Article
Energy & Fuels
Xinglong Zhao, Bingxiang Huang, Qingwang Cai, Long Zhao, Bin Chen
Summary: Pore pressure is an important factor in sandstone hydraulic fracturing experiments. The experimental results show that there is a positive correlation between breakdown pressure and pore pressure. As pore pressure increases, the energy released during fracturing and the initial rupture range also increase. The results provide a theoretical basis for unconventional oil and gas resource exploitation.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2023)
Article
Engineering, Chemical
Xinglong Zhao, Bingxiang Huang, Zhanwei Wu, Yang Han, Xiaoke Han
Summary: The initial pore pressure gradient along the borehole radial direction has a significant impact on the initiation and instability of a hydraulic crack tip and its propagation. Experimental results reveal that considering the borehole radial pore pressure gradient leads to a higher crack propagation pressure compared to the initiation pressure. The pore pressure gradient increases the resistance to hydraulic fracture propagation.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Mechanics
Tai Cheng, Hongru Li, Manchao He, Yingming Xiao
Summary: In this study, a series of tests were conducted on sandstone specimens immersed in water for different durations, and the mechanical properties and acoustic emission (AE) characteristics were analyzed. The results showed that the uniaxial compressive strength and elastic modulus decreased, while Poisson's ratio increased with the passage of immersion time. The mechanical parameters exhibited exponential correlation with immersion time and linear correlation with water content. The dominant failure mode evolved from tensile failure to shear failure gradually, and the AE intensity and frequency weakened. The weakening in rock strength and AE signals were attributed to the transformation in micro-fracture form induced by the deterioration of grain cementation.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Jiuzhou Huang, Wen Hua, Dengsong Li, Xiang Chen, Xutao You, Shiming Dong, Jianxiong Li
Summary: Fracture tests were conducted on cracked Brazilian disc specimens to study the compression-shear fracture properties of sandstone under confining pressure. The results show that the confining pressure environment contributes to the increase in the strength of the sandstone. The fracture toughness of sandstone specimens exhibits a linear correlation with the confining pressure.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Engineering, Geological
Guohua Zhang, Bowen Zhang, Junpeng Zou, Feng Xiong, Zhiping Lin, Zhanrong Zhang
Summary: The presence of water in sandstone joints affects their shear characteristics, which is important for evaluating the stability of rock slopes or tunnels subjected to water fluctuations. This study conducted direct shear tests on sandstone joint specimens collected from the Three Gorges hydropower station, China, with different immersion durations in water. The immersion duration did not affect the shear mode of the joints, but the shear curves were divided into three stages. The peak and residual shear strengths of the sandstone joints decreased after immersion due to the lubricant and chemical dissolution effects. A semi-empirical shear strength criterion was proposed to predict the peak shear strength after immersion.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Matthew R. Kuhn
Summary: The paper presents a multi-phase, multi-scale rational method for modeling and predicting free-field wave propagation and the weakening and liquefaction of near-surface soils using the discrete element method (DEM). The method involves analyzing various conditions and phenomena related to seismic shaking and post-shaking consolidation period, as well as refining the DEM for realistically simulating soil behavior and solving propagation and liquefaction factors.
Article
Mechanics
Tao Tan, Yanlin Zhao, Xun Zhao, Le Chang, Sheng Ren
Summary: This study investigates the mechanical properties of water-saturated sandstone under hydro-mechanical coupling through triaxial compression tests. The results show that the peak deviation stress, residual deviation stress, initial deviation stress of dilation, and deformation modulus of water-saturated sandstone are affected by both pore water pressure and confining pressure. Additionally, the effective cohesion, effective residual cohesion, effective angle of internal friction, and effective residual angle of internal friction are determined.
Article
Geochemistry & Geophysics
Zhenkai Wu, Jie Zhang, Xizhe Li, Hanmin Xiao, Xuewei Liu, Yuan Rao, Yang Li, Yongcheng Luo, Longfei Ma
Summary: This study established an experimental method for studying stress sensitivity during reservoir depletion mining and water injection development, and investigated the influence of different degrees of microcrack development on stress sensitivity. The results showed that axial compression loading acts as preloading stress and realizes the stress sensitivity process under certain conditions.
Article
Geochemistry & Geophysics
Zoe Braden, Whitney M. Behr
Summary: The study focuses on the deformation structures and conditions of mafic oceanic crust during subduction in the Chugach accretionary complex of south-central Alaska. It reveals that basalt disintegrates into chlorite-rich fault gouge under lithostatic pore fluid pressures, leading to weakening through cataclasis, dilatational shear fracturing, and slip on shear bands. This process occurs in a narrower fault zone with higher stress and pore fluid pressure fluctuations compared to sediment-hosted megathrusts.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Crystallography
Ying Zhang, Xu Wu, Qifeng Guo, Zhaohong Zhang, Meifeng Cai
Summary: This study focused on the nonlinear seepage behaviors of flow in pore-fracture media. Forchheimer's law was found to describe the nonlinear characteristics of flow in the pore-fracture media. A nonlinear inertial-parameter equation of fluid flow was proposed, and the applicability of different methods to evaluate Darcy's law was discussed.
Article
Geochemistry & Geophysics
William M. Kibikas, Stephen J. Bauer
Summary: The stress history of rocks in the subsurface has a significant impact on their mechanical and petrophysical properties, which is crucial for various geophysical and industrial applications. Laboratory experiments demonstrated that cyclic loading conditions significantly affect the nonrecoverable strain and permeability of rocks, with cyclic loading leading to a greater reduction in porosity and permeability compared to static conditions.
Article
Mechanics
Yaocong Han, Hailiang Jia, Ting Wang, Lei Wang, Qiang Li, Yabiao Wang
Summary: Testing the mechanical properties and pore phase composition of water saturated sandstone at different freezing temperatures, this study found that the fracture toughness and crack growth rate of frozen rocks are significantly influenced by the freezing temperature.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Engineering, Geological
Caoyuan Niu, Zheming Zhu, Shuai Deng, Peng Ying, Hao Qiu, Fei Wang, Lei Zhou
Summary: The moisture content of rocks in nature can affect their dynamic fracture behavior significantly. Impact tests on sandstone specimens showed that fracture toughness increased with loading rate, with saturated sandstone specimens being more sensitive to rate changes. Water weakening and water enhancing effects, along with rate effects, are important factors in the dynamic fracture behavior of rocks.
INTERNATIONAL JOURNAL OF GEOMECHANICS
(2021)
Article
Green & Sustainable Science & Technology
Yuru Yang, Wenping Li, Qinggang Lu
Summary: Rock mass stability in underground engineering construction is influenced by water-rock interaction. Weakly cemented Cretaceous sandstones have low strength and strong water-holding capacity, making them prone to weakening. This study tested the uniaxial compressive and tensile strength of weakly cemented Cretaceous sandstones from different sedimentary facies under natural and saturated conditions, and monitored the loading process using acoustic emission technique. The results show that water significantly weakens the mechanical properties of weakly cemented sandstone. The presence of water decreased the UCS and TS of saturated sandstone by 41.24% and 35.95% respectively for braided river facies, and 32.90% and 26.98% respectively for desert facies. The AE characteristics of sandstone from different facies showed similar weakening effects of water, including decreased cumulative AE energy, fluctuation in b-value, and reduction in peak frequency distribution range. The presence of high quartz and low feldspar content in braided fluvial facies sandstone strengthened its mechanical properties compared to desert facies and lessened the effect of water weakening.
Review
Engineering, Geological
Ali Keneti, Mehdi Pouragha, Bre-Anne Sainsbury
Summary: This study provides a comprehensive review of the geomechanical data for Hawkesbury Sandstone in the Sydney region, focusing on the strength-scale dependency. Large-scale, Synthetic Rock Mass (SRM) tests have been conducted to establish a strength-scale relationship that considers defect spacing, providing valuable insights for rock mass design.
ENGINEERING GEOLOGY
(2021)
Article
Engineering, Geological
K. M. A. S. Bandara, P. G. Ranjith, W. G. P. Kumari
Summary: The study revealed that fractures generated in shale and siltstone formations during hydraulic fracturing exhibit different characteristics, and flow behavior is influenced by factors such as fracture tortuosity and proppant concentration.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Environmental
Yi Xue, Jia Liu, P. G. Ranjith, Zhizhen Zhang, Feng Gao, Songhe Wang
Summary: This study conducted triaxial compression tests on coal under different gas pressure conditions to explore the influence mechanism of gas pressure on coal deformation, failure, and energy evolution. The mechanical properties, acoustic emission energy characteristics, and nonlinear characteristics of coal containing gas were obtained based on the test data. A theoretical formula for analyzing energy evolution was introduced and verified by test data. The research results indicate that energy rate can be used as a new effective mechanical parameter to analyze and predict the damage and failure characteristics of coal. The findings on energy dissipation characteristics and the defined ratio of dissipative energy rate and input energy rate provide insights for understanding the fracturing evolution and energy driving mechanism of coal.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2022)
Article
Construction & Building Technology
M. H. Samarakoon, P. G. Ranjith, W. A. M. Wanniarachchi
Summary: This study examines the effects of carbonation on the properties and mechanisms of cement, showing that alkali-activated cements with higher calcium content exhibit better mechanical properties and a denser microstructure when exposed to carbonate brine.
CEMENT & CONCRETE COMPOSITES
(2022)
Article
Thermodynamics
Jizhao Xu, Cheng Zhai, Pathegama Gamage Ranjith, Shuxun Sang, Yong Sun, Yuzhou Cong, Wei Tang, Yangfeng Zheng
Summary: The study investigated the effects of liquid CO2 on coal strength, finding that the coupled effects of liquid CO2 temperature and adsorption can influence coal fracture behavior and crack morphology.
Article
Energy & Fuels
Jizhao Xu, Cheng Zhai, P. G. Ranjith, Shuxun Sang, Xu Yu, Yong Sun, Yuzhou Cong, Yangfeng Zheng, Wei Tang
Summary: The study found that coal affected by liquid CO2 exhibited more complex destruction patterns, larger fractal dimensions, and greater structure degradation. The affected coals showed diverse mechanical responses, with temperature shock and CO2 adsorption potentially leading to crack growth and strength deterioration, ultimately destroying the coal with smaller yield strength.
Article
Energy & Fuels
David Lall, Vikram Vishal, M. V. Lall, P. G. Ranjith
Summary: The study found that gas production was less efficient in the presence of a permeable heterogeneity compared to other scenarios. The permeability affects the vertical extent of dissolved methane volume during thermal stimulation and huff and puff, while well depth influences the radial extent of dissociated molecules.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Geological
Chunlin Zhong, Zhenyu Zhang, P. G. Ranjith, Chengpeng Zhang, Kangsheng Xue
Summary: The study found that pore water can affect the radial and volumetric strain evolution of coal, leading to dilation deformation. Additionally, due to the water propping effect, the cracks in saturated coal cannot close tightly during loading, causing sliding and generating numerous tensile cracks. Loading frequency can impact the decay of pore pressure, consequently influencing the number of cracks in coal.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Energy & Fuels
Shashika Gajanayake, Ranjith Pathegama Gamage, Pabasara Wanniarachchige, Decheng Zhang
Summary: This study conducted molecular dynamic simulations to investigate the effects of temperature, pressure, and initial CO2 concentration on gas replacement characteristics for methane recovery and CO2 storage. The results showed that higher temperatures resulted in greater methane recovery, but diminished CO2 storage capacity. Higher initial CO2 concentrations facilitated better CO2 penetration into the hydrate structure, leading to increased methane recovery and improved CO2 storage.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2022)
Article
Thermodynamics
P. Cheng, C. P. Zhang, Z. Y. Ma, J. P. Zhou, D. C. Zhang, X. F. Liu, H. Chen, P. G. Ranjith
Summary: Nanoindentation tests were conducted to investigate the effects of ScCO2-water treatment on shale matrix micromechanics, revealing significant heterogeneity in the properties of different minerals. Observation of indentation morphologies showed that considerable micro-fractures were generated in clay minerals, correlated to significant plastic deformation and layered crystal structures.
Article
Engineering, Civil
S. D. D. A. Gedara, P. L. P. Wasantha, B. Teodosio, J. Li
Summary: This study investigates the influence of specimen size on axial and radial strains in core shrinkage tests. It found that larger specimens showed lower strains, attributing this behavior to the presence of more shrinkage cracks. Additionally, the axial and volumetric strains did not show significant variations with different length-to-diameter ratios.
TRANSPORTATION GEOTECHNICS
(2022)
Article
Engineering, Geological
K. M. A. S. Bandara, P. G. Ranjith, W. Zheng, D. D. Tannant, V. R. S. De Silva, T. D. Rathnaweera
Summary: This study provides a grain-scale analysis of the fracture evolution mechanisms of proppant crushing, rock fracture damage during proppant embedment, and the influence of realistic reservoir/fracture fluid on proppant embedment. The results reveal that the selection of an appropriate proppant type is vital in quantifying the degree of proppant crushing and embedment within fractures.
Article
Energy & Fuels
B. Balinee, P. G. Ranjith, Herbert E. Huppert
Summary: The article discusses the impact of building material production on global carbon emissions and presents methods to reduce environmental impact through the use of waste and carbon sequestration. By incorporating discarded aluminum foil and industrial waste gases into cement, the performance and sustainability of cement can be improved. This approach significantly reduces carbon emissions, lowers costs, and stores a large amount of CO2.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Green & Sustainable Science & Technology
Kiran Sapkota, Ehsan Yaghoubi, P. L. P. Wasantha, Rudi Van Staden, Sam Fragomeni
Summary: The feasibility of increasing the percentage of recycled aggregates to 100% in hot mix asphalt (HMA) was investigated. Recycled concrete aggregate (RCA), recycled glass (RG), and reclaimed asphalt pavement (RAP) were used to develop HMAs suitable for roads. The proposed recycled material HMA exhibited superior mechanical and resilient modulus performances, providing evidence-based insights into the increased proportion of recycled materials in the construction of asphalt pavements.
Article
Engineering, Geological
V. R. S. De Silva, H. Konietzky, H. Mearten, P. G. Ranjith, W. G. P. Kumari
Summary: This study proposes a novel approach called the hybrid rock pre-conditioning method to enhance the sustainability and efficiency of low-grade ore mining. The method involves the use of soundless cracking demolition agents (SCDAs) to initiate radial fractures in a predrilled host rock, followed by hydraulic stimulation to extend the fractures. The results show that this method can create a high density of fractures around the injection well, and key factors such as rock mass heterogeneity and stress anisotropy affect its performance.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Energy & Fuels
M. H. Samarakoon, P. G. Ranjith
Summary: Ensuring the intactness of cement sheaths is crucial for deep well applications in extreme underground conditions. This study investigates the behavior of wellbore materials, including steel casing, annulus cement sheaths, and surrounding rock formations, under continuous steam injection. The results show that materials in carbonate formations are more vulnerable to stress than those in sandstone formations, and the retention time of maximum temperature in cement sheaths is shorter in sandstone than in carbonate. It is also found that the cement sheaths in compliant formations like sandstone may fail due to tensile cracking along the thinnest thickness.
GEOENERGY SCIENCE AND ENGINEERING
(2023)