Applications, such as the long term in-situ monitoring of geotechnical structures and of agricult... more Applications, such as the long term in-situ monitoring of geotechnical structures and of agricultural soils, motivate the use of wireless sensors that are of a passive design. However, the effectiveness of such passive devices will be dependent on the power received via a forward interrogation link and the power returned to a data collector via a reverse link. For these applications, link losses will be determined by the transmission medium, i.e., soil. This paper presents a pathloss study of microwave attenuation versus soil type and moisture. Then, we present results for a passive frequency doubling reflectenna (FDR), operating at 1.3 GHz for the forward link and 2.6 GHz for the reverse, buried at various depths in agricultural soil of different moistures. Results indicate that a FDR-based wireless sensors operating in this frequency range could be effectively embedded to a depth of 0.5 m or more, significantly deeper than reported for other passive technologies.
This report presents an evaluation of the Standard Penetration Test (SPT) hammer energy delivered... more This report presents an evaluation of the Standard Penetration Test (SPT) hammer energy delivered to the SPT sampler during the performance of ASTM D1586, “Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils.” Delivered kinetic energy was measured from SPT hammers from the Vermont Agency of Transportation (VTrans) and companies that do work for the State of Vermont. The variability of the measurements was assessed and a summary of the energy transfer ratios are provided. This report also supplies some guidance on recommended frequency of SPT hammer energy measurement on VTrans equipment. Nine different SPT hammer configurations were tested in this study. Variables included hammer type, drill rod type, drill rig type, operator, drilling method, and soil gradation. This study attempted to isolate these variables in order to quantify the contribution of each variable on the measured SPT hammer energy. A number of variables (e.g., rod type, soil g...
This article describes the approach, methods, and findings of a quantitative analysis of the seis... more This article describes the approach, methods, and findings of a quantitative analysis of the seismic vulnerability in low-to-moderate seismic hazard regions of the Central and Eastern United States for system-wide assessment of typical multiple span bridges built in the 1950s through the 1960s. There is no national database on the status of seismic vulnerability of bridges, and thus no means to estimate the system-wide damage and retrofit costs for bridges. The study involved 380 nonlinear analyses using actual time-history records matched to four representative low-to-medium hazard target spectra corresponding with peak ground accelerations from approximately 0.06 to 0.3 g. Ground motions were obtained from soft and stiff site seismic classification locations and applied to models of four typical multiple-girder with concrete bent bridges. Multiple-girder bridges are the largest single category, comprising 55% of all multiple span bridges in the United States. Aging and deteriorati...
Applications, such as the long term in-situ monitoring of geotechnical structures and of agricult... more Applications, such as the long term in-situ monitoring of geotechnical structures and of agricultural soils, motivate the use of wireless sensors that are of a passive design. However, the effectiveness of such passive devices will be dependent on the power received via a forward interrogation link and the power returned to a data collector via a reverse link. For these applications, link losses will be determined by the transmission medium, i.e., soil. This paper presents a pathloss study of microwave attenuation versus soil type and moisture. Then, we present results for a passive frequency doubling reflectenna (FDR), operating at 1.3 GHz for the forward link and 2.6 GHz for the reverse, buried at various depths in agricultural soil of different moistures. Results indicate that a FDR-based wireless sensors operating in this frequency range could be effectively embedded to a depth of 0.5 m or more, significantly deeper than reported for other passive technologies.
Unpaved roads in Vermont are subject to deterioration from seasonal freezing and thawing, and man... more Unpaved roads in Vermont are subject to deterioration from seasonal freezing and thawing, and many towns have roads that suffer chronic serviceability problems during the so-called "spring thaw," or mud season. Several techniques thought to mitigate deterioration of unpaved roads during spring thaw were constructed on test sections of unpaved roads in two towns. Each potential remedy was aimed at providing some combination of limiting the availability of moisture in the winter, improving drainage during spring, and strengthening the upper portion of the road. Each technique used local and/or commercially available materials, and all were easy to construct, i.e., a town road crew could build them. For two spring thaw seasons, we compared strength estimates based on dynamic cone penetrometer tests and the percentage of the road surface rutted for treated and control sections. Methods that permanently improved the strength of the top 12 inches of the road or decreased the wat...
Service learning (SL) is a teaching and learning approach that couples service to a community par... more Service learning (SL) is a teaching and learning approach that couples service to a community partner with academic learning for students. Often the objectives of SL courses include academic or technical enhancement, civic engagement, and development of personal and interpersonal skills. A key component of SL is critical reflection, which is expected to help the students understand the significance of civic engagement as well as course contents. The civic engagement aspect of this educational approach aligns well with the service-oriented nature of the civil engineering profession. SL projects have been conducted in the Civil and Environmental Engineering Capstone Senior Design course at the University of Vermont since 2006. Students submit written semi-guided reflections on their experience at the conclusion of the course. The student reflections from 2011 through 2014 (n = 154 male and 61 female from a total of 50 different SL projects) were analyzed to assess if there is any difference in the attitude toward SL between male versus female students. The results of this analysis are presented here.
Service learning (SL) is an educational approach that couples service to a community partner with... more Service learning (SL) is an educational approach that couples service to a community partner with academic learning for students. Often SL goals include those related to academic or technical enhancement, civic engagement, and personal and interpersonal skills. The civic engagement aspect of this approach meshes well with the service-oriented nature of the civil engineering profession. This paper presents pedagogical aspects of SL, its benefits, and ideas on how it can be implemented within undergraduate engineering courses, specifically geotechnical engineering courses. Some examples of SL projects undertaken in a foundation engineering course and the civil and environmental senior capstone course at the University of Vermont are also presented.
Transportation Research Record: Journal of the Transportation Research Board, 2014
For cast-in-place abutments and retaining walls, structural backfill is preferred to be free-drai... more For cast-in-place abutments and retaining walls, structural backfill is preferred to be free-draining, which generally implies less than 5% fines content. This fines content is expected to eliminate the need to design for hydrostatic pressures. The availability of high-quality structural backfill with naturally low fines content is declining. This situation warrants an evaluation of whether granular backfill materials with greater than 5% fines content could be successfully used in practice. Flexible wall, hydraulic conductivity tests on a granular structural backfill with 0%, 5%, 10%, 15%, 20%, and 25% nonplastic fines content were conducted at 41, 83, and 124 kPa (6, 12, and 18 psi) confining pressures followed by consolidated drained triaxial compression tests for obtaining associated drained shear strength parameters of these gradations. The 15.2-cm (6-in.) diameter specimens were prepared at optimum moisture content and 95% of maximum standard Proctor density. To enable a compa...
Contamination on a construction site can lead to increased risk of unanticipated construction del... more Contamination on a construction site can lead to increased risk of unanticipated construction delays and increased costs. In response, some owners are opting for proactive approaches to handling contamination starting with the design stage. In many instances this involves preparing soil management plans as part of the construction bid documents. Thee Massachusetts Bay Transportation Authority's (MBTA's) Draw Number 7 Bridge Replacement project recently completed near Boston involved such planning to address contamination expected during excavation. Risks were allocated between the owner and contractor based on their source and the responsibility each entity had in managing those risks. This example illustrates key elements of that successfully executed contaminated soil management plan.
Applications, such as the long term in-situ monitoring of geotechnical structures and of agricult... more Applications, such as the long term in-situ monitoring of geotechnical structures and of agricultural soils, motivate the use of wireless sensors that are of a passive design. However, the effectiveness of such passive devices will be dependent on the power received via a forward interrogation link and the power returned to a data collector via a reverse link. For these applications, link losses will be determined by the transmission medium, i.e., soil. This paper presents a pathloss study of microwave attenuation versus soil type and moisture. Then, we present results for a passive frequency doubling reflectenna (FDR), operating at 1.3 GHz for the forward link and 2.6 GHz for the reverse, buried at various depths in agricultural soil of different moistures. Results indicate that a FDR-based wireless sensors operating in this frequency range could be effectively embedded to a depth of 0.5 m or more, significantly deeper than reported for other passive technologies.
This report presents an evaluation of the Standard Penetration Test (SPT) hammer energy delivered... more This report presents an evaluation of the Standard Penetration Test (SPT) hammer energy delivered to the SPT sampler during the performance of ASTM D1586, “Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils.” Delivered kinetic energy was measured from SPT hammers from the Vermont Agency of Transportation (VTrans) and companies that do work for the State of Vermont. The variability of the measurements was assessed and a summary of the energy transfer ratios are provided. This report also supplies some guidance on recommended frequency of SPT hammer energy measurement on VTrans equipment. Nine different SPT hammer configurations were tested in this study. Variables included hammer type, drill rod type, drill rig type, operator, drilling method, and soil gradation. This study attempted to isolate these variables in order to quantify the contribution of each variable on the measured SPT hammer energy. A number of variables (e.g., rod type, soil g...
This article describes the approach, methods, and findings of a quantitative analysis of the seis... more This article describes the approach, methods, and findings of a quantitative analysis of the seismic vulnerability in low-to-moderate seismic hazard regions of the Central and Eastern United States for system-wide assessment of typical multiple span bridges built in the 1950s through the 1960s. There is no national database on the status of seismic vulnerability of bridges, and thus no means to estimate the system-wide damage and retrofit costs for bridges. The study involved 380 nonlinear analyses using actual time-history records matched to four representative low-to-medium hazard target spectra corresponding with peak ground accelerations from approximately 0.06 to 0.3 g. Ground motions were obtained from soft and stiff site seismic classification locations and applied to models of four typical multiple-girder with concrete bent bridges. Multiple-girder bridges are the largest single category, comprising 55% of all multiple span bridges in the United States. Aging and deteriorati...
Applications, such as the long term in-situ monitoring of geotechnical structures and of agricult... more Applications, such as the long term in-situ monitoring of geotechnical structures and of agricultural soils, motivate the use of wireless sensors that are of a passive design. However, the effectiveness of such passive devices will be dependent on the power received via a forward interrogation link and the power returned to a data collector via a reverse link. For these applications, link losses will be determined by the transmission medium, i.e., soil. This paper presents a pathloss study of microwave attenuation versus soil type and moisture. Then, we present results for a passive frequency doubling reflectenna (FDR), operating at 1.3 GHz for the forward link and 2.6 GHz for the reverse, buried at various depths in agricultural soil of different moistures. Results indicate that a FDR-based wireless sensors operating in this frequency range could be effectively embedded to a depth of 0.5 m or more, significantly deeper than reported for other passive technologies.
Unpaved roads in Vermont are subject to deterioration from seasonal freezing and thawing, and man... more Unpaved roads in Vermont are subject to deterioration from seasonal freezing and thawing, and many towns have roads that suffer chronic serviceability problems during the so-called "spring thaw," or mud season. Several techniques thought to mitigate deterioration of unpaved roads during spring thaw were constructed on test sections of unpaved roads in two towns. Each potential remedy was aimed at providing some combination of limiting the availability of moisture in the winter, improving drainage during spring, and strengthening the upper portion of the road. Each technique used local and/or commercially available materials, and all were easy to construct, i.e., a town road crew could build them. For two spring thaw seasons, we compared strength estimates based on dynamic cone penetrometer tests and the percentage of the road surface rutted for treated and control sections. Methods that permanently improved the strength of the top 12 inches of the road or decreased the wat...
Service learning (SL) is a teaching and learning approach that couples service to a community par... more Service learning (SL) is a teaching and learning approach that couples service to a community partner with academic learning for students. Often the objectives of SL courses include academic or technical enhancement, civic engagement, and development of personal and interpersonal skills. A key component of SL is critical reflection, which is expected to help the students understand the significance of civic engagement as well as course contents. The civic engagement aspect of this educational approach aligns well with the service-oriented nature of the civil engineering profession. SL projects have been conducted in the Civil and Environmental Engineering Capstone Senior Design course at the University of Vermont since 2006. Students submit written semi-guided reflections on their experience at the conclusion of the course. The student reflections from 2011 through 2014 (n = 154 male and 61 female from a total of 50 different SL projects) were analyzed to assess if there is any difference in the attitude toward SL between male versus female students. The results of this analysis are presented here.
Service learning (SL) is an educational approach that couples service to a community partner with... more Service learning (SL) is an educational approach that couples service to a community partner with academic learning for students. Often SL goals include those related to academic or technical enhancement, civic engagement, and personal and interpersonal skills. The civic engagement aspect of this approach meshes well with the service-oriented nature of the civil engineering profession. This paper presents pedagogical aspects of SL, its benefits, and ideas on how it can be implemented within undergraduate engineering courses, specifically geotechnical engineering courses. Some examples of SL projects undertaken in a foundation engineering course and the civil and environmental senior capstone course at the University of Vermont are also presented.
Transportation Research Record: Journal of the Transportation Research Board, 2014
For cast-in-place abutments and retaining walls, structural backfill is preferred to be free-drai... more For cast-in-place abutments and retaining walls, structural backfill is preferred to be free-draining, which generally implies less than 5% fines content. This fines content is expected to eliminate the need to design for hydrostatic pressures. The availability of high-quality structural backfill with naturally low fines content is declining. This situation warrants an evaluation of whether granular backfill materials with greater than 5% fines content could be successfully used in practice. Flexible wall, hydraulic conductivity tests on a granular structural backfill with 0%, 5%, 10%, 15%, 20%, and 25% nonplastic fines content were conducted at 41, 83, and 124 kPa (6, 12, and 18 psi) confining pressures followed by consolidated drained triaxial compression tests for obtaining associated drained shear strength parameters of these gradations. The 15.2-cm (6-in.) diameter specimens were prepared at optimum moisture content and 95% of maximum standard Proctor density. To enable a compa...
Contamination on a construction site can lead to increased risk of unanticipated construction del... more Contamination on a construction site can lead to increased risk of unanticipated construction delays and increased costs. In response, some owners are opting for proactive approaches to handling contamination starting with the design stage. In many instances this involves preparing soil management plans as part of the construction bid documents. Thee Massachusetts Bay Transportation Authority's (MBTA's) Draw Number 7 Bridge Replacement project recently completed near Boston involved such planning to address contamination expected during excavation. Risks were allocated between the owner and contractor based on their source and the responsibility each entity had in managing those risks. This example illustrates key elements of that successfully executed contaminated soil management plan.
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