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Embodied energy and gas emissions of retaining wall structures / Toru Inui in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 10 (Octobre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 10 (Octobre 2011) . - pp. 958-967 Titre : Embodied energy and gas emissions of retaining wall structures Type de document : texte imprimé Auteurs : Toru Inui, Auteur ; Chris Chau, Auteur ; Kenichi Soga, Auteur Année de publication : 2012 Article en page(s) : pp. 958-967 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Retaining  walls  Embodied  energy  Gas  emissions  Highways  and  roads Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The embodied energy (EE) and gas emissions of four design alternatives for an embankment retaining wall system are analyzed for a hypothetical highway construction project. The airborne emissions considered are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulphur oxides (SOX), and nitrogen oxides (NOX). The process stages considered in this study are the initial materials production, transportation of construction machineries and materials, machinery operation during installation, and machinery depreciations. The objectives are (1) to determine whether there are statistically significant differences among the structural alternatives; (2) to understand the relative proportions of impacts for the process stages within each design; (3) to contextualize the impacts to other aspects in life by comparing the computed EE values to household energy consumption and car emission values; and (4) to examine the validity of the adopted EE as an environmental impact indicator through comparison with the amount of gas emissions. For the project considered in this study, the calculated results indicate that propped steel sheet pile wall and minipile wall systems have less embodied energy and gas emissions than cantilever steel tubular wall and secant concrete pile wall systems. The difference in CO2 emission for the retaining wall of 100 m length between the most and least environmentally preferable wall design is equivalent to an average 2.0 L family car being driven for 6.2 million miles (or 62 cars with a mileage of 10,000  miles/year for 10 years). The impacts in construction are generally notable and careful consideration and optimization of designs will reduce such impacts. The use of recycled steel or steel pile as reinforcement bar is effective in reducing the environmental impact. The embodied energy value of a given design is correlated to the amount of gas emissions. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i10/p958_s1?isAuthorized=no [article] Embodied energy and gas emissions of retaining wall structures [texte imprimé] / Toru Inui, Auteur ; Chris Chau, Auteur ; Kenichi Soga, Auteur . - 2012 . - pp. 958-967. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 10 (Octobre 2011) . - pp. 958-967 Mots-clés : Retaining  walls  Embodied  energy  Gas  emissions  Highways  and  roads Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The embodied energy (EE) and gas emissions of four design alternatives for an embankment retaining wall system are analyzed for a hypothetical highway construction project. The airborne emissions considered are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulphur oxides (SOX), and nitrogen oxides (NOX). The process stages considered in this study are the initial materials production, transportation of construction machineries and materials, machinery operation during installation, and machinery depreciations. The objectives are (1) to determine whether there are statistically significant differences among the structural alternatives; (2) to understand the relative proportions of impacts for the process stages within each design; (3) to contextualize the impacts to other aspects in life by comparing the computed EE values to household energy consumption and car emission values; and (4) to examine the validity of the adopted EE as an environmental impact indicator through comparison with the amount of gas emissions. For the project considered in this study, the calculated results indicate that propped steel sheet pile wall and minipile wall systems have less embodied energy and gas emissions than cantilever steel tubular wall and secant concrete pile wall systems. The difference in CO2 emission for the retaining wall of 100 m length between the most and least environmentally preferable wall design is equivalent to an average 2.0 L family car being driven for 6.2 million miles (or 62 cars with a mileage of 10,000  miles/year for 10 years). The impacts in construction are generally notable and careful consideration and optimization of designs will reduce such impacts. The use of recycled steel or steel pile as reinforcement bar is effective in reducing the environmental impact. The embodied energy value of a given design is correlated to the amount of gas emissions. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i10/p958_s1?isAuthorized=no

Factors affecting efficiency of microbially induced calcite precipitation / Ahmed Al Qabany in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 8 (Août 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 992–1001 Titre : Factors affecting efficiency of microbially induced calcite precipitation Type de document : texte imprimé Auteurs : Ahmed Al Qabany, Auteur ; Kenichi Soga, Auteur ; Carlos Santamarina, Auteur Année de publication : 2012 Article en page(s) : pp. 992–1001 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Ground  improvement  Soil  treatment  Chemical  treatment  Microbial  carbonate  precipitation  Scanning  electron  microscopy  Soil  properties Résumé : Microbially induced carbonate precipitation (MICP) using ureolytic bacteria shows promise in the field of geotechnical engineering for several different applications, such as ground improvement and groundwater control. This study examined optimal use and efficient control of Sporosarcina pasteurii to induce the precipitation of CaCO3 in open environments. Laboratory tests were conducted to investigate the effect of changing treatment factors, such as chemical concentrations, retention times, and effective input rates (mol/L/h) on chemical efficiency. Chemical efficiency was measured based on weight measurements of CaCO3 precipitation compared with the amount of chemical reactants injected to samples. Based on the experimental results, the optimal time required for the precipitation process to take place in porous media for a specific range of bacterial optical density was determined. Results show that, below a certain urea and CaCl2 input rate (0.042  mol/L/h) and for a bacterial optical density (OD600) between 0.8 and 1.2, the reaction efficiency remained high and the amount of precipitation was not affected by the liquid medium concentration (for input concentrations up to 1 M). However, the precipitation pattern at the pore scale was found to be affected by the injected concentration. Scanning electron microscopy images taken of different samples at different levels of cementation showed that, for the same amount of precipitation, the use of lower chemical concentrations in injections resulted in better distribution of calcite precipitation, especially at lower cementation levels. This variation in precipitation pattern is expected to affect the use of MICP for different applications. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000666 [article] Factors affecting efficiency of microbially induced calcite precipitation [texte imprimé] / Ahmed Al Qabany, Auteur ; Kenichi Soga, Auteur ; Carlos Santamarina, Auteur . - 2012 . - pp. 992–1001. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 992–1001 Mots-clés : Ground  improvement  Soil  treatment  Chemical  treatment  Microbial  carbonate  precipitation  Scanning  electron  microscopy  Soil  properties Résumé : Microbially induced carbonate precipitation (MICP) using ureolytic bacteria shows promise in the field of geotechnical engineering for several different applications, such as ground improvement and groundwater control. This study examined optimal use and efficient control of Sporosarcina pasteurii to induce the precipitation of CaCO3 in open environments. Laboratory tests were conducted to investigate the effect of changing treatment factors, such as chemical concentrations, retention times, and effective input rates (mol/L/h) on chemical efficiency. Chemical efficiency was measured based on weight measurements of CaCO3 precipitation compared with the amount of chemical reactants injected to samples. Based on the experimental results, the optimal time required for the precipitation process to take place in porous media for a specific range of bacterial optical density was determined. Results show that, below a certain urea and CaCl2 input rate (0.042  mol/L/h) and for a bacterial optical density (OD600) between 0.8 and 1.2, the reaction efficiency remained high and the amount of precipitation was not affected by the liquid medium concentration (for input concentrations up to 1 M). However, the precipitation pattern at the pore scale was found to be affected by the injected concentration. Scanning electron microscopy images taken of different samples at different levels of cementation showed that, for the same amount of precipitation, the use of lower chemical concentrations in injections resulted in better distribution of calcite precipitation, especially at lower cementation levels. This variation in precipitation pattern is expected to affect the use of MICP for different applications. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000666

Monitoring twin tunnel interaction using distributed optical fiber strain measurements / Hisham Mohamad in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 8 (Août 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 957–967 Titre : Monitoring twin tunnel interaction using distributed optical fiber strain measurements Type de document : texte imprimé Auteurs : Hisham Mohamad, Auteur ; Kenichi Soga, Auteur ; Peter J. Bennett, Auteur Année de publication : 2012 Article en page(s) : pp. 957–967 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Twin  tunnels  Instrumentation  Weathered  granites  TBM  Fiber  optics  BOTDR  Soil-structure  interactions  Deformation  Ground  settlement Résumé : In this field trial, a new monitoring technique using distributed strain sensing known as Brillouin optical time-domain reflectometry (BOTDR) was introduced to monitor the behavior of bolted-concrete linings of a recently completed tunnel when a second bored tunnel was constructed side by side at a distance less than one tunnel diameter apart. This was done by measuring circumferential strains in 12 rings using optical fiber that was installed using the point-fixing method. The strain distributions around the circumference of the rings show a generally similar profile. Maximum compressive strains measured below the tunnel springline nearest to the excavated tunnel were larger than the maximum tensile strains measured at the tunnel crown, distorting the circular tunnel into an oval/ellipsoid that was about symmetrical to the horizontal axis. Several methods were introduced to compare strain measurements made by BOTDR and diameter changes recorded by tape extensometer. This involves the use of a symmetrical tunnel distortion model and the basic differential equation for a circular arch. The calculated results showed some degree of similarity between the two methods. The analysis highlighted the importance of measuring the axial strain in the tunnel ring and subtracting the axial strain component to calculate the actual deflection of the lining as a result of bending. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000656 [article] Monitoring twin tunnel interaction using distributed optical fiber strain measurements [texte imprimé] / Hisham Mohamad, Auteur ; Kenichi Soga, Auteur ; Peter J. Bennett, Auteur . - 2012 . - pp. 957–967. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 957–967 Mots-clés : Twin  tunnels  Instrumentation  Weathered  granites  TBM  Fiber  optics  BOTDR  Soil-structure  interactions  Deformation  Ground  settlement Résumé : In this field trial, a new monitoring technique using distributed strain sensing known as Brillouin optical time-domain reflectometry (BOTDR) was introduced to monitor the behavior of bolted-concrete linings of a recently completed tunnel when a second bored tunnel was constructed side by side at a distance less than one tunnel diameter apart. This was done by measuring circumferential strains in 12 rings using optical fiber that was installed using the point-fixing method. The strain distributions around the circumference of the rings show a generally similar profile. Maximum compressive strains measured below the tunnel springline nearest to the excavated tunnel were larger than the maximum tensile strains measured at the tunnel crown, distorting the circular tunnel into an oval/ellipsoid that was about symmetrical to the horizontal axis. Several methods were introduced to compare strain measurements made by BOTDR and diameter changes recorded by tape extensometer. This involves the use of a symmetrical tunnel distortion model and the basic differential equation for a circular arch. The calculated results showed some degree of similarity between the two methods. The analysis highlighted the importance of measuring the axial strain in the tunnel ring and subtracting the axial strain component to calculate the actual deflection of the lining as a result of bending. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000656

Performance monitoring of a secant-piled wall using distributed fiber optic strain sensing / Hisham Mohamad in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1236-1243 Titre : Performance monitoring of a secant-piled wall using distributed fiber optic strain sensing Type de document : texte imprimé Auteurs : Hisham Mohamad, Auteur ; Kenichi Soga, Auteur ; Adam Pellew, Auteur Année de publication : 2012 Article en page(s) : pp. 1236-1243 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Monitoring  Retaining  wall  Excavation  BOTDR  Sensors  Inclinometer  Piles  Struts  Deformation Résumé : An optical fiber strain-sensing technique, on the basis of Brillouin optical time domain reflectometry (BOTDR), was used to monitor the performance of a secant pile wall subjected to multiple props during construction of an adjacent basement in London. Details of the installation of sensors and data processing are described. Distributed strain profiles were obtained by deriving strain measurements from optical fibers installed on opposite sides of the pile to allow monitoring of both axial and lateral movements along the pile. Methods for analyzing the thermal strain and temperature compensation are also presented. Measurements obtained from the BOTDR were found to be in good agreement with inclinometer data from the adjacent piles. The relative merits of the two different techniques are discussed. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1236_s1?isAuthorized=no [article] Performance monitoring of a secant-piled wall using distributed fiber optic strain sensing [texte imprimé] / Hisham Mohamad, Auteur ; Kenichi Soga, Auteur ; Adam Pellew, Auteur . - 2012 . - pp. 1236-1243. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1236-1243 Mots-clés : Monitoring  Retaining  wall  Excavation  BOTDR  Sensors  Inclinometer  Piles  Struts  Deformation Résumé : An optical fiber strain-sensing technique, on the basis of Brillouin optical time domain reflectometry (BOTDR), was used to monitor the performance of a secant pile wall subjected to multiple props during construction of an adjacent basement in London. Details of the installation of sensors and data processing are described. Distributed strain profiles were obtained by deriving strain measurements from optical fibers installed on opposite sides of the pile to allow monitoring of both axial and lateral movements along the pile. Methods for analyzing the thermal strain and temperature compensation are also presented. Measurements obtained from the BOTDR were found to be in good agreement with inclinometer data from the adjacent piles. The relative merits of the two different techniques are discussed. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1236_s1?isAuthorized=no