199 results on '"Filz, George M."'
Search Results
2. 3D Numerical Analyses of Column-Supported Embankments: Failure Heights, Failure Modes, and Deformations
- Author
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Huang, Zhanyu, Ziotopoulou, Katerina, and Filz, George M
- Subjects
Civil Engineering ,Environmental Engineering ,Geological & Geomatics Engineering - Abstract
Design of column-supported embankments (CSE) requires the evaluation of global stability using the conventional limit equilibrium method (LEM). Yet, for CSEs using unreinforced concrete columns and load transferring geogrids, the failure mechanisms and corresponding soil-structure interactions are not well understood. There is increasing evidence pointing to large bending moments in columns and failure of columns in flexure, as opposed to a failure by shear as assumed in limit equilibrium analyses. In response to these design uncertainties, the failure height, failure mode, and deformations of eight column-supported embankment scenarios were investigated using three-dimensional (3D) numerical analyses. For the same embankment scenarios at failure height, factors of safety (FS) were then calculated using the two-dimensional (2D) LEM for investigating its applicability in evaluating global stability of CSEs. The 3D numerical analyses examined CSE stability for the limiting conditions at undrained end-of-construction and after long-term dissipation of excess pore water pressures. The numerical model included representations of flexural tensile failure in the concrete columns and tensile failure in the geosynthetic reinforcement. Scenarios consisted of a base case with typical concrete column design, five single-parameter variations using base case conditions, and two multiparameter variations using base case conditions. The undrained condition was the most critical, and two failure modes were found: (1) multisurface shearing in the embankment coupled with bending failure of columns and near-circular shear failure in the clay, and (2) multisurface shearing in the embankment coupled with bending failure of columns and shearing in the upper portion of the soft foundation clay. Both failure modes were accompanied by a rupture of the geosynthetic when included in the load transfer platform. Soil-column interactions were complex, and many columns failed in bending at lower embankment heights than those that produced collapse. The factors of safety calculated using the LEM were overstated. This is because the LEM assumes failure by shear, which has limited applicability for examining the complex mechanisms by which CSEs fail. The practical implication is that the LEM should not be used for evaluating global stability of this system type and, by extension, other system types in which soil-structure interactions result in failures controlled by mechanisms other than shear.
- Published
- 2020
3. Lateral Thrust Distribution of Column-Supported Embankments for Limiting Cases of Lateral Spreading
- Author
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Huang, Zhanyu, Ziotopoulou, Katerina, and Filz, George M
- Subjects
Civil Engineering ,Environmental Engineering ,Geological & Geomatics Engineering - Abstract
Lateral spreading analysis of column-supported embankments (CSEs) requires an understanding of lateral thrust distribution. This includes quantifying the portion of thrust that is resisted by tension in geosynthetic reinforcements installed in the load transfer platform. Results from a three-dimensional (3D) numerical parametric study using a half-embankment domain and totaling 140 scenarios are presented in terms of lateral thrust distribution. Forces examined include the lateral thrusts in the embankment and foundation soil, the geosynthetic tension, and the base shear at depth, and results are presented for the limiting cases of lateral spreading (i.e., undrained end-of-construction and long-term dissipated). Results show that lateral thrusts induced by embankment loading are significant in the embankment, foundation soil, and base shear beneath the columns. However, the portion of lateral thrust carried by the geosynthetic is limited, though it increases with the geosynthetic stiffness. Results also indicate that lateral spreading in CSEs is more critical at the undrained end-of-construction condition than in the long-term condition after excess pore water pressures have dissipated. Correlations for the thrust distribution at these limiting conditions and different embankment locations (i.e., centerline, shoulder, and toe) are provided.
- Published
- 2020
4. Effect of Exposure to Water at Different Temperatures during Curing on the Strength of Cement-Treated Soil
- Author
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Ju, Hwanik, primary, Abdelaziz, Sherif L., additional, and Filz, George M., additional
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- 2023
- Full Text
- View/download PDF
5. Negative Effect of Tannic Acid on the Strength of Cement-Stabilized Soil
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Ju, Hwanik, primary, Abdelaziz, Sherif L., additional, and Filz, George M., additional
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- 2023
- Full Text
- View/download PDF
6. Constant Curing Temperature Effect on the Strength of Cement-Treated Soil
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Ju, Hwanik, primary, Nevárez-Garibaldi, Roberto, additional, Abdelaziz, Sherif L., additional, and Filz, George M., additional
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- 2023
- Full Text
- View/download PDF
7. Deformation and Stability Analyses of a Pile Supported T-Wall with Deep Mixed Shear Panels in Plaquemines Parish, Louisianna
- Author
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Adams, Tiffany E., Filz, George M., Cali, Peter R., Woodward, Mark L., Liu, Hanlong, editor, Deng, An, editor, and Chu, Jian, editor
- Published
- 2008
- Full Text
- View/download PDF
8. Influence of Organic Matter on Strength Development of Cement-Water Slurry
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Ju, Hwanik, primary, Brand, Alexander S., additional, Abdelaziz, Sherif L., additional, and Filz, George M., additional
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- 2022
- Full Text
- View/download PDF
9. Failure Heights and Failure Modes of Eight Column-Supported Embankments via 3D Numerical Analyses
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Huang, Zhanyu, primary, Ziotopoulou, Katerina, additional, and Filz, George M., additional
- Published
- 2021
- Full Text
- View/download PDF
10. Atomic Force Microscopy Method for Measuring Smectite Coefficients of Friction
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Kosoglu, Laura M., Bickmore, Barry R., Filz, George M., and Madden, Andrew S.
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- 2010
- Full Text
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11. The effect of variability in hydraulic conductivity on contaminant transport through soil-bentonite cutoff walls
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Britton, Jeremy P., Filz, George M., and Little, John C.
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Hydraulics -- Research ,Bentonite -- Research ,Environmental engineering -- Research ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
Statistical analyses of data sets from five case histories indicate that soil-bentonite hydraulic conductivity is distributed log normally. The advection-diffusion equation was used to investigate the impact of log-normal variation in hydraulic conductivity on both steady-state and transient contaminant flux through a cutoff wall with idealized initial and boundary conditions. The results demonstrate that contaminant flux through cutoff walls increases as the variability in hydraulic conductivity increases while all other variables are held constant, including the area-weighted average conductivity. The effect of variability is most pronounced when advective transport and diffusive transport act in opposite directions, as occurs for circumferential cutoff walls that are operated with inward-directed hydraulic gradients to contain contaminated ground water. In this case, the increase in total outward flux due to variability of hydraulic conductivity occurs because the increase in inward advective flux in areas where the seepage velocity is higher than average is more than offset by the increase in outward diffusive flux in areas where the seepage velocity is lower than average. DOI: 10.1061/(ASCE) 1090-0241 (2005) 131:8 (951) CE Database subject headings: Bentonite; Core walls; Hydraulic Conductivity; Contaminants; Transport rate.
- Published
- 2005
12. Measuring the hydraulic conductivity of soil-bentonite backfill
- Author
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Britton, Jeremy P., Filz, George M., and Herring, Wayne E.
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Environmental engineering -- Research ,Soils -- Research ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
The hydraulic conductivity of soil--bentonite backfill in three pilot-scale cutoff walls was measured using laboratory tests on disturbed samples, laboratory tests on undisturbed samples, piezocone dissipation tests, and piezometer tests (also known as slug tests or single-well tests). In addition, a global measurement of the average hydraulic conductivity of the soil--bentonite backfill in one of the cutoff walls was made using the pilot-scale test facility. Two main factors distinguish these five different methods of measuring hydraulic conductivity: remolding and sample size. Remolding of samples tested in American Petroleum Institute filter press equipment significantly reduced their hydraulic conductivity compared to the hydraulic conductivity of undisturbed samples, which were of similar size. For the other tests, where the degree and extent of remolding were less significant, hydraulic conductivity was found to increase as sample size increased, with the global measurement producing the highest value. The existence of bentonite filter cakes on trench walls reduces the influence of sample size on the equivalent hydraulic conductivity of the barrier. Findings regarding locating defects with a piezocone and hydraulic fracture in piezometer tests are also presented. CE Database subject headings: Core walls; Hydraulic conductivity; Laboratory tests; In situ tests; Piezometers; Backfills.
- Published
- 2004
13. Stability of long trenches in sand supported by bentonite-water slurry
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Filz, George M., Adams, Tiffany, and Davidson, Richard R.
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Sand -- Research ,Slurry ,Bentonite ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
The most important mechanism by which bentonite-water slurry supports long trenches in sand is lateral pressure from the slurry. The effectiveness of this support can be compromised if filter cakes do not form on the trench walls. Criteria for filter cake formation are presented, along with the depth of slurry penetration and effects of the slurry on the strength of coarse granular soil when filter cakes do not form. Closed-form expressions are provided for global stability when filter cakes do form and for local stability when they do not form. A method for analyzing global stability when filter cakes do not form is also discussed. Increasing the bentonite concentration of the slurry has three beneficial impacts on stability: (1) the stagnation gradient increases, which improves local and global stability in cases where filter cakes do not form, (2) larger particles can become suspended in the slurry, which promotes filter cake formation on the walls of trenches excavated in coarse soils, and (3) more particles and larger particles can become suspended in the slurry, which increases the unit weight of the slurry and improves stability whether or not filter cakes form. DOI: 10.1061/(ASCE)1090-0241(2004)130:9(915) CE Database subject headings: Slurry trenches; Core walls; Sand; Slurries; Filters.
- Published
- 2004
14. Extended hyperbolic model for sand-to-concrete interfaces
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Gomez, Jesus E., Filz, George M., and Ebeling, Robert M.
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Shear strength of soils -- Testing ,Sand ,Piling (Civil engineering) ,Functions, Exponential -- Usage ,Soil mechanics -- Models ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
A relatively simple, four-parameter extended hyperbolic model for interfaces was developed for use in soil-structure interaction analyses. The model accommodates arbitrary stress path directions and includes three important elements: (1) development of a yield surface during interface shear; (2) a formulation for yield-inducing shear stiffness that is applicable to any stress path orientation; and (3) a formulation for unloading-reloading shear stiffness. The model was evaluated against the results of shear tests performed at the interface between three different types of sand and a concrete surface under a variety of stress paths. Comparisons between measured and calculated interface response indicate that the model provides accurate estimates of the response of sand-to-concrete interfaces. CE Database subject headings: Models; Sand; Concrete; Soil-structure interaction; Interfaces; Retaining walls.
- Published
- 2003
15. Composite compressibility model for municipal solid waste
- Author
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Marques, Afonso Celso Moruzzi, Filz, George M., and Vilar, Orencio Monje
- Subjects
Sao Paulo, Brazil (City) -- Waste management ,Sanitary landfills ,Compressibility -- Research ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
Three important mechanisms that contribute to the compression of municipal solid waste are instantaneous compression in response to applied load, secondary mechanical creep, and time-dependent biological decomposition. A composite compressibility model that explicitly takes these mechanisms into account was developed and implemented in a computer program to calculate landfill settlements. The model performance was assessed using data from the Bandeirantes Landfill, which is a well-documented landfill located in Sao Paulo, Brazil, and upon which an instrumented test fill was constructed. Model parameter values were obtained by nonlinear regression analysis, and it was found that the composite model tracked observed patterns of landfill settlement very well. Furthermore, the average parameter values from nonlinear regression analyses for 20 instruments exhibited small deviations between calculated and observed settlements, indicating that a single set of parameter values can provide reasonably good representation of all the waste in the vicinity of the test fill. Recommendations for applying the model to other landfills are provided. DOI: 10.1061/(ASCE)1090-0241(2003)129:4(372) CE Database subject headings: Municipal wastes; Solid wastes; Compressibility; Landfills; Settlement.
- Published
- 2003
16. Sheet pile tensions in cellular structures
- Author
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Wissmann, Kord J., Filz, George M., Mosher, Reed L., and Martin, James R., II
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Environmental engineering -- Research ,Coffer-dams -- Research ,Sheet-steel -- Research ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
Cellular structures constructed of interlocking steel sheet piles are used in marine environments as cofferdams, bulkheads, mooring dolphins, and lock guide walls. In addition to providing safety against sliding, bearing failure, overturning, and tilting, cellular structures must also be designed to prevent sheet pile interlock rupture, which can lead to catastrophic failure if the cell fill is lost. Methods commonly used to estimate sheet pile interlock tensions were developed in the 1940's, 1950's, and 1970's. These methods are based on empirical observations, and they do not explicitly account for soil-structure interactions. This paper presents the results of finite element analyses and instrumentation measurements performed to examine soil-structure interaction effects on sheet pile tensions. The finite-element analyses were used to compute sheet pile tensions at five instrumented cells, and the results are compared with measurements. The calibrated finite-element model was then used to investigate the effects of varying cell geometry, interlock behavior, sheet pile penetration depth, and foundation stiffness on sheet pile tensions. The instrumentation measurements provide data for estimating changes in sheet pile tensions due to cell fill densification, cofferdam unwatering, and bulkhead backfilling. CE Database keywords: Sheet piles; Tensions; Cofferdams; Bulkheads; Instrumentation; Finite-element method.
- Published
- 2003
17. Barrier-controlled monitored natural attenuation
- Author
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Filz, George M., Widdowson, Mark A., and Little, John C.
- Subjects
Pollution control industry -- Research ,Environmental remediation -- Research ,Benzene ,Environmental issues ,Science and technology - Abstract
An analytical conceptualization of the management of a contaminated groundwater site with a vertical barrier is formulated to act in tandem with monitored natural attenuation in the remediation of benzene. The barrier-controlled monitored natural attenuation (BCMNA) scheme is designed to control the rate of contaminant release.
- Published
- 2001
18. Lateral Thrust Distribution in Column-Supported Embankments: A Parametric Study via 3D Simulations
- Author
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Huang, Zhanyu, primary, Ziotopoulou, Katerina, additional, and Filz, George M., additional
- Published
- 2020
- Full Text
- View/download PDF
19. 3D Numerical Limiting Case Analyses of Lateral Spreading in a Column-Supported Embankment
- Author
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Huang, Zhanyu, primary, Ziotopoulou, Katerina, additional, and Filz, George M., additional
- Published
- 2019
- Full Text
- View/download PDF
20. Theory
- Author
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Filz, George M. and Duncan, J. Michael
- Subjects
Shear (Mechanics) -- Research ,Walls -- Research ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
Retaining walls that do not move are customarily designed based on the assumption of at-rest conditions, with no consideration of vertical shear loads applied by the backfill. However, field and laboratory measurements have shown that vertical shear loads do act on nonmoving walls. A simple theory for calculating the magnitude of vertical shear loads on nonmoving walls is presented in this paper, and typical results from the theory are discussed. A companion paper presents the results of finite-element calculations, case history data, and recommendations for retaining wall design.
- Published
- 1997
21. Applications
- Author
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Filz, George M., Duncan, J. Michael, and Ebeling, Robert M.
- Subjects
Shear (Mechanics) -- Research ,Concrete walls -- Research ,Foundations (Building) -- Research ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
Massive concrete walls constructed on rock foundations, as well as other nonmoving retaining walls, are customarily designed for at-rest earth pressures. Vertical shear loads applied by the backfill are usually not considered in design of nonmoving walls, even though many field and laboratory measurements have shown that such loads exist. Vertical shear loads can be very beneficial for stability of retaining walls, because they provide restoring moments to counteract overturning moments from lateral earth loads. In this paper, model test results and case history data are reviewed, the results of finite-element calculations are presented, and a simple design procedure is developed. It is shown that significant economies can result from consideration of vertical shear forces in design of nonmoving retaining walls.
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- 1997
22. Settlement and Vertical Load Transfer in Column-Supported Embankments
- Author
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Filz, George M., primary, Sloan, Joel A., additional, McGuire, Michael P., additional, Smith, Miriam, additional, and Collin, James, additional
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- 2019
- Full Text
- View/download PDF
23. A tiered, system-of-systems modeling framework for resolving complex socio-environmental policy issues
- Author
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Little, John C., primary, Hester, Erich T., additional, Elsawah, Sondoss, additional, Filz, George M., additional, Sandu, Adrian, additional, Carey, Cayelan C., additional, Iwanaga, Takuya, additional, and Jakeman, Anthony J., additional
- Published
- 2019
- Full Text
- View/download PDF
24. Fiber Reinforcement for Rapid Stabilization of Soft Clay Soils
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Rafalko, Susan D., primary, Brandon, Thomas L., primary, Filz, George M., primary, and Mitchell, James K., primary
- Published
- 2006
- Full Text
- View/download PDF
25. Numerical Predictions of Deformations in Geosynthetic-Reinforced Column-Supported Embankments: Validation of Manual Dissipation of Excess Pore Pressure Approach for Undrained and Drained Analyses
- Author
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Huang, Zhanyu, primary, Ziotopoulou, Katerina, additional, and Filz, George M., additional
- Published
- 2018
- Full Text
- View/download PDF
26. Numerical Methods to Model Excavation of Soil Adjacent to Retaining Structures
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Gutierrez, Marte S., primary, Ebeling, Robert M., primary, and Filz, George M., primary
- Published
- 2002
- Full Text
- View/download PDF
27. Extended Load/Unload/Reload Hyperbolic Model for Interfaces: Parameter Values and Model Performance for the Contact Between Concrete and Coarse Sand
- Author
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Gomez, Jesus E., primary, Filz, George M., primary, and Ebeling, Robert M., primary
- Published
- 2000
- Full Text
- View/download PDF
28. Development of an Improved Numerical Model for Concrete-to-Soil Interfaces in Soil-Structure Interaction Analyses. Report 1 Preliminary Study
- Author
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Gomez, Jesus E., primary, Filz, George M., primary, and Ebeling, Robert M., primary
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- 1999
- Full Text
- View/download PDF
29. Bench-Scale Test Apparatus for Modeling Column-Supported Embankments
- Author
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McGuire, Michael P., primary and Filz, George M., additional
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- 2017
- Full Text
- View/download PDF
30. PROGRESSIVE FAILURE OF LINED WASTE IMPOUNDMENTS
- Author
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Filz, George M., Esterhuizen, Jacob J. B., and Duncan, J. Michael
- Subjects
Geosynthetics -- Research ,Sanitary landfills -- Environmental aspects ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
Progressive failure can occur along geosynthetic interfaces in lined waste landfills when peak strengths are greater than residual strengths. A displacement-softening formulation for geosynthetic interfaces was used in finite-element analyses of lined waste impoundments to evaluate the significance of progressive failure effects. First, the Kettleman Hills landfill was analyzed, and good agreement was found between the calculated and observed failure heights. Next, parametric analyses of municipal solid waste landfills were performed. Progressive failure was significant in all cases. Limit equilibrium analyses were also performed, and recommendations are provided for incorporating progressive failure effects in limit equilibrium analyses of municipal solid waste landfills.
- Published
- 2001
31. CONSTITUTIVE BEHAVIOR OF GEOSYNTHETIC INTERFACES
- Author
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Esterhuizen, Jacob J. B., Filz, George M., and Duncan, J. Michael
- Subjects
Geosynthetics -- Research ,Fills (Earthwork) -- Analysis ,Earth sciences ,Engineering and manufacturing industries ,Science and technology - Abstract
New displacement-softening and work-softening models were developed to describe the sliding of geosynthetic interfaces, such as those in landfill liners. The displacement-softening formulation is based on the assumption that strength reduction at the interface can be related to nonrecoverable (plastic) shear displacement. The model uses three relationships: (1) the peak strength envelope; (2) the residual strength envelope; and (3) the residual factor versus displacement ratio relationship, which is a nondimensional expression of the rate at which displacement-softening occurs. The displacement-softening model is accurate for shearing when the normal stress stays constant. When normal stress increases during shearing, the displacement-softening formulation overpredicts damage to geosynthetic interfaces. The work-softening model was developed to compute interface softening during conditions of increasing normal stress. This formulation is based on the assumption that the postpeak reduction in shear strength can be attributed to plastic shear work rather than plastic shear displacement. By calculating an equivalent plastic shear displacement for a given amount of plastic shear work, the work-softening model can be formulated using the same basic relationships as the displacement-softening model. The work-softening model significantly outperformed the displacement-softening model when simulating laboratory tests under conditions of increasing normal stress.
- Published
- 2001
32. Deep Mixing Grows Up: The Evolution of Deep-Mixing Technology in the U.S. Market over the Last Decade
- Author
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Filz, George M., primary and Bruce, Donald A., additional
- Published
- 2016
- Full Text
- View/download PDF
33. Sustainability Comparison of a Geosynthetic-Reinforced Soil Abutment and a Traditionally-Founded Abutment: A Case History
- Author
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Phillips, Erin K., primary, Shillaber, Craig M., additional, Mitchell, James K., additional, Dove, Joseph E., additional, and Filz, George M., additional
- Published
- 2016
- Full Text
- View/download PDF
34. Stability of Column-Supported Embankments
- Author
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Filz, George M., Michael P. Navin, Civil and Environmental Engineering, Virginia Transportation Research Council, and Virginia Tech
- Subjects
Column-supported embankment ,Deep mixing ,Reliability analysis ,Numerical analysis - Abstract
Column-supported embankments have a great potential for application in the coastal regions of Virginia, where highway embankments are often constructed on soft ground. The columns can be driven piles, vibro-concrete columns, deep-mixing-method columns, stone columns, or other suitable types. Column-supported embankments are used to accelerate construction by eliminating consolidation times that are needed for preloading and surcharging operations associated with conventional prefabricated vertical drains. This study has resulted in a development of new numerical stress-strain analyses to evaluate the stability of embankments supported on columns installed by deep mixing method. Such analyses reflect the multiple realistic failure mechanisms that can occur when strong columns are installed in weak soil. Detailed recommendations for performing numerical analyses are presented. The findings are also expected to apply to vibro-concrete columns, because they, like deep-mixing-method columns, are strong in compression but weak in bending and tension. The study also recommends the use of reliability analyses in conjunction with the stability analysis. Reliability analyses are necessary, because deep-mixed materials can be highly variable and because typical variations in the strength of the surrounding clay can induce abrupt tensile failure in columns. Additional benefit of the reliability-based design is that it permits rational development of statistically-based specifications for constructing deep-mixed materials. Virginia Department of Transportation 73977
- Published
- 2006
35. Design of Bridging Layers in Geosynthetic-Reinforced, Column-Supported Embankments
- Author
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Filz, George M., Miriam E. Smith, Civil and Environmental Engineering, Virginia Transportation Research Council, and Virginia Tech
- Subjects
Column-supported embankment ,Geosynthetic-reinforced ,Bridging layer - Abstract
The cost of column-supported embankments depends, in part, on the spacing between the columns and the size of the columns and pile caps. Geosynthetic reinforcement is often employed in bridging layers to enhance load transfer to the columns and to increase the column spacing. The number, stiffness, and strength of geosynthetic layers are selected based on considerations of load transfer and deformation. In this research, a new method was developed for calculating the load on the geosynthetic reinforcement. The new method employs one of the existing mechanistically based approaches and combines it with consideration of the stiffnesses of the embankment, geosynthetic reinforcement, columns, and existing site soil. The new method was verified against the results of a large numerical parameter study, for which the numerical procedures themselves were verified against closed-form solutions for membranes, pilot-scale experiments, and field case histories. The new method for calculating load on the geosynthetic was integrated into a 10-step design procedure for geosynthetic-reinforced bridging layers in column-supported embankments. The design procedure addresses such details as the thickness and type of the bridging layer soil, selection of the geosynthetic reinforcement, if needed, and the embankment settlement. The necessary calculations have been programmed into a Microsoft Excel workbook. The workbook may be accessed at www.virginiadot.org/vtrc/main/online%5Freports/pdf/geogridbridge.pdf Virginia Department of Transportation 73977
- Published
- 2006
36. Specifications for Embankment and Subgrade Compaction
- Author
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Michael P. McGuire, Filz, George M., Civil and Environmental Engineering, Virginia Transportation Research Council, and Virginia Tech
- Subjects
Subgrade compaction ,Embankment specifications ,Performance based specifications ,Earthworks specifications - Abstract
Six approaches were developed for specifying embankment and subgrade compaction and/or verifying compaction quality on Virginia Department of Transportation (VDOT) construction projects. These approaches, along with VDOT's current practices, were qualitatively evaluated for applicability considering the benefits and risks of each approach. Based on the findings, the use of specifications based on embankment performance measurements is viable for large design-build or design-build-maintain projects. The use of these specifications permits greater innovation on the part of the contractor while shifting more of the overall project risk to the contractor. The contractor's increased stake in the post-construction performance of the embankment aims to promote high quality workmanship with reduced oversight by VDOT. The primary risks faced by VDOT through the use of performance specifications include: (1) disputes between VDOT and the contractor over deficient embankment performance during the warranty period; (2) the difficulty of repairing underlying embankments when finished roadway features, such as pavements, are already in place; and (3) the uncertainty that construction defects will be manifested in a measurable way during the finite term of the performance period. There was considerable support, in both published sources and the responses generated from the survey of experts conducted for this project, for full time visual inspection of embankment construction. To the extent that is feasible considering fiscal and policy constraints, it is recommended that VDOT increase the number of experienced inspectors on embankment construction projects. Three approaches were considered to increase the number of inspectors. The first of these was simply for VDOT to hire more experienced inspectors; however, it is understood that this approach is very unlikely to be feasible. Another approach is for VDOT to outsource inspection work to a private engineering firm. The use of this approach allows for rapid adaptation of the inspection labor supply to changing construction demands. A potential shortcoming of this approach is that VDOT may see an increase in overall project costs compared to hiring its own inspectors. A third approach considered to increase the number of inspectors available on VDOT projects is to have the contractor contract with a private engineering firm to provide outside inspectors. This approach is not recommended based on extensive concerns expressed by the project focus group and the surveyed experts about the potential for a conflict of interest. This study also considered the use of a pay factor for embankment construction to motivate the contractor to deliver high quality compaction. The pay factor developed for this project links the contractor's payment to the results of field density tests. A shortcoming of this approach is that it increases the potential for disputes between the contractor and VDOT because every density test has the potential to influence the contractors pay. Another recommendation of this study is to significantly increase the minimum frequency of field density and compaction moisture content testing for embankment construction. It is important to highlight that an increased test frequency should not be considered as a replacement for observation by an experienced earthwork inspector. Virginia Department of Transportation 71180
- Published
- 2005
37. Stabilization of Soft Clay Subgrades in Virginia: Phase I Laboratory Study
- Author
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Christopher M. Geiman, Filz, George M., Brandon, Thomas L., Civil and Environmental Engineering, and Virginia Tech
- Subjects
Subgrade ,Soft clay ,Stabilization - Abstract
Many pavement subgrades in Virginia consist of wet, highly plastic clay or other troublesome soils. Such soils can be treated with traditional lime and cement stabilization methods. Alternatives, including lignosulfonates and polymers, are available, but their performance record is mixed and solid engineering data are lacking, which prevents reliable design. The goal of this research was to screen a suite of traditional and non-traditional stabilizers against three Virginia soils that have caused problems during construction or resulted in poor performance in service. The selected stabilizers were: quicklime, hydrated lime, pelletized lime, cement, lignosulfonate, synthetic polymer, magnesium chloride, and a proprietary cementitious stabilizer. A laboratory procedure was developed and applied to three Virginia soils obtained from Northern Virginia, Staunton, and Lynchburg. Key findings from the research include: (1) traditional lime and cement stabilizers were far more effective than liquid stabilizers (lignosulfonate, synthetic polymer, and magnesium chloride) in increasing strength; (2) the liquid stabilizers were ineffective on soils with a high moisture content; (3) the proprietary cementitious stabilizer was more effective in increasing strength than lime for all cases tested but not was not as effective as the cement stabilizer; (4) quicklime and hydrated lime increased the workability of the soils although they did not produce strengths comparable to cement; (5) the strength of soils stabilized with cement and the proprietary cementitious stabilizer can be estimated based on the water-amendment ratio of the mixture; and (6) the strength of soils stabilized with lime can be estimated based on a combination of the plasticity index and the water-amendment ratio of the mixture. The benefits of subgrade stabilization are that it improves the strength, stiffness, and durability of soft subgrade soils. Such improvement allows a reduction in the required thickness of overlying pavement courses and/or an increase in pavement life. Quantifying the life cycle cost benefits requires performing pavement design studies based on anticipated traffic levels, desired serviceability, etc. The preferred design method would be a mechanistic design, which requires resilient modulus values for the stabilized subgrade and other pavement layers. Neither resilient modulus testing nor pavement design studies were included in the scope of the work for this project, but they should be included in subsequent phases. Virginia Department of Transportation 71177
- Published
- 2005
38. Deformation and Stability Analyses of a Pile Supported T-Wall with Deep Mixed Shear Panels in Plaquemines Parish, Louisianna
- Author
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Adams, Tiffany E., primary, Filz, George M., additional, Cali, Peter R., additional, and Woodward, Mark L., additional
- Full Text
- View/download PDF
39. Full-Scale Investigation of Differential Settlements beneath a GRS Bridge Abutment: An Overview
- Author
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Kost, Andrew D., primary, Filz, George M., additional, Cousins, Tommy, additional, and Brown, Michael C., additional
- Published
- 2014
- Full Text
- View/download PDF
40. Full-Scale Investigation of Differential Settlements beneath a Geosynthetic-Reinforced Soil Bridge Abutment
- Author
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Kost, Andrew D., primary, Filz, George M., additional, Cousins, Tommy, additional, and Brown, Michael C., additional
- Published
- 2014
- Full Text
- View/download PDF
41. Factors Affecting Strength Gain in Lime-Cement Columns and Development of a Laboratory Testing Procedure
- Author
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Jesse R. Jacobson, Filz, George M., Mitchell, James K., Civil and Environmental Engineering, Virginia Transportation Research Council, and Virginia Tech
- Subjects
Ground improvement ,Lime-cement-soil ,Lime-cement columns - Abstract
Lime-cement columns were constructed to improve soft ground as part of a test embankment program at the I-95/Route interchange in Alexandria, Virginia. Two different commercial laboratories performed tests on treated soil, and they produced very different measurements of unconfined compressive strength. Further, both sets of results were different from test results available in the published literature for similar soils. This situation created uncertainties and a conservative design philosophy. The goals of this research project were to assess factors that influence strength gain of lime-cement-soil mixtures, to develop a detailed laboratory test procedure that produces consistent results, and to determine the reasons that the strengths measured by the private firms were so different. A suitable laboratory procedure was developed and applied to three soils: one from the I-95/Route interchange site and two from the site of a potential future application of lime-cement columns in West Point, Virginia, at State Route 33. Key findings from the research were that (1) drying and subsequent restoration of soil moisture prior to treatment can decrease the strength of the mixture, (2) the mixture strength decreases as the ratio of soil water content to cement content increases for 100 percent cement-soil mixtures, (3) the addition of lime can increase the mixture strength for some soils and decrease the strength for others, and (4) presenting the test results in the form of contour plots of unconfined compressive strength can be very useful. The reasons for the different results from the two private firms are explained by differences in the test procedures that were used. Virginia Department of Transportation 01-0978-12 FHWA 01-0978-12
- Published
- 2003
42. Thermal Response of Integral Abutment Bridges with Mechanically Stabilized Earth Walls
- Author
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Civil and Environmental Engineering, Arenas, Alfredo E., Filz, George M., Cousins, Thomas E., Civil and Environmental Engineering, Arenas, Alfredo E., Filz, George M., and Cousins, Thomas E.
- Abstract
The advantages of integral abutment bridges (IABs) include reduced maintenance costs and increased useful life spans. However, improved procedures are necessary to account for the impacts of cyclic thermal displacements on IAB components, including the foundation piling and the components of mechanically stabilized earth (MSE) walls that are often used around IABs. As requested by the Virginia Center for Transportation Innovation and Research and the Virginia Department of Transportation (VDOT), this research focused on IABs with foundation piling in the backfill of MSE walls that have a "U-back" configuration, which indicates that the MSE wall has three faces, one parallel to the abutment and two parallel to the bridge alignment. During this research, more than 65 three-dimensional numerical analyses were performed to investigate and quantify how different structural and geotechnical bridge components behave during thermal expansion and contraction of the bridge. In addition, a separate series of three-dimensional numerical models were developed to evaluate the usefulness of corrugated steel pipes in-filled with loose sand around the abutment piles. The results of this research quantify the influence of design parameter variations on the effects of thermal displacement on system components, and thus provide information necessary for IAB design. One of the findings is that corrugated steel pipes around abutment piles are not necessary. An estimate of the cost savings from eliminating these pipes is presented. One of the most important outputs of this research is an easy-to-use Excel spreadsheet, named IAB v3, that quantifies the impact of thermal displacement in the longitudinal direction, but also in the transverse direction when the abutment wall is at a skew angle to the bridge alignment. The spreadsheet accommodates seven different pile sizes, which can be oriented for weak or strong axis bending, with variable offset of the abutment from the MSE wall and for va
- Published
- 2013
43. Erosion Protection for Soil Slopes Along Virginia's Highways
- Author
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Scarborough, Jessee A., Filz, George M., Mitchell, James K., Brandon, Thomas L., Civil and Environmental Engineering, and Virginia Tech
- Subjects
Erosion ,Erosion control ,USLE ,Erosion protection ,Soil slopes - Abstract
A survey of the state of practice for designing slope erosion control measures within VDOT's nine districts has been conducted. On the basis of the survey, it is clear that there are no specific design procedures currently in use within VDOT for dealing with slope erosion. VDOT designers generally try to limit erosion by diverting runoff from adjacent areas, controlling concentrated flows on slopes, and establishing vegetation on slopes as quickly as possible. In addition, the Federal Highway Administration (FHWA) and the Departments of Transportation in states surrounding Virginia (Maryland, West Virginia, Kentucky, Tennessee, and North Carolina) were contacted. The state of practice for the FHWA and for these states appears to be similar to that used by VDOT. A review of the literature for soil erosion was performed. The universal soil loss equation (USLE), an empirical equation developed by the U.S. Department of Agriculture, was found to provide the best available quantitative tool for evaluating factors controlling the erosion process and determining what level of protection is appropriate. The authors recommend that the USLE be used to supplement VDOT's current principle-based design practices. Virginia Department of Transportation 99-1017-11
- Published
- 2000
44. Rapid Stabilization/Polymerization of Wet Clay Soils; Literature Review
- Author
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VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Brandon, Thomas L., Brown, Jonathan J., Daniels, W. L., DeFazio, Thomas L., Filz, George M., Mitchell, James K., Musselman, Jared, Forsha, Clinton, VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Brandon, Thomas L., Brown, Jonathan J., Daniels, W. L., DeFazio, Thomas L., Filz, George M., Mitchell, James K., Musselman, Jared, and Forsha, Clinton
- Abstract
This report is written in response to a request from the Air Force Research Laboratory concerning research on rapid stabilization/polymerization of wet clay soils. The purpose of this report is to document the findings of a literature review (Phase I) carried out by the team assembled at Virginia Tech. The literature review covers approximately 200 papers, most of which deal with clay stabilization. This report contains the findings of this literature review, which are categorized by soil type, stabilization type, as well as other factors. This report also includes the recommendations of the Virginia Tech research team for a proposed research program for Phase II.
- Published
- 2009
45. Rapid Chemical Stabilization of Soft Clay Soils
- Author
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VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan D., Brandon, Thomas L., Filz, George M., Mitchell, James K., VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan D., Brandon, Thomas L., Filz, George M., and Mitchell, James K.
- Abstract
Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have been the most effective stabilizers for road and airfield applications, although many nontraditional stabilizers also have been developed and used. The most effective stabilizer to increase the strength of two soft clay soils within 72 h for contingency airfields to support C-17 and C-130 aircraft traffic needed to be determined. The treatment of one clay with cement resulted in relatively high unconfined compressive strengths (UCS), whereas treating the same clay with quicklime and calcium carbide resulted in lower UCS. The treatment of another clay with higher plasticity resulted in similar UCS for cement, quicklime, and calcium carbide. Secondary stabilizers, including sodium silicate, superabsorbent polymers, a superplasticizer, and an accelerator, were ineffective in increasing the UCS of a soil trained cement, quicklime, or calcium carbide., Pub. in Jnl. of the Transportation Research Board, n2026 p39-46, Transportation Research Board of the National Academies, Washington, DC, 2007.
- Published
- 2008
46. Fiber Reinforcement for Rapid Stabilization of Soft Clay Soils
- Author
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VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan D., Brandon, Thomas L., Filz, George M., Mitchell, James K., VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan D., Brandon, Thomas L., Filz, George M., and Mitchell, James K.
- Abstract
Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have been the most effective stabilizers for road and airfield applications, although recent developments show promise from nontraditional stabilizers, such as reinforcing fibers. The benefits derived from fibers may depend on whether they are used alone or in combination with chemical stabilizers. The ability of stabilizers to increase the strength of two soft clay soils within 72 hours to support C-17 and C-130 aircraft traffic on contingency airfields was investigated. Laboratory test results shows that longer fibers increased the strength and toughness the most for a clay treated only with fibers. For a clay treated with fibers in addition to a chemical stabilizer, shorter fibers increased toughness the most, but the fibers had little effect on strength. Higher dosage rates of fibers had increasing effectiveness, but mixing became difficult for fiber contents above 1%. Poly(vinyl) alcohol fibers were anticipated to perform better than other inert fibers because of hydrogen bonding between the fibers and clay minerals, but these fibers performed similarly to other fibers., Published in Transportation Research Record, Journal of the Transportation Research Board, no. 2026 p21-29, 2007.
- Published
- 2008
47. Load Distribution on Geosynthetic Reinforcement in Column-Supported Embankments
- Author
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Filz, George M., primary and Sloan, Joel A., additional
- Published
- 2013
- Full Text
- View/download PDF
48. Fiber Reinforcement for Rapid Stabilization of Soft Clay Soils
- Author
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VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan D., Brandon, Thomas L., Filz, George M., Mitchell, James K., VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan D., Brandon, Thomas L., Filz, George M., and Mitchell, James K.
- Abstract
Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have been the most effective stabilizers for road and airfield applications, although recent developments show promise from nontraditional stabilizers, such as reinforcing fibers. The benefits derived from fibers may depend on whether they are used alone or in combination with chemical stabilizers. The purpose of the research described in this paper is to investigate the ability of stabilizers to increase the strength of two soft clay soils within 72 hours to support C-17 and C-130 aircraft traffic on contingency airfields. Laboratory test results showed that longer fibers increased the strength and toughness the most for a clay treated only with fibers. For a clay treated with fibers in addition to a chemical stabilizer, shorter fibers increased toughness the most, but the fibers had little effect on strength. Higher dosage rates of fibers had increasing effectiveness, but mixing became difficult for fiber contents above 1%. Poly(vinyl) alcohol (PVA) fibers were anticipated to perform better than other inert fibers due to hydrogen bonding between the fibers and clay minerals, but these fibers performed similar to other fibers., The original document contains color images. All DTIC reproductions will be in black and white.
- Published
- 2006
49. Rapid Soil Stabilization of Soft Clay Soils for Contingency Airfields
- Author
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VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan, Brandon, Thomas L., Filz, George M., Mitchell, James K., VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, Rafalko, Susan, Brandon, Thomas L., Filz, George M., and Mitchell, James K.
- Abstract
Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have consistently been found to be among the most effective stabilizers for road and airfield applications, although recent developments show promise using nontraditional stabilizers. The purpose of this research is to determine the most effective stabilizers and dosage rates of stabilizers to increase the strength of soft clay soils (initial CBR = 2) within 72 hours for contingency airfields to support C-17 and C-130 aircraft traffic. Pavement design charts for various aircraft loading conditions were generated using the Pavement- Transportation Computer Assisted Structural Engineering Program, which was developed by the Engineering Research and Development Center to determine ranges of required strength and thickness for an underlying subbase layer and a top base layer, such as stabilized soil, crushed-aggregate, or aluminum matting. From laboratory studies, the required design strengths for many loading conditions were achieved by treating clay with 2%-4% pelletized quicklime for the underlying subbase layer, and treating clay with 2%- 4% pelletized quicklime, 1% RSC15 fibers, and 11% Type III cement for the top base layer. While the base layer requires a minimum thickness of six inches, the required subbase layer thickness is often quite large and may be difficult to construct. However, newly developed construction equipment currently used for subgrade stabilization on civilian projects should be able to stabilize the soil down to these large required depths and make construction possible.
- Published
- 2006
50. Design of Bridging Layers in Geosynthetic-Reinforced, Column-Supported Embankments
- Author
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Civil and Environmental Engineering, Filz, George M., Miriam E. Smith, Civil and Environmental Engineering, Filz, George M., and Miriam E. Smith
- Abstract
The cost of column-supported embankments depends, in part, on the spacing between the columns and the size of the columns and pile caps. Geosynthetic reinforcement is often employed in bridging layers to enhance load transfer to the columns and to increase the column spacing. The number, stiffness, and strength of geosynthetic layers are selected based on considerations of load transfer and deformation. In this research, a new method was developed for calculating the load on the geosynthetic reinforcement. The new method employs one of the existing mechanistically based approaches and combines it with consideration of the stiffnesses of the embankment, geosynthetic reinforcement, columns, and existing site soil. The new method was verified against the results of a large numerical parameter study, for which the numerical procedures themselves were verified against closed-form solutions for membranes, pilot-scale experiments, and field case histories. The new method for calculating load on the geosynthetic was integrated into a 10-step design procedure for geosynthetic-reinforced bridging layers in column-supported embankments. The design procedure addresses such details as the thickness and type of the bridging layer soil, selection of the geosynthetic reinforcement, if needed, and the embankment settlement. The necessary calculations have been programmed into a Microsoft Excel workbook. The workbook may be accessed at www.virginiadot.org/vtrc/main/online%5Freports/pdf/geogridbridge.pdf
- Published
- 2006
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