Underground hydrogen storage has gained interest in recent years due to the enormous demand for clean energy.Hydrogen is more diffusive than air,with a smaller density and lower viscosity.These unique properties intro...Underground hydrogen storage has gained interest in recent years due to the enormous demand for clean energy.Hydrogen is more diffusive than air,with a smaller density and lower viscosity.These unique properties introduce distinctive hydrodynamic phenomena in hydrogen storage,one of which is fingering.Fingering could induce the fluid trapped in small clusters of pores,leading to a dramatic decrease in hydrogen saturation and a lower recovery rate.In this study,numerical simulations are performed at the microscopic scale to understand the evolution of hydrogen saturation and the impacts of injection and withdrawal cycles.Two sets of micromodels with different porosity(0.362 and 0.426)and minimum sizes of pore throats(0.362 mm and 0.181 mm)are developed in the numerical model.A parameter analysis is then conducted to understand the influence of injection velocity(in the range of 10^(-2)m/s to 10^(-5)m/s)and porous structure on the fingering pattern,followed by an image analysis to capture the evolution of the fingering pattern.Viscous fingering,capillary fingering,and crossover fingering are observed and identified under different boundary conditions.The fractal dimension,specific area,mean angle,and entropy of fingers are proposed as geometric descriptors to characterize the shape of the fingering pattern.When porosity increases from 0.362 to 0.426,the saturation of hydrogen increases by 26.2%.Narrower pore throats elevate capillary resistance,which hinders fluid invasion.These results underscore the importance of pore structures and the interaction between viscous and capillary forces for hydrogen recovery efficiency.This work illuminates the influence of the pore structures and the fluid properties on the immiscible displacement of hydrogen and can be further extended to optimize the injection strategy of hydrogen in underground hydrogen storage.展开更多
The effective early warning of surrounding rock mass deformation is crucial in geotechnical engineering for ensuring the safety and stability of underground constructions.This study introduces a novel risk early warni...The effective early warning of surrounding rock mass deformation is crucial in geotechnical engineering for ensuring the safety and stability of underground constructions.This study introduces a novel risk early warning model based on multi-parameter fuzzy comprehensive evaluation,which quantitatively assesses the risk state of the surrounding rock mass.The microseismic(MS)monitoring system is set up for the underground powerhouse.The spatial and temporal distribution of MS events and the frequency characteristics of MS signals are analyzed during the top arch excavation.The early warning indices for characterizing MS spatial aggregation and frequency-energy dispersion are proposed based on the octree theory to assess the deformation of the surrounding rock mass.The risk warning model for the surrounding rock mass in underground engineering is developed through the integration of the formulated index and the frequency characteristics of MS signals.The results indicate that the multiparameter fuzzy comprehensive assessment model can achieve three-dimensional visualization of risk warnings for the surrounding rock mass.The quantitative results regarding warning time and potential deformation areas are highly consistent with the characteristics of MS precursors.These research results can provide an important reference for early warning of surrounding rock mass risk in similar underground projects.展开更多
Coal mine underground reservoirs help address the severe water imbalance in ecologically fragile mining regions of western China,but evaluating their storage capacity remains challenging due to the coupled effects of ...Coal mine underground reservoirs help address the severe water imbalance in ecologically fragile mining regions of western China,but evaluating their storage capacity remains challenging due to the coupled effects of gangue deformation,saturation,and goaf geometry.This study investigates the deformation and void evolution of fragmented gangue with varying lithologies,particle sizes,and water contents through an independent-developed testing system and theoretical model.A planar micro-unit model and a three-dimensional spatial structure model are proposed to quantify the storage coefficient and total reservoir capacity of underground water storage structures.These models incorporate the effects of stratified lithologies,saturation-induced softening,and spatially distributed stress conditions.The methodology is applied to the underground reservoir in Chahasu coal mine,and the results show that under increasing stress,storage coefficients decline exponentially,with pronounced differences between single-and double-lithology structures.The storage coefficient in the spatial model demonstrate greater resilience to stress concentration compared to planar models,and further analysis identifies critical thresholds in roof fracture distances and stress-recovery times affecting long-term storage performance.This research provides a comprehensive framework for evaluating underground reservoir storage potential,offering theoretical support and engineering guidance for the sustainable utilization of mine water.展开更多
Discontinuities in rock masses critically impact the stability and safety of underground engineering.Mainstream discontinuities identificationmethods,which rely on normal vector estimation and clustering algorithms,su...Discontinuities in rock masses critically impact the stability and safety of underground engineering.Mainstream discontinuities identificationmethods,which rely on normal vector estimation and clustering algorithms,suffer from accuracy degradation,omission of critical discontinuities when orientation density is unevenly distributed,and need manual intervention.To overcome these limitations,this paper introduces a novel discontinuities identificationmethod based on geometric feature analysis of rock mass.By analyzing spatial distribution variability of point cloud and integrating an adaptive region growing algorithm,the method accurately detects independent discontinuities under complex geological conditions.Given that rock mass orientations typically follow a Fisher distribution,an adaptive hierarchical clustering algorithm based on statistical analysis is employed to automatically determine the optimal number of structural sets,eliminating the need for preset clusters or thresholds inherent in traditional methods.The proposed approach effectively handles diverse rock mass shapes and sizes,leveraging both local and global geometric features to minimize noise interference.Experimental validation on three real-world rock mass models,alongside comparisons with three conventional directional clustering algorithms,demonstrates superior accuracy and robustness in identifying optimal discontinuity sets.The proposed method offers a reliable and efficienttool for discontinuities detection and grouping in underground engineering,significantlyenhancing design and construction outcomes.展开更多
Scientific and technological advancements are rapidly transforming underground engineering,shifting from labor-intensive,time-consuming methods to automated,real-time systems.This timely and comprehensive review cover...Scientific and technological advancements are rapidly transforming underground engineering,shifting from labor-intensive,time-consuming methods to automated,real-time systems.This timely and comprehensive review covers in-situ testing,intelligent monitoring,and geophysical testing methods,highlighting fundamental principles,testing apparatuses,data processing techniques,and engineering applications.The state-of-the-art summary emphasizes not only cutting-edge innovations for complex and harsh environments but also the transformative role of artificial intelligence and machine learning in data interpretations.The integration of big data and advanced algorithms is particularly impactful,enabling the identification,prediction,and mitigation of potential risks in underground projects.Key aspects of the discussion include detection capabilities,method integration,and data convergence of intelligent technologies to drive enhanced safety,operational efficiency,and predictive reliability.The review also examines future trends in intelligent technologies,emphasizing unified platforms that combine multiple methods,real-time data,and predictive analytics.These advancements are shaping the evolution of underground construction and maintenance,aiming for risk-free,high-efficiency underground engineering.展开更多
The large-scale accumulation of industrial solid waste,including red mud and coal gangue,coupled with goafs left by under-ground mining activities,poses significant challenges to sustainable human development.In this ...The large-scale accumulation of industrial solid waste,including red mud and coal gangue,coupled with goafs left by under-ground mining activities,poses significant challenges to sustainable human development.In this study,red mud,coal gangue,and othersolid wastes were used to prepare underground backfilling materials.The utilization rate of the total solid waste reached 95%,with redmud accounting for approximately 40wt% of the total.The unconfined compressive strength,setting time,and slump tests were conduc-ted to evaluate the mechanical properties of the material.At the optimal ratio,the 7-and 28-d strengths reach 4.4 and 6.9 MPa,respect-ively.The initial and final setting times were 200 and 250 min,respectively,whereas the initial and 1-h slump exceed 250 and 210 mm,respectively.X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM)wereemployed to explore the microstructure,phase composition,and chemical bonding within the material.Needle-like,clustered,and granu-lar hydration products were observed,and the primary crystalline structures were identified as ettringite,gmelinite,C-A-S-H,andC-S-H.In addition,a thorough environmental risk assessment was conducted,complemented by detailed economic cost and carbonemission calculations.During the creation of backfill material,hazardous elements from solid waste are immobilized through adsorption,precipitation,and incorporation into the crystal lattice.The immobilization efficiencies for Ni,Al,Cr^(6+),and As were 97.03%,94.32%,86.43%,and 84.22%,respectively,at a pH of 8.49.Moreover,the use of solid waste as a raw material results in considerable cost savingsand marked reduction in carbon emissions.This study innovatively promotes the green cycle of alumina production in the bauxite miningindustry.展开更多
This study investigates the mechanical response of an underground cavern subjected to cyclic high gas pressure,aiming to establish a theoretical foundation for the design of lined rock caverns(LRCs)for energy storage ...This study investigates the mechanical response of an underground cavern subjected to cyclic high gas pressure,aiming to establish a theoretical foundation for the design of lined rock caverns(LRCs)for energy storage with high internal pressure,e.g.compressed air energy storage(CAES)underground caverns or hydrogen storage caverns.Initially,the stress paths of the surrounding rock during the excavation,pressurization,and depressurization processes are delineated.Analytical expressions for the stress and deformation of the surrounding rock are derived based on the MohreCoulomb criterion.These expressions are then employed to evaluate the displacement of cavern walls under varying qualities of surrounding rock,the contact pressure between the steel lining and the surrounding rock subject to different gas storage pressures,the load-bearing ratio of the surrounding rock,and the impact of lining thickness on the critical gas pressure.Furthermore,the deformation paths of the surrounding rock are evaluated,along with the effects of tunnel depth and diameter on residual deformation of the surrounding rock,and the critical minimum gas pressure at which the surrounding rock and the lining do not detach.The results indicate that residual deformation of the surrounding rock occurs after depressurization under higher internal pressure for higher-quality rock masses,leading to detachment between the surrounding rock and the steel lining.The findings indicate that thicker linings correspond to higher critical minimum gas pressures.However,for lower-quality surrounding rock,thicker linings correspond to lower critical minimum gas pressures.These findings will provide invaluable insights for the design of LRCs for underground energy storage caverns.展开更多
Hydrogen,a genuinely clean energy,is a promising alternative to fossil fuels.Inspired by underground gas storage of methane,establishing underground hydrogen storage(UHS)in depleted oil and gas reservoirs has emerged ...Hydrogen,a genuinely clean energy,is a promising alternative to fossil fuels.Inspired by underground gas storage of methane,establishing underground hydrogen storage(UHS)in depleted oil and gas reservoirs has emerged as a significant research focus.Carbonate reservoirs,where widely-presented fractures can facilitate the high-speed injection and production of gases,are hence ideal candidates for building underground hydrogen storage facilities.During the cyclic injection and extraction processes of UHS,the formation is subjected to stress disturbances,leading to stress sensitivity.Understanding the stress sensitivity patterns of carbonate rocks is crucial for optimizing injection and production strategies.This study reconstructed three-dimensional digital models of fractured carbonate rocks from the L gas field using micro-CT scanning technology.Utilizing the finite element method,we investigated the microscopic permeability characteristics of carbonate rocks and analyzed the impact of stress loading direction and confining stress on stress sensitivity.The findings reveal that the stress loading direction significantly influences the stress sensitivity of fractured carbonate rocks.When a stress of 60 MPa is applied perpendicular to the fracture direction,the permeability reduction ratio can reach 17.32%.In contrast,when the same stress is applied parallel to the fracture direction,the permeability reduction ratio is only 4.82%.Furthermore,a simulation of UHS with cyclic injection and production of H2 in the target block was conducted.When both permeability and porosity stress sensitivity were considered,the working gas volume for UHS decreased by only 3.4%,demonstrating that fractured carbonate reservoirs are feasible candidates for constructing underground hydrogen storage.展开更多
The Kuye River Basin has experienced a rapid depletion of groundwater due to the increased coal production.In this study,by introducing the empirical equations derived from the three zone theory in the coal mining ind...The Kuye River Basin has experienced a rapid depletion of groundwater due to the increased coal production.In this study,by introducing the empirical equations derived from the three zone theory in the coal mining industry in China as a boundary condition,a calculation model was developed by coupling the soil and water assessment tool and visual modular three-dimensional finite-difference ground-water flow model(SWAT-VISUAL MODFLOW).The model was applied to several coal mines in the basin to quantify the groundwater impact of underground mining.For illustration purposes,two underground water observation stations and one water level station were selected for groundwater change simulation in 2009,producing the results that agreed well with the observed data.We found that groundwater level was closely related to the height of the fractured water-conducting zone caused by underground mining,and a higher height led to a lower groundwater level.This finding was further supported by the calculation that underground mining was responsible for 23.20mm aquifer breakages in 2009.Thus,preventing surface subsidence due to underground mining can help protecting the basin's groundwater.展开更多
Prosthetic devices designed to assist individuals with damaged or missing body parts have made significant strides,particularly with advancements in machine intelligence and bioengineering.Initially focused on movemen...Prosthetic devices designed to assist individuals with damaged or missing body parts have made significant strides,particularly with advancements in machine intelligence and bioengineering.Initially focused on movement assistance,the field has shifted towards developing prosthetics that function as seamless extensions of the human body.During this progress,a key challenge remains the reduction of interface artifacts between prosthetic components and biological tissues.Soft electronics offer a promising solution due to their structural flexibility and enhanced tissue adaptability.However,achieving full integration of prosthetics with the human body requires both artificial perception and efficient transmission of physical signals.In this context,synaptic devices have garnered attention as next-generation neuromorphic computing elements because of their low power consumption,ability to enable hardware-based learning,and high compatibility with sensing units.These devices have the potential to create artificial pathways for sensory recognition and motor responses,forming a“sensory-neuromorphic system”that emulates synaptic junctions in biological neurons,thereby connecting with impaired biological tissues.Here,we discuss recent developments in prosthetic components and neuromorphic applications with a focus on sensory perception and sensorimotor actuation.Initially,we explore a prosthetic system with advanced sensory units,mechanical softness,and artificial intelligence,followed by the hardware implementation of memory devices that combine calculation and learning functions.We then highlight the importance and mechanisms of soft-form synaptic devices that are compatible with sensing units.Furthermore,we review an artificial sensory-neuromorphic perception system that replicates various biological senses and facilitates sensorimotor loops from sensory receptors,the spinal cord,and motor neurons.Finally,we propose insights into the future of closed-loop neuroprosthetics through the technical integration of soft electronics,including bio-integrated sensors and synaptic devices,into prosthetic systems.展开更多
This special issue of Deep Underground Science and Engineering(DUSE)showcases pioneering research on the transformative role of machine learning(ML)and Big Data in deep underground engineering.Edited by vip editors ...This special issue of Deep Underground Science and Engineering(DUSE)showcases pioneering research on the transformative role of machine learning(ML)and Big Data in deep underground engineering.Edited by vip editors Prof.Asoke Nandi(Brunel University of London,UK),Prof.Ru Zhang(Sichuan University,China),Prof.Tao Zhao(Chinese Academy of Sciences,China),and Prof.Tao Lei(Shaanxi University of Science and Technology,China),this issue highlights the innovative applications of ML technique in reshaping structural safety,tunneling operations,and geotechnical investigations.展开更多
Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the p...Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the pushing force acting on the wellbore in different sizes and directions within a circular range,ultimately allowing the wellbore trajectory to be drilled in a predetermined direction.By analyzing its mathematical principles and the actual characteristics of the instrument,a vector force closed-loop control method,including steering and holding modes,was designed.The adjustment criteria for the three hydraulic modules are determined to achieve rapid adjustment of the vector force.The theoretical feasibility of the developed method was verified by comparing its results with the on-site application data of an imported rotary guidance system.展开更多
Deep Underground Science and Engineering(DUSE)is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground.This issue contains one perspective...Deep Underground Science and Engineering(DUSE)is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground.This issue contains one perspective article,two review articles,six research articles,and one case study article.These articles focus on underground energy storage,multiscale modeling for correlation between micro-scale damage and macro-scale structural degradation,mineralization and formation of gold mine,interface and fracture seepage,experimental study on tunnel-sand-pile interaction,and high water-content materials for deep underground space backfilling,analytical solutions for the crack evolution direction in brittle rocks,and a case study on the squeezing-induced failure in a water drainage tunnel and the rehabilitation measures.展开更多
Soft rock is one of the common geological conditions in coal mine underground water reservoir engineering.The cross-scale correlation analysis of water erosion soft lithology deterioration is very important for the sa...Soft rock is one of the common geological conditions in coal mine underground water reservoir engineering.The cross-scale correlation analysis of water erosion soft lithology deterioration is very important for the safety and stability of coal mine underground reservoir(CMUR)engineering.To address the issues of grain crowding and segmentation difficulties in cross-scale corelation analysis,as well as the limitations of traditional etching methods,this study proposes an image grain segmentation method based on deep learning algorithms,utilizing scanning electron microscopy and image process-ing techniques.The method successfully segments crowded grains and eliminates the interference from misplaced particles.In addition,indoor uniaxial compression tests were conducted to obtain the mechanical properties of sandstone samples with different water content.By quantitatively characterizing the macroscopic and microscopic deterioration degree of red sandstone samples with different water contents,the relationship between the strength changes of rock samples and the pet-rographic parameters such as grain size and grain shape is analyzed,and the influence law of soft lithology deterioration in CMUR engineering is revealed.The results indicate:(1)Water significantly weakens the mechanical properties and stability of soft rock.With increasing water content,the strength of sandstone samples continuously decreases,and the failure mode transitions from brittle to ductile failure.(2)The deterioration of micro-micro structures is the main cause of the decrease in mechanical properties of water-eroded soft rock.Grain size,grain area,and aspect ratio are negatively correlated with water content,indicating that hydrophilic minerals in soft rock dissolve under the action of water,leading to rock damage.(3)Grain size,area,and aspect ratio can serve as significant indicators for quantifying the strength changes of water-eroded soft rock.The research findings can be applied to stability assessment and disaster prevention in CMUR engineering.展开更多
Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane ex...Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.展开更多
To investigate the fracture propagation characteristics and failure mechanism of anti-dip rock slope induced by underground mining,the Jiguanling landslide in Wulong,Chongqing,China is taken as the prototype,and physi...To investigate the fracture propagation characteristics and failure mechanism of anti-dip rock slope induced by underground mining,the Jiguanling landslide in Wulong,Chongqing,China is taken as the prototype,and physical model test is utilized to study the fracture evolution process,deformation characteristics and failure mechanism of anti-dip rock slope.In this study,the digital image correlation(DIC)technique and pressure acquisition system are combined to analyze the displacement and stress field of rock slope during underground mining stages.The results show that the anti-dip rock slope experiences four stages during underground coal mining:tensile fracture propagation in upper toppling zone,shallow damage in the lower shear zone,coal seam roof caving,failure of the whole slope.There is a phenomenon of local tensile and compressive stress conversion in upper toppling zone after roof caving.The appearance of coal seam roof caving increases the compressive area and pressure of the shear zone,leading to the failure of the shear blocks at the front edge,and ultimately causing failure of the whole slope.Mining with retained coal pillar before shallow failure in the shear zone can effectively block the impact of lower mining on the upper toppling zone,achieve a 16%contraction in toppling zone,and improve the stability of the slope.The failure mode of slope can be summarized as shear–slip–toppling collapse failure.This paper improves the understanding on the failure mechanism of anti-dip rock slope caused by underground mining.展开更多
Conventional open-loop deep brain stimulation(DBS)systems with fixed parameters fail to accommodate interindividual pathological differences in Parkinson's disease(PD)management while potentially inducing adverse ...Conventional open-loop deep brain stimulation(DBS)systems with fixed parameters fail to accommodate interindividual pathological differences in Parkinson's disease(PD)management while potentially inducing adverse effects and causing excessive energy consumption.In this paper,we present an adaptive closed-loop framework integrating a Yogi-optimized proportional–integral–derivative neural network(Yogi-PIDNN)controller.The Yogi-augmented gradient adaptation mechanism accelerates the convergence of general PIDNN controllers in high-dimensional nonlinear control systems while reducing control energy usage.In addition,a system identification method establishes input–output dynamics for pre-training stimulation waveforms,bypassing real-time parameter-tuning constraints and thereby enhancing closed-loop adaptability.Finally,a theoretical analysis based on Lyapunov stability criteria establishes a sufficient condition for closed-loop stability within the identified model.Computational validations demonstrate that our approach restores thalamic relay reliability while reducing energy consumption by(81.0±0.7)%across multi-frequency tests.This study advances adaptive neuromodulation by synergizing data-driven pre-training with stability-guaranteed real-time control,offering a novel framework for energy-efficient and personalized Parkinson's therapy.展开更多
The supply of energy is a severe challenge for every country,particularly those that are industrially developed and highly populated.Natural gas is among the most essential energy sources due to its reasonably low cos...The supply of energy is a severe challenge for every country,particularly those that are industrially developed and highly populated.Natural gas is among the most essential energy sources due to its reasonably low cost and high heating value.One of the elements of a sustainable energy supply is underground gas storage(UGS).UGS systems consist of a cushion gas(base gas)and a working gas.The cushion gas is injected into a reservoir to sustain the pressure and remain there until the period of storage ends,while the working gas is the main gas to be stored and produced.Unlike prior studies on fully depleted fields,our research emphasizes the potential of UGS in the presence of remaining oil and integrates key concepts,such as enhanced oil recovery and CO_(2)sequestration.A simulation study was conducted using Qatari Advanced Simulator for Reservoirs software to determine the feasibility of a UGS system in a partially depleted oil reservoir.N_(2) and CO_(2)gases were considered and analyzed over short,medium,and long injection/withdrawal cycles to investigate their potential as cushion gases for natural gas storage in a partially depleted oil reservoir.It was found that using CO_(2)as a cushion gas produces 32%,57%,and 90%of CH_(4) according to short-,medium-,and long-term energy storage scenarios,respectively,with the CH_(4) production higher than when using N2.This study sheds light on the feasibility of implementing underground gas storage systems in partially depleted oil reservoirs.展开更多
[Objectives]This study was conducted to investigate water pollution in the Huanghou Underground River Basin.[Methods]Five representative water quality indicators,ammonia nitrogen(NH+4-N),nitrate nitrogen(NO_(3)^(-)-N)...[Objectives]This study was conducted to investigate water pollution in the Huanghou Underground River Basin.[Methods]Five representative water quality indicators,ammonia nitrogen(NH+4-N),nitrate nitrogen(NO_(3)^(-)-N),permanganate index(COD Mn),total phosphorus(TP),and nitrite nitrogen(NO_(2)^(-)-N),were selected.The single-factor pollution index(P i),Nemerow pollution index(P N),and water quality index(WQI)were calculated to quantitatively assess pollution characteristics and evaluate water quality in the basin.[Results]The overall water quality in the Huanghou Underground River Basin fell within the"slightly polluted to good"range,with pollution primarily concentrated in the upstream areas.The downstream water quality was generally better,as most pollutants from the upstream were diluted or degraded during migration,resulting in little impact on the downstream areas.[Conclusions]This study provides a theoretical basis for understanding the pollution characteristics and evaluation of water quality in the Huanghou Underground River Basin.展开更多
The big underground powerhouse cavern of the China Baihetan hydropower plant is 438m long,34m wide,and 88.7m high.It is cut by a weak interlayer shear zone and its high sidewall poses a huge stability problem.This pap...The big underground powerhouse cavern of the China Baihetan hydropower plant is 438m long,34m wide,and 88.7m high.It is cut by a weak interlayer shear zone and its high sidewall poses a huge stability problem.This paper reports our successful solution of this problem through numerical simulations and a replacement-tunnel scheme in the detailed design stage and close site monitoring in the excavation stage.Particularly,in the detail design stage,mechanical parameters of the shear zone were carefully determined through laboratory experiments and site tests.Then,deformation of the surrounding rocks and the shear zone under high in situ stress conditions was predicted using 3 Dimensional Distinct Element Code(3DEC).Subsequently,a replacement-tunnel scheme was proposed for the treatment on the shear zone to prevent severe unloading relaxation of surrounding rocks.In the construction period,excavation responses were closely monitored on deformations of surrounding rocks and the shear zone.The effect of local cracking in the replacement tunnels on sidewall stability was evaluated using the strength reduction method.These monitoring results were compared with the predicted numerical simulation in the detailed design stage.It is found that the shear zone greatly modified the deformation mode of the cavern surrounding rocks.Without any treatment,rock mass deformation on the downstream sidewall was larger than 125mm and the shearing deformation of the shear zone was 60–70 mm.These preset replacement tunnels can reduce not only the unloading and relaxation of rock masses but also the maximum shearing deformation of the shear zone by 10–20 mm.The predictions by numerical simulation were in good agreement with the monitoring results.The proposed tunnel-replacement scheme can not only restrain the shear zone deformation but also enhance the safety of surrounding rocks and concrete tunnels.This design procedure offers a good reference for interaction between a big underground cavern and a weak layer zone in the future.展开更多
基金supported by the National Key Research and Development Project(Grant No.2023YFE0110900)the National Natural Science Foundation of China(Grant Nos.42320104003,42477168).
文摘Underground hydrogen storage has gained interest in recent years due to the enormous demand for clean energy.Hydrogen is more diffusive than air,with a smaller density and lower viscosity.These unique properties introduce distinctive hydrodynamic phenomena in hydrogen storage,one of which is fingering.Fingering could induce the fluid trapped in small clusters of pores,leading to a dramatic decrease in hydrogen saturation and a lower recovery rate.In this study,numerical simulations are performed at the microscopic scale to understand the evolution of hydrogen saturation and the impacts of injection and withdrawal cycles.Two sets of micromodels with different porosity(0.362 and 0.426)and minimum sizes of pore throats(0.362 mm and 0.181 mm)are developed in the numerical model.A parameter analysis is then conducted to understand the influence of injection velocity(in the range of 10^(-2)m/s to 10^(-5)m/s)and porous structure on the fingering pattern,followed by an image analysis to capture the evolution of the fingering pattern.Viscous fingering,capillary fingering,and crossover fingering are observed and identified under different boundary conditions.The fractal dimension,specific area,mean angle,and entropy of fingers are proposed as geometric descriptors to characterize the shape of the fingering pattern.When porosity increases from 0.362 to 0.426,the saturation of hydrogen increases by 26.2%.Narrower pore throats elevate capillary resistance,which hinders fluid invasion.These results underscore the importance of pore structures and the interaction between viscous and capillary forces for hydrogen recovery efficiency.This work illuminates the influence of the pore structures and the fluid properties on the immiscible displacement of hydrogen and can be further extended to optimize the injection strategy of hydrogen in underground hydrogen storage.
基金support from the Sichuan Science and Technology Program(Grant No.2023NSFSC0812).
文摘The effective early warning of surrounding rock mass deformation is crucial in geotechnical engineering for ensuring the safety and stability of underground constructions.This study introduces a novel risk early warning model based on multi-parameter fuzzy comprehensive evaluation,which quantitatively assesses the risk state of the surrounding rock mass.The microseismic(MS)monitoring system is set up for the underground powerhouse.The spatial and temporal distribution of MS events and the frequency characteristics of MS signals are analyzed during the top arch excavation.The early warning indices for characterizing MS spatial aggregation and frequency-energy dispersion are proposed based on the octree theory to assess the deformation of the surrounding rock mass.The risk warning model for the surrounding rock mass in underground engineering is developed through the integration of the formulated index and the frequency characteristics of MS signals.The results indicate that the multiparameter fuzzy comprehensive assessment model can achieve three-dimensional visualization of risk warnings for the surrounding rock mass.The quantitative results regarding warning time and potential deformation areas are highly consistent with the characteristics of MS precursors.These research results can provide an important reference for early warning of surrounding rock mass risk in similar underground projects.
基金supported by the National Natural Science Foundation of China(Nos.52404153,52504157 and 52504156)the Natural Science Foundation of Jiangsu Province(No.BK20241649).
文摘Coal mine underground reservoirs help address the severe water imbalance in ecologically fragile mining regions of western China,but evaluating their storage capacity remains challenging due to the coupled effects of gangue deformation,saturation,and goaf geometry.This study investigates the deformation and void evolution of fragmented gangue with varying lithologies,particle sizes,and water contents through an independent-developed testing system and theoretical model.A planar micro-unit model and a three-dimensional spatial structure model are proposed to quantify the storage coefficient and total reservoir capacity of underground water storage structures.These models incorporate the effects of stratified lithologies,saturation-induced softening,and spatially distributed stress conditions.The methodology is applied to the underground reservoir in Chahasu coal mine,and the results show that under increasing stress,storage coefficients decline exponentially,with pronounced differences between single-and double-lithology structures.The storage coefficient in the spatial model demonstrate greater resilience to stress concentration compared to planar models,and further analysis identifies critical thresholds in roof fracture distances and stress-recovery times affecting long-term storage performance.This research provides a comprehensive framework for evaluating underground reservoir storage potential,offering theoretical support and engineering guidance for the sustainable utilization of mine water.
基金the National Key Research and Development Program of China(Grant No.2023YFC3009400).
文摘Discontinuities in rock masses critically impact the stability and safety of underground engineering.Mainstream discontinuities identificationmethods,which rely on normal vector estimation and clustering algorithms,suffer from accuracy degradation,omission of critical discontinuities when orientation density is unevenly distributed,and need manual intervention.To overcome these limitations,this paper introduces a novel discontinuities identificationmethod based on geometric feature analysis of rock mass.By analyzing spatial distribution variability of point cloud and integrating an adaptive region growing algorithm,the method accurately detects independent discontinuities under complex geological conditions.Given that rock mass orientations typically follow a Fisher distribution,an adaptive hierarchical clustering algorithm based on statistical analysis is employed to automatically determine the optimal number of structural sets,eliminating the need for preset clusters or thresholds inherent in traditional methods.The proposed approach effectively handles diverse rock mass shapes and sizes,leveraging both local and global geometric features to minimize noise interference.Experimental validation on three real-world rock mass models,alongside comparisons with three conventional directional clustering algorithms,demonstrates superior accuracy and robustness in identifying optimal discontinuity sets.The proposed method offers a reliable and efficienttool for discontinuities detection and grouping in underground engineering,significantlyenhancing design and construction outcomes.
基金supported by Ministry of Education of Singapore,under Academic Research Fund Tier 1(Grant Number RG143/23).
文摘Scientific and technological advancements are rapidly transforming underground engineering,shifting from labor-intensive,time-consuming methods to automated,real-time systems.This timely and comprehensive review covers in-situ testing,intelligent monitoring,and geophysical testing methods,highlighting fundamental principles,testing apparatuses,data processing techniques,and engineering applications.The state-of-the-art summary emphasizes not only cutting-edge innovations for complex and harsh environments but also the transformative role of artificial intelligence and machine learning in data interpretations.The integration of big data and advanced algorithms is particularly impactful,enabling the identification,prediction,and mitigation of potential risks in underground projects.Key aspects of the discussion include detection capabilities,method integration,and data convergence of intelligent technologies to drive enhanced safety,operational efficiency,and predictive reliability.The review also examines future trends in intelligent technologies,emphasizing unified platforms that combine multiple methods,real-time data,and predictive analytics.These advancements are shaping the evolution of underground construction and maintenance,aiming for risk-free,high-efficiency underground engineering.
基金financially supported by the National Nature Science Foundation of China(No.U23A20557)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2022QNRC001)Fundamental Research Funds for the Central Universities,China(No.00007720)。
文摘The large-scale accumulation of industrial solid waste,including red mud and coal gangue,coupled with goafs left by under-ground mining activities,poses significant challenges to sustainable human development.In this study,red mud,coal gangue,and othersolid wastes were used to prepare underground backfilling materials.The utilization rate of the total solid waste reached 95%,with redmud accounting for approximately 40wt% of the total.The unconfined compressive strength,setting time,and slump tests were conduc-ted to evaluate the mechanical properties of the material.At the optimal ratio,the 7-and 28-d strengths reach 4.4 and 6.9 MPa,respect-ively.The initial and final setting times were 200 and 250 min,respectively,whereas the initial and 1-h slump exceed 250 and 210 mm,respectively.X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM)wereemployed to explore the microstructure,phase composition,and chemical bonding within the material.Needle-like,clustered,and granu-lar hydration products were observed,and the primary crystalline structures were identified as ettringite,gmelinite,C-A-S-H,andC-S-H.In addition,a thorough environmental risk assessment was conducted,complemented by detailed economic cost and carbonemission calculations.During the creation of backfill material,hazardous elements from solid waste are immobilized through adsorption,precipitation,and incorporation into the crystal lattice.The immobilization efficiencies for Ni,Al,Cr^(6+),and As were 97.03%,94.32%,86.43%,and 84.22%,respectively,at a pH of 8.49.Moreover,the use of solid waste as a raw material results in considerable cost savingsand marked reduction in carbon emissions.This study innovatively promotes the green cycle of alumina production in the bauxite miningindustry.
基金supported by the State Key Laboratory of Disaster Reduction in Civil Engineering(Grant No.SLDRCE23-02)Ningbo PublicWelfare Fund Project(Grant No.2023S100)the National Key Research and Development Program of China(Grant No.2024YFE0105800).
文摘This study investigates the mechanical response of an underground cavern subjected to cyclic high gas pressure,aiming to establish a theoretical foundation for the design of lined rock caverns(LRCs)for energy storage with high internal pressure,e.g.compressed air energy storage(CAES)underground caverns or hydrogen storage caverns.Initially,the stress paths of the surrounding rock during the excavation,pressurization,and depressurization processes are delineated.Analytical expressions for the stress and deformation of the surrounding rock are derived based on the MohreCoulomb criterion.These expressions are then employed to evaluate the displacement of cavern walls under varying qualities of surrounding rock,the contact pressure between the steel lining and the surrounding rock subject to different gas storage pressures,the load-bearing ratio of the surrounding rock,and the impact of lining thickness on the critical gas pressure.Furthermore,the deformation paths of the surrounding rock are evaluated,along with the effects of tunnel depth and diameter on residual deformation of the surrounding rock,and the critical minimum gas pressure at which the surrounding rock and the lining do not detach.The results indicate that residual deformation of the surrounding rock occurs after depressurization under higher internal pressure for higher-quality rock masses,leading to detachment between the surrounding rock and the steel lining.The findings indicate that thicker linings correspond to higher critical minimum gas pressures.However,for lower-quality surrounding rock,thicker linings correspond to lower critical minimum gas pressures.These findings will provide invaluable insights for the design of LRCs for underground energy storage caverns.
基金National Natural Science Foundation of China,52304048Ye Tian,China Postdoctoral Science Foundation,2022M722637,Ye Tian。
文摘Hydrogen,a genuinely clean energy,is a promising alternative to fossil fuels.Inspired by underground gas storage of methane,establishing underground hydrogen storage(UHS)in depleted oil and gas reservoirs has emerged as a significant research focus.Carbonate reservoirs,where widely-presented fractures can facilitate the high-speed injection and production of gases,are hence ideal candidates for building underground hydrogen storage facilities.During the cyclic injection and extraction processes of UHS,the formation is subjected to stress disturbances,leading to stress sensitivity.Understanding the stress sensitivity patterns of carbonate rocks is crucial for optimizing injection and production strategies.This study reconstructed three-dimensional digital models of fractured carbonate rocks from the L gas field using micro-CT scanning technology.Utilizing the finite element method,we investigated the microscopic permeability characteristics of carbonate rocks and analyzed the impact of stress loading direction and confining stress on stress sensitivity.The findings reveal that the stress loading direction significantly influences the stress sensitivity of fractured carbonate rocks.When a stress of 60 MPa is applied perpendicular to the fracture direction,the permeability reduction ratio can reach 17.32%.In contrast,when the same stress is applied parallel to the fracture direction,the permeability reduction ratio is only 4.82%.Furthermore,a simulation of UHS with cyclic injection and production of H2 in the target block was conducted.When both permeability and porosity stress sensitivity were considered,the working gas volume for UHS decreased by only 3.4%,demonstrating that fractured carbonate reservoirs are feasible candidates for constructing underground hydrogen storage.
基金National Key Research and Development Program of China,Grant/Award Number:2021YFC3201103-01Project Funds of Administration for Market Regulation Henan Province,Grant/Award Number:20241110011+1 种基金Special Funding for Basic Research Expenses for Central Government Departmentaffiliated Institutes,Grant/Award Number:HKYJBYW-2024-06The Open Foundation of the Yellow River Institute of Hydraulic Research,Grant/Award Number:LYBEPR202206。
文摘The Kuye River Basin has experienced a rapid depletion of groundwater due to the increased coal production.In this study,by introducing the empirical equations derived from the three zone theory in the coal mining industry in China as a boundary condition,a calculation model was developed by coupling the soil and water assessment tool and visual modular three-dimensional finite-difference ground-water flow model(SWAT-VISUAL MODFLOW).The model was applied to several coal mines in the basin to quantify the groundwater impact of underground mining.For illustration purposes,two underground water observation stations and one water level station were selected for groundwater change simulation in 2009,producing the results that agreed well with the observed data.We found that groundwater level was closely related to the height of the fractured water-conducting zone caused by underground mining,and a higher height led to a lower groundwater level.This finding was further supported by the calculation that underground mining was responsible for 23.20mm aquifer breakages in 2009.Thus,preventing surface subsidence due to underground mining can help protecting the basin's groundwater.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2020R1C1C1005567)supported by the NAVER Digital Bio Innovation Research Fund,funded by NAVER Corporation(Grant No.[37-2023-0040])+3 种基金supported by Institute of Information&communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(No.2020-0-00261,Development of low power/low delay/self-power suppliable RF simultaneous information and power transfer system and stretchable electronic epineurium for wireless nerve bypass implementation)supported by Institute for Basic Science(IBS-R015-D1,IBSR015-D2)supported by a grant of the Korea-US Collaborative Research Fund(KUCRF)funded by the Ministry of Science and ICT and Ministry of Health&Welfare,Republic of Korea(Grant Number.RS-2024-00467213)。
文摘Prosthetic devices designed to assist individuals with damaged or missing body parts have made significant strides,particularly with advancements in machine intelligence and bioengineering.Initially focused on movement assistance,the field has shifted towards developing prosthetics that function as seamless extensions of the human body.During this progress,a key challenge remains the reduction of interface artifacts between prosthetic components and biological tissues.Soft electronics offer a promising solution due to their structural flexibility and enhanced tissue adaptability.However,achieving full integration of prosthetics with the human body requires both artificial perception and efficient transmission of physical signals.In this context,synaptic devices have garnered attention as next-generation neuromorphic computing elements because of their low power consumption,ability to enable hardware-based learning,and high compatibility with sensing units.These devices have the potential to create artificial pathways for sensory recognition and motor responses,forming a“sensory-neuromorphic system”that emulates synaptic junctions in biological neurons,thereby connecting with impaired biological tissues.Here,we discuss recent developments in prosthetic components and neuromorphic applications with a focus on sensory perception and sensorimotor actuation.Initially,we explore a prosthetic system with advanced sensory units,mechanical softness,and artificial intelligence,followed by the hardware implementation of memory devices that combine calculation and learning functions.We then highlight the importance and mechanisms of soft-form synaptic devices that are compatible with sensing units.Furthermore,we review an artificial sensory-neuromorphic perception system that replicates various biological senses and facilitates sensorimotor loops from sensory receptors,the spinal cord,and motor neurons.Finally,we propose insights into the future of closed-loop neuroprosthetics through the technical integration of soft electronics,including bio-integrated sensors and synaptic devices,into prosthetic systems.
文摘This special issue of Deep Underground Science and Engineering(DUSE)showcases pioneering research on the transformative role of machine learning(ML)and Big Data in deep underground engineering.Edited by vip editors Prof.Asoke Nandi(Brunel University of London,UK),Prof.Ru Zhang(Sichuan University,China),Prof.Tao Zhao(Chinese Academy of Sciences,China),and Prof.Tao Lei(Shaanxi University of Science and Technology,China),this issue highlights the innovative applications of ML technique in reshaping structural safety,tunneling operations,and geotechnical investigations.
基金supported by the Opening Foundation of China National Logging Corporation(CNLC20229C06)the China Petroleum Technical Service Corporation's science project'Development and application of 475 rotary steering system'(2024T-001001)。
文摘Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the pushing force acting on the wellbore in different sizes and directions within a circular range,ultimately allowing the wellbore trajectory to be drilled in a predetermined direction.By analyzing its mathematical principles and the actual characteristics of the instrument,a vector force closed-loop control method,including steering and holding modes,was designed.The adjustment criteria for the three hydraulic modules are determined to achieve rapid adjustment of the vector force.The theoretical feasibility of the developed method was verified by comparing its results with the on-site application data of an imported rotary guidance system.
文摘Deep Underground Science and Engineering(DUSE)is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground.This issue contains one perspective article,two review articles,six research articles,and one case study article.These articles focus on underground energy storage,multiscale modeling for correlation between micro-scale damage and macro-scale structural degradation,mineralization and formation of gold mine,interface and fracture seepage,experimental study on tunnel-sand-pile interaction,and high water-content materials for deep underground space backfilling,analytical solutions for the crack evolution direction in brittle rocks,and a case study on the squeezing-induced failure in a water drainage tunnel and the rehabilitation measures.
基金supported by the National Natural Science Foundation of China(51774196,52304093)China Postdoctoral Science Foundation(2023M741968)Shandong Provincial Natural Science Foundation(ZR2023ME086).
文摘Soft rock is one of the common geological conditions in coal mine underground water reservoir engineering.The cross-scale correlation analysis of water erosion soft lithology deterioration is very important for the safety and stability of coal mine underground reservoir(CMUR)engineering.To address the issues of grain crowding and segmentation difficulties in cross-scale corelation analysis,as well as the limitations of traditional etching methods,this study proposes an image grain segmentation method based on deep learning algorithms,utilizing scanning electron microscopy and image process-ing techniques.The method successfully segments crowded grains and eliminates the interference from misplaced particles.In addition,indoor uniaxial compression tests were conducted to obtain the mechanical properties of sandstone samples with different water content.By quantitatively characterizing the macroscopic and microscopic deterioration degree of red sandstone samples with different water contents,the relationship between the strength changes of rock samples and the pet-rographic parameters such as grain size and grain shape is analyzed,and the influence law of soft lithology deterioration in CMUR engineering is revealed.The results indicate:(1)Water significantly weakens the mechanical properties and stability of soft rock.With increasing water content,the strength of sandstone samples continuously decreases,and the failure mode transitions from brittle to ductile failure.(2)The deterioration of micro-micro structures is the main cause of the decrease in mechanical properties of water-eroded soft rock.Grain size,grain area,and aspect ratio are negatively correlated with water content,indicating that hydrophilic minerals in soft rock dissolve under the action of water,leading to rock damage.(3)Grain size,area,and aspect ratio can serve as significant indicators for quantifying the strength changes of water-eroded soft rock.The research findings can be applied to stability assessment and disaster prevention in CMUR engineering.
基金supported by the National Natural Science Foundation of China(Grant No.52274177)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202401501)+1 种基金Chongqing Graduate Student Research Innovation Program(Grant No.CYS240800)The Science and Technology Innovation Project for Graduate Students of Chongqing University of Science and Technology(Grant No.YKJCX2420702).
文摘Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.
基金supported by the National Natural Science Foundation of China(52474092 and 52074042).
文摘To investigate the fracture propagation characteristics and failure mechanism of anti-dip rock slope induced by underground mining,the Jiguanling landslide in Wulong,Chongqing,China is taken as the prototype,and physical model test is utilized to study the fracture evolution process,deformation characteristics and failure mechanism of anti-dip rock slope.In this study,the digital image correlation(DIC)technique and pressure acquisition system are combined to analyze the displacement and stress field of rock slope during underground mining stages.The results show that the anti-dip rock slope experiences four stages during underground coal mining:tensile fracture propagation in upper toppling zone,shallow damage in the lower shear zone,coal seam roof caving,failure of the whole slope.There is a phenomenon of local tensile and compressive stress conversion in upper toppling zone after roof caving.The appearance of coal seam roof caving increases the compressive area and pressure of the shear zone,leading to the failure of the shear blocks at the front edge,and ultimately causing failure of the whole slope.Mining with retained coal pillar before shallow failure in the shear zone can effectively block the impact of lower mining on the upper toppling zone,achieve a 16%contraction in toppling zone,and improve the stability of the slope.The failure mode of slope can be summarized as shear–slip–toppling collapse failure.This paper improves the understanding on the failure mechanism of anti-dip rock slope caused by underground mining.
基金supported by the National Natural Science Foundation of China(Grant Nos.12372064 and 12172291)the Youth and Middle-Aged Science and Technology Development Program of Shanghai Institute of Technology(Grant No.ZQ2024-10)。
文摘Conventional open-loop deep brain stimulation(DBS)systems with fixed parameters fail to accommodate interindividual pathological differences in Parkinson's disease(PD)management while potentially inducing adverse effects and causing excessive energy consumption.In this paper,we present an adaptive closed-loop framework integrating a Yogi-optimized proportional–integral–derivative neural network(Yogi-PIDNN)controller.The Yogi-augmented gradient adaptation mechanism accelerates the convergence of general PIDNN controllers in high-dimensional nonlinear control systems while reducing control energy usage.In addition,a system identification method establishes input–output dynamics for pre-training stimulation waveforms,bypassing real-time parameter-tuning constraints and thereby enhancing closed-loop adaptability.Finally,a theoretical analysis based on Lyapunov stability criteria establishes a sufficient condition for closed-loop stability within the identified model.Computational validations demonstrate that our approach restores thalamic relay reliability while reducing energy consumption by(81.0±0.7)%across multi-frequency tests.This study advances adaptive neuromodulation by synergizing data-driven pre-training with stability-guaranteed real-time control,offering a novel framework for energy-efficient and personalized Parkinson's therapy.
基金support provided by Hamad bin Khalifa University,Qatar Foundation,Qatar(210028127).
文摘The supply of energy is a severe challenge for every country,particularly those that are industrially developed and highly populated.Natural gas is among the most essential energy sources due to its reasonably low cost and high heating value.One of the elements of a sustainable energy supply is underground gas storage(UGS).UGS systems consist of a cushion gas(base gas)and a working gas.The cushion gas is injected into a reservoir to sustain the pressure and remain there until the period of storage ends,while the working gas is the main gas to be stored and produced.Unlike prior studies on fully depleted fields,our research emphasizes the potential of UGS in the presence of remaining oil and integrates key concepts,such as enhanced oil recovery and CO_(2)sequestration.A simulation study was conducted using Qatari Advanced Simulator for Reservoirs software to determine the feasibility of a UGS system in a partially depleted oil reservoir.N_(2) and CO_(2)gases were considered and analyzed over short,medium,and long injection/withdrawal cycles to investigate their potential as cushion gases for natural gas storage in a partially depleted oil reservoir.It was found that using CO_(2)as a cushion gas produces 32%,57%,and 90%of CH_(4) according to short-,medium-,and long-term energy storage scenarios,respectively,with the CH_(4) production higher than when using N2.This study sheds light on the feasibility of implementing underground gas storage systems in partially depleted oil reservoirs.
基金Supported by Guizhou Provincial Key Technology R&D Program(No.2202023QKHZC).
文摘[Objectives]This study was conducted to investigate water pollution in the Huanghou Underground River Basin.[Methods]Five representative water quality indicators,ammonia nitrogen(NH+4-N),nitrate nitrogen(NO_(3)^(-)-N),permanganate index(COD Mn),total phosphorus(TP),and nitrite nitrogen(NO_(2)^(-)-N),were selected.The single-factor pollution index(P i),Nemerow pollution index(P N),and water quality index(WQI)were calculated to quantitatively assess pollution characteristics and evaluate water quality in the basin.[Results]The overall water quality in the Huanghou Underground River Basin fell within the"slightly polluted to good"range,with pollution primarily concentrated in the upstream areas.The downstream water quality was generally better,as most pollutants from the upstream were diluted or degraded during migration,resulting in little impact on the downstream areas.[Conclusions]This study provides a theoretical basis for understanding the pollution characteristics and evaluation of water quality in the Huanghou Underground River Basin.
基金Program of China Three Gorges Corporation,Grant/Award Number:BHT 0679-1。
文摘The big underground powerhouse cavern of the China Baihetan hydropower plant is 438m long,34m wide,and 88.7m high.It is cut by a weak interlayer shear zone and its high sidewall poses a huge stability problem.This paper reports our successful solution of this problem through numerical simulations and a replacement-tunnel scheme in the detailed design stage and close site monitoring in the excavation stage.Particularly,in the detail design stage,mechanical parameters of the shear zone were carefully determined through laboratory experiments and site tests.Then,deformation of the surrounding rocks and the shear zone under high in situ stress conditions was predicted using 3 Dimensional Distinct Element Code(3DEC).Subsequently,a replacement-tunnel scheme was proposed for the treatment on the shear zone to prevent severe unloading relaxation of surrounding rocks.In the construction period,excavation responses were closely monitored on deformations of surrounding rocks and the shear zone.The effect of local cracking in the replacement tunnels on sidewall stability was evaluated using the strength reduction method.These monitoring results were compared with the predicted numerical simulation in the detailed design stage.It is found that the shear zone greatly modified the deformation mode of the cavern surrounding rocks.Without any treatment,rock mass deformation on the downstream sidewall was larger than 125mm and the shearing deformation of the shear zone was 60–70 mm.These preset replacement tunnels can reduce not only the unloading and relaxation of rock masses but also the maximum shearing deformation of the shear zone by 10–20 mm.The predictions by numerical simulation were in good agreement with the monitoring results.The proposed tunnel-replacement scheme can not only restrain the shear zone deformation but also enhance the safety of surrounding rocks and concrete tunnels.This design procedure offers a good reference for interaction between a big underground cavern and a weak layer zone in the future.
