ºÝºÝߣshows by User: MahirBadanagki / http://www.slideshare.net/images/logo.gif ºÝºÝߣshows by User: MahirBadanagki / Wed, 25 Jul 2018 01:25:09 GMT ºÝºÝߣShare feed for ºÝºÝߣshows by User: MahirBadanagki Influence of Dense Granular Columns on the Performance of Level and Gently Sloping Liquefiable Sites /slideshow/influence-of-dense-granular-columns-on-the-performance-of-level-and-gently-sloping-liquefiable-sites/107378985 badanagkietal-180725012509
Dense granular columns are often used as a liquefaction mitigation measure to (1) enhance drainage; (2) provide shear reinforcement; and (3) densify and increase lateral stresses in the surrounding soil during installation. However, the independent influence and contribution of these mitigation mechanisms on the excess pore pressures, accelerations (or shear stresses), and lateral and vertical deformations are not sufficiently understood to facilitate a reliable design. This paper presents the results of a series of dynamic centrifuge tests to fundamentally evaluate the influence of dense granular columns on the seismic performance of level and gently sloped sites, including a liquefiable layer of clean sand. Specific consideration was given to the relative importance of enhanced drainage and shear reinforcement. Granular columns with greater area replacement ratios (Ar), for example Ar greater than about 20%, were shown to be highly effective in reducing the seismic settlement and lateral deformations in gentle slopes, owing primarily to the expedited dissipation of excess pore water pressures. The influence of granular columns on accelerations (and therefore, the shear stress demand) in the surrounding soil depended on the column’s Ar and drainage capacity. Increasing Ar from 0 to 10% was shown to reduce the accelerations across a range of frequencies in the surrounding soil due to the shear reinforcement effect alone. However, enhanced drainage simultaneously increased the rate of excess pore pressure dissipation, helping the surrounding soil regain more quickly its shear strength and stiffness. At short drainage distances or higher Ar values (for example, 20%), this could notably amplify the acceleration and shear stress demand on soil, particularly at greater frequencies that influence PGA. The experimental insight presented in this paper aims to improve our understanding of the mechanics of liquefaction and lateral spreading mitigation with granular columns, and it may be used to validate the numerical models used in their design. ]]>
Dense granular columns are often used as a liquefaction mitigation measure to (1) enhance drainage; (2) provide shear reinforcement; and (3) densify and increase lateral stresses in the surrounding soil during installation. However, the independent influence and contribution of these mitigation mechanisms on the excess pore pressures, accelerations (or shear stresses), and lateral and vertical deformations are not sufficiently understood to facilitate a reliable design. This paper presents the results of a series of dynamic centrifuge tests to fundamentally evaluate the influence of dense granular columns on the seismic performance of level and gently sloped sites, including a liquefiable layer of clean sand. Specific consideration was given to the relative importance of enhanced drainage and shear reinforcement. Granular columns with greater area replacement ratios (Ar), for example Ar greater than about 20%, were shown to be highly effective in reducing the seismic settlement and lateral deformations in gentle slopes, owing primarily to the expedited dissipation of excess pore water pressures. The influence of granular columns on accelerations (and therefore, the shear stress demand) in the surrounding soil depended on the column’s Ar and drainage capacity. Increasing Ar from 0 to 10% was shown to reduce the accelerations across a range of frequencies in the surrounding soil due to the shear reinforcement effect alone. However, enhanced drainage simultaneously increased the rate of excess pore pressure dissipation, helping the surrounding soil regain more quickly its shear strength and stiffness. At short drainage distances or higher Ar values (for example, 20%), this could notably amplify the acceleration and shear stress demand on soil, particularly at greater frequencies that influence PGA. The experimental insight presented in this paper aims to improve our understanding of the mechanics of liquefaction and lateral spreading mitigation with granular columns, and it may be used to validate the numerical models used in their design. ]]> Wed, 25 Jul 2018 01:25:09 GMT /slideshow/influence-of-dense-granular-columns-on-the-performance-of-level-and-gently-sloping-liquefiable-sites/107378985 MahirBadanagki@slideshare.net(MahirBadanagki) Influence of Dense Granular Columns on the Performance of Level and Gently Sloping Liquefiable Sites MahirBadanagki Dense granular columns are often used as a liquefaction mitigation measure to (1) enhance drainage; (2) provide shear reinforcement; and (3) densify and increase lateral stresses in the surrounding soil during installation. However, the independent influence and contribution of these mitigation mechanisms on the excess pore pressures, accelerations (or shear stresses), and lateral and vertical deformations are not sufficiently understood to facilitate a reliable design. This paper presents the results of a series of dynamic centrifuge tests to fundamentally evaluate the influence of dense granular columns on the seismic performance of level and gently sloped sites, including a liquefiable layer of clean sand. Specific consideration was given to the relative importance of enhanced drainage and shear reinforcement. Granular columns with greater area replacement ratios (Ar), for example Ar greater than about 20%, were shown to be highly effective in reducing the seismic settlement and lateral deformations in gentle slopes, owing primarily to the expedited dissipation of excess pore water pressures. The influence of granular columns on accelerations (and therefore, the shear stress demand) in the surrounding soil depended on the column’s Ar and drainage capacity. Increasing Ar from 0 to 10% was shown to reduce the accelerations across a range of frequencies in the surrounding soil due to the shear reinforcement effect alone. However, enhanced drainage simultaneously increased the rate of excess pore pressure dissipation, helping the surrounding soil regain more quickly its shear strength and stiffness. At short drainage distances or higher Ar values (for example, 20%), this could notably amplify the acceleration and shear stress demand on soil, particularly at greater frequencies that influence PGA. The experimental insight presented in this paper aims to improve our understanding of the mechanics of liquefaction and lateral spreading mitigation with granular columns, and it may be used to validate the numerical models used in their design. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/badanagkietal-180725012509-thumbnail.jpg?width=120&amp;height=120&amp;fit=bounds" /><br> Dense granular columns are often used as a liquefaction mitigation measure to (1) enhance drainage; (2) provide shear reinforcement; and (3) densify and increase lateral stresses in the surrounding soil during installation. However, the independent influence and contribution of these mitigation mechanisms on the excess pore pressures, accelerations (or shear stresses), and lateral and vertical deformations are not sufficiently understood to facilitate a reliable design. This paper presents the results of a series of dynamic centrifuge tests to fundamentally evaluate the influence of dense granular columns on the seismic performance of level and gently sloped sites, including a liquefiable layer of clean sand. Specific consideration was given to the relative importance of enhanced drainage and shear reinforcement. Granular columns with greater area replacement ratios (Ar), for example Ar greater than about 20%, were shown to be highly effective in reducing the seismic settlement and lateral deformations in gentle slopes, owing primarily to the expedited dissipation of excess pore water pressures. The influence of granular columns on accelerations (and therefore, the shear stress demand) in the surrounding soil depended on the column’s Ar and drainage capacity. Increasing Ar from 0 to 10% was shown to reduce the accelerations across a range of frequencies in the surrounding soil due to the shear reinforcement effect alone. However, enhanced drainage simultaneously increased the rate of excess pore pressure dissipation, helping the surrounding soil regain more quickly its shear strength and stiffness. At short drainage distances or higher Ar values (for example, 20%), this could notably amplify the acceleration and shear stress demand on soil, particularly at greater frequencies that influence PGA. The experimental insight presented in this paper aims to improve our understanding of the mechanics of liquefaction and lateral spreading mitigation with granular columns, and it may be used to validate the numerical models used in their design.
Influence of Dense Granular Columns on the Performance of Level and Gently Sloping Liquefiable Sites from Mahir Badanagki, Ph.D.
]]> 153 5 https://cdn.slidesharecdn.com/ss_thumbnails/badanagkietal-180725012509-thumbnail.jpg?width=120&height=120&fit=bounds document Black http://activitystrea.ms/schema/1.0/post http://activitystrea.ms/schema/1.0/posted 0 Evaluating 2D numerical simulations of granular columns in level and gently sloping liquefiable sites using centrifuge experiments /slideshow/evaluating-2d-numerical-simulations-of-granular-columns-in-level-and-gently-sloping-liquefiable-sites-using-centrifuge-experiments/95542997 evaluating2dnumericalsimulationsofgranularcolumnsinlevelandgentlyslpingliquefiablesitesusingcentrifu-180430210524
The response of a layered liquefiable soil profile, with granular columns as a mitigation strategy, was evaluated via numerical and centrifuge modeling. Comparisons were made for a level site containing a single granular column and for a pair of gentle slopes, one of which was mitigated with a network of dense granular columns. The results reveal the abilities and limitations of two state-of-the-art soil constitutive models. All simulations were performed in 2-dimensions using: 1) the pressure-dependent, multi-yield-surface, plasticity-based soil constitutive model (PDMY02); and 2) the bounding surface, plasticity-based, Manzari-Dafalias (M-D) soil constitutive model, both implemented in OpenSees. Numerical model parameters were previously calibrated via element testing. Both constitutive models under-predicted PGA near the surface at different distances from the granular column, but they better predicted spectral accelerations at periods exceeding 0.5 s (particularly M-D). The M-D model generally predicted seismic settlements well, while PDMY02 notably underestimated soil's volumetric compressibility and strains. Both models accurately predicted the peak value and generation of excess pore pressures during shaking for the unmitigated slope, leading to a successful prediction of lateral deformations. However, lateral movement of the treated slope was poorly predicted by both models due to inaccuracies in predicting the dissipation rate in the presence of drains. Both models came close to predicting the performance of gently sloping, liquefiable sites when untreated. But further advances are required to better predict the rate of excess pore pressure dissipation and seismic performance when the slope is treated with granular columns.]]>
The response of a layered liquefiable soil profile, with granular columns as a mitigation strategy, was evaluated via numerical and centrifuge modeling. Comparisons were made for a level site containing a single granular column and for a pair of gentle slopes, one of which was mitigated with a network of dense granular columns. The results reveal the abilities and limitations of two state-of-the-art soil constitutive models. All simulations were performed in 2-dimensions using: 1) the pressure-dependent, multi-yield-surface, plasticity-based soil constitutive model (PDMY02); and 2) the bounding surface, plasticity-based, Manzari-Dafalias (M-D) soil constitutive model, both implemented in OpenSees. Numerical model parameters were previously calibrated via element testing. Both constitutive models under-predicted PGA near the surface at different distances from the granular column, but they better predicted spectral accelerations at periods exceeding 0.5 s (particularly M-D). The M-D model generally predicted seismic settlements well, while PDMY02 notably underestimated soil's volumetric compressibility and strains. Both models accurately predicted the peak value and generation of excess pore pressures during shaking for the unmitigated slope, leading to a successful prediction of lateral deformations. However, lateral movement of the treated slope was poorly predicted by both models due to inaccuracies in predicting the dissipation rate in the presence of drains. Both models came close to predicting the performance of gently sloping, liquefiable sites when untreated. But further advances are required to better predict the rate of excess pore pressure dissipation and seismic performance when the slope is treated with granular columns.]]> Mon, 30 Apr 2018 21:05:24 GMT /slideshow/evaluating-2d-numerical-simulations-of-granular-columns-in-level-and-gently-sloping-liquefiable-sites-using-centrifuge-experiments/95542997 MahirBadanagki@slideshare.net(MahirBadanagki) Evaluating 2D numerical simulations of granular columns in level and gently sloping liquefiable sites using centrifuge experiments MahirBadanagki The response of a layered liquefiable soil profile, with granular columns as a mitigation strategy, was evaluated via numerical and centrifuge modeling. Comparisons were made for a level site containing a single granular column and for a pair of gentle slopes, one of which was mitigated with a network of dense granular columns. The results reveal the abilities and limitations of two state-of-the-art soil constitutive models. All simulations were performed in 2-dimensions using: 1) the pressure-dependent, multi-yield-surface, plasticity-based soil constitutive model (PDMY02); and 2) the bounding surface, plasticity-based, Manzari-Dafalias (M-D) soil constitutive model, both implemented in OpenSees. Numerical model parameters were previously calibrated via element testing. Both constitutive models under-predicted PGA near the surface at different distances from the granular column, but they better predicted spectral accelerations at periods exceeding 0.5 s (particularly M-D). The M-D model generally predicted seismic settlements well, while PDMY02 notably underestimated soil's volumetric compressibility and strains. Both models accurately predicted the peak value and generation of excess pore pressures during shaking for the unmitigated slope, leading to a successful prediction of lateral deformations. However, lateral movement of the treated slope was poorly predicted by both models due to inaccuracies in predicting the dissipation rate in the presence of drains. Both models came close to predicting the performance of gently sloping, liquefiable sites when untreated. But further advances are required to better predict the rate of excess pore pressure dissipation and seismic performance when the slope is treated with granular columns. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/evaluating2dnumericalsimulationsofgranularcolumnsinlevelandgentlyslpingliquefiablesitesusingcentrifu-180430210524-thumbnail.jpg?width=120&amp;height=120&amp;fit=bounds" /><br> The response of a layered liquefiable soil profile, with granular columns as a mitigation strategy, was evaluated via numerical and centrifuge modeling. Comparisons were made for a level site containing a single granular column and for a pair of gentle slopes, one of which was mitigated with a network of dense granular columns. The results reveal the abilities and limitations of two state-of-the-art soil constitutive models. All simulations were performed in 2-dimensions using: 1) the pressure-dependent, multi-yield-surface, plasticity-based soil constitutive model (PDMY02); and 2) the bounding surface, plasticity-based, Manzari-Dafalias (M-D) soil constitutive model, both implemented in OpenSees. Numerical model parameters were previously calibrated via element testing. Both constitutive models under-predicted PGA near the surface at different distances from the granular column, but they better predicted spectral accelerations at periods exceeding 0.5 s (particularly M-D). The M-D model generally predicted seismic settlements well, while PDMY02 notably underestimated soil&#39;s volumetric compressibility and strains. Both models accurately predicted the peak value and generation of excess pore pressures during shaking for the unmitigated slope, leading to a successful prediction of lateral deformations. However, lateral movement of the treated slope was poorly predicted by both models due to inaccuracies in predicting the dissipation rate in the presence of drains. Both models came close to predicting the performance of gently sloping, liquefiable sites when untreated. But further advances are required to better predict the rate of excess pore pressure dissipation and seismic performance when the slope is treated with granular columns.
Evaluating 2D numerical simulations of granular columns in level and gently sloping liquefiable sites using centrifuge experiments from Mahir Badanagki, Ph.D.
]]> 129 2 https://cdn.slidesharecdn.com/ss_thumbnails/evaluating2dnumericalsimulationsofgranularcolumnsinlevelandgentlyslpingliquefiablesitesusingcentrifu-180430210524-thumbnail.jpg?width=120&height=120&fit=bounds document Black http://activitystrea.ms/schema/1.0/post http://activitystrea.ms/schema/1.0/posted 0 Seismic performance of a layered liquefiable site validation of numerical simulations using centrifuge modeling /slideshow/seismic-performance-of-a-layered-liquefiable-site-validation-of-numerical-simulations-using-centrifuge-modeling-75243580/75243580 seismicperformanceofalayeredliquefiablesitevalidationofnumericalsimulationsusingcentrifugemodeling-170420190907
In this paper, the results of a centrifuge experiment modeling of a layered soil profile, including a liquefiable layer of Ottawa sand, are used to evaluate the predictive capabilities of two state ofthe-art constitutive models.]]>
In this paper, the results of a centrifuge experiment modeling of a layered soil profile, including a liquefiable layer of Ottawa sand, are used to evaluate the predictive capabilities of two state ofthe-art constitutive models.]]> Thu, 20 Apr 2017 19:09:06 GMT /slideshow/seismic-performance-of-a-layered-liquefiable-site-validation-of-numerical-simulations-using-centrifuge-modeling-75243580/75243580 MahirBadanagki@slideshare.net(MahirBadanagki) Seismic performance of a layered liquefiable site validation of numerical simulations using centrifuge modeling MahirBadanagki In this paper, the results of a centrifuge experiment modeling of a layered soil profile, including a liquefiable layer of Ottawa sand, are used to evaluate the predictive capabilities of two state ofthe-art constitutive models. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/seismicperformanceofalayeredliquefiablesitevalidationofnumericalsimulationsusingcentrifugemodeling-170420190907-thumbnail.jpg?width=120&amp;height=120&amp;fit=bounds" /><br> In this paper, the results of a centrifuge experiment modeling of a layered soil profile, including a liquefiable layer of Ottawa sand, are used to evaluate the predictive capabilities of two state ofthe-art constitutive models.
Seismic performance of a layered liquefiable site validation of numerical simulations using centrifuge modeling from Mahir Badanagki, Ph.D.
]]> 157 5 https://cdn.slidesharecdn.com/ss_thumbnails/seismicperformanceofalayeredliquefiablesitevalidationofnumericalsimulationsusingcentrifugemodeling-170420190907-thumbnail.jpg?width=120&height=120&fit=bounds document Black http://activitystrea.ms/schema/1.0/post http://activitystrea.ms/schema/1.0/posted 0 Sustainable stabilization of sulfate bearing soils with expansive soil-rubber technology /slideshow/sustainable-stabilization-of-sulfate-bearing-soils-with-expansive-soilrubber-technology/75243468 sustainablestabilizationofsulfate-bearingsoilswithexpansivesoil-rubbertechnology-170420190455
The beneficial use of scrap tire rubber mixed with expansive soils is of interest to civil engineering applications since the swell percent and the swell pressure can be potentially reduced with no deleterious effect to the shear strength of the mixture. The two main objectives of this research were (1) to propose a new subgrade soil stabilization protocol to allow CDOT to rely upon an alternative stabilization method that is not subject to the typical problems associated with calcium-based stabilization of sulfate-rich soils, and (2) to develop a new database of MEPDG parameters for local soil samples obtained from CDOT and to provide advanced testing and analysis of the stiffness degradation of these materials.]]>
The beneficial use of scrap tire rubber mixed with expansive soils is of interest to civil engineering applications since the swell percent and the swell pressure can be potentially reduced with no deleterious effect to the shear strength of the mixture. The two main objectives of this research were (1) to propose a new subgrade soil stabilization protocol to allow CDOT to rely upon an alternative stabilization method that is not subject to the typical problems associated with calcium-based stabilization of sulfate-rich soils, and (2) to develop a new database of MEPDG parameters for local soil samples obtained from CDOT and to provide advanced testing and analysis of the stiffness degradation of these materials.]]> Thu, 20 Apr 2017 19:04:55 GMT /slideshow/sustainable-stabilization-of-sulfate-bearing-soils-with-expansive-soilrubber-technology/75243468 MahirBadanagki@slideshare.net(MahirBadanagki) Sustainable stabilization of sulfate bearing soils with expansive soil-rubber technology MahirBadanagki The beneficial use of scrap tire rubber mixed with expansive soils is of interest to civil engineering applications since the swell percent and the swell pressure can be potentially reduced with no deleterious effect to the shear strength of the mixture. The two main objectives of this research were (1) to propose a new subgrade soil stabilization protocol to allow CDOT to rely upon an alternative stabilization method that is not subject to the typical problems associated with calcium-based stabilization of sulfate-rich soils, and (2) to develop a new database of MEPDG parameters for local soil samples obtained from CDOT and to provide advanced testing and analysis of the stiffness degradation of these materials. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/sustainablestabilizationofsulfate-bearingsoilswithexpansivesoil-rubbertechnology-170420190455-thumbnail.jpg?width=120&amp;height=120&amp;fit=bounds" /><br> The beneficial use of scrap tire rubber mixed with expansive soils is of interest to civil engineering applications since the swell percent and the swell pressure can be potentially reduced with no deleterious effect to the shear strength of the mixture. The two main objectives of this research were (1) to propose a new subgrade soil stabilization protocol to allow CDOT to rely upon an alternative stabilization method that is not subject to the typical problems associated with calcium-based stabilization of sulfate-rich soils, and (2) to develop a new database of MEPDG parameters for local soil samples obtained from CDOT and to provide advanced testing and analysis of the stiffness degradation of these materials.
Sustainable stabilization of sulfate bearing soils with expansive soil-rubber technology from Mahir Badanagki, Ph.D.
]]> 250 3 https://cdn.slidesharecdn.com/ss_thumbnails/sustainablestabilizationofsulfate-bearingsoilswithexpansivesoil-rubbertechnology-170420190455-thumbnail.jpg?width=120&height=120&fit=bounds document Black http://activitystrea.ms/schema/1.0/post http://activitystrea.ms/schema/1.0/posted 0 https://public.slidesharecdn.com/v2/images/profile-picture.png https://cdn.slidesharecdn.com/ss_thumbnails/badanagkietal-180725012509-thumbnail.jpg?width=320&height=320&fit=bounds slideshow/influence-of-dense-granular-columns-on-the-performance-of-level-and-gently-sloping-liquefiable-sites/107378985 Influence of Dense Gra... https://cdn.slidesharecdn.com/ss_thumbnails/evaluating2dnumericalsimulationsofgranularcolumnsinlevelandgentlyslpingliquefiablesitesusingcentrifu-180430210524-thumbnail.jpg?width=320&height=320&fit=bounds slideshow/evaluating-2d-numerical-simulations-of-granular-columns-in-level-and-gently-sloping-liquefiable-sites-using-centrifuge-experiments/95542997 Evaluating 2D numerica... https://cdn.slidesharecdn.com/ss_thumbnails/seismicperformanceofalayeredliquefiablesitevalidationofnumericalsimulationsusingcentrifugemodeling-170420190907-thumbnail.jpg?width=320&height=320&fit=bounds slideshow/seismic-performance-of-a-layered-liquefiable-site-validation-of-numerical-simulations-using-centrifuge-modeling-75243580/75243580 Seismic performance of...