Article
Engineering, Geological
Wenbo Pan, Zixin Zhang, Shuaifeng Wang, Qinghua Lei
Summary: In this study, a seismo-hydro-mechanical simulation was conducted to analyze the impact of earthquakes on the hydrogeological properties of a nuclear waste repository. The simulation results showed that the changes in fracture transmissivity induced by earthquakes follow a power-law decay.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Energy & Fuels
A. Lavrov
Summary: The study found that the transmissivity of self-affine fractures decreased significantly with decreasing grid size, despite the average aperture of the fractures remaining the same. This decrease was attributed to an increase in flow tortuosity.
JOURNAL OF PETROLEUM EXPLORATION AND PRODUCTION TECHNOLOGY
(2021)
Article
Energy & Fuels
Kc Bijay, Ehsan Ghazanfari
Summary: The study found that hydro-shearing in EGS leads to permanent shear slip in fractures, significantly enhancing permeability. Thermal stress at elevated temperatures could also contribute to mechanical crushing of asperities and weak fractures, resulting in more gouge particles.
Article
Mechanics
Tao Li, Qiang Zhang, Qian Yin, Jiayu Gu, Binsong Jiang
Summary: The nonlinear flow behavior of granite with a single fracture at different shear displacements was investigated using a high-precision non-pulse long-time permeability test system. It was found that shear displacement has a significant influence on the flow characteristic parameters, critical Reynolds number, and critical hydraulic gradient.
INTERNATIONAL JOURNAL OF APPLIED MECHANICS
(2023)
Article
Geosciences, Multidisciplinary
Johannes Herrmann, Valerian Schuster, Chaojie Cheng, Harald Milsch, Erik Rybacki
Summary: In this study, we experimentally determined the hydraulic properties of fractures in different rock types. The results show that the transmissivity of fractures decreases with increasing confining pressure and differential stress, while temperature only affects the transmissivity when the fracture aperture is low. Increasing the surface roughness of fractures leads to higher initial transmissivity. Fractures in slate, graywacke, quartzite, and granite samples exhibit the highest initial transmissivity, while claystone and granitic gouge material have lower transmissivity.
Article
Materials Science, Multidisciplinary
Ruozhang Li, Dongwu Li, Wenming Zhang
Summary: This study investigates the effects of rate on fibrillar adhesive surfaces. A theoretical framework is proposed based on the Lee & Radok corresponding principle, and simulation results reveal the influence of rate on adhesion response, preload dependence, and effective work of adhesion. The study finds that the preload has a critical value for the pull-off force. Additionally, it is discovered that the viscoelastic-induced adhesion enhancement can be approximately decoupled as a multiplicative term in the overall effective work of adhesion.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Engineering, Multidisciplinary
Hsien-Chang Kao, Po-Yi Chou, Nian-Chang Wu, Chun-Te Wang, Nien-Sheng Hsu
Summary: This study proposes a modified design for inflatable-packer system, which includes modifications to the pneumatic control device and stratified analysis of hydrostatic pressure. This allows for independent inflation of the two packers, addressing leakage issues and enabling the conversion between single and double packer testing modes.
Article
Engineering, Multidisciplinary
Hsien-Chang Kao, Po-Yi Chou, Nian-Chang Wu, Chun-Te Wang, Nien-Sheng Hsu
Summary: Inflatable-packer testing is commonly used in geotechnical investigations, but the issue of leakage around the packers can lead to wellbore failure and equipment stuck. To address this problem, modifying the pneumatic control device to a 2-in-1 inflatable-packer system and conducting stratified analysis of hydrostatic pressure is necessary. This allows for separate inflation of each packer element and diverse control tasks, including in-situ conversion between single and double packer testing modes.
Article
Engineering, Geological
Alejandro Cardona, Thomas Finkbeiner, J. Carlos Santamarina
Summary: Fractures in rocks play a key role in establishing internal plumbing and preferential flow paths. Surface roughness and matedness of fractures determine the geometric aperture, with measurements showing a relation between roughness wavelength and amplitude consistent with fractal topography. Normal loading shifts the aperture distribution towards smaller sizes, while shear displacement affects mean and standard deviation of initially mated fractures. The cubic law is valid locally when fracture roughness follows a power law, aiding in numerical analyses of transmissivity. Flow trajectories redistribute with increasing normal stress, and shear displacement induces early aperture anisotropy in initially mated fractures that decreases with unmating. Transmissivity evolution can be accurately captured with power and logistic functions for normal stress and shear displacement, respectively. Positive feedback during reactive fluid flow heightens channeling, as supported by radial transmissivity measurements.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Thermodynamics
Xueling Liu, Yuanming Wang, Shuai Li, Jiansheng Wang
Summary: This study constructs a three-dimensional physical model of a single fracture with undulated surface morphology in hot dry rock to investigate the convection heat transfer characteristics of supercritical CO2. The results show that the local convection heat transfer coefficients at different positions in the fracture exhibit opposite variation trends, and increase with the decrease of flow rate, the increase of pressure and inlet temperature.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Geosciences, Multidisciplinary
S. S. Kasyap, K. Senetakis
Summary: The influence of laboratory specimen size on the mechanical behavior of geological structures is examined in this study. The results show that specimen size affects the peak friction and shearing stiffness, with larger specimens requiring more displacement to reach the peak friction and exhibiting lower shearing stiffness. The weakening behavior in the gouge layer is also intensified at larger normal stresses and increasing gouge layer size.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Engineering, Geological
Yuedu Chen, Weiguo Liang, A. P. S. Selvadurai, Zhihong Zhao
Summary: The evolution of fracture geometries during shear significantly affects fluid flow in rock fractures. Shear dilation initially increases permeability but is later offset by gouge formation, resulting in reduced fracture permeability. The distribution, location, and size of contacts evolving during shear also play a significant role in determining fracture permeability. Fracture permeability is not only affected by the aperture, but also by the presence of asperity degradation and gouge formation within the fracture.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Geochemistry & Geophysics
Philipp Braun, Georgios Tzortzopoulos, Ioannis Stefanou
Summary: Laboratory experiments using sand-based 3D-printed materials were conducted to investigate frictional properties, bulk mechanical parameters, and viscous behavior. A special focus was placed on the post-peak softening behavior, with a model designed to simulate earthquake-like instabilities and oscillating friction coefficients during slip. The study also examined the creation of a gouge-like layer due to granular debonding during sliding, showing potential for new surrogate experiments in fault mechanics and geomechanics.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Multidisciplinary Sciences
Siyi Liu, Jinlong He, Yifan Rao, Zhaohe Dai, Huilin Ye, John C. Tanir, Ying Li, Nanshu Lu
Summary: Three-dimensional surface-conformable electronics have potential applications in curved displays, bioelectronics, and biomimetics. Flexibility and stretchability are challenges for fully conforming electronics to nondevelopable surfaces. This study investigates the conformability of circular sheets on spherical surfaces and identifies a scaling law that predicts their conformability. The effects of radial slits on improving conformability are quantified, providing practical guidelines for achieving high conformability.
Article
Green & Sustainable Science & Technology
Shuai Zheng, Sanbai Li, Dongxiao Zhang
Summary: The paper proposes an extended embedded discrete fracture model (XEDFM) for simulating fluid and heat flow in fractured reservoirs with 3-D non-planar fracture networks, which offers more flexibility and advantages compared to conventional models. By systematically validating XEDFM, the study investigates the impacts of fracture roughness and heat extraction strategy on hydrothermal behaviors and heat mining efficiency.
Article
Engineering, Geological
Shucai Li, Jie Hu, Florian Amann, Liping Li, Hongliang Liu, Shaoshuai Shi, Pooya Hamdi
Summary: The paper introduces a new rock testing system that can simulate complex tensile-compressive-shear stress states. The system allows for laboratory tests under various failure modes and provides valuable information on failure characteristics.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2022)
Article
Geochemistry & Geophysics
Mengke An, Fengshou Zhang, Ki-Bok Min, Derek Elsworth, Changrong He, Luanxiao Zhao
Summary: This study investigates the impact of heterogeneity and contiguity of epidote-patch structure on frictional instability and finds that the mode of epidote precipitation controls the response of mixed gouges. The presence of epidote coatings on fractures/faults can enhance velocity-weakening behavior, supporting the potential seismic reactivation of faults.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
X. Sun, Y. Yao, D. Liu, D. Elsworth
Summary: This study investigates the mechanisms and relationships between CO2 adsorption and coal wettability by combining direct measurements and molecular dynamic simulations. The researchers find that coal wettability significantly weakens under increasing CO2 pressure. This study provides a robust method and results for accurately predicting CO2 storage capacity in coalbeds and enhanced methane recovery.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Engineering, Geological
Ali Aminzadeh, Florian Amann
Summary: This article studies the stresses at the center of a disk made of transversely isotropic rocks in Brazil. It finds that the solution for these stresses depends on the radius of the disk, the applied load, the material orientation, and two dimensionless ratios related to Young's modulus and apparent shear modulus. Finite element simulations are conducted to determine the stresses at the disk center, and an approximate formula is derived from analytical results. The formula is compared to numerical solutions, and simple and practical equations are proposed for estimating the stresses at the center of the disk specimen.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Review
Environmental Sciences
Maximilian Noethen, Hannes Hemmerle, Peter Bayer
Summary: Anthropogenic warming of the atmosphere is a pressing challenge in the 21st century, but knowledge on subsurface warming is lacking. This review proposes a classification based on heat source geometry, scale, process, and intention of heat release. It explores the intensities of subsurface warming, heat flux density, and implications for processes and ecosystems, as well as the potential of recycling waste heat with geothermal installations.
CRITICAL REVIEWS IN ENVIRONMENTAL SCIENCE AND TECHNOLOGY
(2023)
Article
Geochemistry & Geophysics
Fengshou Zhang, Rui Huang, Mengke An, Ki-Bok Min, Derek Elsworth, Hannes Hofmann, Xiaoguang Wang
Summary: Experiments on simulated granite fault gouges suggest that fluid injection can induce earthquakes, and variations in effective stress and mineral composition are important factors affecting fault strength and stability.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Engineering, Environmental
Bo Zhang, Kai Gu, Peter Bayer, Fulin Xiang, Zhuang Wei, Baojun Wang, Bin Shi
Summary: This study aims to develop a convenient method to investigate vertical water flow in slopes on the sub-meter scale. The method is successfully validated in a laboratory tank with a series of experiments and has the ability to estimate flow rates greater than 1.0 x 10(-6) m.s(-1) and identify the influence of moving water on thermal profiles even at a flow rate of 1.0 x 10(-7) m.s(-1).
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2023)
Article
Geochemistry & Geophysics
Peng Dong, Rong Chen, Kaiwen Xia, Wei Yao, Zhigang Peng, Derek Elsworth
Summary: This study investigates dynamically triggered earthquakes on laboratory faults and reveals that the triggering process has two distinct phases, with a slow phase only present for a specific seismic condition and absent for supershear events.
SEISMOLOGICAL RESEARCH LETTERS
(2023)
Retraction
Construction & Building Technology
Manuel Entfellner, Pooya Hamdi, Xiaoyue Wang, Helmut Wannenmacher, Florian Amann
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
(2023)
Article
Environmental Sciences
Bo Zhang, Kai Gu, Peter Bayer, Haibo Qi, Bin Shi, Baojun Wang, Yuehua Jiang, Quanping Zhou
Summary: The thermal response test (TRT) establishes a relationship between groundwater flow rate and temperature response curve. To minimize the borehole effects in the test, practical solutions for in situ heating and temperature sensing are needed. Numerical models were used to study the effect of grout and jacket on the simulated thermal response, and these findings were applied to develop groundwater flow rate estimation procedures. The developed approach was successfully applied in a case study, validating its applicability in the field.
WATER RESOURCES RESEARCH
(2023)
Article
Geochemistry & Geophysics
L. Winhausen, K. Khaledi, M. Jalali, M. Bretthauer, F. Amann
Summary: This study investigates the anisotropic behavior of Opalinus Clay, a selected host rock for nuclear waste disposal in Switzerland, by examining its unconfined compressive and tensile strength, poromechanical response, and effective shear strength. The results reveal that the rock exhibits a directional dependency in its strength properties, with the lowest values observed at specific angles between the bedding orientation and the load direction. The study also shows that the orientation of the bedding plane with respect to the maximum principal stress significantly influences the poromechanical behavior and the effective strength of the rock.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geosciences, Multidisciplinary
Lisa Maria Ringel, Mohammadreza Jalali, Peter Bayer
Summary: In this study, the authors used a stochastic inversion method to infer the structural and hydraulic properties of a highly fractured zone at the Grimsel Test Site in Switzerland. The results revealed the presence of two preferential flow paths, with an increased probability of fractures linking the paths as the distance to the second injection borehole decreased.
HYDROLOGY AND EARTH SYSTEM SCIENCES
(2022)
Article
Green & Sustainable Science & Technology
Arslan Ahmed, Fosca Conti, Peter Bayer, Markus Goldbrunner
Summary: Snowfall and ice formation on road surface can be a safety hazard for driving, and the traditional methods of using salt and de-icing chemicals have environmental and economic disadvantages. Hydronic road heating systems, which circulate a mixture of ethanol and water under the asphalt, provide a valid alternative. This study compares the environmental impact of using salts versus using a road heating system, and the results show that the heating system emits less CO2 over its lifetime.
ENVIRONMENTAL AND CLIMATE TECHNOLOGIES
(2022)
Article
Geochemistry & Geophysics
Lisa Winhausen, Kavan Khaledi, Mohammadreza Jalali, Janos L. Urai, Florian Amann
Summary: This study investigates the failure mode of Opalinus Clay under different stress conditions. The results show a transition from brittle to ductile deformation with increasing stress, and the deformation localizes in distinct shear bands. The study also reveals less dilation in the shear zones at higher stresses.
Article
Geochemistry & Geophysics
Xiaodong Ma, Marian Hertrich, Florian Amann, Kai Broeker, Nima Gholizadeh Doonechaly, Valentin Gischig, Rebecca Hochreutener, Philipp Kaestli, Hannes Krietsch, Michele Marti, Barbara Naegeli, Morteza Nejati, Anne Obermann, Katrin Plenkers, Antonio P. Rinaldi, Alexis Shakas, Linus Villiger, Quinn Wenning, Alba Zappone, Falko Bethmann, Raymi Castilla, Francisco Seberto, Peter Meier, Thomas Driesner, Simon Loew, Hansruedi Maurer, Martin O. Saar, Stefan Wiemer, Domenico Giardini
Summary: The increased interest in subsurface development and associated seismicity requires a better understanding of hydro-seismo-mechanical coupling in fractured rock masses. In order to bridge the knowledge gap between laboratory and reservoir scales, controllable in situ experiments are necessary. The BedrettoLab provides a testing ground for studying the hydro-seismo-mechanical response of fractured crystalline rock masses.