E. Palmeira, José Melchior Filho, Ewerton C. A. Fonseca
The use of geosynthetic reinforcement in piled embankments over soft soils is an effective solution for the reduction of settlements and to increase the embankment stability. The most efficient position for the reinforcement layer is on the pile cap or head. However, a direct contact of the reinforcement with sharp edges may damage it, compromising its efficiency to transfer loads to the piles. This paper investigates the possibility of mechanical damages in geosynthetic reinforcements on pile caps by large scale laboratory tests. Tests with and without pieces of nonwoven geotextile protective layer between the caps and the reinforcements were executed. Wide strip tensile tests were performed on exhumed reinforcement specimens after the tests to assess tensile strength and stiffness variations. A statistical analysis of the results shows reductions in tensile strength of unprotected reinforcement layers of up to 28%. A mechanical damage index is introduced and its correlation with calculated reduction factors is investigated. The use of a piece of a thick geotextile layer to protect the reinforcement against mechanical damage can be effective. However, the geotextile product must be properly specified and installed with due care.
{"title":"An evaluation of reinforcement mechanical damages in geosynthetic reinforced piled embankments","authors":"E. Palmeira, José Melchior Filho, Ewerton C. A. Fonseca","doi":"10.28927/sr.2022.000522","DOIUrl":"https://doi.org/10.28927/sr.2022.000522","url":null,"abstract":"The use of geosynthetic reinforcement in piled embankments over soft soils is an effective solution for the reduction of settlements and to increase the embankment stability. The most efficient position for the reinforcement layer is on the pile cap or head. However, a direct contact of the reinforcement with sharp edges may damage it, compromising its efficiency to transfer loads to the piles. This paper investigates the possibility of mechanical damages in geosynthetic reinforcements on pile caps by large scale laboratory tests. Tests with and without pieces of nonwoven geotextile protective layer between the caps and the reinforcements were executed. Wide strip tensile tests were performed on exhumed reinforcement specimens after the tests to assess tensile strength and stiffness variations. A statistical analysis of the results shows reductions in tensile strength of unprotected reinforcement layers of up to 28%. A mechanical damage index is introduced and its correlation with calculated reduction factors is investigated. The use of a piece of a thick geotextile layer to protect the reinforcement against mechanical damage can be effective. However, the geotextile product must be properly specified and installed with due care.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44352166","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}
In the design of piles partially embedded in rock, the main factors that influence the strength and deformability of the rock and the transmission of loads from pile to rock are of utmost relevance to pile behavior. Most empirical methods were developed based on data from specific regions. Differences in geological conditions, drilling methods and other features are not considered in most procedures. The article deals with a case of piles partially embedded in rock located in the town of São Lourenço da Mata, Pernambuco, Brazil. The rock mass consists of ancient deposits, formed mainly by granites of different compositions, gneiss and schists. The deposits have been deformed by several tectonic processes. Results from 99 dynamic loading tests enabled comparison between the mobilized lateral and pile toe resistance, with the estimated capacity obtained from the design methods known in the literature. In the prediction, the lateral shear resistance due to pile penetration in residual soil was also considered. Because failure was not reached in the dynamic tests, the estimated capacity was higher than the mobilized resistance. The resistances mobilized by the pile shaft friction in soil, by the pile shaft friction in rock and by the mobilized toe resistance in rock in the dynamic loading tests are compared to design methods known in the literature. Five static loading tests indicated failure loads greater than the mobilized resistance in the dynamic methods. The comparisons allow recommendations of the most consistent design methods to use in similar cases in practice.
在部分嵌入岩石中的桩的设计中，影响岩石强度和变形能力以及荷载从桩向岩石传递的主要因素与桩的性能密切相关。大多数实证方法都是根据特定地区的数据制定的。大多数程序都没有考虑地质条件、钻探方法和其他特征的差异。本文介绍了位于巴西伯南布哥州São Lourenço da Mata镇的一个部分嵌入岩石的桩的案例。岩体由古代矿床组成，主要由不同成分的花岗岩、片麻岩和片岩形成。矿床经过多次构造作用而变形。99次动载试验的结果使动员的侧向阻力和桩趾阻力能够与文献中已知的设计方法获得的估计承载力进行比较。在预测中，还考虑了桩在残积土中渗透产生的侧向剪切阻力。由于在动态试验中未达到失效，因此估计的承载力高于动员的阻力。将动载试验中桩身在土壤中的摩擦力、桩身在岩石中的摩擦力和桩脚在岩石中移动的阻力与文献中已知的设计方法进行了比较。五次静态载荷试验表明，破坏载荷大于动态方法中的动员阻力。这些比较允许在实践中的类似情况下使用最一致的设计方法的建议。
{"title":"A case study of bearing capacity of piles partially embedded in rock","authors":"Marília Silva, R. Coutinho, B. Danziger","doi":"10.28927/sr.2022.075521","DOIUrl":"https://doi.org/10.28927/sr.2022.075521","url":null,"abstract":"In the design of piles partially embedded in rock, the main factors that influence the strength and deformability of the rock and the transmission of loads from pile to rock are of utmost relevance to pile behavior. Most empirical methods were developed based on data from specific regions. Differences in geological conditions, drilling methods and other features are not considered in most procedures. The article deals with a case of piles partially embedded in rock located in the town of São Lourenço da Mata, Pernambuco, Brazil. The rock mass consists of ancient deposits, formed mainly by granites of different compositions, gneiss and schists. The deposits have been deformed by several tectonic processes. Results from 99 dynamic loading tests enabled comparison between the mobilized lateral and pile toe resistance, with the estimated capacity obtained from the design methods known in the literature. In the prediction, the lateral shear resistance due to pile penetration in residual soil was also considered. Because failure was not reached in the dynamic tests, the estimated capacity was higher than the mobilized resistance. The resistances mobilized by the pile shaft friction in soil, by the pile shaft friction in rock and by the mobilized toe resistance in rock in the dynamic loading tests are compared to design methods known in the literature. Five static loading tests indicated failure loads greater than the mobilized resistance in the dynamic methods. The comparisons allow recommendations of the most consistent design methods to use in similar cases in practice.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42518994","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}
Bosco Álvarez, Hernández Palma, D. Besenzon, X. Vera-Grunauer, S. Amoroso
According to previously available research and seismic microzonation studies a large area of the Guayaquil (Ecuador, South America) sits on estuarine deltaic deposits which consist of weak and highly compressible clays with diatoms. The nature of these fine-grained deposits may determine difficulties in a proper estimation of the soil properties. In this respect, the paper provides a detailed geotechnical and geophysical characterization of these soft clays, carried out in the estuarine complex of the Ecuadorean city. Borehole logs, standard penetration tests (SPT), piezocone tests (CPTu), a seismic dilatometer test (SDMT), a non-invasive geophysical survey, and laboratory tests were performed and then compared to analyze the static and dynamic geotechnical parameters of these deposits. The interpretation of the results highlighted the higher reliability of CPTu and SDMT rather than SPT and characterization lab testing to estimate soil shear strength, compressibility and stress history due to the soft nature of these clays, underlining also a certain sensitivity to the presence of the diatoms.
{"title":"Geotechnical characterization of the estuarine deltaic deposits in the Guayaquil city through in situ and laboratory tests","authors":"Bosco Álvarez, Hernández Palma, D. Besenzon, X. Vera-Grunauer, S. Amoroso","doi":"10.28927/sr.2022.074021","DOIUrl":"https://doi.org/10.28927/sr.2022.074021","url":null,"abstract":"According to previously available research and seismic microzonation studies a large area of the Guayaquil (Ecuador, South America) sits on estuarine deltaic deposits which consist of weak and highly compressible clays with diatoms. The nature of these fine-grained deposits may determine difficulties in a proper estimation of the soil properties. In this respect, the paper provides a detailed geotechnical and geophysical characterization of these soft clays, carried out in the estuarine complex of the Ecuadorean city. Borehole logs, standard penetration tests (SPT), piezocone tests (CPTu), a seismic dilatometer test (SDMT), a non-invasive geophysical survey, and laboratory tests were performed and then compared to analyze the static and dynamic geotechnical parameters of these deposits. The interpretation of the results highlighted the higher reliability of CPTu and SDMT rather than SPT and characterization lab testing to estimate soil shear strength, compressibility and stress history due to the soft nature of these clays, underlining also a certain sensitivity to the presence of the diatoms.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42658180","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}
Although embankments on soft soils with prefabricated vertical drains (PVDs) under vacuum preloading have been widely studied, there is a lack of studies in the literature in which overall stability is analysed through three-dimensional (3D) mechanical-hydraulic coupled modelling. In order to contribute to overcome such deficiency, this paper presents 3D numerical analyses of an embankment on soft soils incorporating PVDs and vacuum preloading. A finite element code, which includes 3D fully coupled analysis, is used and a method for overall stability study – which uses the 3D numerical results obtained with the finite element code – is presented and applied. A parametric study is performed in order to analyse the influence of the magnitude of the vacuum preload and the staged construction of the embankment (time of vacuum application before completion of the embankment). Overall stability, excess pore pressures, settlements, horizontal displacements and stress levels are analysed.
{"title":"Vacuum preloading and PVDs in soft soils beneath embankments: 3D coupled analysis incorporating overall stability study","authors":"J. Borges","doi":"10.28927/sr.2022.072821","DOIUrl":"https://doi.org/10.28927/sr.2022.072821","url":null,"abstract":"Although embankments on soft soils with prefabricated vertical drains (PVDs) under vacuum preloading have been widely studied, there is a lack of studies in the literature in which overall stability is analysed through three-dimensional (3D) mechanical-hydraulic coupled modelling. In order to contribute to overcome such deficiency, this paper presents 3D numerical analyses of an embankment on soft soils incorporating PVDs and vacuum preloading. A finite element code, which includes 3D fully coupled analysis, is used and a method for overall stability study – which uses the 3D numerical results obtained with the finite element code – is presented and applied. A parametric study is performed in order to analyse the influence of the magnitude of the vacuum preload and the staged construction of the embankment (time of vacuum application before completion of the embankment). Overall stability, excess pore pressures, settlements, horizontal displacements and stress levels are analysed.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42242565","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}
Eliu Carbaja, Mariana Diniz, R. Rodríguez-Pacheco, A. Cavalcante
Mining is an important economic activity in the modern world. However, despite the generated benefits, mining produces tremendous volumes of tailings, an environmental liability with numerous adverse effects. Researches about contaminant transport in tailings dam are important to assess the degree of contamination and to propose preventive or remedial measures. In geotechnical practice, the flow of solutes is generally characterized by numerical solution of the Richards equation to describe water movement followed by advection-dispersion equation to describe contaminant movement. This study aimed to model and simulate contaminant transport in a laboratory column test, using a new analytical formulation and mathematical codes, through tailings in transient unsaturated conditions. The analytical solution for the Richards equation was used to simulate the variation in the volumetric water content and to determine the transient contaminant plume using the advection-dispersion equation subsequently. The models were used to calibrate experimental data from hydraulic characterization and contamination tests. Finally, the normalized contaminant plume (cw/c0) was simulated as a function of time and space. Comparisons with experimental data showed that the analytical formulations adequately expressed the process of contaminant infiltration through the unsaturated porous medium. The formulations offered effectively and are configured as a new approach to solve various contamination problems in transient unsaturated conditions, providing insights into many complex processes that occur in the lab tests and requires far less computational effort compared with current programs to modeling the solute transport using numerical solutions, as the versatile commercial Software HYDRUS.
{"title":"Contaminant transport model in transient and unsaturated conditions applied to laboratory column test with tailings","authors":"Eliu Carbaja, Mariana Diniz, R. Rodríguez-Pacheco, A. Cavalcante","doi":"10.28927/sr.2022.076021","DOIUrl":"https://doi.org/10.28927/sr.2022.076021","url":null,"abstract":"Mining is an important economic activity in the modern world. However, despite the generated benefits, mining produces tremendous volumes of tailings, an environmental liability with numerous adverse effects. Researches about contaminant transport in tailings dam are important to assess the degree of contamination and to propose preventive or remedial measures. In geotechnical practice, the flow of solutes is generally characterized by numerical solution of the Richards equation to describe water movement followed by advection-dispersion equation to describe contaminant movement. This study aimed to model and simulate contaminant transport in a laboratory column test, using a new analytical formulation and mathematical codes, through tailings in transient unsaturated conditions. The analytical solution for the Richards equation was used to simulate the variation in the volumetric water content and to determine the transient contaminant plume using the advection-dispersion equation subsequently. The models were used to calibrate experimental data from hydraulic characterization and contamination tests. Finally, the normalized contaminant plume (cw/c0) was simulated as a function of time and space. Comparisons with experimental data showed that the analytical formulations adequately expressed the process of contaminant infiltration through the unsaturated porous medium. The formulations offered effectively and are configured as a new approach to solve various contamination problems in transient unsaturated conditions, providing insights into many complex processes that occur in the lab tests and requires far less computational effort compared with current programs to modeling the solute transport using numerical solutions, as the versatile commercial Software HYDRUS.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47912570","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}
Sayed Alipoori, G. Lashkaripour, M. Ghafoori, N. Moghadas
This paper deals with engineering geological properties of Qadis Khordak dam site in Northwest Afghanistan. This study is based on on-site and laboratory tests, surface discontinuity surveying, drilled borehole and permeability test of dam foundation. The engineering geological properties at the dam site were studied in order to evaluate geotechnical characteristics of rock masses at dam foundation, geotechnical properties of alluvium at dam axis, reservoir and borrow materials. The structural geological studies also carried out due to stability and safety of dam on their abutments reservoir and seismicity. Existence of a fault, high permeable zone at dam foundation and the thickness of alluvium at dam axis, are the most engineering geological issues that cause change on dam type selection. In the feasibility phase, the dam type was chosen as the concrete face rock-fill dam, because of state of engineering geological properties of dam site. However, in the design phase dam type has been changed as a rock-fill with a clay core.
{"title":"Effect of engineering geological properties on dam type selection of the Qadis Khordak Dam, Afghanistan","authors":"Sayed Alipoori, G. Lashkaripour, M. Ghafoori, N. Moghadas","doi":"10.28927/sr.2022.070621","DOIUrl":"https://doi.org/10.28927/sr.2022.070621","url":null,"abstract":"This paper deals with engineering geological properties of Qadis Khordak dam site in Northwest Afghanistan. This study is based on on-site and laboratory tests, surface discontinuity surveying, drilled borehole and permeability test of dam foundation. The engineering geological properties at the dam site were studied in order to evaluate geotechnical characteristics of rock masses at dam foundation, geotechnical properties of alluvium at dam axis, reservoir and borrow materials. The structural geological studies also carried out due to stability and safety of dam on their abutments reservoir and seismicity. Existence of a fault, high permeable zone at dam foundation and the thickness of alluvium at dam axis, are the most engineering geological issues that cause change on dam type selection. In the feasibility phase, the dam type was chosen as the concrete face rock-fill dam, because of state of engineering geological properties of dam site. However, in the design phase dam type has been changed as a rock-fill with a clay core.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49412967","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}
Thiago Barreto, L. Repsold, N. G. Souza e Silva, M. Casagrande
Butadiene-styrene copolymer (SBR) is an elastomer composed of 75% butadiene and 25% styrene and is widely used in the automotive industry in tire production. This elastomer can be produced from two polymerization processes: emulsion or solution polymerization. This paper presents the mechanical behavior of a polymer reinforced sand compared to pure sand. Direct shear tests were performed on pure sand specimens and with the addition of modified styrene butadiene-styrene copolymer (XSBR). The polymeric sand specimens had 10% moisture content, 50% relative density, with water-polymer mass ratios of 1:1, 1:2, and 1:4, with no curing time, or with curing times 48, 72, 96, 576, and 720 h. Improvements were verified in the strength parameters of sand specimens with polymer addition, while comparing with pure sand parameters, showing that the improvement of soils with polymers is satisfactory for application in geotechnical works, such as: embankments in soft soils, soils for shallow foundations and for slope stability.
{"title":"Influence of addition of butadiene copolymer and modified styrene on the mechanical behavior of a sand","authors":"Thiago Barreto, L. Repsold, N. G. Souza e Silva, M. Casagrande","doi":"10.28927/sr.2022.074521","DOIUrl":"https://doi.org/10.28927/sr.2022.074521","url":null,"abstract":"Butadiene-styrene copolymer (SBR) is an elastomer composed of 75% butadiene and 25% styrene and is widely used in the automotive industry in tire production. This elastomer can be produced from two polymerization processes: emulsion or solution polymerization. This paper presents the mechanical behavior of a polymer reinforced sand compared to pure sand. Direct shear tests were performed on pure sand specimens and with the addition of modified styrene butadiene-styrene copolymer (XSBR). The polymeric sand specimens had 10% moisture content, 50% relative density, with water-polymer mass ratios of 1:1, 1:2, and 1:4, with no curing time, or with curing times 48, 72, 96, 576, and 720 h. Improvements were verified in the strength parameters of sand specimens with polymer addition, while comparing with pure sand parameters, showing that the improvement of soils with polymers is satisfactory for application in geotechnical works, such as: embankments in soft soils, soils for shallow foundations and for slope stability.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47660453","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}
J. P. Silva, P. Cacciari, V. Torres, L. F. Ribeiro, A. Assis
Understanding the geotechnical properties of iron ore tailings is currently one of the major challenges in the mining industry. With transitions from drained to undrained conditions occurring in seconds, recent dam problems have been a challenge to solve with classical soil mechanics, which provides few means to explain how such phenomena develop. There is also an increasing propensity in technical and scientific circles to seek constitutive models that are based on critical state soil mechanics and that allow for the analysis of tailings behaviour. However, there is still a lack of knowledge and information about the critical state properties of iron ore tailings. The present research experimentally and numerically investigated the effectiveness of modelling the behaviour of iron ore tailings. The aim of these experiments was to assess the critical state parameters of tailings from a significant iron ore operation site in Quadrilátero Ferrífero (Minas Gerais state, Brazil). The results indicated that the selected numerical model (NorSand) was adequate to evaluate the behaviour of the studied mine tailings. The numerical results showed consistent adherence to the experimental results of both drained and undrained tests, with deformations below 5% and samples in which the state parameter had a small magnitude.
{"title":"Behavioural analysis of iron ore tailings through critical state soil mechanics","authors":"J. P. Silva, P. Cacciari, V. Torres, L. F. Ribeiro, A. Assis","doi":"10.28927/sr.2022.071921","DOIUrl":"https://doi.org/10.28927/sr.2022.071921","url":null,"abstract":"Understanding the geotechnical properties of iron ore tailings is currently one of the major challenges in the mining industry. With transitions from drained to undrained conditions occurring in seconds, recent dam problems have been a challenge to solve with classical soil mechanics, which provides few means to explain how such phenomena develop. There is also an increasing propensity in technical and scientific circles to seek constitutive models that are based on critical state soil mechanics and that allow for the analysis of tailings behaviour. However, there is still a lack of knowledge and information about the critical state properties of iron ore tailings. The present research experimentally and numerically investigated the effectiveness of modelling the behaviour of iron ore tailings. The aim of these experiments was to assess the critical state parameters of tailings from a significant iron ore operation site in Quadrilátero Ferrífero (Minas Gerais state, Brazil). The results indicated that the selected numerical model (NorSand) was adequate to evaluate the behaviour of the studied mine tailings. The numerical results showed consistent adherence to the experimental results of both drained and undrained tests, with deformations below 5% and samples in which the state parameter had a small magnitude.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44720301","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}
Dionatas Andreghetto, L. Festugato, G. Miguel, Andressa Silva
Soil mechanical fully understanding requires considering a three dimensional approach, including soil response under the second principal stress and its potential anisotropy. In order to achieve such soil mechanical understanding, a true triaxial apparatus might be used. Therefore, in the present research an automated true triaxial apparatus was developed comprising its cubical cell, data acquisition and stress control systems. The manufactured apparatus was validated by means a laboratory test campaign where true triaxial test responses were compared to standard drained triaxial tests. True triaxial and standard drained triaxial tests were carried out on both naturally and artificially cemented soils. Results were gathered and compared. A soil mechanical compatibility was observed when test results of the newest true triaxial equipment were compared to test results obtained from a well validated standard triaxial apparatus. Thereby, the present paper reports an affordable successful true triaxial apparatus development demonstrating its efficiency for regular soil mechanical tests. Finally, a full stress rosette was established for a uniform fine sand where some small anisotropy was detected.
{"title":"Automated true triaxial apparatus development for soil mechanics investigation","authors":"Dionatas Andreghetto, L. Festugato, G. Miguel, Andressa Silva","doi":"10.28927/sr.2022.077321","DOIUrl":"https://doi.org/10.28927/sr.2022.077321","url":null,"abstract":"Soil mechanical fully understanding requires considering a three dimensional approach, including soil response under the second principal stress and its potential anisotropy. In order to achieve such soil mechanical understanding, a true triaxial apparatus might be used. Therefore, in the present research an automated true triaxial apparatus was developed comprising its cubical cell, data acquisition and stress control systems. The manufactured apparatus was validated by means a laboratory test campaign where true triaxial test responses were compared to standard drained triaxial tests. True triaxial and standard drained triaxial tests were carried out on both naturally and artificially cemented soils. Results were gathered and compared. A soil mechanical compatibility was observed when test results of the newest true triaxial equipment were compared to test results obtained from a well validated standard triaxial apparatus. Thereby, the present paper reports an affordable successful true triaxial apparatus development demonstrating its efficiency for regular soil mechanical tests. Finally, a full stress rosette was established for a uniform fine sand where some small anisotropy was detected.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47931862","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}
A. Viana da Fonseca, D. Cordeiro, F. Molina-Gómez, D. Besenzon, A. Fonseca, C. Ferreira
Dam B1 was approximately 85 m high and 700 m long along the crown when it suddenly failed in 25th of January, after 41 years of operations and deposition of tailings at the Paraopeba mining complex (Côrrego de Feijão), in Minas Gerais, Brazil. More than 250 people died and vast economic, social and environmental damages resulted from the collapse. Given the need to geotechnically characterise the tailings within the dam for a credible computational model of the failure, an extensive sampling and laboratory testing campaign took place. The geotechnical laboratory of the Civil Engineering Department at the Faculty of Engineering of the University of Porto (Portugal) was invited by CIMNE, under a contract with VALE, with MPF agreement, to conduct this program. This paper will present a description of the sampling campaigns in the remaining post-mortem dam/reservoir tailings were the failure instability mechanics developed and the experimental program undertaken to test the tailings in advanced laboratory tests. The results that embrace evaluations of the physical, hydraulic and mechanical properties, deduced from integral samples selectively collected and prepared as described, which allowed to define the geotechnical parameters necessary for the referred analyses are here resumed.
在巴西米纳斯吉拉斯的Paraopeba采矿综合体（Côrrego de Feijão）进行了41年的运营和尾矿沉积后，B1大坝于1月25日突然溃坝，大坝高约85米，沿坝顶长约700米。坍塌造成250多人死亡，巨大的经济、社会和环境损失。鉴于需要对大坝内的尾矿进行岩土工程表征，以建立可靠的失效计算模型，因此开展了广泛的采样和实验室测试活动。根据与VALE签订的合同和MPF协议，CIMNE邀请葡萄牙波尔图大学工程学院土木工程系的岩土工程实验室开展该项目。本文将介绍剩余死后大坝/水库尾矿的取样活动，包括开发的破坏不稳定力学和在高级实验室测试中测试尾矿的实验程序。根据所述选择性收集和制备的整体样本推断出的物理、水力和机械性能评估结果，允许定义所述分析所需的岩土参数。
{"title":"The mechanics of iron tailings from laboratory tests on reconstituted samples collected in post-mortem Dam I in Brumadinho","authors":"A. Viana da Fonseca, D. Cordeiro, F. Molina-Gómez, D. Besenzon, A. Fonseca, C. Ferreira","doi":"10.28927/sr.2022.001122","DOIUrl":"https://doi.org/10.28927/sr.2022.001122","url":null,"abstract":"Dam B1 was approximately 85 m high and 700 m long along the crown when it suddenly failed in 25th of January, after 41 years of operations and deposition of tailings at the Paraopeba mining complex (Côrrego de Feijão), in Minas Gerais, Brazil. More than 250 people died and vast economic, social and environmental damages resulted from the collapse. Given the need to geotechnically characterise the tailings within the dam for a credible computational model of the failure, an extensive sampling and laboratory testing campaign took place. The geotechnical laboratory of the Civil Engineering Department at the Faculty of Engineering of the University of Porto (Portugal) was invited by CIMNE, under a contract with VALE, with MPF agreement, to conduct this program. This paper will present a description of the sampling campaigns in the remaining post-mortem dam/reservoir tailings were the failure instability mechanics developed and the experimental program undertaken to test the tailings in advanced laboratory tests. The results that embrace evaluations of the physical, hydraulic and mechanical properties, deduced from integral samples selectively collected and prepared as described, which allowed to define the geotechnical parameters necessary for the referred analyses are here resumed.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45351263","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}
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