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Numerical study on gas production via a horizontal well from hydrate reservoirs with different slope angles in the South China Sea

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Deep Underground Science and engineering 2024年第2期3卷 171-181页

作者： Tingting Luo Jianlin Song Xiang Sun Fanbao Cheng Madhusudhan Bangalore Narasimha Murthy Yulu Chen Yi Zhao Yongchen Song School of Mechanics and Civil engineering China University of Mining and TechnologyXuzhouChina Institute of Rock and soil Mechanics Chinese Academy of SciencesWuhanChina Key laboratory of Ocean Energy Utilization and Energy conservation of Ministry of Education Dalian University of TechnologyDalianChina Faculty of engineering and the Environment University of SouthamptonSouthamptonUK

It is important to study the effect of hydrate production on the physical and mechanical properties of low-permeability clayey–silty reservoirs for the largescale exploitation of hydrate reservoirs in the South China *** this study,a multiphysical-field coupling model,combined with actual exploration drilling data and the mechanical experimental data of hydrate cores in the laboratory,was established to investigate the physical and mechanical properties of low-permeability reservoirs with different slope angles during 5-year hydrate production by the depressurization method via a horizontal *** result shows that the permeability of reservoirs severely affects gas production rate,and the maximum gas production amount of a 20-m-long horizontal well can reach186.8 m3/day during the 5-year hydrate *** with smaller slope angles show higher gas production *** depressurization propagation and hydrate dissociation mainly develop along the direction parallel to the ***,the mean effective stress of reservoirs is concentrated in the near-wellbore area with the on-going hydrate production,and gradually decreases with the increase of the slope *** from the effective stress distribution law,the total reservoir settlement amount first decreases and then increases with the increase of the slope *** maximum settlement of reservoirs with a 0°slope angle is up to 3.4 m,and the displacement in the near-wellbore area is as high as2.2 m after 5 years of hydrate *** is concluded that the pore pressure drop region of low-permeability reservoirs in the South China Sea is limited,and various slope angles further lead to differences in effective stress and strain of reservoirs during hydrate production,resulting in severe uneven settlement of reservoirs.

关键词： effective stress low‐permeability reservoirs natural gas hydrate production numerical simulation settlement slope angle the South China

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Spectral purification improves monitoring accuracy of the comprehensive growth evaluation index for film-mulched winter wheat

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Journal of Integrative Agriculture 2024年第5期23卷 1523-1540页

作者： Zhikai Cheng Xiaobo Gu Yadan Du Zhihui Zhou Wenlong Li Xiaobo Zheng Wenjing Cai Tian Chang Key laboratory of Agricultural soil and Water engineering in Arid and Semiarid AreasMinistry of Education/Northwest A&F University Yangling712100China

In order to further improve the utility of unmanned aerial vehicle(UAV)remote-sensing for quickly and accurately monitoring the growth of winter wheat under film mulching, this study examined the treatments of ridge mulching,ridge–furrow full mulching, and flat cropping full mulching in winter *** on the fuzzy comprehensive evaluation (FCE) method, four agronomic parameters (leaf area index, above-ground biomass, plant height, and leaf chlorophyll content) were used to calculate the comprehensive growth evaluation index (CGEI) of the winter wheat, and 14 visible and near-infrared spectral indices were calculated using spectral purification technology to process the remote-sensing image data of winter wheat obtained by multispectral *** machine learning algorithms, partial least squares, support vector machines, random forests, and artificial neural network networks(ANN), were used to build the winter wheat growth monitoring model under film mulching, and accuracy evaluation and mapping of the spatial and temporal distribution of winter wheat growth status were carried *** results showed that the CGEI of winter wheat under film mulching constructed using the FCE method could objectively and comprehensively evaluate the crop growth *** accuracy of remote-sensing inversion of the CGEI based on the ANN model was higher than for the individual agronomic parameters, with a coefficient of determination of 0.75,a root mean square error of 8.40, and a mean absolute value error of *** purification could eliminate the interference of background effects caused by mulching and soil, effectively improving the accuracy of the remotesensing inversion of winter wheat under film mulching, with the best inversion effect achieved on the ridge–furrow full mulching area after spectral *** results of this study provide a theoretical reference for the use of UAV remote-sensing to monitor the growth status of winter wheat with film mulching.

关键词： mulched winter wheat machine learning fuzzy comprehensive evaluation comprehensive growth evaluation index unmanned aerial vehicle

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A modified 3D mean strain energy density criterion for predicting shale mixed-mode I/III fracture toughness

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Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2411-2428页

作者： Kun Zheng Chaolin Wang Yu Zhao Jing Bi Haifeng Liu College of Civil engineering Guizhou UniversityGuiyang550025China State Key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

The fracture toughness of rocks is a critical fracturing parameter in geo-energy exploitation playing a significant role in fracture mechanics and hydraulic *** edge-notched disk bending(ENDB)specimens are employed to measure the entire range of mixed-modeⅠ/Ⅲfracture toughness of Longmaxi *** theoretically interpret the fracture mechanisms,this research first introduces the detailed derivations of three established fracture *** distinguishing the volumetric and distortional strain energy densities,an improved three-dimensional mean strain energy density(MSED)criterion is *** the critical volumetric to distortional MSED ratio decreases,the transition from tensiondominated fracture to shear-dominated fracture is *** results indicate that both peak load and applied energy increase significantly with the transition from pure mode I(i.e.,tension)to pure modeⅢ(i.e.,torsion or tearing)since mode-Ⅲcracking happens in a twisted manner and mode-Ⅰcracking occurs in a coplanar *** macroscopic fracture signatures are consistent with those of triaxial hydraulic *** average ratio of pure mode-Ⅲfracture toughness to pure mode-Ⅰfracture toughness is 0.68,indicating that the obtained mode-Ⅲfracture resistance for a tensionbased loading system is apparent rather than *** to the three mainstream fracture criteria,the present fracture criterion exhibits greater competitiveness and can successfully evaluate and predict mixed-modeⅠ/Ⅲfracture toughness of distinct materials and loading methods.

关键词： Longmaxi shale Hydraulic fracturing Fracture mechanisms Fracture criteria Mixed-mode I/III fracture toughness Edge-notched disk bending

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Change of pore water near the freezing front during soil freezing: Migration and mechanisms

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Pedosphere 2024年第4期34卷 770-782页

作者： Yajun SHI Wei MA Lianhai ZHANG Chengsong YANG Fei SHANG Cheng CHEN State Key laboratory of Frozen soil engineering Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Joint NMR laboratory for Freeze-Thaw Processes in soils of State Key laboratory of Frozen soil engineering and Suzhou Niumag Analytical Instrument Corporation

The formation and growth of segregation ice dominate the frost heave during soil freezing, which is closely related to water migration. To analyze segregation ice during soil freezing for different soils, a freezing-thawing experiment was conducted with Lanzhou loess(LZL) and Qinghai-Tibet Plateau silty clay(QSC) using a novel layered nuclear magnetic resonance approach. During LZL freezing, the unfrozen water content first increased and then decreased with decreasing temperature near the freezing front, but decreased with decreasing temperature in other layers, whereas during the freezing of QSC, the unfrozen water content in different layers(including the freezing front) decreased with decreased temperature. Notably, the increased liquid water near the freezing front during LZL freezing was primarily adsorbed water. In addition to the temperature gradient, the squeezing action during soil freezing was another important factor affecting water migration, especially at the early stage of soil freezing. However, which of the two factors, squeezing action and temperature gradient, was the dominant one causing water migration depended on soil structure. At the early stage of soil freezing, the squeezing action had a significant effect on the water migration of LZL, but no significant effect on that of QSC. Furthermore, water accumulation of LZL near the freezing front due to squeezing action at the early stage of freezing limited the formation and growth of segregation ice. This study provided an improved understanding for ice segregation and water migration during soil freezing.

关键词： frozen soil nuclear magnetic resonance segregation ice unfrozen water water migration

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Three-dimensional stress variation characteristics in deep hard rock of CJPL-Ⅱ project based on in-situ monitoring

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International Journal of Mining Science and Technology 2024年第2期34卷 179-195页

作者： Minzong Zheng Shaojun Li Zejie Feng Huaisheng Xu Yaxun Xiao State Key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

In deep hard rock excavation, stress plays a pivotal role in inducing stress-controlled failure. While the impact of excavation-induced stress disturbance on rock failure and tunnel stability has undergone comprehensive examination through laboratory tests and numerical simulations, its validation through insitu stress tests remains unexplored. This study analyzes the three-dimensional stress changes in the surrounding rock at various depths, monitored during the excavation of B2 Lab in China Jinping Underground laboratory Phase Ⅱ(CJPL-Ⅱ). The investigation delves into the three-dimensional stress variation characteristics in deep hard rock, encompassing stress components and principal stress. The results indicate changes in both the magnitude and direction of the principal stress during tunnel excavation. To quantitatively describe the degree of stress disturbance, a series of stress evaluation indexes are established based on the distances between stress tensors, including the stress disturbance index(SDI), the principal stress magnitude disturbance index(SDIm), and the principal stress direction disturbance index(SDId). The SDI indicates the greatest stress disturbance in the surrounding rock is 4.5 m from the tunnel wall in B2 Lab. SDIm shows that the principal stress magnitude disturbance peaks at2.5 m from the tunnel wall. SDId reveals that the largest change in principal stress direction does not necessarily occur near the tunnel wall but at a specific depth from it. The established relationship between SDI and the depth of the excavation damaged zone(EDZ) can serve as a criterion for determining the depth of the EDZ in deep hard rock engineering. Additionally, it provides a reference for future construction and support considerations.

关键词： Disturbance stress Tensor distance Stress disturbance index Principal stress direction Underground research laboratory

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Generalized nth-Order Perturbation Method Based on Loop Subdivision Surface Boundary Element Method for Three-Dimensional Broadband Structural Acoustic Uncertainty Analysis

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Computer Modeling in engineering & Sciences 2024年第8期140卷 2053-2077页

作者： Ruijin Huo Qingxiang Pei Xiaohui Yuan Yanming Xu College of Architecture and Civil engineering Xinyang Normal UniversityXinyang464000China Henan Unsaturated soil and Special soil engineering Technology Research Center Xinyang Normal UniversityXinyang464000China Henan International Joint laboratory of Structural Mechanics and Computational Simulation College of Architecture and Civil EngineeringHuanghuai UniversityZhumadian463000China

In this paper,a generalized nth-order perturbation method based on the isogeometric boundary element method is proposed for the uncertainty analysis of broadband structural acoustic scattering *** Burton-Miller method is employed to solve the problem of non-unique solutions that may be encountered in the external acoustic field,and the nth-order discretization formulation of the boundary integral equation is *** addition,the computation of loop subdivision surfaces and the subdivision rules are *** order to confirm the effectiveness of the algorithm,the computed results are contrasted and analyzed with the results under Monte Carlo simulations(MCs)through several numerical examples.

关键词： Perturbation method loop subdivision surface isogeometric boundary element method uncertainty analysis

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Coupling effect of cement-stabilization and biopolymer-modification on the mechanical behavior of dredged sediment

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Journal of Rock Mechanics and Geotechnical engineering 2024年第8期16卷 3284-3298页

作者： Lei Lang Jiangshan Li Xiao Huang Ping Wang Wei Zhang State Key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Hubei Provincial Key laboratory of Contaminated Sludge and soil Science and engineering Wuhan430071China University of Chinese Academy of Sciences Beijing100049China

Nowadays,biopolymer stabilization as a promising eco-friendly approach in soft ground improvement has attracted wide ***,the feasibility of using biopolymer as a green additive of cementstabilized dredged sediment(CDS)with high water content is still *** this study,guar gum(GG)and xanthan gum(XG)were adopted as typical biopolymers,and a series of unconfined compressive strength(UCS),splitting tensile strength(STS)and scanning electron microscopy(SEM)tests were performed to evaluate the mechanical and microstructural properties of XG-and GG-modified CDSs considering several factors including biopolymer modification,binderesoil ratio and wateresolid ***,the micro-mechanisms revealing the evolutions of mechanical properties of biopolymermodified CDS were *** results indicate that the addition of XG can effectively improve the strength of CDS,while the GG has a side *** XG content of 9%was recommended,which can improve the 7 d-and 28 d-UCSs by 196%and 51.8%,together with the 7 d-and 28 d-STSs by 118.3%and 42.2%,*** the binderesoil ratio or decreasing the wateresolid ratio significantly improved the strength gaining but aggravated the brittleness characteristics of *** XG to CDS contributed to the formation of microstructure with more compactness and higher cementation degrees of ordinary Portland cement(OPC)-XG-stabilized DS(CXDS).The micro-mechanism models revealing the interactions of multiple media including OPC cementation,biopolymer film bonding and bridging effects inside CXDS were *** key findings confirm the feasibility of XG modification as a green and high-efficiency mean for improving the mechanical properties of CDS.

关键词： Dredged sediment(DS) Stabilization Biopolymer modification Mechanical properties Micro-mechanism

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Modeling wave propagation across rock masses using an enriched 3D numerical manifold method

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Science China(Technological Sciences) 2024年第3期67卷 835-852页

作者： YANG YongTao LI JunFeng WU WenAn State Key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China Key laboratory of Urban Security and Disaster engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China University of Chinese Academy of Sciences Beijing 100049China

The three-dimensional numerical manifold method(3DNMM) method is further enriched to simulate wave propagation across homogeneous/jointed rock masses. For the purpose of minimizing negative effects from artificial boundaries, a viscous nonreflecting boundary, which can effectively absorb the energy of a wave, is firstly adopted to enrich 3DNMM. Then, to simulate the elastic recovery property of an infinite problem domain, a viscoelastic boundary, which is developed from the viscous nonreflecting boundary, is further adopted to enrich 3DNMM. Finally, to eliminate the noise caused by scattered waves, a force input method which can input the incident wave correctly is incorporated into 3DNMM. Five typical numerical tests on P/S-wave propagation across jointed/homogeneous rock masses are conducted to validate the enriched 3DNMM. Numerical results indicate that wave propagation problems within homogeneous and jointed rock masses can be correctly and reliably modeled with the enriched 3DNMM.

关键词： 3D numerical manifold method viscous nonreflecting boundary rock masses force input method wave propagation

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Uncertainty quantification of inverse analysis for geomaterials using probabilistic programming

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Journal of Rock Mechanics and Geotechnical engineering 2024年第3期16卷 895-908页

作者： Hongbo Zhao Shaojun Li Xiaoyu Zang Xinyi Liu Lin Zhang Jiaolong Ren School of Civil engineering and Geomatics Shandong University of TechnologyZibo255000China State Key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

Uncertainty is an essentially challenging for safe construction and long-term stability of geotechnical *** inverse analysis is commonly utilized to determine the physico-mechanical ***,conventional inverse analysis cannot deal with uncertainty in geotechnical and geological *** this study,a framework was developed to evaluate and quantify uncertainty in inverse analysis based on the reduced-order model(ROM)and probabilistic *** ROM was utilized to capture the mechanical and deformation properties of surrounding rock mass in geomechanical *** programming was employed to evaluate uncertainty during construction in geotechnical engineering.A circular tunnel was then used to illustrate the proposed framework using analytical and numerical *** results show that the geomechanical parameters and associated uncertainty can be properly obtained and the proposed framework can capture the mechanical behaviors under ***,a slope case was employed to demonstrate the performance of the developed *** results prove that the proposed framework provides a scientific,feasible,and effective tool to characterize the properties and physical mechanism of geomaterials under uncertainty in geotechnical engineering problems.

关键词： Geological engineering Geotechnical engineering Inverse analysis Uncertainty quantification Probabilistic programming

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Prediction model on hydrolysis kinetics of phthalate monoester:A density functional theory study

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Journal of Environmental Sciences 2024年第1期135卷 51-58页

作者： Tong Xu Jingwen Chen Deming Xia Weihao Tang Jiansheng Cui Chun Liu Shuangjiang Li College of Environmental Science and engineering Hebei University of Science and TechnologyShijiazhuang 050000China Key laboratory of Industrial Ecology and Environmental engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China National-Regional Joint engineering Research Center for soil Pollution Control and Remediation in South China Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and ManagementInstitute of Eco-environmental and Soil SciencesGuangdong Academy of SciencesGuangzhou 510650China

As primary degradation products of phthalate esters,phthalate monoesters(MPEs)have been widely detected in various aquatic environments and drawn growing toxicological *** kinetics that is of importance for assessing environmental persistence of chemicals remain elusive for ***,kinetics of base-catalyzed and neutral hydrolysis for 18 MPEs with different leaving groups was investigated by density functional theory *** indicate that MPEs with leaving groups having p Kaof<10 prefer dissociative transition *** are more persistent than their parents,and their hydrolysis half-lives were calculated to vary from 3.4 min to 79.2 years(p H=7–9).A quantitative structure-activity relationship model was developed for predicting the hydrolysis kinetics *** was found that p Kaof the leaving groups and electronegativity of the MPEs are key factors determining the hydrolysis *** work may lay a theoretical foundation for better understanding the chemical process that governs MPE persistence in aquatic environments.

关键词： Phthalate monoesters Phthalate esters Hydrolysis Density functional theory Quantitative structure-activity relationship

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