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Title: Stability Analysis of Geosynthetic Reinforced MSW Landfill Slopes Considering Effects of Biodegradation and Extreme Wind Loading.
Creator: Pant, Sharmila, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: A numerical investigation was conducted to evaluate the geotechnical safety and slope stability of Municipal Solid Waste (MSW) landfills, considering the effects of geosynthetic reinforcements, biodegradation of the waste, and associated changes in material properties, and extreme wind force simulating hurricane conditions. Three different landfill slopes, 1:1, 1:2, and 1:3 having the height of 122m and width of 2134m, were analyzed using Limit Equilibrium Method (SLOPE/W) and Finite Element...
Show moreA numerical investigation was conducted to evaluate the geotechnical safety and slope stability of Municipal Solid Waste (MSW) landfills, considering the effects of geosynthetic reinforcements, biodegradation of the waste, and associated changes in material properties, and extreme wind force simulating hurricane conditions. Three different landfill slopes, 1:1, 1:2, and 1:3 having the height of 122m and width of 2134m, were analyzed using Limit Equilibrium Method (SLOPE/W) and Finite Element Modeling (ANSYS). Techniques developed in this study were used to analyze a case history involving a geogrid reinforced mixed landfill expansion located in Austria. It was found that few years after construction of the landfill, there is a significant decrease in the FS due to biodegradation. Extreme wind loading was also found to cause a substantial loss in the FS. The geosynthetic reinforcement increased the slope stability and approximately compensated for the damaging effects of biodegradation and wind loading.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004707, http://purl.flvc.org/fau/fd/FA00004707
Subject Headings: Engineering geology -- Mathematical models, Fills (Earthwork), Geogrids -- Performance, Geosynthetics, Reinforced soils, Retaining walls -- Performance, Sanitary landfills, Slopes (Soil mechanics) -- Stability, Soil stabilization, Structural analysis (Engineering)
Format: Document (PDF)

Title: Cascading effects of vegetation on peat soil properties and crayfish survival in the Florida Everglades.
Creator: Chapman, Alexander, Benscoter, Brian, Dorn, Nathan, Graduate College
Date Issued: 2013-04-12
PURL: http://purl.flvc.org/fcla/dt/3361281
Subject Headings: Everglades (Fla.), Peat soils, Crayfish, Cattails, Multitrophic interactions (Ecology)
Format: Document (PDF)

Title: Response analysis of structures including effects of soil-structure interaction.
Creator: Yu, Jun., Florida Atlantic University, Yong, Yan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The objective of the study is to determine the structural response to external force and earthquake excitations with consideration of soil-structure interaction. The physical model concerned herein is an N-story building on a rigid or flexible foundation embedded in a layered soil medium. In this substructure approach, the soil medium and the structure are treated as one-dimensional waveguides and their motions are characterized as wave scattering. To include effects of soil-structure...
Show moreThe objective of the study is to determine the structural response to external force and earthquake excitations with consideration of soil-structure interaction. The physical model concerned herein is an N-story building on a rigid or flexible foundation embedded in a layered soil medium. In this substructure approach, the soil medium and the structure are treated as one-dimensional waveguides and their motions are characterized as wave scattering. To include effects of soil-structure interaction, the foundation response is expressed as a summation of influence functions, which are defined as the response to a simple stress distribution over the contact surface between the soil and foundation. The analysis, therefore, is carried out without solving integral equations. The coupling effect is recovered by using equilibrium, compatibility and reciprocal conditions. As a result, the structural response solution is expressed in terms of parameters of a seismic source and external excitations, and can be used in a statistical analysis if uncertainties of these parameters are taken into account.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/12425
Subject Headings: Soil-structure interaction, Earthquake engineering, Structural dynamics, Foundations
Format: Document (PDF)

Title: The laboratory measurement of soluble phosphorus diffusion coefficients in kaolinite and bentonite clay sediments.
Creator: Donovan, William Cullen., Florida Atlantic University, Scarlatos, Panagiotis (Pete) D.
Abstract/Description: The specific effects of sediment resuspension on the rate and amount of phosphorus diffusion by commercially available kaolinite and bentonite soils were examined in a laboratory setting by amending the soils with phosphorus fertilizer (46% P2O5), reacting them in a plexiglass container (by removing a partition) and allowing the soils to mix with the overlying water column as they spread along the container bottom. The concentration of total phosphorus was measured at 1, 3, 6, 12, 24 and 36...
Show moreThe specific effects of sediment resuspension on the rate and amount of phosphorus diffusion by commercially available kaolinite and bentonite soils were examined in a laboratory setting by amending the soils with phosphorus fertilizer (46% P2O5), reacting them in a plexiglass container (by removing a partition) and allowing the soils to mix with the overlying water column as they spread along the container bottom. The concentration of total phosphorus was measured at 1, 3, 6, 12, 24 and 36 hours after reaction occurred. A computer program was written to calculate the diffusion coefficients (D) for the different soil and fertilizer treatments. Correcting the D values for adsorption resulted in effective diffusion coefficients (De) values, averaged across all retardation factors, of 0.010; 0.0017 and 0.0124 cm^2/day for the 13,944; 9,295 and 4,648 mu g/1 phosphorus fertilizer kaolinite treatments and 0.0002; 0.0006 and 0.0013 cm^2/day for the 13,654; 9,103 and 4,552 mu g/1 phosphorus fertilizer bentonite treatments. The diffusion coefficients for the kaolinite soil treatments were consistently greater than those for the bentonite treatments.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14928
Subject Headings: Kaolinite, Bentonite, Soils--Phosphorus content, Sedimentation analysis
Format: Document (PDF)

Title: An experimental and analytical investigation of viscoelastic pipe-soil interaction.
Creator: Ahn, Woo-Suk., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: An overview of the current issues of HDPE pipe-soil systems is followed by a comprehensive literature review addressing current specifications, design methods, and relevant research projects. The following experimental tasks are described: (i) environmental stress cracking resistance (modified AASHTO M294), (ii) creep (10,000 hour parallel plate loading at super ambient temperatures), (iii) performance of buried pipes, subjected to live loading in a soil chamber, and (iv) field monitoring....
Show moreAn overview of the current issues of HDPE pipe-soil systems is followed by a comprehensive literature review addressing current specifications, design methods, and relevant research projects. The following experimental tasks are described: (i) environmental stress cracking resistance (modified AASHTO M294), (ii) creep (10,000 hour parallel plate loading at super ambient temperatures), (iii) performance of buried pipes, subjected to live loading in a soil chamber, and (iv) field monitoring. The findings include (i) satisfactory short-term environmental stress cracking resistance, (ii) temperature-dependency of the flexural modulus, (iii) the evidence of transition between slow crack growth and rapid crack propagation due to imperfect installation, and (iv) high load carrying capacity for the properly installed pipe in uniform backfill, showing an over-deflection failure mode with top flattening. The analytical investigations are as follows: (i) Bidirectional shift-constructed master curve, based on accelerated creep test values for long-term modulus prediction that showed good agreement with the Arrhenius equation-based analysis, (ii) Development of a seven-degree Voigt-Kelvin viscoelastic model based on the bidirectional shift-constructed master curve for analytical prediction of the long-term modulus, (iii) Comparison of two-dimensional and three-dimensional harmonic FEM analyses with the measured response of pipe-soil interaction, that demonstrated the analytical predictability of the pattern of deformation and stress distribution, and (iv) Determination of axial stress distribution along the pipe in non-uniform backfill condition, evaluated by approximate analysis based on finite differencing the deflection profile obtained from the assembly of individual finite segments/sections. This overcomes the limitation of the harmonic FEM analysis for pipe-soil interaction involving non-uniform soil conditions longitudinally and/or varying soil thickness circumferentially. The findings include (i) importance of axial stress contribution at failure, (ii) top flattening failure mode due to over-deflection preceding buckling or yielding, and (iii) critical adverse effect of the non-uniform backfill condition that can lead to joint opening, localized buckling, liner tearing/debonding, or cracking. The work has "spin off" applications to the coastal and offshore environments for sewage outfalls, marine pipelines etc.
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Date Issued: 1998
PURL: http://purl.flvc.org/fcla/dt/12550
Subject Headings: Soil-structure interaction, Pipe, Plastic--Testing, Underground pipelines
Format: Document (PDF)

Title: Soil-geosynthetic reinforcement interaction for mechanically stabilized earth (MSE) wall systems.
Creator: Navarrete, Fernando Manuel., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The dissertation is an experimental and analytical investigation of the long term performance of mechanically stabilized earth (MSE) walls with geosynthetics, with particular focus on rational methods to enable the determination of the applicable factors for use in Load Resistance Factor Design (LRFD). An overview of current issues concerning MSE walls is followed by an extensive literature review addressing MSE walls, pullout strength, creep and creep rupture, durability and degradation,...
Show moreThe dissertation is an experimental and analytical investigation of the long term performance of mechanically stabilized earth (MSE) walls with geosynthetics, with particular focus on rational methods to enable the determination of the applicable factors for use in Load Resistance Factor Design (LRFD). An overview of current issues concerning MSE walls is followed by an extensive literature review addressing MSE walls, pullout strength, creep and creep rupture, durability and degradation, design methodology, analytical prediction, and field evaluation of MSE walls. The experimental tasks comprise: (i) creep and creep rupture, (ii) durability and degradation, (iii) small scale testing of MSE walls with a model prototype ratio of 1:5.5, and (iv) construction of prototype MSE wall and instrumentation for long-term performance. The analytical work comprises finite difference modeling using the Fast Lagrangian Analysis of Continua (FLAC) software, (i) For creep up to 10,000 hours accelerated exposure for HDPE and PET geogrids, with super-ambient temperatures and soil water conditions related to soil conditions in Florida, the significant part of creep was due to temperatures and not solution exposures, with creep rupture occurring primarily for HDPE. (ii) For durability, performance at ambient temperatures was extrapolated, based on the Arrhenius method. The variation in degradation between the different solutions was minimal, indicating hydrolysis as the main cause for PET at elevated temperatures. (iii) Two HDPE and two PET reinforcement small scale (1:5.5) MSE walls were tested, with different surcharges each for 72 hour periods. Panel movements, strains in the reinforcement, and wall settlements were measured, indicating values smaller than the predicted, mostly for the smaller surcharges due to distortion caused by scaling neglecting the gravity effect. (iv) For analysis with FLAC computer software, two correction factors "a" and "b" were applied to correct the discrepancies between the model and the test values. The PET MSE small scale wall showed more deviation because the material has a low modulus of elasticity. (v) A preliminary comparison of the small scale and the prototype MSE wall behavior indicated discrepancies due to distortion scaling related to the lack of gravity simulation.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/11968
Subject Headings: Geosynthetics, Load factor design, Retaining walls, Soil stabilization
Format: Document (PDF)

Title: Water and Soil Salinity Mapping for Southern Everglades using Remote Sensing Techniques and In Situ Observations.
Creator: Khadim, Fahad Khan, Su, Hongbo, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Everglades National Park is a hydro-ecologically significant wetland experiencing salinity ingress over the years. This motivated our study to map water salinity using a spatially weighted optimization model (SWOM); and soil salinity using land cover classes and EC thresholds. SWOM was calibrated and validated at 3-km grids with actual salinity for 1998–2001, and yielded acceptable R2 (0.89-0.92) and RMSE (1.73-1.92 ppt). Afterwards, seasonal water salinity mapping for 1996–97, 2004–05, and...
Show moreEverglades National Park is a hydro-ecologically significant wetland experiencing salinity ingress over the years. This motivated our study to map water salinity using a spatially weighted optimization model (SWOM); and soil salinity using land cover classes and EC thresholds. SWOM was calibrated and validated at 3-km grids with actual salinity for 1998–2001, and yielded acceptable R2 (0.89-0.92) and RMSE (1.73-1.92 ppt). Afterwards, seasonal water salinity mapping for 1996–97, 2004–05, and 2016 was carried out. For soil salinity mapping, supervised land cover classification was firstly carried out for 1996, 2000, 2006, 2010 and 2015; with the first four providing average accuracies of 82%-94% against existing NLCD classifications. The land cover classes and EC thresholds helped mapping four soil salinity classes namely, the non saline (EC = 0~2 dS/m), low saline (EC = 2~4 dS/m), moderate saline (EC = 4~8 dS/m) and high saline (EC >8 dS/m) areas.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004860, http://purl.flvc.org/fau/fd/FA00004860
Subject Headings: Everglades National Park (Fla.)--Environmental conditions., Florida Bay (Fla.)--Environmental conditions., Remote sensing., Multispectral imaging., Environmental monitoring--Remote sensing., Geographic information systems., Soils--Remote sensing., Soil moisture--Measurement., Soil mapping.
Format: Document (PDF)

Title: Innovative Expansion of Landfill Capacity Using Geogrid Reinforcements.
Creator: Templeton, R. Hayes, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: An analytical investigation was conducted to evaluate the geotechnical safety and stability of MSW landfills constructed with significantly steepened slopes achieved through geosynthetic reinforcement. The primary motivation for this endeavor was to propose a new design/construction methodology for innovative expansion of landfill capacity. A 2-D plane strain linear elastic analysis was performed with ANSYS finite element software on full-scale MSW landfill structures (with and without...
Show moreAn analytical investigation was conducted to evaluate the geotechnical safety and stability of MSW landfills constructed with significantly steepened slopes achieved through geosynthetic reinforcement. The primary motivation for this endeavor was to propose a new design/construction methodology for innovative expansion of landfill capacity. A 2-D plane strain linear elastic analysis was performed with ANSYS finite element software on full-scale MSW landfill structures (with and without geogrids), having slopes of 1:1, 1:2, and 1:3. Both local and global factors of safety were determined employing the Mohr-Coulomb failure criteria, and compared with traditional solutions using the Bishop's Modified Method. It was found that the landfill slopes could be steepened up to 1:1 using geogrid reinforcement, resulting in higher storage capacity and consequential environmental and economic benefits.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012561
Subject Headings: Sanitary landfills--Design and construction, Refuse and refuse disposal, Soil mechanics--Mathematical models, Geosynthetics--Mathematical models, Soil stabilization
Format: Document (PDF)

Title: Evaluating the effectiveness of seed banks for the recovery of sawgrass in A.R.M Loxahatchee National Wildlife Refuge.
Creator: Yeyati, Nestor, Lange, James J., Benscoter, Brian
Date Issued: 2013-04-05
PURL: http://purl.flvc.org/fcla/dt/3361240
Subject Headings: Arthur R. Marshall Loxahatchee National Wildlife Refuge (Fla.), Cladium, Everglades (Fla.), Soil seed banks
Format: Document (PDF)

Title: CHANGES IN PHYSICAL PROPERTIES OF THE PEAT SOIL MATRIX ACROSS A SALINITY GRADIENT IN THE EVERGLADES: IMPLICATIONS FOR ACCELERATING PEAT COLLAPSE DURING SEA LEVEL RISE.
Creator: Florey, Maxwell, Comas, Xavier, Florida Atlantic University, Department of Geosciences, Charles E. Schmidt College of Science
Abstract/Description: Peatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal...
Show morePeatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal peat soils described the effect of pore dilation as a result of increased salinity in peat soils, while recent studies in Everglades peat soils showed specific salinity thresholds that may represent a permanent loss of the structural integrity of the peat matrix that may represent early stages of peat collapse. While most of these previous efforts have focused on drivers, recent work has also explored conceptual models to better understand the mechanisms inducing peat collapse. However, few datasets exists that consistently compare differences in physical properties under different in‐situ salinity conditions. In this study differences in the physical properties of peat soils across a salinity gradient along the western edge of Big Cypress National Preserve are investigated to test how differences in salinity may induce physical changes in the soil matrix. The physical properties targeted for this study include porosity, hydraulic conductivity, and carbon content. Measurements are conducted at the laboratory scale using peat cores and monoliths collected at selected locations to investigate: 1) how overall soil physical properties change spatially over a salinity gradient at the km scale moving from permanently saline to freshwater conditions; and 2) how physical properties change spatially at specific sites as dependant on vegetation boundaries and proximity to collapsed soils. This study has implications for better understanding the potential relation between physical changes of the soil matrix and the phenomena of peat collapse in the Everglades as saltwater intrusion progresses inward and alters freshwater ecosystems. Furthermore, a better mechanistic understanding of the peat collapse phenomenon can potentially help mitigate its occurrence.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013809
Subject Headings: Peat soils, Salinity, Sea level, Big Cypress National Preserve (Fla.), Everglades (Fla.)
Format: Document (PDF)

Title: Effects of Granulometric Parameters and Mix Proportions on the Shear Strength of Binary Granular Mixtures.
Creator: Gonzalez Moya, Daniel E., Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Geotechnical engineers are commonly faced with the need to perform ground improvement techniques to achieve the necessary bearing capacity for a project. Some of the most common techniques involve the excavation and replenishment of problematic geomaterial with one of better quality. Common projects, such as road embankments and retaining walls, also require the selection of backfill material. The guidelines for selecting backfill material are typically limited to complying with certain...
Show moreGeotechnical engineers are commonly faced with the need to perform ground improvement techniques to achieve the necessary bearing capacity for a project. Some of the most common techniques involve the excavation and replenishment of problematic geomaterial with one of better quality. Common projects, such as road embankments and retaining walls, also require the selection of backfill material. The guidelines for selecting backfill material are typically limited to complying with certain gradation bands, relative densities and allowable fines content. Round-grained silica sand, and beach sand from Boca Raton, FL, were used to generate a total of 16 binary granular mixtures containing different amounts of finer material, for which a series of direct shear tests were conducted. Based on the experimental results, it may be possible to provide an alternative criteria for selecting backfill material based on granulometric parameters and the amount of finer material.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004714, http://purl.flvc.org/fau/fd/FA00004714
Subject Headings: Continuum mechanics, Geotechnical engineering, Granular materials -- Dynamic testing, Micromechanics -- Mathematical models, Soil liquefaction
Format: Document (PDF)

Title: ADVANCING THE CULTIVABILITY OF SOIL BACTERIA USING A DYNAMIC SOIL ENVIRONMENT AND SOIL EXTRACT METHOD.
Creator: España, Erick, Brooks, Randy W., Esiobu, Nwadiuto, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Bacteria are inarguably the most ubiquitous and adaptive organisms on the planet. The vast, diverse community of microbes residing in soil are mostly studied using sequencing technologies because over 99% of them are currently uncultivable in the laboratory. This lack of diverse bacterial cultivation presents a serious challenge for modern microbiological and medical science where the discovery of novel antibiotic producers and microbial products has been outpaced by the rise in drug...
Show moreBacteria are inarguably the most ubiquitous and adaptive organisms on the planet. The vast, diverse community of microbes residing in soil are mostly studied using sequencing technologies because over 99% of them are currently uncultivable in the laboratory. This lack of diverse bacterial cultivation presents a serious challenge for modern microbiological and medical science where the discovery of novel antibiotic producers and microbial products has been outpaced by the rise in drug resistance. This study designed and tested two new cost-effective culture systems called the “Dynamic Soil Environment” and Soil Extract Systems with the goal of increasing the cultivable communities of diverse bacteria in a soil sample over standard methods. Illumina MiSeq sequencing and DADA2 pipeline protocols were used to analyze community DNA from cultivated samples and source soil metagenomes. Autoclaved soil extract media in the Soil Extract Experiment yielded a statistically significantly greater Shannon’s (p = 0.008) and Simpson’s diversity (p = 0.007) of bacteria over pH modified (6.4) nutrient agar media over 30 days of incubation. Autoclaved soil extract media was also able to cultivate, on average, 33% of species in bulk soil sequences compared to 27% from standard nutrient agar however these differences weren’t statistically significant. The length of incubation had a lesser effect than media type on yield of bacteria over 30 days in batch culture conditions. Species richness and diversity generally decreased over time except in soil extract samples. In the Dynamic Soil Environment experiment, membrane plates placed on a live soil environment produced a slightly higher diversity than autoclaved membrane plates and control plates without soil, however, these differences were not statistically significant except when analyzed with Chao1 diversity (0.041). Cultivated bacterial diversity and communities differed more according to media type than soil environment with statistically significant differences between standard and pH modified nutrient agar. Media with a 5.8 pH buffer produced a significantly higher relative abundance of the well-known antibiotic-producers, Actinobacteria (t(10) = -5.715, p < .000) and also Proteobacteria (t(10) = -10.127, p < .000). This study establishes cost-effective methods of cultivating more diverse bacterial communities for low-funded laboratories. Culture conditions for the reliable cultivation of higher relative abundances of bacterial groups belonging to Actinobacteria and Proteobacteria are also established with the Dynamic Soil Environment Experiment.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013304
Subject Headings: Bacteriological Techniques--methods, Bacteriology--Cultures and culture media, Soil
Format: Document (PDF)

Title: Non-destructive evaluation of reinforced asphalt pavement built over soft organic soils.
Creator: Pohly, Daniel D., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Research, tests and analysis are presented on several reinforcements placed in the asphalt overlay of a roadway built over soft organic soils. Non-destructive Evaluation (NDE) methods and statistical analysis were used to characterize the pavement before and after rehabilitative construction. Before reconstruction, falling weight deflectometer, rut and ride tests were conducted to evaluate the existing pavement and determine the statistical variability of critical site characteristics. Twenty...
Show moreResearch, tests and analysis are presented on several reinforcements placed in the asphalt overlay of a roadway built over soft organic soils. Non-destructive Evaluation (NDE) methods and statistical analysis were used to characterize the pavement before and after rehabilitative construction. Before reconstruction, falling weight deflectometer, rut and ride tests were conducted to evaluate the existing pavement and determine the statistical variability of critical site characteristics. Twenty-four 500ft. test sections were constructed on the roadway including sixteen reinforced asphalt and eight control sections at two test locations that possessed significantly different subsoil characteristics. NDE tests were repeated after reconstruction to characterize the improvements of the test sections. Test results were employed to quantify the stiffness properties of the pavement based on load-deflection data to evaluate the relative performance of the reinforced sections. Statistical analysis of the data showed the stiffness of the reinforced sections was consistently higher than the control sections.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/368253
Subject Headings: Soil remediation, Technological innovations, Structural stability, Design, Pavements, Performance, Management, Data processing, Structural analysis (Engineering)
Format: Document (PDF)

Title: Investigating biogenic gas dynamics from peat soils of the Everglades using hydrogeophysical methods.
Creator: Wright, William J., Comas, Xavier, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description: Peat soils are known to be a significant emitter of atmospheric greenhouse gasses. However, the spatial and temporal variability in production and release of greenhouse gases (such as methane) in peat soils remains uncertain, particularly for low-latitude peatlands like the Florida Everglades, as the majority of studies on gas dynamics in peatlands focus on northern peatlands. The purpose of the work outlined here is focused on understanding the spatial and temporal variability in biogenic...
Show morePeat soils are known to be a significant emitter of atmospheric greenhouse gasses. However, the spatial and temporal variability in production and release of greenhouse gases (such as methane) in peat soils remains uncertain, particularly for low-latitude peatlands like the Florida Everglades, as the majority of studies on gas dynamics in peatlands focus on northern peatlands. The purpose of the work outlined here is focused on understanding the spatial and temporal variability in biogenic gas dynamics (i.e. production and release of methane and carbon dioxide) by implementing various experiments in the Florida Everglades at different scales of measurement, using noninvasive hydrogeophysical methods. Non-invasive methods include ground-penetrating radar (GPR), gas traps, time-lapse cameras, and hydrostatic pressure head measurements, that were constrained with direct measurements on soil cores like porosity, and gas composition using gas chromatography. By utilizing the measurements of in-situ gas volumes, we are able to estimate gas production using a mass balance approach, explore spatial and temporal variabilities of gas dynamics, and better constrain gas ebullition models. A better understanding of the spatial and temporal variability in gas production and release in peat soils from the Everglades has implications regarding the role of subtropical wetlands in the global carbon cycle, and can help providing better production and flux estimates to help global climate researchers improve their predictions and models for climate change.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013146
Subject Headings: Peat soils, Gas dynamics, Carbon cycle (Biogeochemistry), Everglades (Fla), Biogenic gas
Format: Document (PDF)

Title: Investigating variability of biogenic gas dynamics in peat soils using high temporal frequency hydrogeophysical methods.
Creator: Wright, William J., Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description: Peat soils are known to be a significant source of atmospheric greenhouse gasses. However, the releases of methane and carbon dioxide gasses from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Furthermore, most research work performed on peatlands has been focused on temperate to sub-arctic peatlands, while recent works have suggested that gas production rates from low-latitude peat soils are higher than those from colder...
Show morePeat soils are known to be a significant source of atmospheric greenhouse gasses. However, the releases of methane and carbon dioxide gasses from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Furthermore, most research work performed on peatlands has been focused on temperate to sub-arctic peatlands, while recent works have suggested that gas production rates from low-latitude peat soils are higher than those from colder climates. The purpose of the work proposed here is to introduce an autonomous Ground Penetrating Radar (GPR) method for investigating the timing of gas releases from peat soils at the lab scale utilizing samples originating from Maine and the Florida Everglades, and at the field scale in a Maine peatland. Geophysical data are supported by direct gas flux measurements using the flux chamber method enhanced by timelapse photography, and terrestrial LiDAR (TLS) monitoring surface deformation.
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Date Issued: 2013
PURL: http://purl.flvc.org/fcla/dt/3361256
Subject Headings: Gas dynamics, Wetland ecology, Soil permeability, Estuarine sediments, Ground penetrating radar, Hydrogeology, Geophysics
Format: Document (PDF)

Title: Patterns of inorganic phosphate and carbohydrate allocation in sawgrass (Cladium jamaicense Crantz) and southern cattail (Typha domingensis Pers.) grown at low and high phosphate levels.
Creator: Hill, Brian, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: In recent history, C. jamaicense has been displaced by another native monocot, T. domingensis, predominantly resulting from increased phosphorous enrichment in the Everglades. This study aimed to elucidate these two species responses to low and high [Pi] in terms of allocation, photosynthate partitioning and growth. C. jamaicense growth was independent of Pi, while T. domingensis growth increased with [Pi]. Under high [Pi], allocation to younger T. domingensis shoots occurred, while C....
Show moreIn recent history, C. jamaicense has been displaced by another native monocot, T. domingensis, predominantly resulting from increased phosphorous enrichment in the Everglades. This study aimed to elucidate these two species responses to low and high [Pi] in terms of allocation, photosynthate partitioning and growth. C. jamaicense growth was independent of Pi, while T. domingensis growth increased with [Pi]. Under high [Pi], allocation to younger T. domingensis shoots occurred, while C. jamaicense shoots retained more [Pi], while low [Pi] resulted in homogeneous allocation patterns for both species. Additionally, Pi deficiencies induced carbohydrate levels in older shoots of T. domingensis, while [Pi] had no effect on photosynthate partitioning patterns in C. jamaicense. ACP activity was induced by Pi deficiency in all T. domingensis shoots and increased with shoot age, while no effect was observed in C. jamaicense. Results indicate these two species differ in allocation strategies when [Pi] is altered.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/238480
Subject Headings: Nitrogen-fixing algae, Biogeochemical cycles, Phosphorus, Psychological transport, Soil stabilization, Ecosystem management, Vegetation dynamics
Format: Document (PDF)

Title: THE EFFECTS OF WILLOW SHRUB ENCROACHMENT ON SOIL ORGANIC CARBON STORAGE IN A SOUTH FLORIDA HERBACEOUS WETLAND.
Creator: Dell, Jessica Ann, Benscoter, Brian, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description: Storing almost a third of the global soil carbon pool, wetlands are an essential component of the carbon cycle, and carbon-rich peat soil accumulates when carbon input through primary productivity exceeds output through decomposition. However, woody shrub encroachment in herbaceous wetlands can alter soil carbon processes, potentially diminishing stored carbon. To examine the effects of shrub encroachment on soil carbon, I compared soil carbon input through litterfall and fine root production...
Show moreStoring almost a third of the global soil carbon pool, wetlands are an essential component of the carbon cycle, and carbon-rich peat soil accumulates when carbon input through primary productivity exceeds output through decomposition. However, woody shrub encroachment in herbaceous wetlands can alter soil carbon processes, potentially diminishing stored carbon. To examine the effects of shrub encroachment on soil carbon, I compared soil carbon input through litterfall and fine root production, output through decomposition, and below-canopy microclimate conditions between Carolina willow shrub (Salix caroliniana) and herbaceous sawgrass (Cladium jamaicense) in the Blue Cypress Marsh Conservation Area (BCMCA), FL. To assess the level of production and its response to water level, I compared aboveground green biomass by measuring normalized difference vegetation index (NDVI) and photosynthetic stress by measuring photochemical reflectance index (PRI) between sawgrass and willow. I collected willow litterfall using litter traps and measured sawgrass and willow fine root production with fine root ingrowth bags. Litter decomposition was measured with decomposition bags deployed using a reciprocal litter placement design at BCMCA and incubated in a greenhouse to examine the effects of char and water level on decomposition. Above and belowground microclimate conditions were measured using sensors installed within sawgrass and willow canopies. Despite experiencing more photosynthetic stress, willow produced more green biomass than sawgrass. However, willow produced fewer fine roots than sawgrass and these roots were deeper within the soil. Willow litter decomposed faster even though sawgrass decomposition increased under drier conditions. Compared to the sawgrass canopy, the willow canopy had greater light availability, lower evaporative demand plus warmer and drier soils; however, litter decomposition did not differ between the canopies. These results suggest that willow encroachment can reduce the amount and alter the distribution of carbon within an herbaceous wetland, likely resulting in a net loss of soil carbon. Although willow encroachment may increase aboveground biomass carbon stocks, these stocks will likely be offset by a loss of soil carbon due to reduced fine root production and increased decomposition. Therefore, the transition from herbaceous wetland to shrub wetland will likely result in a loss of stored soil carbon.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013621
Subject Headings: Wetlands, Blue Cypress Water Management Area (Fla), Carbon cycle (Biogeochemistry), Soils
Format: Document (PDF)

Title: Evaluation of flexible pipes under shallow burial depths.
Creator: Wang, Ning., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Flexible plastic and metal pipes are increasingly being used for drainage and storm sewers. When flexible pipes are buried at shallow depths, the pipe behavior will not depend on the dead load pressure above the crown, but rather on the live load pressure (vehicle load). Field tests were designed to evaluate the performance of large diameter flexible pipes of 36 in. (915 mm.) and 48 in. (1050 mm.) under shallow burial depths subjected to the actual vehicle loading. The test pipes included...
Show moreFlexible plastic and metal pipes are increasingly being used for drainage and storm sewers. When flexible pipes are buried at shallow depths, the pipe behavior will not depend on the dead load pressure above the crown, but rather on the live load pressure (vehicle load). Field tests were designed to evaluate the performance of large diameter flexible pipes of 36 in. (915 mm.) and 48 in. (1050 mm.) under shallow burial depths subjected to the actual vehicle loading. The test pipes included high-density polyethylene (HDPE) pipes, polyvinyl chloride (PVC) pipes, steel pipes and aluminum pipes. AASHTO standard pipe installation procedures were followed and pipes subjected to vehicle loads simulating the effect of HS 20-44 trucks. Measurements of interior pipe-wall strains, soil pressures at different depths and pipe deformations were taken to determine the influence of surface vehicle loads. Results of field tests are compared with those based on theoretical analyses.
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Date Issued: 2002
PURL: http://purl.flvc.org/fcla/dt/12929
Subject Headings: Underground pipelines--Design and construction, Soil-structure interaction, Structural analysis (Engineering), Earth pressure
Format: Document (PDF)

Title: Effect of median grain size ratio on the compaction behavior of binary granular mixes.
Creator: Brenner, Tara Devine., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Optimization of compaction in granular material without the use of traditional ground improvement methods may be possible by optimizing the percentage of finer material and the median grain size ratio in binary soil mixtures. In this study, the median grain size ratio D50/d50 was explored as a fundamental parpmeter affecting the compaction characteristics of binary mixes made from natural sands as opposed to singular measurements such as fines content and mean grain size traditionally used to...
Show moreOptimization of compaction in granular material without the use of traditional ground improvement methods may be possible by optimizing the percentage of finer material and the median grain size ratio in binary soil mixtures. In this study, the median grain size ratio D50/d50 was explored as a fundamental parpmeter affecting the compaction characteristics of binary mixes made from natural sands as opposed to singular measurements such as fines content and mean grain size traditionally used to represent granular soils. A total of 18 binary granular mixes were synthetically generated from natural sands obtained from Longboat Key, Florida and evaluated through grain size analysis, laboratory compaction and determination of relative density. Results indicate that the D50/d50 ratio shows promise as a fundamental parameter for compaction optimization in binary mixes with values exceeding six approaching the densest packing configuations.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3358329
Subject Headings: Granular materials, Dynamic testing, Engineering geology, Soil mechanics, Testing, Micromechanics, Mathematical models
Format: Document (PDF)

Title: A study of the relationships between historical land use and petroleum contamination in southeastern Palm Beach County, Florida.
Creator: Peterson, Andrew Brian., Florida Atlantic University, Finkl, Charles W.
Abstract/Description: Protection of groundwater resources in southeastern Florida is essential because of increasing demands on water quality and supply. Because water is furnished to public and private water systems from production wells that tap the non-artesian surficial aquifer, contamination of groundwater from leaking petroleum storage tanks must be curtailed. In the study, a series of land use maps is developed based on aerial photographs (1970, 1984, and 1991) for a 40 square mile area in southeastern Palm...
Show moreProtection of groundwater resources in southeastern Florida is essential because of increasing demands on water quality and supply. Because water is furnished to public and private water systems from production wells that tap the non-artesian surficial aquifer, contamination of groundwater from leaking petroleum storage tanks must be curtailed. In the study, a series of land use maps is developed based on aerial photographs (1970, 1984, and 1991) for a 40 square mile area in southeastern Palm Beach County, Florida. The locations of petroleum storage tank systems and contaminated sites are mapped. The point biserial correlation coefficient is used to examine the strength of the relationships between historical land use, storage tank system capacity, and the presence of petroleum. contamination. The results indicate no correlation between the intensity of urbanization (historical land use) and petroleum contamination and positive correlation between petroleum storage system capacity and petroleum contamination.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15162
Subject Headings: Land use--Florida--Palm Beach County, Groundwater, Petroleum products--Underground storage--Environmental aspects, Oil pollution of soils
Format: Document (PDF)

FAU Theses and Dissertations (42)	+ -
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Soil stabilization (7)	+ -
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Everglades (Fla.) (4)	+ -
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Carbon cycle (Biogeochemistry) (3)	+ -
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