M. Almeida, M. Marques, Mario Riccio, D. Fagundes, Bruno Lima, Uberescilas Polido, Alessandro Cirone, Iman Hosseinpour
Soft ground improvement techniques have evolved substantially in Brazil in recent years. However, their application in soft and very soft clays requires a good understanding of the fundamentals of ground improvement techniques suited to the problem as well as the actual field behavior when implemented on a real scale. This paper describes some of the most widely used ground improvement techniques in the context of very soft clays in Brazil. The techniques described in the paper use prefabricated vertical drains (PVD) such as vacuum preloading; or combine PVD and rigid inclusion, such as CPR grouting; or are purely column-like elements such as piled embankments (including those executed with the deep mixing technique, DSM); or combine column-like elements with the drainage function, such as stone columns and geosynthetic encased columns; or use cementitious binders such as shallow soil mixing. The paper reference condition is a soft clay foundation in which no strengthening is implemented, such as, an embankment with basal reinforcement or soft clay with vertical prefabricated drains, or the use of vacuum preloading to speed up the consolidation rate. The applications of the ground improvement techniques are illustrated by case histories, numerical analyses, or physical models. Different types of measurements are used to evaluate the performance of each technique, including settlements, horizontal displacements, excess pore pressures, embankment applied stresses, stress concentration factors, and clay strength following the ground treatment. The settlement improvement factor β, the ratio between the settlements for untreated and treated conditions, is shown to be a suitable parameter to assess the degree of improvement imposed in the soft foundation by ranking the various methods in increased order of strengthening effect.
{"title":"Ground improvement techniques applied to very soft clays: state of knowledge and recent advances","authors":"M. Almeida, M. Marques, Mario Riccio, D. Fagundes, Bruno Lima, Uberescilas Polido, Alessandro Cirone, Iman Hosseinpour","doi":"10.28927/sr.2023.008222","DOIUrl":"https://doi.org/10.28927/sr.2023.008222","url":null,"abstract":"Soft ground improvement techniques have evolved substantially in Brazil in recent years. However, their application in soft and very soft clays requires a good understanding of the fundamentals of ground improvement techniques suited to the problem as well as the actual field behavior when implemented on a real scale. This paper describes some of the most widely used ground improvement techniques in the context of very soft clays in Brazil. The techniques described in the paper use prefabricated vertical drains (PVD) such as vacuum preloading; or combine PVD and rigid inclusion, such as CPR grouting; or are purely column-like elements such as piled embankments (including those executed with the deep mixing technique, DSM); or combine column-like elements with the drainage function, such as stone columns and geosynthetic encased columns; or use cementitious binders such as shallow soil mixing. The paper reference condition is a soft clay foundation in which no strengthening is implemented, such as, an embankment with basal reinforcement or soft clay with vertical prefabricated drains, or the use of vacuum preloading to speed up the consolidation rate. The applications of the ground improvement techniques are illustrated by case histories, numerical analyses, or physical models. Different types of measurements are used to evaluate the performance of each technique, including settlements, horizontal displacements, excess pore pressures, embankment applied stresses, stress concentration factors, and clay strength following the ground treatment. The settlement improvement factor β, the ratio between the settlements for untreated and treated conditions, is shown to be a suitable parameter to assess the degree of improvement imposed in the soft foundation by ranking the various methods in increased order of strengthening effect.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43104008","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 improvement of sandy soils by incorporating new stabilizing agents in a physical and/or chemical process has become the subject of many studies in recent decades. In addition, the use of industrial wastes in this process can bring significant benefits to the environment and savings in natural resources. This work aims to evaluate the implications of incorporating porcelain polishing waste (PPW) and hydrated lime on the mechanical properties of an aeolian dune sand from the city of Natal/RN. Tests of unconfined compressive strength and split tensile strength were performed on compacted soil specimens with different contents of PPW (10%, 20% and 30%), hydrated lime (3%, 5% and 7%) and relative densities (25%, 50% and 75%). To evaluate the effects of each factor, the Response Surface Methodology with Central Composite Design was used. The results have shown that all three factors have a positive effect on the response variables. The highest strengths were obtained in regions combining high values of relative density and PPW content and an optimum lime content was found. An inversely proportional correlation and good fit to the experimental data was obtained between the strength values and the porosity/binder index (η / Biv). The strength gains were attributed to densification of the soil structure and cementation of the particles by the compounds formed in the reaction between lime and PPW. The results also showed an increase in the strength with curing time, indicating a pozzolanic activity of the mixtures.
{"title":"Compressive and tensile strength of aeolian sand stabilized with porcelain polishing waste and hydrated lime","authors":"José Silva, Olavo F. dos Santos Júnior, W. Paiva","doi":"10.28927/sr.2023.002322","DOIUrl":"https://doi.org/10.28927/sr.2023.002322","url":null,"abstract":"The improvement of sandy soils by incorporating new stabilizing agents in a physical and/or chemical process has become the subject of many studies in recent decades. In addition, the use of industrial wastes in this process can bring significant benefits to the environment and savings in natural resources. This work aims to evaluate the implications of incorporating porcelain polishing waste (PPW) and hydrated lime on the mechanical properties of an aeolian dune sand from the city of Natal/RN. Tests of unconfined compressive strength and split tensile strength were performed on compacted soil specimens with different contents of PPW (10%, 20% and 30%), hydrated lime (3%, 5% and 7%) and relative densities (25%, 50% and 75%). To evaluate the effects of each factor, the Response Surface Methodology with Central Composite Design was used. The results have shown that all three factors have a positive effect on the response variables. The highest strengths were obtained in regions combining high values of relative density and PPW content and an optimum lime content was found. An inversely proportional correlation and good fit to the experimental data was obtained between the strength values and the porosity/binder index (η / Biv). The strength gains were attributed to densification of the soil structure and cementation of the particles by the compounds formed in the reaction between lime and PPW. The results also showed an increase in the strength with curing time, indicating a pozzolanic activity of the mixtures.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46434131","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}
K. Rammah, Mostafa Ismail, J. Costa, Mario Riccio Filho
Seismic tomography has been extensively used in geophysics for different purposes, including geological mapping, characterisation of inner earth structure and prospecting for oil and gas. In geophysics, seismic or electromagnetic waves are commonly used to provide tomographic information. In the geotechnical area, seismic tomography is emerging as a promising technique that can be used to determine the spatial variability of shear wave velocities and hence the small strain stiffness of geomaterials, especially when used in the centrifuge where in-situ stress conditions can be mimicked closely. This paper describes the development of a seismic tomography technique in the centrifuge. This technology can be used to image variations of soil stiffness under various mechanical, chemical and physical conditions. The paper describes the various components of the system, which includes arrays of small-size bender elements, hardware and software used to transmit, receive and acquire the shear wave signals during a centrifuge test. The paper illustrates the performance of the system at both 1g and in the centrifuge. Results of tomographic inversion performed on travel-time data obtained from these tests are discussed.
{"title":"A new seismic tomography system for geotechnical centrifuges","authors":"K. Rammah, Mostafa Ismail, J. Costa, Mario Riccio Filho","doi":"10.28927/sr.2023.000922","DOIUrl":"https://doi.org/10.28927/sr.2023.000922","url":null,"abstract":"Seismic tomography has been extensively used in geophysics for different purposes, including geological mapping, characterisation of inner earth structure and prospecting for oil and gas. In geophysics, seismic or electromagnetic waves are commonly used to provide tomographic information. In the geotechnical area, seismic tomography is emerging as a promising technique that can be used to determine the spatial variability of shear wave velocities and hence the small strain stiffness of geomaterials, especially when used in the centrifuge where in-situ stress conditions can be mimicked closely. This paper describes the development of a seismic tomography technique in the centrifuge. This technology can be used to image variations of soil stiffness under various mechanical, chemical and physical conditions. The paper describes the various components of the system, which includes arrays of small-size bender elements, hardware and software used to transmit, receive and acquire the shear wave signals during a centrifuge test. The paper illustrates the performance of the system at both 1g and in the centrifuge. Results of tomographic inversion performed on travel-time data obtained from these tests are discussed.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45023684","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. Jatoliya, Subhojit Saha, Bheem Pratap, Somenath Mondal, B. Rao
Negative traits of bauxite residue (BR) include low shear strength, inconsistent compaction characteristics and dispersion, render it unsuited geomaterial for engineering applications. The present study aims at stabilizing BR with the combination of lime (L) and graphene oxide (GO) in suitable proportions and investigating their impact on improvement in engineering properties (viz., density, unconfined compressive strength (UCS), dispersion, and durability). Lime of 2-10% and GO of 0.05-0.1% dosages (% weight of BR) are selected for experimentation purpose. Results demonstrate that L and GO together, not the individual additive, is effective to stabilize BR. A substantial improvement in UCS from 710 kPa of raw BR to 3890 kPa after treating with 10% L and 0.1% GO with 60 days curing period has been observed. 6% L and 0.05% GO for strength only in the short-term, and 10% L and 0.05% GO in durability aspect in the long-term are found as optimum dosages. Drastic decline in turbidity from 453 to 83 NTU establishes that L (6%) and GO (0.05%) addition completely alleviates dispersion behavior in BR. Though GO addition is trivial, its effect on strength and durability enhancement of BR is significant. Cementitious gel formations and bonding mechanism leading to particle aggregations are evidenced as the reason behind the improvement in strength and durability of BR. To verify the applicability of amended BR, the obtained findings are compared vis-à-vis with standards, which illustrated that the amended BR could be an excellent resource material in road construction, especially in base or sub-base courses.
{"title":"Assessment of bauxite residue stabilized with lime and graphene oxide as a geomaterial for road applications","authors":"A. Jatoliya, Subhojit Saha, Bheem Pratap, Somenath Mondal, B. Rao","doi":"10.28927/sr.2023.003722","DOIUrl":"https://doi.org/10.28927/sr.2023.003722","url":null,"abstract":"Negative traits of bauxite residue (BR) include low shear strength, inconsistent compaction characteristics and dispersion, render it unsuited geomaterial for engineering applications. The present study aims at stabilizing BR with the combination of lime (L) and graphene oxide (GO) in suitable proportions and investigating their impact on improvement in engineering properties (viz., density, unconfined compressive strength (UCS), dispersion, and durability). Lime of 2-10% and GO of 0.05-0.1% dosages (% weight of BR) are selected for experimentation purpose. Results demonstrate that L and GO together, not the individual additive, is effective to stabilize BR. A substantial improvement in UCS from 710 kPa of raw BR to 3890 kPa after treating with 10% L and 0.1% GO with 60 days curing period has been observed. 6% L and 0.05% GO for strength only in the short-term, and 10% L and 0.05% GO in durability aspect in the long-term are found as optimum dosages. Drastic decline in turbidity from 453 to 83 NTU establishes that L (6%) and GO (0.05%) addition completely alleviates dispersion behavior in BR. Though GO addition is trivial, its effect on strength and durability enhancement of BR is significant. Cementitious gel formations and bonding mechanism leading to particle aggregations are evidenced as the reason behind the improvement in strength and durability of BR. To verify the applicability of amended BR, the obtained findings are compared vis-à-vis with standards, which illustrated that the amended BR could be an excellent resource material in road construction, especially in base or sub-base courses.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43508334","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}
Manuella Morais, William Levandoski, Joice Reis, Francisco Rosa, E. Korf
The foundry industry generates large amounts of residual byproducts, such as waste foundry sand (WFS). This high generation has motivated studies concerning the disposition of WFS, which in turn can be used for road subbases. Nevertheless, paving applications are still limited, especially regarding the behavior of WFS when added to a mixture of crushed materials. Hence, the objective of this study was to evaluate WFS reuse in mixtures with crushed materials, applied as granular layers of granulometric stabilized pavements. The crushed materials and WFS were characterized by size distribution, physical aspects, and different mixtures, and later submitted to mechanical testing. Initial tests were utilized to define mixtures (crushed material + WFS) that fulfilled the technical requirements for road subbases. California bearing ratio and resilient modulus tests indicated that WFS additions up to 12% for “A” grading improved the bearing capacity of the mixture; while in “E” grading, WFS additions up to 38% resulted in no expressive improvement in bearing characteristics. Thus, for both gradings, a structure with high density, strength, and low susceptibility to deformations can be used for road subbase construction without technical issues. Finally, the highest WFS content (38%) mixture was environmentally classified as a Class II A non-inert waste, indicating its environmental viability for road applications.
{"title":"Environmental and technical feasibility of a waste foundry sand applied to pavement granular layers","authors":"Manuella Morais, William Levandoski, Joice Reis, Francisco Rosa, E. Korf","doi":"10.28927/sr.2023.001722","DOIUrl":"https://doi.org/10.28927/sr.2023.001722","url":null,"abstract":"The foundry industry generates large amounts of residual byproducts, such as waste foundry sand (WFS). This high generation has motivated studies concerning the disposition of WFS, which in turn can be used for road subbases. Nevertheless, paving applications are still limited, especially regarding the behavior of WFS when added to a mixture of crushed materials. Hence, the objective of this study was to evaluate WFS reuse in mixtures with crushed materials, applied as granular layers of granulometric stabilized pavements. The crushed materials and WFS were characterized by size distribution, physical aspects, and different mixtures, and later submitted to mechanical testing. Initial tests were utilized to define mixtures (crushed material + WFS) that fulfilled the technical requirements for road subbases. California bearing ratio and resilient modulus tests indicated that WFS additions up to 12% for “A” grading improved the bearing capacity of the mixture; while in “E” grading, WFS additions up to 38% resulted in no expressive improvement in bearing characteristics. Thus, for both gradings, a structure with high density, strength, and low susceptibility to deformations can be used for road subbase construction without technical issues. Finally, the highest WFS content (38%) mixture was environmentally classified as a Class II A non-inert waste, indicating its environmental viability for road applications.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41356342","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}
Rajendra Roka, António Figueiredo, Ana María Vieira, José Cardoso
Shallow geothermal energy systems (SGES) are being widely recognized throughout the world in the era of renewable energy promotion. The world is aiming to promote and implement the concept of nearly zero energy consumption in the building sector. Shallow geothermal energy systems have huge potential to meet the heating and cooling demand of a building with low carbon emissions. However, the shallow geothermal system exploration rate and its global contribution to renewable energy used in the buildings sector is yet relatively low. Therefore, this study explores specific barriers which hinder the promotion of shallow geothermal energy systems through a systematic review of the literature. The study was carried out by investigating published papers indexed in Scopus and Web of science core collection databases. The selected papers are focused on shallow geothermal energy systems and barriers to their promotion. Only review and research articles types were included in the analysis and constrained to the topic of closed-loop shallow geothermal energy systems. This system’s promotion has been influenced by the lack of legislation, little knowledge about the conductivity of soil and by high initial investment cost at its topmost. The least influencing barrier is considered to be the heating and cooling efficiency of shallow geothermal energy systems.
浅层地热能系统（SGES）在可再生能源推广的时代得到了全世界的广泛认可。世界的目标是在建筑行业推广和实施几乎零能源消耗的概念。浅层地热能系统具有巨大的潜力，可以满足低碳排放建筑的供暖和制冷需求。然而，浅层地热系统的勘探率及其对建筑行业可再生能源的全球贡献仍然相对较低。因此，本研究通过对文献的系统回顾，探讨了阻碍浅层地热能系统推广的具体障碍。这项研究是通过调查Scopus和Web of science核心收藏数据库中已发表的论文进行的。所选论文的重点是浅层地热能系统及其推广障碍。分析中只包括综述和研究文章类型，并仅限于闭环浅层地热能系统的主题。该系统的推广受到了缺乏立法、对土壤导电性知之甚少以及最高初始投资成本高的影响。影响最小的障碍被认为是浅层地热能系统的加热和冷却效率。
{"title":"A systematic review on shallow geothermal energy system: a light into six major barriers","authors":"Rajendra Roka, António Figueiredo, Ana María Vieira, José Cardoso","doi":"10.28927/sr.2023.007622","DOIUrl":"https://doi.org/10.28927/sr.2023.007622","url":null,"abstract":"Shallow geothermal energy systems (SGES) are being widely recognized throughout the world in the era of renewable energy promotion. The world is aiming to promote and implement the concept of nearly zero energy consumption in the building sector. Shallow geothermal energy systems have huge potential to meet the heating and cooling demand of a building with low carbon emissions. However, the shallow geothermal system exploration rate and its global contribution to renewable energy used in the buildings sector is yet relatively low. Therefore, this study explores specific barriers which hinder the promotion of shallow geothermal energy systems through a systematic review of the literature. The study was carried out by investigating published papers indexed in Scopus and Web of science core collection databases. The selected papers are focused on shallow geothermal energy systems and barriers to their promotion. Only review and research articles types were included in the analysis and constrained to the topic of closed-loop shallow geothermal energy systems. This system’s promotion has been influenced by the lack of legislation, little knowledge about the conductivity of soil and by high initial investment cost at its topmost. The least influencing barrier is considered to be the heating and cooling efficiency of shallow geothermal energy systems.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49366129","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}
Silvrano Adonias Dantas Neto, Matheus Albino, Ana Leite, A. Abreu
The purpose of this article is to present predictive models of dilation and shear stress of rock discontinuities by applying the neuro-fuzzy technique, which uses a) the high capacity of artificial neural networks (ANN) to understand and to model complex multivariate phenomena, and b) the concepts of fuzzy sets theory to consider the variability of the input parameters in the proposed models’ responses. To develop the proposed models, experimental results were obtained from large-scale direct shear tests performed on different types of rock discontinuities and boundary conditions. The input variables of the proposed neuro-fuzzy models are the normal boundary stiffness, the ratio of fill thickness to asperity height, the initial normal stress, the joint roughness coefficient, the uniaxial compressive strength of the intact rock, the basic friction angle of the intact rock, the friction angle of the infill, and the shear displacement. The proposed models for dilation and shear stress provided results that fitted satisfactorily the experimental data, and the analyses of their performances indicated that they can represent the influence of the input variables on the shear behavior parameters of the rock discontinuities. The results from the neuro-fuzzy systems developed are also closer to the experimental data than those estimated by using traditional analytical methodologies existing in Rock Mechanics. This occurs because once considering the uncertainty of the input data, a more representative shear behavior prediction can be made by the neuro-fuzzy models.
{"title":"Development of neuro-fuzzy models for predicting shear behavior of rock joints","authors":"Silvrano Adonias Dantas Neto, Matheus Albino, Ana Leite, A. Abreu","doi":"10.28927/sr.2022.003322","DOIUrl":"https://doi.org/10.28927/sr.2022.003322","url":null,"abstract":"The purpose of this article is to present predictive models of dilation and shear stress of rock discontinuities by applying the neuro-fuzzy technique, which uses a) the high capacity of artificial neural networks (ANN) to understand and to model complex multivariate phenomena, and b) the concepts of fuzzy sets theory to consider the variability of the input parameters in the proposed models’ responses. To develop the proposed models, experimental results were obtained from large-scale direct shear tests performed on different types of rock discontinuities and boundary conditions. The input variables of the proposed neuro-fuzzy models are the normal boundary stiffness, the ratio of fill thickness to asperity height, the initial normal stress, the joint roughness coefficient, the uniaxial compressive strength of the intact rock, the basic friction angle of the intact rock, the friction angle of the infill, and the shear displacement. The proposed models for dilation and shear stress provided results that fitted satisfactorily the experimental data, and the analyses of their performances indicated that they can represent the influence of the input variables on the shear behavior parameters of the rock discontinuities. The results from the neuro-fuzzy systems developed are also closer to the experimental data than those estimated by using traditional analytical methodologies existing in Rock Mechanics. This occurs because once considering the uncertainty of the input data, a more representative shear behavior prediction can be made by the neuro-fuzzy models.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48995475","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}
André Delmondes Filho, E. Cavalcante, Carlos Cardoso Júnior, Demóstenes Cavalcanti Júnior
This paper aims to analyze the behavior of a soil-nailed excavation located in Salvador, Bahia, Brazil. Numerical stress-strain modeling was conducted, using finite element method. The horizontal displacement profiles obtained for the wall face in the numerical analysis presented a good correlation compared to field instrumentation monitoring with inclinometers. The results showed that the magnitude of the maximum numerical and experimental displacements was lower than the simplified models recommended by international manuals and technical literature. However, the monitoring data was compatible with other cases of instrumented nailed excavations in silt-sandy soil in the city of Salvador. Numerical models also adequately represented the distribution of tensile forces in nails. The maximum tensile forces observed numerically were smaller than those calculated using analytical methods. It was emphasized that the results of field monitoring and numerical models correspond to a stage immediately after the end of the retaining structure execution, not considering the evolution of deformations in long term.
{"title":"Study of the behavior of an instrumented soil nail wall in Salvador-Brazil","authors":"André Delmondes Filho, E. Cavalcante, Carlos Cardoso Júnior, Demóstenes Cavalcanti Júnior","doi":"10.28927/sr.2022.076221","DOIUrl":"https://doi.org/10.28927/sr.2022.076221","url":null,"abstract":"This paper aims to analyze the behavior of a soil-nailed excavation located in Salvador, Bahia, Brazil. Numerical stress-strain modeling was conducted, using finite element method. The horizontal displacement profiles obtained for the wall face in the numerical analysis presented a good correlation compared to field instrumentation monitoring with inclinometers. The results showed that the magnitude of the maximum numerical and experimental displacements was lower than the simplified models recommended by international manuals and technical literature. However, the monitoring data was compatible with other cases of instrumented nailed excavations in silt-sandy soil in the city of Salvador. Numerical models also adequately represented the distribution of tensile forces in nails. The maximum tensile forces observed numerically were smaller than those calculated using analytical methods. It was emphasized that the results of field monitoring and numerical models correspond to a stage immediately after the end of the retaining structure execution, not considering the evolution of deformations in long term.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43048792","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}
Joaquim Castro Neto, P. Albuquerque, Yuri M. Barbosa, L. Fiscina
This work aims to analyze the behavior of a new post-grouted micropile setup developed in tropical soil. Its main innovation is the use of high mechanical resistance steel pipes (N80 class) for drilling and as a structural component of the micropiles. The pipes have special manchette valves uniformly spaced to allow neat cement grout injection into the soil. Two instrumented micropiles with 0.3 m diameter (after injection) and lengths of 19.4 m and 21 m were installed at Experimental Site III of the University of Campinas (Unicamp). The geological profile of this site presents a sandy clay surface layer (porous and collapsible) followed by a layer of sandy silt (diabase residual soil). The piles were subjected to compressive slow maintained loading tests and were instrumented along their depth with strain gages. No geotechnical failure was observed during the load test. The maximum load achieved by the MC1 and MC2 micropiles were 2.210 kN and 2.470 kN, respectively. The load test data were extrapolated to estimate the ultimate geotechnical pile capacity. The extrapolated geotechnical failure load was above 2.500 kN for both micropiles and similar to those estimated by the Federal Highway Administration FHWA (2005) load capacity method. It was verified that (1) the pile material undergoes creep under stress above 25 MPa on the transversal section of the pile and (2) the debonding effect during the loading process. The micropiles showed higher values of skin friction compared with other piles installed in the same geological-geotechnical context (tropical soil).
{"title":"Experimental study on the behavior of a new post-grouted micropile in a tropical soil","authors":"Joaquim Castro Neto, P. Albuquerque, Yuri M. Barbosa, L. Fiscina","doi":"10.28927/sr.2022.005322","DOIUrl":"https://doi.org/10.28927/sr.2022.005322","url":null,"abstract":"This work aims to analyze the behavior of a new post-grouted micropile setup developed in tropical soil. Its main innovation is the use of high mechanical resistance steel pipes (N80 class) for drilling and as a structural component of the micropiles. The pipes have special manchette valves uniformly spaced to allow neat cement grout injection into the soil. Two instrumented micropiles with 0.3 m diameter (after injection) and lengths of 19.4 m and 21 m were installed at Experimental Site III of the University of Campinas (Unicamp). The geological profile of this site presents a sandy clay surface layer (porous and collapsible) followed by a layer of sandy silt (diabase residual soil). The piles were subjected to compressive slow maintained loading tests and were instrumented along their depth with strain gages. No geotechnical failure was observed during the load test. The maximum load achieved by the MC1 and MC2 micropiles were 2.210 kN and 2.470 kN, respectively. The load test data were extrapolated to estimate the ultimate geotechnical pile capacity. The extrapolated geotechnical failure load was above 2.500 kN for both micropiles and similar to those estimated by the Federal Highway Administration FHWA (2005) load capacity method. It was verified that (1) the pile material undergoes creep under stress above 25 MPa on the transversal section of the pile and (2) the debonding effect during the loading process. The micropiles showed higher values of skin friction compared with other piles installed in the same geological-geotechnical context (tropical soil).","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48943769","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}
For predicting the size of rock fragments during drilling and blasting operations, this article uses GPR, RVM, and MPMR. The current analysis makes use of a blast data set generated in a prior investigation. In this study, a portion of the blast data was utilized to train a model to determine the mean particle size arising from blast fragmentation for each of the similarity groups generated. The particle size was modeled as a function of seven different variables. The dataset contains information about the bench height and drilled burden ratio (H / B), spacing to burden ratio (S / B), burden to hole diameter ratio (B / D), stemming to burden ratio (T / B), powder factor (Pf ), modulus of elasticity (E), and in-situ block size (XB) are the input and output is X50. By comparing forecasts with actual mean particle size values and predictions based on one of the most widely used fragmentation estimation techniques in the blasted literature, the capacity of the generated models may be established. The statistical parameters, actual vs predicted curve, Taylor diagram, error bar, and developed discrepancy ratio are used to analysis the performance of models. A comparative study has been carried out between the developed RVM, GPR, and MPMR. The results show the developed models have the capability for prediction of X50. From these comparisons, the MPMR has the highest value with a high degree of precision and robustness in the size of rock fragments X50.
{"title":"Determination of the size of rock fragments using RVM, GPR, and MPMR","authors":"Pradeep Thangavel, P. Samui","doi":"10.28927/sr.2022.008122","DOIUrl":"https://doi.org/10.28927/sr.2022.008122","url":null,"abstract":"For predicting the size of rock fragments during drilling and blasting operations, this article uses GPR, RVM, and MPMR. The current analysis makes use of a blast data set generated in a prior investigation. In this study, a portion of the blast data was utilized to train a model to determine the mean particle size arising from blast fragmentation for each of the similarity groups generated. The particle size was modeled as a function of seven different variables. The dataset contains information about the bench height and drilled burden ratio (H / B), spacing to burden ratio (S / B), burden to hole diameter ratio (B / D), stemming to burden ratio (T / B), powder factor (Pf ), modulus of elasticity (E), and in-situ block size (XB) are the input and output is X50. By comparing forecasts with actual mean particle size values and predictions based on one of the most widely used fragmentation estimation techniques in the blasted literature, the capacity of the generated models may be established. The statistical parameters, actual vs predicted curve, Taylor diagram, error bar, and developed discrepancy ratio are used to analysis the performance of models. A comparative study has been carried out between the developed RVM, GPR, and MPMR. The results show the developed models have the capability for prediction of X50. From these comparisons, the MPMR has the highest value with a high degree of precision and robustness in the size of rock fragments X50.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46645315","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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