The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform

Dimitrios Zekkos - One of the best experts on this subject based on the ideXlab platform.

  • drained response of municipal solid waste in large scale triaxial shear testing
    Waste Management, 2012
    Co-Authors: Dimitrios Zekkos, Jonathan D. Bray, Michael F Riemer
    Abstract:

    A comprehensive laboratory investigation was performed on municipal solid waste (MSW) from a landfill located in northern California using a large-scale triaxial (TX) apparatus. An improved, standardized waste specimen preparation method was developed and used to prepare 27 large-scale TX specimens (d = 300 mm, h = 600–630 mm). The effects of waste composition, confining Stress, Unit weight, loading rate, and Stress path on the drained Stress–strain response of MSW were investigated. Waste composition has a significant effect on its Stress–strain response. The commonly observed upward curvature of the Stress–strain response of specimens composed of larger-sized waste materials results from the fibrous constituents (primarily paper, plastic and wood) reinforcing the waste matrix. This effect is greatest when the MSW specimen is sheared across the long axis of the fibrous particles. Due to this significant strain hardening effect and waste’s in situ Stress state, a limiting strain failure criterion of 5% axial strain from the Ko field consolidation state is judged to be most appropriate. Results from this test program and data from the literature indicate that the TX compression secant friction angle of MSW varies from 34° to 44°, with 39° as a best estimate, at a confining Stress of one atmosphere (assuming c = 0). The friction angle decreases as confining Stress increases. The friction angles measured in this testing program are representative of failure surfaces that are oriented at an angle to the predominant orientation of the long axis of the fibrous waste particles. These friction angles are higher than those obtained in direct shear tests where shearing typically occurs parallel to the orientation of the fibrous waste particles.

  • large scale direct shear testing of municipal solid waste
    Waste Management, 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Abstract Large direct shear testing (300 mm × 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress–displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW’s strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion = 15 kPa, friction angle = 36° at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5° for every log-cycle increase in normal Stress.

  • Large-scale direct shear testing of municipal solid waste.
    Waste management (New York N.Y.), 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Large direct shear testing (300 mm x 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress-displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW's strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion=15 kPa, friction angle=36 degrees at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5 degrees for every log-cycle increase in normal Stress.

  • shear modulus and material damping of municipal solid waste based on large scale cyclic triaxial testing
    Canadian Geotechnical Journal, 2008
    Co-Authors: Dimitrios Zekkos, Jonathan D. Bray, Michael F Riemer
    Abstract:

    Representative dynamic properties of municipal solid waste (MSW) are required to perform reliable seismic analyses of MSW landfills. A comprehensive large-scale cyclic triaxial laboratory testing program was performed on MSW retrieved from a landfill in the San Francisco Bay area to evaluate the small-strain shear modulus, and strain-dependent normalized shear modulus reduction and material damping ratio relationships of MSW. The effects of waste composi- tion, confining Stress, Unit weight, time under confinement, and loading frequency on these dynamic properties were evaluated. The small-strain shear modulus depends primarily on waste composition, confining Stress, Unit weight, and time under confinement. The normalized shear modulus reduction and material damping curves for MSW depend on waste composition and confining Stress. Based on the results of this study and a review of literature, strain-dependent shear modulus reduction and material damping relationships are recommended for use in landfill design.

Andreas Theodoratos - One of the best experts on this subject based on the ideXlab platform.

  • large scale direct shear testing of municipal solid waste
    Waste Management, 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Abstract Large direct shear testing (300 mm × 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress–displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW’s strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion = 15 kPa, friction angle = 36° at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5° for every log-cycle increase in normal Stress.

  • Large-scale direct shear testing of municipal solid waste.
    Waste management (New York N.Y.), 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Large direct shear testing (300 mm x 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress-displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW's strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion=15 kPa, friction angle=36 degrees at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5 degrees for every log-cycle increase in normal Stress.

Jonathan D. Bray - One of the best experts on this subject based on the ideXlab platform.

  • drained response of municipal solid waste in large scale triaxial shear testing
    Waste Management, 2012
    Co-Authors: Dimitrios Zekkos, Jonathan D. Bray, Michael F Riemer
    Abstract:

    A comprehensive laboratory investigation was performed on municipal solid waste (MSW) from a landfill located in northern California using a large-scale triaxial (TX) apparatus. An improved, standardized waste specimen preparation method was developed and used to prepare 27 large-scale TX specimens (d = 300 mm, h = 600–630 mm). The effects of waste composition, confining Stress, Unit weight, loading rate, and Stress path on the drained Stress–strain response of MSW were investigated. Waste composition has a significant effect on its Stress–strain response. The commonly observed upward curvature of the Stress–strain response of specimens composed of larger-sized waste materials results from the fibrous constituents (primarily paper, plastic and wood) reinforcing the waste matrix. This effect is greatest when the MSW specimen is sheared across the long axis of the fibrous particles. Due to this significant strain hardening effect and waste’s in situ Stress state, a limiting strain failure criterion of 5% axial strain from the Ko field consolidation state is judged to be most appropriate. Results from this test program and data from the literature indicate that the TX compression secant friction angle of MSW varies from 34° to 44°, with 39° as a best estimate, at a confining Stress of one atmosphere (assuming c = 0). The friction angle decreases as confining Stress increases. The friction angles measured in this testing program are representative of failure surfaces that are oriented at an angle to the predominant orientation of the long axis of the fibrous waste particles. These friction angles are higher than those obtained in direct shear tests where shearing typically occurs parallel to the orientation of the fibrous waste particles.

  • large scale direct shear testing of municipal solid waste
    Waste Management, 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Abstract Large direct shear testing (300 mm × 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress–displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW’s strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion = 15 kPa, friction angle = 36° at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5° for every log-cycle increase in normal Stress.

  • Large-scale direct shear testing of municipal solid waste.
    Waste management (New York N.Y.), 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Large direct shear testing (300 mm x 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress-displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW's strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion=15 kPa, friction angle=36 degrees at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5 degrees for every log-cycle increase in normal Stress.

  • shear modulus and material damping of municipal solid waste based on large scale cyclic triaxial testing
    Canadian Geotechnical Journal, 2008
    Co-Authors: Dimitrios Zekkos, Jonathan D. Bray, Michael F Riemer
    Abstract:

    Representative dynamic properties of municipal solid waste (MSW) are required to perform reliable seismic analyses of MSW landfills. A comprehensive large-scale cyclic triaxial laboratory testing program was performed on MSW retrieved from a landfill in the San Francisco Bay area to evaluate the small-strain shear modulus, and strain-dependent normalized shear modulus reduction and material damping ratio relationships of MSW. The effects of waste composi- tion, confining Stress, Unit weight, time under confinement, and loading frequency on these dynamic properties were evaluated. The small-strain shear modulus depends primarily on waste composition, confining Stress, Unit weight, and time under confinement. The normalized shear modulus reduction and material damping curves for MSW depend on waste composition and confining Stress. Based on the results of this study and a review of literature, strain-dependent shear modulus reduction and material damping relationships are recommended for use in landfill design.

Michael F Riemer - One of the best experts on this subject based on the ideXlab platform.

  • drained response of municipal solid waste in large scale triaxial shear testing
    Waste Management, 2012
    Co-Authors: Dimitrios Zekkos, Jonathan D. Bray, Michael F Riemer
    Abstract:

    A comprehensive laboratory investigation was performed on municipal solid waste (MSW) from a landfill located in northern California using a large-scale triaxial (TX) apparatus. An improved, standardized waste specimen preparation method was developed and used to prepare 27 large-scale TX specimens (d = 300 mm, h = 600–630 mm). The effects of waste composition, confining Stress, Unit weight, loading rate, and Stress path on the drained Stress–strain response of MSW were investigated. Waste composition has a significant effect on its Stress–strain response. The commonly observed upward curvature of the Stress–strain response of specimens composed of larger-sized waste materials results from the fibrous constituents (primarily paper, plastic and wood) reinforcing the waste matrix. This effect is greatest when the MSW specimen is sheared across the long axis of the fibrous particles. Due to this significant strain hardening effect and waste’s in situ Stress state, a limiting strain failure criterion of 5% axial strain from the Ko field consolidation state is judged to be most appropriate. Results from this test program and data from the literature indicate that the TX compression secant friction angle of MSW varies from 34° to 44°, with 39° as a best estimate, at a confining Stress of one atmosphere (assuming c = 0). The friction angle decreases as confining Stress increases. The friction angles measured in this testing program are representative of failure surfaces that are oriented at an angle to the predominant orientation of the long axis of the fibrous waste particles. These friction angles are higher than those obtained in direct shear tests where shearing typically occurs parallel to the orientation of the fibrous waste particles.

  • shear modulus and material damping of municipal solid waste based on large scale cyclic triaxial testing
    Canadian Geotechnical Journal, 2008
    Co-Authors: Dimitrios Zekkos, Jonathan D. Bray, Michael F Riemer
    Abstract:

    Representative dynamic properties of municipal solid waste (MSW) are required to perform reliable seismic analyses of MSW landfills. A comprehensive large-scale cyclic triaxial laboratory testing program was performed on MSW retrieved from a landfill in the San Francisco Bay area to evaluate the small-strain shear modulus, and strain-dependent normalized shear modulus reduction and material damping ratio relationships of MSW. The effects of waste composi- tion, confining Stress, Unit weight, time under confinement, and loading frequency on these dynamic properties were evaluated. The small-strain shear modulus depends primarily on waste composition, confining Stress, Unit weight, and time under confinement. The normalized shear modulus reduction and material damping curves for MSW depend on waste composition and confining Stress. Based on the results of this study and a review of literature, strain-dependent shear modulus reduction and material damping relationships are recommended for use in landfill design.

G A Athanasopoulos - One of the best experts on this subject based on the ideXlab platform.

  • large scale direct shear testing of municipal solid waste
    Waste Management, 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Abstract Large direct shear testing (300 mm × 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress–displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW’s strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion = 15 kPa, friction angle = 36° at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5° for every log-cycle increase in normal Stress.

  • Large-scale direct shear testing of municipal solid waste.
    Waste management (New York N.Y.), 2010
    Co-Authors: Dimitrios Zekkos, G A Athanasopoulos, Athena Grizi, Jonathan D. Bray, Andreas Theodoratos
    Abstract:

    Large direct shear testing (300 mm x 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining Stress, Unit weight, and loading rate on the Stress-displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW's strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining Stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion=15 kPa, friction angle=36 degrees at a normal Stress of 1 atmosphere, and a decrease in the friction angle of 5 degrees for every log-cycle increase in normal Stress.