Special Issue "Geomechanics for Energy and a Sustainable Environment"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Energy and Environment".

Deadline for manuscript submissions: closed (10 October 2019).

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Gye-Chun Cho
Website
Guest Editor
Korea Advanced Institute of Science and Technology, Department Civil and Environmental Engineering, 291 Daehak Ro, Daejeon 34141, South Korea
Interests: geotechnical engineering; energy geotechnology; bio-soil; rock excavation
Special Issues and Collections in MDPI journals
Dr. Ilhan Chang
Website
Guest Editor
University of New South Wales (UNSW), School of Engineering and Informational Technology, Canberra, ACT 2600, Australia
Interests: geotechnical engineering; ground improvement; bio-soil; sustainability
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Energy consumption is strongly correlated to the development and quality of civilization. On average, 85% of primary energy comes from fossil fuels; as a result, carbon-based resources face depletion, and there are concerns about climate change. Energy geotechnology must play a key role in the development of a sustainable energy scheme involving energy resources, such as natural carbohydrates, nuclear energy, and renewable sources (wind, solar, geothermal, hydropower, biofuels, and tidal and wave energy), but it must not be restricted. Moreover, geotechnical engineering is required to provide new techniques to preserve the environment from a sustainability perspective, including CO2 emission and energy-related wastes (e.g., bottom and fly ashes, and nuclear wastes) reduction, as well as the introduction of new, environmentally-friendly, and low-carbon emitting materials for geotechnical engineering practices.

The Special Issue welcomes contributions to resolve energy and environment-related geotechnical engineering issues from fundamental research to practical implementation scales. The aim of this Special Issue is to provide a source of Geomechanics for Energy and the Sustainable Environment that deals with conventional and renewable energy sources, recent attempts in CO2 and industrial waste decution, and the development of new materials/methods for sustainable development.

Prof. Gye-Chun Cho
Dr. Ilhan Chang
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • energy geotechnology
  • geoenvironmental engineering
  • climate change
  • carbon dioxide
  • sustainability
  • fossil fuel
  • renewable energy
  • nuclear energy
  • wastes
  • methane gas hydrate
  • recovery enhancement
  • bio-soils

Published Papers (6 papers)

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Research

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Open AccessArticle
Direct Shear Experimental Study on the Mobilized Dilation Behavior of Granite in Alxa Candidate Area for High-Level Radioactive Waste Disposal
Energies 2020, 13(1), 122; https://doi.org/10.3390/en13010122 - 25 Dec 2019
Abstract
Dilation behavior is of great importance for reasonable modeling of the stability of the host rock of the repository for high-level radioactive waste disposal. It is a suitable method for carrying out direct shear experiments to analyze the dilation behavior of rock with [...] Read more.
Dilation behavior is of great importance for reasonable modeling of the stability of the host rock of the repository for high-level radioactive waste disposal. It is a suitable method for carrying out direct shear experiments to analyze the dilation behavior of rock with well understood physical meanings. Based on a series of direct shear experiments on granite samples from the Alxa candidate area under different normal stresses, the shear stress‒shear strain and shear stress‒normal strain relations have been studied in detail. Five typical stages have been divided associated with the fracturing process and deformation behaviors of the granite samples during the experimental process, and the method to determine the typical stress thresholds has been proposed. It has also been found that the increasing normal stress may reduce the maximum dilation angle, and when the normal stress is relatively lower, the negative dilation angle may occur during the post-peak stage. According to the data collected from the direct shear tests, an empirical model of the mobilized dilation angle dependent on normal stress and plastic shear strain is proposed. This mobilized dilation angle has clear physical meanings and can be used in plastic constitutive models of the host rock of the repository, and this analysis can also be put forward to other types of geomechanical problems, including the deformation behaviors related to landslide, earthquake, and so on. Full article
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Open AccessArticle
Mobilized Mohr-Coulomb and Hoek-Brown Strength Parameters during Failure of Granite in Alxa Area in China for High-Level Radioactive Waste Disposal
Energies 2019, 12(22), 4237; https://doi.org/10.3390/en12224237 - 06 Nov 2019
Abstract
Strength parameters of the host rock is of paramount importance for modelling the behaviors of underground disposal repository of high-level radioactive waste (HLW). Mobilization of strength parameters should be studied for a better understanding and modelling on the mechanical behaviors of the surrounding [...] Read more.
Strength parameters of the host rock is of paramount importance for modelling the behaviors of underground disposal repository of high-level radioactive waste (HLW). Mobilization of strength parameters should be studied for a better understanding and modelling on the mechanical behaviors of the surrounding rock, considering the effect of temperature induced by the nuclear waste. The granite samples cored from NRG01 borehole in Alxa candidate area in China for HLW disposal are treated by different temperatures (T = 20 °C, 100 °C and 200 °C), and then are used to carry out a series of uniaxial and tri-axial compression experiments under various confining pressures (σ3 = 0, 5, 10, 20, and 30 MPa) in this study. With the recorded axial stress—axial strain and axial stress—lateral strain curves, mobilization of both Mohr-Coulomb and Hoek-Brown strength parameters are analyzed with the increasing plastic shear strain. It has been found that NRG01 granite samples show generally similar cohesion weakening and friction strengthening behaviors, as well as the non-simultaneous mobilization of Hoek-Brown strength parameters ( m b and s ), under the effect of various treatment temperatures. Furthermore, the samples treated by higher temperatures show lower initial values of cohesion, but their initial friction angle and m b values are relatively higher. This should be mainly owing to the thermally induced cracks in the samples. This study should be helpful for a better modelling on the mechanical behaviors of NRG01 granite samples as the host rock of a possible HLW disposal repository. Full article
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Open AccessArticle
The Effects of Coupling Stiffness and Slippage of Interface Between the Wellbore and Unconsolidated Sediment on the Stability Analysis of the Wellbore Under Gas Hydrate Production
Energies 2019, 12(21), 4177; https://doi.org/10.3390/en12214177 - 01 Nov 2019
Abstract
Gas hydrates have great potential as future energy resources. Several productivity and stability analyses have been conducted for the Ulleung Basin, and the depressurization method is being considered for production. Under depressurization, ground settlement occurs near the wellbore and axial stress develops. For [...] Read more.
Gas hydrates have great potential as future energy resources. Several productivity and stability analyses have been conducted for the Ulleung Basin, and the depressurization method is being considered for production. Under depressurization, ground settlement occurs near the wellbore and axial stress develops. For a safe production test, it is essential to perform a stability analysis for the wellbore and hydrate-bearing sediments. In this study, the development of axial stress on the wellbore was investigated considering the coupling stiffness of the interface between the wellbore and sediment. A coupling stiffness model, which can consider both confining stress and slippage phenomena, was suggested and applied in a numerical simulation. Parametric analyses were conducted to investigate the effects of coupling stiffness and slippage on axial stress development. The results show that shear coupling stiffness has a significant effect on wellbore stability, while normal coupling stiffness has a minor effect. In addition, the maximum axial stress of the well bore has an upper limit depending on the magnitude of the confining stress, and the axial stress converges to this upper limit due to slipping at the interface. The results can be used as fundamental data for the design of wellbore under depressurization-based gas production. Full article
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Open AccessArticle
Effect of Clay Content on the Mechanical Properties of Hydrate-Bearing Sediments during Hydrate Production via Depressurization
Energies 2019, 12(14), 2684; https://doi.org/10.3390/en12142684 - 12 Jul 2019
Cited by 1
Abstract
The effects of sediments with different clay contents on the mechanical properties of hydrate deposits were studied using a high-pressure, low-temperature triaxial apparatus with in-situ synthesis, as well as the mechanical properties of self-developed hydrate sediments. Through multi-stage loading, triaxial compression tests were [...] Read more.
The effects of sediments with different clay contents on the mechanical properties of hydrate deposits were studied using a high-pressure, low-temperature triaxial apparatus with in-situ synthesis, as well as the mechanical properties of self-developed hydrate sediments. Through multi-stage loading, triaxial compression tests were conducted by adding quartz sand with different clay contents as the sediment skeleton, and the stress–strain relationship of the shearing process and the strength of sediments with different clay contents were determined. Volumetric changes were also observed during shearing. The results show that the strength of hydrate sediments decreases with the increasing clay content of sediments; in the processes of depressurization and shearing, the hydrate samples exhibited obvious shear shrinkage, regardless of the sediment particle size. Full article
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Open AccessArticle
Lattice Boltzmann Simulation for the Forming Process of Artificial Frozen Soil Wall
Energies 2019, 12(1), 46; https://doi.org/10.3390/en12010046 - 24 Dec 2018
Cited by 1
Abstract
A lattice Boltzmann model is proposed to simulate the forming process of artificial frozen soil wall. The enthalpy method is applied to deal with the latent-heat source term, and the adjustable thermal diffusivity is utilized to handle the change of thermophysical parameters. The [...] Read more.
A lattice Boltzmann model is proposed to simulate the forming process of artificial frozen soil wall. The enthalpy method is applied to deal with the latent-heat source term, and the adjustable thermal diffusivity is utilized to handle the change of thermophysical parameters. The model is tested by the heat conduction with solid–liquid phase change in semi-infinite space, which shows a good consistence between the numerical and analytical solutions, and the mesh resolution has little effect on the numerical results. Lastly, the development of frozen soil wall is discussed when the freezing pipes are arranged in a square. The results show that the evolution of temperature field with time is closely related to the distance from the freezing pipe. For the soil near freezing pipe, the temperature gradient is larger, the soil temperature drops rapidly and freezes in a short time. The time history curve of temperature is relatively smooth. For the soil far away from freezing pipe, the temperature evolution curve has obvious multistage, which can be divided into four stages: cooling, phase change, partly frozen and completely frozen. The spacing of freezing pipes has a significant influence on the overlapping time of artificial frozen soil wall, and there is a power function relationship between them. Full article
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Review

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Open AccessFeature PaperReview
Global CO2 Emission-Related Geotechnical Engineering Hazards and the Mission for Sustainable Geotechnical Engineering
Energies 2019, 12(13), 2567; https://doi.org/10.3390/en12132567 - 03 Jul 2019
Cited by 4
Abstract
Global warming and climate change caused by greenhouse gas (GHG) emissions have rapidly increased the occurrence of abnormal climate events, and both the scale and frequency of geotechnical engineering hazards (GEHs) accordingly. In response, geotechnical engineers have a responsibility to provide countermeasures to [...] Read more.
Global warming and climate change caused by greenhouse gas (GHG) emissions have rapidly increased the occurrence of abnormal climate events, and both the scale and frequency of geotechnical engineering hazards (GEHs) accordingly. In response, geotechnical engineers have a responsibility to provide countermeasures to mitigate GEHs through various ground improvement techniques. Thus, this study provides a comprehensive review of the possible correlation between GHG emissions and GEHs using statistical data, a review of ground improvement methods that have been studied to reduce the carbon footprint of geotechnical engineering, and a discussion of the direction in which geotechnical engineering should proceed in the future. Full article
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