The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Paal Skalle - One of the best experts on this subject based on the ideXlab platform.
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An Experimental Investigation of Shale Mechanical Properties Through Drained and Undrained Test Mechanisms
Rock Mechanics and Rock Engineering, 2013Co-Authors: Md. Aminul Islam, Paal SkalleAbstract:Shale mechanical properties are evaluated from laboratory Tests after a complex workflow that covers tasks from sampling to Testing. Due to the heterogeneous nature of shale, it is common to obtain inconsistent Test results when evaluating the mechanical properties. In practice, this variation creates errors in numerical modeling when Test results differ significantly, even when samples are from a similar core specimen. This is because the fundamental models are based on the supplied Test data and a gap is, therefore, always observed during calibration. Thus, the overall goal of this study was to provide additional insight regarding the organization of the non-linear model input parameters in borehole simulations and to assist other researchers involved in the rock physics-related research fields. To achieve this goal, the following parallel activities were carried out: (1) perform triaxial Testing with different sample orientations, i.e., 0°, 45°, 60°, and 90°, including the Brazilian Test and CT scans, to obtain a reasonably accurate description of the anisotropic properties of shale; (2) apply an accurate interpretative method to evaluate the elastic moduli of shale; (3) evaluate and quantify the mechanical properties of shale by accounting for the beddings plane, variable confinement pressures, drained and Undrained Test mechanisms, and cyclic versus monotonic Test effects. The experimental results indicate that shale has a significant level of heterogeneity. Postfailure analysis confirmed that the failure plane coincides nicely with the weak bedding plane. The drained Poisson’s ratios were, on average, 40 % or lower than the Undrained rates. The drained Young’s modulus was approximately 48 % that of the Undrained value. These mechanical properties were significantly impacted by the bedding plane orientation. Based on the Brazilian Test, the predicted tensile strength perpendicular to the bedding plane was 12 % lower than the value obtained using the standard isotropic correlation Test. The cyclic Tests provided approximately 6 % higher rock strength than those predicted by the monotonic Tests.
Sandeep Kumar Chouksey - One of the best experts on this subject based on the ideXlab platform.
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constitutive model for municipal solid waste incorporating mechanical creep and biodegradation induced compression
Waste Management, 2010Co-Authors: G Sivakumar L Babu, Krishna R Reddy, Sandeep Kumar ChoukseyAbstract:A constitutive model is proposed to describe the stress–strain behavior of municipal solid waste (MSW) under loading using the critical state soil mechanics framework. The modified cam clay model is extended to incorporate the effects of mechanical creep and time dependent biodegradation to calculate total compression under loading. Model parameters are evaluated based on one-dimensional compression and triaxial consolidated Undrained Test series conducted on three types of MSW: (a) fresh MSW obtained from working phase of a landfill, (b) landfilled waste retrieved from a landfill after 1.5 years of degradation, and (c) synthetic MSW with controlled composition. The model captures the stress–strain and pore water pressure response of these three types of MSW adequately. The model is useful for assessing the deformation and stability of landfills and any post-closure development structures located on landfills.
Md. Aminul Islam - One of the best experts on this subject based on the ideXlab platform.
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An Experimental Investigation of Shale Mechanical Properties Through Drained and Undrained Test Mechanisms
Rock Mechanics and Rock Engineering, 2013Co-Authors: Md. Aminul Islam, Paal SkalleAbstract:Shale mechanical properties are evaluated from laboratory Tests after a complex workflow that covers tasks from sampling to Testing. Due to the heterogeneous nature of shale, it is common to obtain inconsistent Test results when evaluating the mechanical properties. In practice, this variation creates errors in numerical modeling when Test results differ significantly, even when samples are from a similar core specimen. This is because the fundamental models are based on the supplied Test data and a gap is, therefore, always observed during calibration. Thus, the overall goal of this study was to provide additional insight regarding the organization of the non-linear model input parameters in borehole simulations and to assist other researchers involved in the rock physics-related research fields. To achieve this goal, the following parallel activities were carried out: (1) perform triaxial Testing with different sample orientations, i.e., 0°, 45°, 60°, and 90°, including the Brazilian Test and CT scans, to obtain a reasonably accurate description of the anisotropic properties of shale; (2) apply an accurate interpretative method to evaluate the elastic moduli of shale; (3) evaluate and quantify the mechanical properties of shale by accounting for the beddings plane, variable confinement pressures, drained and Undrained Test mechanisms, and cyclic versus monotonic Test effects. The experimental results indicate that shale has a significant level of heterogeneity. Postfailure analysis confirmed that the failure plane coincides nicely with the weak bedding plane. The drained Poisson’s ratios were, on average, 40 % or lower than the Undrained rates. The drained Young’s modulus was approximately 48 % that of the Undrained value. These mechanical properties were significantly impacted by the bedding plane orientation. Based on the Brazilian Test, the predicted tensile strength perpendicular to the bedding plane was 12 % lower than the value obtained using the standard isotropic correlation Test. The cyclic Tests provided approximately 6 % higher rock strength than those predicted by the monotonic Tests.
G Sivakumar L Babu - One of the best experts on this subject based on the ideXlab platform.
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constitutive model for municipal solid waste incorporating mechanical creep and biodegradation induced compression
Waste Management, 2010Co-Authors: G Sivakumar L Babu, Krishna R Reddy, Sandeep Kumar ChoukseyAbstract:A constitutive model is proposed to describe the stress–strain behavior of municipal solid waste (MSW) under loading using the critical state soil mechanics framework. The modified cam clay model is extended to incorporate the effects of mechanical creep and time dependent biodegradation to calculate total compression under loading. Model parameters are evaluated based on one-dimensional compression and triaxial consolidated Undrained Test series conducted on three types of MSW: (a) fresh MSW obtained from working phase of a landfill, (b) landfilled waste retrieved from a landfill after 1.5 years of degradation, and (c) synthetic MSW with controlled composition. The model captures the stress–strain and pore water pressure response of these three types of MSW adequately. The model is useful for assessing the deformation and stability of landfills and any post-closure development structures located on landfills.
Teng-fong Wong - One of the best experts on this subject based on the ideXlab platform.
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A new methodology to delineate the compactive yield cap of two porous sandstones under Undrained condition
Mechanics of Materials, 2007Co-Authors: Sheryl Tembe, Veronika Vajdova, Patrick Baud, Wenlu Zhu, Teng-fong WongAbstract:Abstract We have developed an experimental methodology to investigate the compactive yield behavior of porous sandstones under Undrained condition and to distinguish it from the conventional method we refer to it as “modified Undrained”. In a conventional Undrained Test a sample is deformed while the confining pressure and pore volume are fixed. Our novel method is designed to simulate Undrained experiments by maintaining a constant pore fluid volume during triaxial loading. However, unlike in typical Undrained experiments where pore pressure is allowed to vary, the modified method maintains a constant pore pressure, and instead relies on the simultaneous manipulation of the confining pressure and axial stress to maintain a constant pore fluid pressure. We apply this method to two sandstones precompacted inelastically to a range of porosities. The stress paths from a modified Undrained Test map out isoporosity stress contours that would coincide with the yield caps, if the elastic strain is negligible. Conventional triaxial experiments under drained condition, in which strain hardening was observed, provide constraints on the yield caps for different values of plastic volumetric strains. While at high mean stresses the yield caps for plastic strains
