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Yunmin Chen - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of settlement behaviors of high-food-waste-content (HFWC) and low-food-waste-content (LFWC) MSWs and assessment of their prediction models
    Science China Technological Sciences, 2019
    Co-Authors: Haolei Qiu, Liangtong Zhan, Yunmin Chen, Guang Zhu, Zhenying Zhang, Yuze Wang
    Abstract:

    Settlement behaviors of high-food-waste-content (HFWC) and low-food-waste-content (LFWC) municipal solid wastes (MSWs) respectively from developing and developed countries were characterized and compared based on a great number of experimental datasets from references. Fresh HFWC-MSW generally has larger Primary Compression ratio compared to fresh LFWC-MSW, due to the release of a large amount of intra-particle water contained in food waste under additional stresses. The slopes of strain-logarithmic time curves with respect to the three secondary Compression phases are characterized as “slight-steep-slight” for LFWC-MSW and “moderate-moderate-slight” for HFWC-MSW. It is difficult to distinguish the first two phases of the secondary Compression in strain-logarithmic time curves for HFWC-MSW. The entropy method was built to evaluate the performance and applicability of nine published settlement models based on the settlement datasets of four large-scale experiments. The computational simplicity, the fitting performance, the prediction performance and the parametric stability were taken as the four criterions in the entropy method. Based on the evaluation results, the models proposed by Sowers et al. (1973) and Gourc et al. (2010) are recommended for predicting settlement at LFWC-MSW landfills, while the hyperbolic model and the Chen et al. (2010) model are recommended for HFWC-MSW landfills.

  • An equivalent-time-lines model for municipal solid waste based on its Compression characteristics.
    Waste Management, 2017
    Co-Authors: Xuecheng Bian, Wenjie Xu, Yunmin Chen
    Abstract:

    Abstract Municipal solid waste (MSW) demonstrates a noticeable time-dependent stress–strain behavior, which contributes greatly to the settlement of landfills and therefore influences both the storage capacity of landfills and the integrity of internal structures. The long-term Compression tests for MSW under different biodegradation conditions were analyzed. It showed that the Primary Compression can affect the secondary Compression due to the biodegradation and mechanical creep. Based on the time-lines model for clays and the Compression characteristics of MSW, relationships between MSW’s viscous strain rate and equivalent time were established, and then the viscous strain functions of MSW under different biodegradation conditions were deduced, and an equivalent-time-lines model for MSW settlement for two biodegradation conditions was developed, including the Type I model for the enhanced biodegradation condition and the Type II model for the normal biodegradation condition. The simulated Compression results of laboratory and field Compression tests under different biodegradation conditions were consistent with the measured data, which showed the reliability of both types of the equivalent-time-lines model for MSW. In addition, investigations of the long-term settlement of landfills from the literature indicated that the Type I model is suitable for predicting settlement in MSW landfills with a distinct biodegradation progress of MSW, a high content of organics in MSW, a short fill age or under an enhanced biodegradation environment; while the Type II model is good at predicting settlement in MSW landfills with a distinct progress of mechanical creep Compression, a low content of organics in MSW, a long fill age or under a normal biodegradation condition. Furthermore, relationships between model parameters and the fill age of landfills were summarized. Finally, the similarities and differences between the equivalent-time-lines model for MSW and the stress-biodegradation model for MSW were discussed.

  • Engineering properties for high kitchen waste content municipal solid waste
    Journal of Rock Mechanics and Geotechnical Engineering, 2015
    Co-Authors: Wu Gao, Liangtong Zhan, Yunmin Chen, Xuecheng Bian
    Abstract:

    Engineering properties of municipal solid waste (MSW) depend largely on the waste's initial composition and degree of degradation. MSWs in developing countries usually have a high kitchen waste content (called HKWC MSW). After comparing and analyzing the laboratory and field test results of physical composition, hydraulic properties, gas generation and gas permeability, and mechanical properties for HKWC MSW and low kitchen waste content MSW (called LKWC MSW), the following findings were obtained: (1) HKWC MSW has a higher initial water content (IWC) than LKWC MSW, but the field capacities of decomposed HKWC and LKWC MSWs are similar; (2) the hydraulic conductivity and gas permeability for HKWC MSW are both an order of magnitude smaller than those for LKWC MSW; (3) compared with LKWC MSW, HKWC MSW has a higher landfill gas (LFG) generation rate but a shorter duration and a lower potential capacity; (4) the Primary Compression feature for decomposed HKWC MSW is similar to that of decomposed LKWC MSW, but the Compression induced by degradation of HKWC MSW is greater than that of LKWC MSW; and (5) the shear strength of HKWC MSW changes significantly with time and strain. Based on the differences of engineering properties between these two kinds of MSWs, the geo-environmental issues in HKWC MSW landfills were analyzed, including high leachate production, high leachate mounds, low LFG collection efficiency, large settlement and slope stability problem, and corresponding advice for the management and design of HKWC MSW landfills was recommended.

  • Mechanical Properties of Municipal Solid Waste from Suzhou Landfill in China
    GeoCongress 2008, 2008
    Co-Authors: Yunmin Chen, Tony L. T. Zhan, Wei-an Ling
    Abstract:

    Landfill expansion is taking place in many cities of China. Knowledge of compressibility and shear strength of MSW are required for the design of a vertical landfill expansion. This paper presents a laboratory study on the mechanical properties of MSW within the Qizhishan landfill in Suzhou of China, which is under design for a vertical and lateral expansion. The laboratory study included 31 one-dimensional Compression tests and 34 triaxial Compression tests on the borehole samples taken at different depths. The experimental results showed that both the mechanical compressibility and shear strength parameters of MSW significantly depended on the embedment depth. The Primary Compression index (Cc) was observed to decrease from 1.0 to 0.3 with an increase in depth from 0 to 37 m. The magnitude of friction angle increased with an increase in the embedment depth of MSW, and the magnitude of cohesion decreased with depth.

Xuecheng Bian - One of the best experts on this subject based on the ideXlab platform.

  • An equivalent-time-lines model for municipal solid waste based on its Compression characteristics.
    Waste Management, 2017
    Co-Authors: Xuecheng Bian, Wenjie Xu, Yunmin Chen
    Abstract:

    Abstract Municipal solid waste (MSW) demonstrates a noticeable time-dependent stress–strain behavior, which contributes greatly to the settlement of landfills and therefore influences both the storage capacity of landfills and the integrity of internal structures. The long-term Compression tests for MSW under different biodegradation conditions were analyzed. It showed that the Primary Compression can affect the secondary Compression due to the biodegradation and mechanical creep. Based on the time-lines model for clays and the Compression characteristics of MSW, relationships between MSW’s viscous strain rate and equivalent time were established, and then the viscous strain functions of MSW under different biodegradation conditions were deduced, and an equivalent-time-lines model for MSW settlement for two biodegradation conditions was developed, including the Type I model for the enhanced biodegradation condition and the Type II model for the normal biodegradation condition. The simulated Compression results of laboratory and field Compression tests under different biodegradation conditions were consistent with the measured data, which showed the reliability of both types of the equivalent-time-lines model for MSW. In addition, investigations of the long-term settlement of landfills from the literature indicated that the Type I model is suitable for predicting settlement in MSW landfills with a distinct biodegradation progress of MSW, a high content of organics in MSW, a short fill age or under an enhanced biodegradation environment; while the Type II model is good at predicting settlement in MSW landfills with a distinct progress of mechanical creep Compression, a low content of organics in MSW, a long fill age or under a normal biodegradation condition. Furthermore, relationships between model parameters and the fill age of landfills were summarized. Finally, the similarities and differences between the equivalent-time-lines model for MSW and the stress-biodegradation model for MSW were discussed.

  • Engineering properties for high kitchen waste content municipal solid waste
    Journal of Rock Mechanics and Geotechnical Engineering, 2015
    Co-Authors: Wu Gao, Liangtong Zhan, Yunmin Chen, Xuecheng Bian
    Abstract:

    Engineering properties of municipal solid waste (MSW) depend largely on the waste's initial composition and degree of degradation. MSWs in developing countries usually have a high kitchen waste content (called HKWC MSW). After comparing and analyzing the laboratory and field test results of physical composition, hydraulic properties, gas generation and gas permeability, and mechanical properties for HKWC MSW and low kitchen waste content MSW (called LKWC MSW), the following findings were obtained: (1) HKWC MSW has a higher initial water content (IWC) than LKWC MSW, but the field capacities of decomposed HKWC and LKWC MSWs are similar; (2) the hydraulic conductivity and gas permeability for HKWC MSW are both an order of magnitude smaller than those for LKWC MSW; (3) compared with LKWC MSW, HKWC MSW has a higher landfill gas (LFG) generation rate but a shorter duration and a lower potential capacity; (4) the Primary Compression feature for decomposed HKWC MSW is similar to that of decomposed LKWC MSW, but the Compression induced by degradation of HKWC MSW is greater than that of LKWC MSW; and (5) the shear strength of HKWC MSW changes significantly with time and strain. Based on the differences of engineering properties between these two kinds of MSWs, the geo-environmental issues in HKWC MSW landfills were analyzed, including high leachate production, high leachate mounds, low LFG collection efficiency, large settlement and slope stability problem, and corresponding advice for the management and design of HKWC MSW landfills was recommended.

Susan E. Mackinnon - One of the best experts on this subject based on the ideXlab platform.

  • The “hierarchical” Scratch Collapse Test for identifying multilevel ulnar nerve Compression
    HAND, 2015
    Co-Authors: Kristen M. Davidge, Gil Gontre, David Tang, Kirsty U. Boyd, Marci S. Damiano, Susan E. Mackinnon
    Abstract:

    Background The Scratch Collapse Test (SCT) is used to assist in the clinical evaluation of patients with ulnar nerve Compression. The purpose of this study is to introduce the hierarchical SCT as a physical examination tool for identifying multilevel nerve Compression in patients with cubital tunnel syndrome. Methods A prospective cohort study (2010–2011) was conducted of patients referred with Primary cubital tunnel syndrome. Five ulnar nerve Compression sites were evaluated with the SCT. Each site generating a positive SCT was sequentially “frozen out” with a topical anesthetic to allow determination of both Primary and secondary ulnar nerve entrapment points. The order or “hierarchy” of Compression sites was recorded. Results Twenty-five patients (mean age 49.6 ± 12.3 years; 64 % female) were eligible for inclusion. The Primary entrapment point was identified as Osborne’s band in 80 % and the cubital tunnel retinaculum in 20 % of patients. Secondary entrapment points were also identified in the following order in all patients: (1) volar antebrachial fascia, (2) Guyon’s canal, and (3) arcade of Struthers. Conclusion The SCT is useful in localizing the site of Primary Compression of the ulnar nerve in patients with cubital tunnel syndrome. It is also sensitive enough to detect secondary Compression points when Primary sites are sequentially frozen out with a topical anesthetic, termed the hierarchical SCT. The findings of the hierarchical SCT are in keeping with the double crush hypothesis described by Upton and McComas in 1973 and the hypothesis of multilevel nerve Compression proposed by Mackinnon and Novak in 1994.

G. L. Sivakumar Babu - One of the best experts on this subject based on the ideXlab platform.

  • Slope Stability and Deformation Analysis of Bangalore MSW Landfills Using Constitutive Model
    International Journal of Geomechanics, 2016
    Co-Authors: Pinom Ering, G. L. Sivakumar Babu
    Abstract:

    Landfill stability and deformation analysis is one of the most important concerns in the design and operation of municipal solid waste (MSW) landfills. Estimation of landfill capacities based on the deformation characteristics of MSW assumes considerable significance in the estimation of additional landfill capacity before closure. In such analysis, it is important to consider mechanisms that occur in the MSW system, such as Primary Compression, time-dependent mechanical creep, and biodegradation effects. In this article, a simple case of landfill slope representing the MSW landfill of Bangalore city is considered, and the results of a stability and deformation analysis based on the constitutive modeling approach are presented. The implications for the slope stability and deformation response of MSW for a 5-m-high landfill cell are explained in terms of vertical and horizontal deformations, volume changes, and factors of safety, considering the effects of loading, mechanical degradation, and biodegradation. The effects of time on the strength and stability of the landfill cell are also observed. The study shows that analysis using the constitutive modeling approach provides useful insights for landfill operations. The model predicts that the effect of different mechanisms in a MSW landfill is to increase the overall stability of the landfill with time, and the horizontal and vertical deformations help in estimating landfill volume changes. The influence of lift thickness on the stability and performance of the landfill is also studied.

  • Approach for the use of MSW settlement predictions in the assessment of landfill capacity based on reliability analysis
    Waste Management, 2013
    Co-Authors: G. L. Sivakumar Babu, Sandeep Kumar Chouksey, Krishna R Reddy
    Abstract:

    In the analysis and design of municipal solid waste (MSW) landfills, there are many uncertainties associated with the properties of MSW during and after MSW placement. Several studies are performed involving different laboratory and field tests to understand the complex behavior and properties of MSW, and based on these studies, different models are proposed for the analysis of time dependent settlement response of MSW. For the analysis of MSW settlement, it is very important to account for the variability of model parameters that reflect different processes such as Primary Compression under loading, mechanical creep and biodegradation. In this paper, regression equations based on response surface method (RSM) are used to represent the complex behavior of MSW using a newly developed constitutive model. An approach to assess landfill capacities and develop landfill closure plans based on prediction of landfill settlements is proposed. The variability associated with model parameters relating to Primary Compression, mechanical creep and biodegradation are used to examine their influence on MSW settlement using reliability analysis framework and influence of various parameters on the settlement of MSW are estimated through sensitivity analysis.

  • Reliability Analysis of Municipal Solid Waste Settlement
    Proceedings of the International Symposium on Engineering under Uncertainty: Safety Assessment and Management (ISEUSAM - 2012), 2012
    Co-Authors: Sandeep Kumar Chouksey, G. L. Sivakumar Babu
    Abstract:

    It is well-known that the disposal of municipal solid waste (MSW) has become one of the challenges in landfill engineering. It is very important to consider mechanical processes that occur in settlement response of MSW with time. In the recent years, most of the researchers carried out different tests to understand the complex behavior of municipal solid waste and based on the observations and proposed different models for the analysis of stress-strain, time-dependent settlement response of MSW. However, in most of the cases, the variability of MSW is not considered. For the analysis of MSW settlement, it is very important to account for the variability of different parameters representing Primary Compression, mechanical creep, and effect of biodegradation. In this chapter, an approach is used to represent the complex behavior of municipal solid waste using response surface method constructed based on a newly developed constitutive model for MSW. The variability associated with parameters relating to Primary Compression, mechanical creep, and biodegradation are used to analyze MSW settlement using reliability analysis framework.

  • Parametric study of MSW landfill settlement model
    Waste Management, 2011
    Co-Authors: G. L. Sivakumar Babu, Krishna R Reddy, Sandeep Kumar Chouksey
    Abstract:

    A newly developed and validated constitutive model that accounts for Primary Compression and time-dependent mechanical creep and biodegradation is used for parametric study to investigate the effects of model parameters on the predicted settlement of municipal solid waste (MSW) with time. The model enables the prediction of stress strain response and yield surfaces for three components of settlement: Primary Compression, mechanical creep, and biodegradation. The MSW parameters investigated include Compression index, coefficient of earth pressure at-rest, overconsolidation ratio, and biodegradation parameters of MSW. A comparison of the predicted settlements for typical MSW landfill conditions showed significant differences in time-settlement response depending on the selected model input parameters. The effect of lift thickness of MSW on predicted settlement is also investigated. Overall, the study shows that the variation in the model parameters can lead to significantly different results; therefore, the model parameter values should be carefully selected to predict landfill settlements accurately. It is shown that the proposed model captures the time settlement response which is in general agreement with the results obtained from the other two reported models having similar features.

Sandeep Kumar Chouksey - One of the best experts on this subject based on the ideXlab platform.

  • Approach for the use of MSW settlement predictions in the assessment of landfill capacity based on reliability analysis
    Waste Management, 2013
    Co-Authors: G. L. Sivakumar Babu, Sandeep Kumar Chouksey, Krishna R Reddy
    Abstract:

    In the analysis and design of municipal solid waste (MSW) landfills, there are many uncertainties associated with the properties of MSW during and after MSW placement. Several studies are performed involving different laboratory and field tests to understand the complex behavior and properties of MSW, and based on these studies, different models are proposed for the analysis of time dependent settlement response of MSW. For the analysis of MSW settlement, it is very important to account for the variability of model parameters that reflect different processes such as Primary Compression under loading, mechanical creep and biodegradation. In this paper, regression equations based on response surface method (RSM) are used to represent the complex behavior of MSW using a newly developed constitutive model. An approach to assess landfill capacities and develop landfill closure plans based on prediction of landfill settlements is proposed. The variability associated with model parameters relating to Primary Compression, mechanical creep and biodegradation are used to examine their influence on MSW settlement using reliability analysis framework and influence of various parameters on the settlement of MSW are estimated through sensitivity analysis.

  • Reliability Analysis of Municipal Solid Waste Settlement
    Proceedings of the International Symposium on Engineering under Uncertainty: Safety Assessment and Management (ISEUSAM - 2012), 2012
    Co-Authors: Sandeep Kumar Chouksey, G. L. Sivakumar Babu
    Abstract:

    It is well-known that the disposal of municipal solid waste (MSW) has become one of the challenges in landfill engineering. It is very important to consider mechanical processes that occur in settlement response of MSW with time. In the recent years, most of the researchers carried out different tests to understand the complex behavior of municipal solid waste and based on the observations and proposed different models for the analysis of stress-strain, time-dependent settlement response of MSW. However, in most of the cases, the variability of MSW is not considered. For the analysis of MSW settlement, it is very important to account for the variability of different parameters representing Primary Compression, mechanical creep, and effect of biodegradation. In this chapter, an approach is used to represent the complex behavior of municipal solid waste using response surface method constructed based on a newly developed constitutive model for MSW. The variability associated with parameters relating to Primary Compression, mechanical creep, and biodegradation are used to analyze MSW settlement using reliability analysis framework.

  • Parametric study of MSW landfill settlement model
    Waste Management, 2011
    Co-Authors: G. L. Sivakumar Babu, Krishna R Reddy, Sandeep Kumar Chouksey
    Abstract:

    A newly developed and validated constitutive model that accounts for Primary Compression and time-dependent mechanical creep and biodegradation is used for parametric study to investigate the effects of model parameters on the predicted settlement of municipal solid waste (MSW) with time. The model enables the prediction of stress strain response and yield surfaces for three components of settlement: Primary Compression, mechanical creep, and biodegradation. The MSW parameters investigated include Compression index, coefficient of earth pressure at-rest, overconsolidation ratio, and biodegradation parameters of MSW. A comparison of the predicted settlements for typical MSW landfill conditions showed significant differences in time-settlement response depending on the selected model input parameters. The effect of lift thickness of MSW on predicted settlement is also investigated. Overall, the study shows that the variation in the model parameters can lead to significantly different results; therefore, the model parameter values should be carefully selected to predict landfill settlements accurately. It is shown that the proposed model captures the time settlement response which is in general agreement with the results obtained from the other two reported models having similar features.