的性能建立具体的指导方针仍然是一个挑战。近年来，二维或三维图像采集、图像分析和粒子扫描技术得到了发展。这些技术从使用测厚仪到使用复杂的扫描仪各不相同。本研究旨在通过实验室测试，通过3D扫描评估颗粒形状参数的演变，以及钢渣在承受接近货运铁路所经历的应力时的降解水平。根据已进行的试验和取得的结果，建议在32.5 t/轴荷载作用下，以钢骨料为压载料的铁路路面，采用均匀系数为1.5≤Cu≤1.6 (AREMA n. 4)的粒度分布，颗粒为:0.625≤伸长率≤0.999,0.567≤平整度≤0.995,0.475≤纵横度≤0.969,0.825≤椭球度≤0.957。这些规格保证了镇流器层的良好性能。此外，研究结果有助于理解循环加载条件下铁流变骨料的行为。
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