Current Search: Soil stabilization (x)
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- Title
- Long-term pullout resistance of geogrid reinforcement for retaining walls.
- Creator
- Gao, Shangsui., Florida Atlantic University, Reddy, Dronnadula V.
- Abstract/Description
-
An experimental and analytical investigation is presented for two types of geogrids: HDPE (High Density Polyethylene) and PET (Polyester). Sand and limerock were used for the backfill material, which meet the FDOT (Florida Department of Transportation) Material Specifications, with simulation of unsaturated and saturated condition. Eight pullout test boxes were designed and constructed, each with a specially designed stainless steel clamp. The measured strain-time relations for unsaturated...
Show moreAn experimental and analytical investigation is presented for two types of geogrids: HDPE (High Density Polyethylene) and PET (Polyester). Sand and limerock were used for the backfill material, which meet the FDOT (Florida Department of Transportation) Material Specifications, with simulation of unsaturated and saturated condition. Eight pullout test boxes were designed and constructed, each with a specially designed stainless steel clamp. The measured strain-time relations for unsaturated and saturated soils for various levels of the pullout force until the peak value (up to 10,000 hours of exposure), and varying distances from the loading end were plotted. The normal and principal stresses in the soil, and the strains along the geogrid were determined from the finite element analysis for the unsaturated soil condition for various pullout force levels. The results were analyzed and a generalized method proposed for practical design using sliding resistance factors.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15689
- Subject Headings
- Retaining walls, Geogrids, Soil stabilization
- Format
- Document (PDF)
- Title
- Time- stress-compressibility characteristics of cementitiously stabilized organic soils.
- Creator
- Sarsour, Anhar, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Effect of cementitious stabilization on the stress-compressibility characteristics of three different South Florida organic soils were evaluated in this study. The objectives of the research were to (l) determine if the secondary compression characteristics of organic soils and peats can be stabilized with (a) cement only, (b) binary blends of cement/slag (C-S), cement/gypsum (C-G), and cement/cement-kiln-dust (C-CKD) and (c) ternary blend of cement-slag-gypsum in equal proportions; (ll)...
Show moreEffect of cementitious stabilization on the stress-compressibility characteristics of three different South Florida organic soils were evaluated in this study. The objectives of the research were to (l) determine if the secondary compression characteristics of organic soils and peats can be stabilized with (a) cement only, (b) binary blends of cement/slag (C-S), cement/gypsum (C-G), and cement/cement-kiln-dust (C-CKD) and (c) ternary blend of cement-slag-gypsum in equal proportions; (ll) quantify the effectiveness of cementitious stabilization by evaluating the time-stress-compressibility (t-log σ'v - e) relationship in terms of the Cα / Cc ratio; and (lll) provide some guidelines for selecting optimum dosage of cementitious materials in deep mixing methods when organic soils and peats are encountered. It was concluded that cementitious mixes containing various waste materials is effective in controlling the secondary compression behavior of organic soils, and therefore should be considered in deep mixing methods as a sustainable practice.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004326, http://purl.flvc.org/fau/fd/FA00004326
- Subject Headings
- Environmental geotechnology, Pavements, Soil cement, Soil consolidation, Soil mechanics, Soil penetration test, Soil stabilization
- Format
- Document (PDF)
- 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.
Show less - Date Issued
- 2019
- PURL
- http://purl.flvc.org/fau/fd/FA00013236
- Subject Headings
- Geosynthetics, Slope stability, Shear strength of soils
- Format
- Document (PDF)
- Title
- Use of piezocone penetration tests for rapid in-situ characterization of Florida organic soil.
- Creator
- Huynh, Hieu H., Florida Atlantic University, Sobhan, Khaled
- Abstract/Description
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Organic soils generally are characterized by low strength and high compressibility. Visual observations of State Road 15/US 98 in western Palm Beach County, Florida indicate numerous cracking and significant rutting and raveling along the roadway caused by the consolidation and long-term secondary compression of the organic soils due to soil and pavement dead load. Since sampling of undisturbed soft organic soils is difficult, and subsequent laboratory tests are expensive and time-consuming,...
Show moreOrganic soils generally are characterized by low strength and high compressibility. Visual observations of State Road 15/US 98 in western Palm Beach County, Florida indicate numerous cracking and significant rutting and raveling along the roadway caused by the consolidation and long-term secondary compression of the organic soils due to soil and pavement dead load. Since sampling of undisturbed soft organic soils is difficult, and subsequent laboratory tests are expensive and time-consuming, there is a need for rapid in-situ characterization of these unstable foundation soils. This study evaluates the capabilities of Piezocone Penetration tests (CPTu), coupled with pore pressure dissipation tests, for estimating the strength, modulus, compressibility, and time rate of consolidation characteristics of organic soils and peat in Florida. The compression index (Cc) and coefficient of consolidation (cv), predicted from CPTu, showed reasonable correlation with laboratory-derived properties.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13379
- Subject Headings
- Soil stabilization--Florida, Soil consolidation--Florida, Soil mechanics--Florida, Soil penetration test
- 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.
Show less - 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
- Studies of specific gene expression of phosphate transporters in sawgrass (Cladium jamaicense crantz) and cattail (Typha domingensis pers.).
- Creator
- Lin, Li, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
In the Florida Everglades, sawgrass has been displaced by cattail, predominantly resulting from phosphate enrichment. It has been found that phosphate transporters and arbuscular mycorrhizal (AM) fungi play an important role in phosphate uptake in the plants. This study aimed to reveal the symbiosis between AM fungi and sawgrass and cattail and identify the phosphate transporters, especially AM-specific phosphate transporters in these two species. AM colonization was only found in sawgrass...
Show moreIn the Florida Everglades, sawgrass has been displaced by cattail, predominantly resulting from phosphate enrichment. It has been found that phosphate transporters and arbuscular mycorrhizal (AM) fungi play an important role in phosphate uptake in the plants. This study aimed to reveal the symbiosis between AM fungi and sawgrass and cattail and identify the phosphate transporters, especially AM-specific phosphate transporters in these two species. AM colonization was only found in sawgrass roots, not cattail, at low phosphate concentrations in lab and field samples by trypan blue staining. AM fungi could increase sawgrass growth and had little effect on cattail growth. Four phosphate transporters were identified in sawgrass. CjPT1, CjPT2 and CjPT3 were expressed in roots and shoots independent of AM fungi and phosphate availability, while CjPT4 appeared to be an AM regulated phosphate transporter gene and its expression was induced by AM fungi.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/1930493
- Subject Headings
- Phosphorus, Physiological transport, Soil stabilization, Vegetation dynamics, Ecosystem management, Soil mineralogy, Plant physiology
- Format
- Document (PDF)
- 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
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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.
Show less - 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
- Cement stabilization of organic soils for controlling secondary compression behavior.
- Creator
- Ramirez, Juan., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Western Palm Beach County, FL is characterized by thick deposits organic soils at shallow depths. Because of their high void ratio and compressibility, these soils undergo large primary consolidation followed by extended periods of secondary compression causing excessive premature structural distress. Although soil stabilization has been largely used with remarkable results in soft, expansive and non-organic soils, limited research and practice exist in the implementation with highly organic...
Show moreWestern Palm Beach County, FL is characterized by thick deposits organic soils at shallow depths. Because of their high void ratio and compressibility, these soils undergo large primary consolidation followed by extended periods of secondary compression causing excessive premature structural distress. Although soil stabilization has been largely used with remarkable results in soft, expansive and non-organic soils, limited research and practice exist in the implementation with highly organic soils. The main motivation of this research was to investigate the effects of cement stabilization on the compressibility behavior of organic rich soils, and develop mix design criteria for optimum cement contents necessary to induce the desired engineering behavior. This optimized mix design may provide guidelines for Deep Mixing Methods in organic soils.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/367760
- Subject Headings
- Soil consolidation, Measurement, Soils, Organic compound content, Soil remediation, Technological innovations, Concrete construction, Structural stability, Design
- 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.
Show less - 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
- 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.
Show less - 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
- 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.
Show less - 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)