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Coupled Effect of Geosynthetics and Randomly Distributed Fibers on the Stability of Reinforced Slopes
Title
Coupled Effect of Geosynthetics and Randomly Distributed Fibers on the Stability of Reinforced Slopes.
Creator
Martins, Caique, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Graduate College
Abstract/Description
The coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in...
Show moreThe coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in both the short-term condition with its' undrained shear strength parameters, and the long-term drained condition. Results indicate that the combination of the techniques was found to have a possible increase of about 40% in the short-term condition and about 60% in the long-term condition of the factor safety associated with the slope.
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Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013236
Subject Headings
Geosynthetics, Slope stability, Shear strength of soils
Format
Document (PDF)
Improved design methods for evaluating the performance of landfill double liner systems
Title
Improved design methods for evaluating the performance of landfill double liner systems.
Creator
Shivashankar, Mirle R., Florida Atlantic University, Fluet, J. E. Jr., Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Many modern landfills are constructed with double liner systems. Leachate leakage rates through double liner systems are calculated using recently developed formulations which are theoretically correct for leakage detection system (LDS) materials that have unrestricted lateral flow properties. But their applicability to geonets, the most commonly used LDS material, has yet to be determined. In double liner systems, the leakage through the primary liner, the properties of the LDS material, and...
Show moreMany modern landfills are constructed with double liner systems. Leachate leakage rates through double liner systems are calculated using recently developed formulations which are theoretically correct for leakage detection system (LDS) materials that have unrestricted lateral flow properties. But their applicability to geonets, the most commonly used LDS material, has yet to be determined. In double liner systems, the leakage through the primary liner, the properties of the LDS material, and the slope of the LDS determine the flow patterns in the LDS. These flow patterns are then used to determine the amount of leachate, if any, which leaks through the bottom liner into the ground. This thesis describes the experimental determination of the flow patterns in the geonets and their relationships to established design formulations.
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Date Issued
1995
PURL
http://purl.flvc.org/fcla/dt/15197
Subject Headings
Sanitary landfills--Leaching, Sanitary landfills--Linings, Geosynthetics
Format
Document (PDF)
Soil-geosynthetic reinforcement interaction for mechanically stabilized earth (MSE) wall systems
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)
Fracture and Fatigue Behavior of Geosynthetic Reinforced Asphalt Concrete for Pavement Overlays
Title
Fracture and Fatigue Behavior of Geosynthetic Reinforced Asphalt Concrete for Pavement Overlays.
Creator
Polidora, Jamie Barbara, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description
Flexible or asphalt pavements constitute nearly 94% of the 2.7 million miles of existing roadways in the United States. In a typical rehabilitation project, the existing asphalt pavement is milled up to a prescribed depth for removing the near surface distresses such as excessive cracking and rutting, and a new overlay is placed. The average time between resurfacing projects varies depending on the level of pavement deterioration which is significantly accelerated when poor subgrade...
Show moreFlexible or asphalt pavements constitute nearly 94% of the 2.7 million miles of existing roadways in the United States. In a typical rehabilitation project, the existing asphalt pavement is milled up to a prescribed depth for removing the near surface distresses such as excessive cracking and rutting, and a new overlay is placed. The average time between resurfacing projects varies depending on the level of pavement deterioration which is significantly accelerated when poor subgrade conditions are encountered. The use of geosynthetic reinforcement within the new asphalt overlay is often perceived as a mitigation strategy that can delay the onset and propagation of reflection cracking, and also control the rutting and differential settlement. However, some mixed reviews about the performance of the geosynthetic reinforced overlays have been reported in the literature. In Phase I of this study, a laboratory investigation was conducted for evaluating the flexural fatigue behavior, permanent deformation response, and fracture characteristics of geogrid reinforced asphalt beam specimens made from a typical overlay material. The laboratory specimens included geogrid as a single-layer inclusion either at the bottom third depth or at the mid height, and as double-layer inclusion, with geogrid placed both at the bottom third and at the middle of the beam. In Phase II, a case study involving geogrid reinforced overlay constructed over a deteriorated pavement underlain by soft subgrade in southeastern Florida was numerically simulated. It was found that the geogrid reinforcement significantly improved the fatigue and fracture properties of the asphalt beams compared to unreinforced specimens. Results from numerical simulation demonstrated that the double reinforced overlay resulted in the minimum tensile stress at the bottom of the asphalt layer (reducing the cracking potential) and minimum vertical strain on the top of the subgrade (reducing the rutting potential), compared to unreinforced or bottom-third reinforced overlays. Accordingly, it is concluded that the double layer reinforcement of asphalt overlays with an appropriate geosynthetic product can be beneficial for the performance and long term preservation of the pavement system when soft soils are encountered.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004972, http://purl.flvc.org/fau/fd/FA00004962
Subject Headings
Dissertations, Academic -- Florida Atlantic University, Reinforced concrete., Asphalt pavements., Geosynthetics., Pavements--Overlays--Evaluation.
Format
Document (PDF)
effect of compressive creep on the structural integrity and drainage capacity of landfill lining systems
Title
The effect of compressive creep on the structural integrity and drainage capacity of landfill lining systems.
Creator
Daniel, Ellen C. Hendrix., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description
Landfilling, by all indications, will continue to be the predominant method of solid waste disposal. Traditional civil engineering drainage medium (i.e. sand or gravel) are being replaced by geosynthetics which are much thinner in an effort to create more usable volume for waste. This study examines the effect of compressive creep of geonets as used in leachate collection and detection systems, and how it affects in-plane drainage. HDPE geonet was subjected to a compressive load of 110 psi....
Show moreLandfilling, by all indications, will continue to be the predominant method of solid waste disposal. Traditional civil engineering drainage medium (i.e. sand or gravel) are being replaced by geosynthetics which are much thinner in an effort to create more usable volume for waste. This study examines the effect of compressive creep of geonets as used in leachate collection and detection systems, and how it affects in-plane drainage. HDPE geonet was subjected to a compressive load of 110 psi. The in plane flow rate of municipal solid waste leachate was measured, as well as the change in thickness, for 120 days. In addition, geonet samples were placed between two pieces of HDPE geomembrane. These samples were subjected to a normal load of 140 psi for 120 days. The samples were then inspected for sign of geonet imprint into the geonet, or for strand layover.
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Date Issued
1995
PURL
http://purl.flvc.org/fcla/dt/15229
Subject Headings
Waste disposal in the ground, Sanitary landfills--Linings, Leachate, Geosynthetics
Format
Document (PDF)
Stability Analysis of Geosynthetic Reinforced MSW Landfill Slopes Considering Effects of Biodegradation and Extreme Wind Loading
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)
Innovative Expansion of Landfill Capacity Using Geogrid Reinforcements
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)