The wide pillars are generally popular due to the high productivity and efficiency in Northwest China.The distribution of lateral abutment pressure in coal pillars is important for mining safety.To reveal the effect o...The wide pillars are generally popular due to the high productivity and efficiency in Northwest China.The distribution of lateral abutment pressure in coal pillars is important for mining safety.To reveal the effect of the first mining on the lateral abutment pressure distribution and evolution in wide pillars,an in-situ experiment,theoretical analysis and numerical simulation were performed.First,the field monitoring of lateral abutment pressure was conducted from the perspective of time and space in the Chahasu Coal Mine,Huangling No.2 Coal Mine and Lingdong Coal Mine during the first mining.Based on the field monitoring stress,a theoretical model was proposed to reveal the lateral abutment pressure distribution.The methodology was demonstrated through a case study.Aiming at the distribution mechanism,a numerical experiment was conducted through the finite-discrete element method(FDEM).Last,field observations of borehole fractures were performed to further study the damage distribution.In addition,two types of lateral abutment pressure evolution with mining advance were discussed.Suggestions on the stress monitoring layout were proposed as well.The results could provide foundations for strata control and disaster prevention in wide pillars in underground coal mines.展开更多
The four-track walking mining vehicle can better cope with the complex terrain of cobalt-rich crusts on the seabed.To explore the influence of different parameters on the obstacle-crossing ability of mining vehicles,t...The four-track walking mining vehicle can better cope with the complex terrain of cobalt-rich crusts on the seabed.To explore the influence of different parameters on the obstacle-crossing ability of mining vehicles,this paper took a certain type of mine vehicle as an example and establish a mechanical model of the mine vehicle.Through this model,the vehicle's traction coefficient variation could be analyzed during the obstacle-crossing process.It also reflected the relationship between the obstacle-crossing ability and the required traction coefficient.Many parameters were used for this analysis including the radius of the guide wheel radius,ground clearance of the driving wheel,the dip angle of the approaching angular and the position of centroid.The result showed that the ability to cross the obstacles requires adhesion coefficient as support.When the ratio between obstacle height and ground clearance of the guide wheel was greater than 0.7,the required adhesion coefficient increased sharply.The ability to cross obstacles will decrease,if the radius of the guide wheel increases,the height of the driving wheel increases or the dip angle of the approaching angular increases.It was most beneficial to cross the obstacle when-the ratio of the distance between the center of mass and the front driving wheel to the wheelbase is between 0.450.48.The results of this paper could provide reference for structural parameter design and performance research for mining vehicles.展开更多
This study demonstrates a practical cycle time analysis of dump truck haulage system of “Ukhaa Khudag” open-pit coal mine located in Umnugobi Province, Mongolia. It examines the possibility of minimizing the cycle t...This study demonstrates a practical cycle time analysis of dump truck haulage system of “Ukhaa Khudag” open-pit coal mine located in Umnugobi Province, Mongolia. It examines the possibility of minimizing the cycle time of the haulage system as well as factors impacting the speed of the dump truck. The current study divides the open pit mine road for the dump trucks into five sections which are bench road, ramp, surface road, dump road uphill, and dump road. Meanwhile, it investigates the influence of the length, the grade, and the rolling resistance of the road section on the cycle time. The data is analyzed using mathematical regression methods via Microsoft Excel program. For each of the five road sections, we compare the statistical calculations of three regression models: linear, quadratic and exponential;thus, a total of thirty regression models are obtained in this research. Accordingly, the cycle time for each road section is predicted by the most accountable model. The loaded and empty direction of the movement is measured and calculated for each road section, and it appears that the difference between the calculated mean value and the actual cycle time of the models is 0.82 seconds with a relative error of 2.51 percent.展开更多
The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influ...The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influence post-peak characteristics can offer valuable insights for the prevention of coal bursts.In this study,the Synthetic Rock Mass method is employed to establish a numerical model,and the factors affecting coal post-peak characteristics are analyzed from four perspectives:coal matrix mechanical parameters,structural weak surface properties,height-to-width ratio,and loading rate.The research identifies four significant influencing factors:deformation modulus,density of discrete fracture networks,height-to-width ratio,and loading rate.The response and sensitivity of post-peak characteristics to single-factor and multi-factor interactions are assessed.The result suggested that feasible prevention and control measures for coal bursts can be formulated through four approaches:weakening the mechanical properties of coal pillars,increasing the number of structural weak surfaces in coal pillars,reducing the width of coal pillars,and optimizing mining and excavation speed.The efficacy of measures aimed at weakening the mechanical properties of coal is successfully demonstrated through a case study on coal burst prevention using large-diameter borehole drilling.展开更多
The pursuit of improved quality of life standards has significantly influenced the contemporary mining model in the 21st century.This era is witnessing an unprecedented transformation driven by pressing concerns relat...The pursuit of improved quality of life standards has significantly influenced the contemporary mining model in the 21st century.This era is witnessing an unprecedented transformation driven by pressing concerns related to sustainability,climate change,the just energy transition,dynamic operating environments,and complex social challenges.Such transitions present both opportunities and obstacles.The aim of this study is to provide an extensive literature review on energy transition to identify the challenges and strategies associated with navigating transformations in energy systems.Understanding these transformations is particularly critical in the face of the severe consequences of global warming,where an accelerated energy transition is viewed as a universal remedy.Adopting a socio-technological systems perspective,specifically through the application of Actor Network Theory(ANT),this research provides a theoretical foundation while categorising challenges into five distinct domains and outlining strategies across these different dimensions.These insights are specifically tailored for emerging market countries to effectively navigate energy transition while fostering the development of resilient societies.Furthermore,our findings highlight that energy transition encompasses more than a mere technological shift;it entails fundamental changes in various systemic socio-economic imperatives.Through focusing on the role of social structures in transitions,this study makes a significant and innovative contribution to ANT,which has historically been criticised for its limited acknowledgement of social structures.Consequently,we propose an emerging market energy transition framework,which not only addresses technological aspects,but also integrates social considerations.This framework paves the way for future research and exploration of energy transition dynamics.The outcomes of this study offer valuable insights to policymakers,researchers,and practitioners engaged in the mining industry,enabling them to comprehend the multifaceted challenges involved and providing practical strategies for effective resolution.Through incorporating the social dimension into the analysis,we enhance the understanding of the complex nature of energy system transformations,facilitating a more holistic approach towards achieving sustainable and resilient energy transitions in emerging markets and beyond.展开更多
This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts.Employing a housemade load fram...This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts.Employing a housemade load frame to simulate various failure scenarios,pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined loads.The experimental results denote that with increased impact energy,maximum and average impact loads on rock bolts escalate significantly under pretension,initiating plastic deformation beyond a certain threshold.Despite minor reductions in the yield load due to impactinduced damage,pretension aids in constraining post-impact deformation rate and fluctuation degree of rock bolts.Moreover,impact-induced plastic deformation causes internal microstructure dislocation,fortifying the stiffness of the rock bolt support system.The magnitude of this fortification is directly related to the plastic deformation induced by the impact.These findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation,emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency.展开更多
Recycling waste frying oils for the synthesis of flotation reagents presents a promising avenue for sustainable waste management.Moreover,it offers a cost-effective solution for crafting a specialized collector design...Recycling waste frying oils for the synthesis of flotation reagents presents a promising avenue for sustainable waste management.Moreover,it offers a cost-effective solution for crafting a specialized collector designed to efficiently remove carbonates and enhance phosphate enrichment in froth flotation processes.This study focuses on the synthesis of an anionic collector using the saponification reaction of a frying oil sample,subsequently applied to the flotation of calcite and dolomite.To elucidate the adsorption mechanisms of the frying oil collector(FrOC)and sodium oleate,a reference collector,on fluorapatite,calcite,dolomite,and quartz surfaces,comprehensive experiments were conducted,including zeta potential measurements and Fourier transform infrared spectroscopy.Results revealed diverse adsorption affinities of the molecules towards these minerals.To assess the practical performance of the collector,flotation tests were conducted using a natural phosphate ore mixture,employing a BoxBehnken experimental design.Notably,under optimized conditions(pH 9,1000 g/t of FrOC,3.5 min of conditioning,and 6 min of flotation),FrOC exhibited excellent performance,with calcite and dolomite recoveries exceeding 80%,while apatite recovery in the concentrate fraction remained below 10%.This work exemplifies both circular economy practices and the distinctive approach to sustainable mineral processing.展开更多
An in-process technology approach is proposed to identify the source of acid mine drainage(AMD)generation and prevent its formation in a porphyry copper waste rock(WR).Adopting actions before stockpiling the WR enable...An in-process technology approach is proposed to identify the source of acid mine drainage(AMD)generation and prevent its formation in a porphyry copper waste rock(WR).Adopting actions before stockpiling the WR enables the establishment of potential contaminants and predicts the more convenient method for AMD prevention.A WR sample was separated into size fractions,and the WR’s net acidgenerating potential was quantified using chemical and mineralogical characterization.The diameter of physical locking of sulfides(DPLS)was determined,and the fractions below the DPLS were desulfurized using flotation.Finally,the WR fractions and tailing from the flotation test were submitted to acid-base accounting and weathering tests to evaluate their acid-generating potential.Results show that the WR’s main sulfide mineral is pyrite,and the DPLS was defined as 850μm.A sulfide recovery of 91%was achieved using a combination of HydroFloat^(®)and Denver cells for a size fraction lower than DPLS.No grinding was conducted.The results show that size fractions greater than DPLS and the desulfurized WR are unlikely to produce AMD.The outcomes show that in-processing technology can be a more proactive approach and an effective tool for avoiding AMD in a porphyry copper WR.展开更多
The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous...The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.展开更多
In the process of production or processing of materials by various methods,there is a need for a large volume of water of the required quality.Today in many regions of the world,there is an acute problem of providing ...In the process of production or processing of materials by various methods,there is a need for a large volume of water of the required quality.Today in many regions of the world,there is an acute problem of providing industry with water of a required quality.Its solution is an urgent and difficult task.The water quality of surface water bodies is formed by a combination of a large number of both natural and anthropogenic factors,and is often significantly heterogeneous not only in the water area,but also in depth.As a rule,the water supply of large industrial enterprises is located along the river network.Mergers are the most important nodes of river systems.Understanding the mechanism of transport of pollutants at the confluence of rivers is critical for assessing water quality.In recent years,thanks to the data of satellite images,the interest of researchers in the phenomenon of mixing the waters of merging rivers has increased.The nature of the merger is influenced by the formation of transverse circulation.Within the framework of this work,a study of vorticity,as well as the width of the mixing zone,depending on the distance from the confluence,the speeds of the merging rivers and the angle of confluence was carried out.Since the consumer properties of water are largely determined by its chemical and physical indicators,the intensity of mixing,determined largely by the nature of the secondary circulation,is of fundamental importance for assessing the distribution of hydrochemical indicators of water quality in the mixing zone.These characteristics are important not only for organizing water intake for drinking and technical purposes with the best consumer properties,but also for organizing an effective monitoring system for confluence zones.展开更多
During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadwa...During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadway.Therefore,studying the mechanical properties and energy evolution rules of coal samples containing holes and filled structures has certain practical significance for achieving coordinated control of coal mine rockburst disasters and the stability of roadway surrounding rocks.To achieve this aim,seven types of burst-prone coal samples were prepared and subject to uniaxial compression experiments with the aid of a TAW-3000 electro-hydraulic servo testing machine.Besides,the stress–strain curves,acoustic emission signals,DIC strain fields and other data were collected during the experiments.Furthermore,the failure modes and energy evolutions of samples with varying drilled hole sizes and filling materials were analyzed.The results show that the indexes related to burst propensity of the drilled coal samples decline to some extent compared with those of the intact one,and the decline is positively corelated to the diameter of the drilled hole.After hole filling,the strain concentration degree around the drilled hole is lowered to a certain degree,and polyurethane filling has a more remarkable effect than cement filling.Meanwhile,hole filling can enhance the strength and deformation resistance of coal.Hole drilling can accelerate the release of accumulated elastic strain energy,turning the acoustic emission events from low-frequency and high-energy ones to high-frequency and low-energy ones,whereas hole filling can reduce the intensity of energy release.The experimental results and theoretical derivation demonstrate that hole filling promotes coal deformability and strength mainly by weakening stress concentration surrounding the drilled holes.Moreover,the fillings can achieve a better filling effect if their elastic modulus and Poisson’s ratio are closer to those of the coal body.展开更多
Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project "Technic...Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project "Technical Revolution in Ecological and Efficient Coal Mining and Utilization & Intelligence and Diverse Coordination of Coal-based Energy System," initiated by Chinese Academy of Engineering, puts forward three stages(3.0, 4.0 and 5.0) of China's coal industry development strategy. Aimed at "reduced staff,ultra-low ecological damage, and emission level near to natural gas," breakthroughs should be achieved in the following three key technologies during the China Coal Industry 3.0 stage(2016–2025): including intelligent coal mining, ecological mining, ultra-low emission and environmental protection. This paper focuses on the development trends of the China Coal Industry 3.0 and its support for China Coal Industry 4.0 and 5.0 is analyzed and prospected as well, which may offer technical assistance and strategy orientation for realizing the transformation from traditional coal energy to clean energy.展开更多
The evolution of mining-induced stress field in longwall panel is closely related to the fracture field and the breaking characteristics of strata.Few laboratory experiments have been conducted to investigate the stre...The evolution of mining-induced stress field in longwall panel is closely related to the fracture field and the breaking characteristics of strata.Few laboratory experiments have been conducted to investigate the stress field.This study investigated its evolution by constructing a large-scale physical model according to the in situ conditions of the longwall panel.Theoretical analysis was used to reveal the mechanism of stress distribution in the overburden.The modelling results showed that:(1)The major principal stress field is arch-shaped,and the strata overlying both the solid zones and gob constitute a series of coordinated load-bearing structures.The stress increasing zone is like a macro stress arch.High stress is especially concentrated on both shoulders of the arch-shaped structure.The stress concentration of the solid zone in front of the gob is higher than the rear solid zone.(2)The characteristics of the vertical stress field in different regions are significantly different.Stress decreases in the zone above the gob and increases in solid zones on both sides of it.The mechanical analysis show that for a given stratum,the trajectories of principal stress are arch-shaped or inverselyarched,referred to as the‘‘principal stress arch’’,irrespective of its initial breaking or periodic breaking,and determines the fracture morphology.That is,the trajectories of tensile principal stress are inversely arched before the first breaking of the strata,and cause the breaking lines to resemble an inverted funnel.In case of periodic breaking,the breaking line forms an obtuse angle with the advancing direction of the panel.Good agreement was obtained between the results of physical modeling and the theoretical analysis.展开更多
In this article an attempt to determine the influence of mining factors on the seismic activity during the longwall mining of the upper layer of coal seam no.405/2 in one of the Polish hard coal mines in the Upper Sil...In this article an attempt to determine the influence of mining factors on the seismic activity during the longwall mining of the upper layer of coal seam no.405/2 in one of the Polish hard coal mines in the Upper Silesian Coal Basin was conducted.Two longwall panels were mined in analogous geological conditions and based on the same mining system and technology.However,there was significant difference with regards to the mining factors,which was reflected in the observed seismic activity.Some tools used in mining seismology were applied to illustrate the aforementioned influence of mining factors,e.g.the frequency-energy distribution,the frequency-magnitude distribution,the 2 D distribution of released seismic energy,the relationship between released seismic energy and the volume of mined coal,the Benioff strain release,and the Gutenberg-Richter(GR)b coefficient distribution(b is the proportion between high and low energy tremors).Concerning the Benioff strain release,a new solution,based on the slope of a fitted line in a moving time window,is proposed.展开更多
Methods of exploitation drainage, which is presently applied in polish hard coal mines in Upper Silesian Coal Basin(Poland), are not effective enough, high risk of methane hazard can be observed, and production capaci...Methods of exploitation drainage, which is presently applied in polish hard coal mines in Upper Silesian Coal Basin(Poland), are not effective enough, high risk of methane hazard can be observed, and production capacity of the mining plant is not fully used. Methane hazard, which may occur during planned coal exploitation, is presented in this paper. Following parameters are taken into consideration in the forecasts: coal extraction parameters, geological and mining conditions, deposit's methane saturation degree and impact of coal exploitation on the degasification coefficient of the seams, which are under the influence of relaxation zone. This paper presents the results of the analysis aiming to verify applicability of drainage ahead of mining of the coal seams by using surface directional wells. Based on the collected data(coal seams' structural maps, profiles of the exploratory wells, geological cross-sections), the lab tests of drilling cores and direct wells' tests, static model of the deposit was constructed and suitable grid of directional wells from the surface was designed. Comparison of forecasted methane emission volume between the two methods is investigated. The results indicated the necessity of performing appropriate deposit's stimulations in order to increase effectiveness of drainage ahead of mining.展开更多
Mining-induced seismicity is a reflection of rock geomechanical evolution of geological environment in the natural and man-made systems and in the mining-technical systems. In order to predict and prevent mining-induc...Mining-induced seismicity is a reflection of rock geomechanical evolution of geological environment in the natural and man-made systems and in the mining-technical systems. In order to predict and prevent mining-induced seismicity, it is necessary to research geodynamics and stress state of intact rock mass, to determine possible deformations and additional stresses as a result of large-scale rock extraction, conditions of accumulated energy release. For that a geodynamical monitoring is required on every stage of deposit development and a closing. The report considers principal influencing factors of preparation and occurrence of mining-induced earthquakes. Also it estimates precursors and indicators of rock mass breaking point, and experience concerning prediction and prevention of mining-induced seismicity in the Khibiny apatite mines in the Murmansk region, which is the largest mining province.展开更多
This paper reviews the major achievements in terms of mechanical behaviors of coal measures,mining stress distribution characteristics and ground control in China’s deep underground coal mining.The three main aspects...This paper reviews the major achievements in terms of mechanical behaviors of coal measures,mining stress distribution characteristics and ground control in China’s deep underground coal mining.The three main aspects of this review are coal measure mechanics,mining disturbance mechanics,and rock support mechanics.Previous studies related to these three topics are reviewed,including the geo-mechanical properties of coal measures,distribution and evolution characteristics of mining-induced stresses,evolution characteristics of mining-induced structures,and principles and technologies of ground control in both deep roadways and longwall faces.A discussion is made to explain the structural and mechanical properties of coal measures in China’s deep coal mining practices,the types and dis-tribution characteristics of in situ stresses in underground coal mines,and the distribution of mining-induced stress that forms under different geological and engineering conditions.The theory of pre-tensioned rock bolting has been proved to be suitable for ground control of deep underground coal roadways.The use of combined ground control technology(e.g.ground support,rock mass modification,and destressing)has been demonstrated to be an effective measure for rock control of deep roadways.The developed hydraulic shields for 1000 m deep ultra-long working face can effectively improve the stability of surrounding rocks and mining efficiency in the longwall face.The ground control challenges in deep underground coal mines in China are discussed,and further research is recommended in terms of theory and technology for ground control in deep roadways and longwall faces.展开更多
Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop...Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.展开更多
The Cheria region in Northeastern Algeria has been facing aquifer overexploitation by the agricultural sector and prolonged droughts,resulting in a considerable decline in groundwater levels.This study investigates th...The Cheria region in Northeastern Algeria has been facing aquifer overexploitation by the agricultural sector and prolonged droughts,resulting in a considerable decline in groundwater levels.This study investigates the feasibility of implementing artificial recharge techniques to replenish the Eocene aquifer which serves as the primary water source in the Cheria region.A 3D transient numerical model,based on the finite difference method,was used to simulate groundwater flow from 2021 to 2031 using Visual MODFLOW Flex.During the modelling process,three scenarios were considered:(1)including pumping without a recharge,(2)recharge of the entire area through efficient infiltration without pumping,and(3)artificial recharge using river water infiltration basins at two sites,Draa Douamis sinkholes and Eocene limestone outcrops.The simulation results showed that aquifer exploitation without recharge caused significant drawdowns,which were 3 m to 7 m in the north-eastern part and 8 m to 12 m in the central and southern parts.In contrast,the second scenario,involving recharge without pumping,showed a rise in groundwater levels of 2 m to 2.7 m in the north-eastern part and 3 m to 3.62 m in the central and southern parts.The third scenario,employing artificial recharge,indicated a positive response to artificial recharge,with increased piezometric levels at the proposed sites,signifying a beneficial impact on the aquifer.These findings underline the potential of artificial recharge as a promising approach to address the groundwater depletion and environmental issues in the Cheria Basin.展开更多
Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,i...Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,it is always challenging to accurately measure rock mass properties.In this study,a three-dimensional(3D)microseismic(MS)data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is proposed.It is a 3D finite element model that takes seepage,damage and stress field effects into account jointly.Multiple factors(i.e.joints,water and microseismicity)are used to optimize the rock mass mechanical parameters at different scales.The model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground mining.It is found that the damage pattern is mostly controlled by the structure,water and rock mass parameters.The damage pattern is evidently different from the two-dimensional result and is more consistent with the field observations.This difference is caused by the MS-derived damage acting on the rock mass.MS data are responsible for gradually correcting the damage zone,changing the direction in which it expands,and promoting it to evolve close to reality.For the crown pillar,the proposed model yields a more trustworthy safety factor.In order to guarantee the stability of the pillar,it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.展开更多
基金We gratefully acknowledge financial support from the National Natural Science Foundation of China(NSFC)(No.51704097)Science Foundation of Henan Polytechnic University(No.J2021–2)+1 种基金Key Research and Development Program of Henan Province,China(No.202102310244)“Science and Technology to Help the Economy 2020”Key Project(No.SQ2020YFF0426364).
文摘The wide pillars are generally popular due to the high productivity and efficiency in Northwest China.The distribution of lateral abutment pressure in coal pillars is important for mining safety.To reveal the effect of the first mining on the lateral abutment pressure distribution and evolution in wide pillars,an in-situ experiment,theoretical analysis and numerical simulation were performed.First,the field monitoring of lateral abutment pressure was conducted from the perspective of time and space in the Chahasu Coal Mine,Huangling No.2 Coal Mine and Lingdong Coal Mine during the first mining.Based on the field monitoring stress,a theoretical model was proposed to reveal the lateral abutment pressure distribution.The methodology was demonstrated through a case study.Aiming at the distribution mechanism,a numerical experiment was conducted through the finite-discrete element method(FDEM).Last,field observations of borehole fractures were performed to further study the damage distribution.In addition,two types of lateral abutment pressure evolution with mining advance were discussed.Suggestions on the stress monitoring layout were proposed as well.The results could provide foundations for strata control and disaster prevention in wide pillars in underground coal mines.
基金Supported by National Ocean Key Special Funds in 12th Five-Year Plan of China (Grant No.DY125-11-T-01)National Natural Science Foundation of China (Grant No.52074294)。
文摘The four-track walking mining vehicle can better cope with the complex terrain of cobalt-rich crusts on the seabed.To explore the influence of different parameters on the obstacle-crossing ability of mining vehicles,this paper took a certain type of mine vehicle as an example and establish a mechanical model of the mine vehicle.Through this model,the vehicle's traction coefficient variation could be analyzed during the obstacle-crossing process.It also reflected the relationship between the obstacle-crossing ability and the required traction coefficient.Many parameters were used for this analysis including the radius of the guide wheel radius,ground clearance of the driving wheel,the dip angle of the approaching angular and the position of centroid.The result showed that the ability to cross the obstacles requires adhesion coefficient as support.When the ratio between obstacle height and ground clearance of the guide wheel was greater than 0.7,the required adhesion coefficient increased sharply.The ability to cross obstacles will decrease,if the radius of the guide wheel increases,the height of the driving wheel increases or the dip angle of the approaching angular increases.It was most beneficial to cross the obstacle when-the ratio of the distance between the center of mass and the front driving wheel to the wheelbase is between 0.450.48.The results of this paper could provide reference for structural parameter design and performance research for mining vehicles.
文摘This study demonstrates a practical cycle time analysis of dump truck haulage system of “Ukhaa Khudag” open-pit coal mine located in Umnugobi Province, Mongolia. It examines the possibility of minimizing the cycle time of the haulage system as well as factors impacting the speed of the dump truck. The current study divides the open pit mine road for the dump trucks into five sections which are bench road, ramp, surface road, dump road uphill, and dump road. Meanwhile, it investigates the influence of the length, the grade, and the rolling resistance of the road section on the cycle time. The data is analyzed using mathematical regression methods via Microsoft Excel program. For each of the five road sections, we compare the statistical calculations of three regression models: linear, quadratic and exponential;thus, a total of thirty regression models are obtained in this research. Accordingly, the cycle time for each road section is predicted by the most accountable model. The loaded and empty direction of the movement is measured and calculated for each road section, and it appears that the difference between the calculated mean value and the actual cycle time of the models is 0.82 seconds with a relative error of 2.51 percent.
基金National NaturalScience Foundation of China(52074151,52274085,52274123)Tiandi Science and Technology Co.,Ltd.Science and Technology Innovation Venture Capital Special Project(TDKC-2022-MS-01,TDKC-2022-QN-01,TDKC-2022-QN-02).
文摘The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influence post-peak characteristics can offer valuable insights for the prevention of coal bursts.In this study,the Synthetic Rock Mass method is employed to establish a numerical model,and the factors affecting coal post-peak characteristics are analyzed from four perspectives:coal matrix mechanical parameters,structural weak surface properties,height-to-width ratio,and loading rate.The research identifies four significant influencing factors:deformation modulus,density of discrete fracture networks,height-to-width ratio,and loading rate.The response and sensitivity of post-peak characteristics to single-factor and multi-factor interactions are assessed.The result suggested that feasible prevention and control measures for coal bursts can be formulated through four approaches:weakening the mechanical properties of coal pillars,increasing the number of structural weak surfaces in coal pillars,reducing the width of coal pillars,and optimizing mining and excavation speed.The efficacy of measures aimed at weakening the mechanical properties of coal is successfully demonstrated through a case study on coal burst prevention using large-diameter borehole drilling.
基金University of the Witwatersrand Additional funding is from the DSI-National Research Foundation(NRF)Thuthuka Grant(Grant UID:121973)and DSI-NRF CIMERA.
文摘The pursuit of improved quality of life standards has significantly influenced the contemporary mining model in the 21st century.This era is witnessing an unprecedented transformation driven by pressing concerns related to sustainability,climate change,the just energy transition,dynamic operating environments,and complex social challenges.Such transitions present both opportunities and obstacles.The aim of this study is to provide an extensive literature review on energy transition to identify the challenges and strategies associated with navigating transformations in energy systems.Understanding these transformations is particularly critical in the face of the severe consequences of global warming,where an accelerated energy transition is viewed as a universal remedy.Adopting a socio-technological systems perspective,specifically through the application of Actor Network Theory(ANT),this research provides a theoretical foundation while categorising challenges into five distinct domains and outlining strategies across these different dimensions.These insights are specifically tailored for emerging market countries to effectively navigate energy transition while fostering the development of resilient societies.Furthermore,our findings highlight that energy transition encompasses more than a mere technological shift;it entails fundamental changes in various systemic socio-economic imperatives.Through focusing on the role of social structures in transitions,this study makes a significant and innovative contribution to ANT,which has historically been criticised for its limited acknowledgement of social structures.Consequently,we propose an emerging market energy transition framework,which not only addresses technological aspects,but also integrates social considerations.This framework paves the way for future research and exploration of energy transition dynamics.The outcomes of this study offer valuable insights to policymakers,researchers,and practitioners engaged in the mining industry,enabling them to comprehend the multifaceted challenges involved and providing practical strategies for effective resolution.Through incorporating the social dimension into the analysis,we enhance the understanding of the complex nature of energy system transformations,facilitating a more holistic approach towards achieving sustainable and resilient energy transitions in emerging markets and beyond.
基金supported by the National Natural Science Foundation of China(Nos.52074151,51927807,and 52274123)Tiandi Science and Technology Co.,Ltd.(No.2022-2-TDMS012)。
文摘This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts.Employing a housemade load frame to simulate various failure scenarios,pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined loads.The experimental results denote that with increased impact energy,maximum and average impact loads on rock bolts escalate significantly under pretension,initiating plastic deformation beyond a certain threshold.Despite minor reductions in the yield load due to impactinduced damage,pretension aids in constraining post-impact deformation rate and fluctuation degree of rock bolts.Moreover,impact-induced plastic deformation causes internal microstructure dislocation,fortifying the stiffness of the rock bolt support system.The magnitude of this fortification is directly related to the plastic deformation induced by the impact.These findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation,emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency.
基金financially supported through the research program between OCP Group and UM6P under the specific agreement AS34-flotation project
文摘Recycling waste frying oils for the synthesis of flotation reagents presents a promising avenue for sustainable waste management.Moreover,it offers a cost-effective solution for crafting a specialized collector designed to efficiently remove carbonates and enhance phosphate enrichment in froth flotation processes.This study focuses on the synthesis of an anionic collector using the saponification reaction of a frying oil sample,subsequently applied to the flotation of calcite and dolomite.To elucidate the adsorption mechanisms of the frying oil collector(FrOC)and sodium oleate,a reference collector,on fluorapatite,calcite,dolomite,and quartz surfaces,comprehensive experiments were conducted,including zeta potential measurements and Fourier transform infrared spectroscopy.Results revealed diverse adsorption affinities of the molecules towards these minerals.To assess the practical performance of the collector,flotation tests were conducted using a natural phosphate ore mixture,employing a BoxBehnken experimental design.Notably,under optimized conditions(pH 9,1000 g/t of FrOC,3.5 min of conditioning,and 6 min of flotation),FrOC exhibited excellent performance,with calcite and dolomite recoveries exceeding 80%,while apatite recovery in the concentrate fraction remained below 10%.This work exemplifies both circular economy practices and the distinctive approach to sustainable mineral processing.
基金supported by Agencia Nacional de Investigación y Desarrollo de Chile(ANID)Anillo-Grant ANID/ACT210027,Fondecyt 1211498,and ANID/AFB230001+1 种基金the ANID scholarship Grant 21210801partially performed by Luis Cisternas during the visit to the Universitédu Québec,supported by MINEDUC-UA project,code ANT1999.
文摘An in-process technology approach is proposed to identify the source of acid mine drainage(AMD)generation and prevent its formation in a porphyry copper waste rock(WR).Adopting actions before stockpiling the WR enables the establishment of potential contaminants and predicts the more convenient method for AMD prevention.A WR sample was separated into size fractions,and the WR’s net acidgenerating potential was quantified using chemical and mineralogical characterization.The diameter of physical locking of sulfides(DPLS)was determined,and the fractions below the DPLS were desulfurized using flotation.Finally,the WR fractions and tailing from the flotation test were submitted to acid-base accounting and weathering tests to evaluate their acid-generating potential.Results show that the WR’s main sulfide mineral is pyrite,and the DPLS was defined as 850μm.A sulfide recovery of 91%was achieved using a combination of HydroFloat^(®)and Denver cells for a size fraction lower than DPLS.No grinding was conducted.The results show that size fractions greater than DPLS and the desulfurized WR are unlikely to produce AMD.The outcomes show that in-processing technology can be a more proactive approach and an effective tool for avoiding AMD in a porphyry copper WR.
基金the National Natural Science Foundation of China(Nos.52304141 and 52074154)。
文摘The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.
基金financial support from the Government of the Perm Territory within the Framework of Scientific Project No.S-26/828the Ministry of Science and High Education of Russia(Theme No.121031700169-1).
文摘In the process of production or processing of materials by various methods,there is a need for a large volume of water of the required quality.Today in many regions of the world,there is an acute problem of providing industry with water of a required quality.Its solution is an urgent and difficult task.The water quality of surface water bodies is formed by a combination of a large number of both natural and anthropogenic factors,and is often significantly heterogeneous not only in the water area,but also in depth.As a rule,the water supply of large industrial enterprises is located along the river network.Mergers are the most important nodes of river systems.Understanding the mechanism of transport of pollutants at the confluence of rivers is critical for assessing water quality.In recent years,thanks to the data of satellite images,the interest of researchers in the phenomenon of mixing the waters of merging rivers has increased.The nature of the merger is influenced by the formation of transverse circulation.Within the framework of this work,a study of vorticity,as well as the width of the mixing zone,depending on the distance from the confluence,the speeds of the merging rivers and the angle of confluence was carried out.Since the consumer properties of water are largely determined by its chemical and physical indicators,the intensity of mixing,determined largely by the nature of the secondary circulation,is of fundamental importance for assessing the distribution of hydrochemical indicators of water quality in the mixing zone.These characteristics are important not only for organizing water intake for drinking and technical purposes with the best consumer properties,but also for organizing an effective monitoring system for confluence zones.
基金National Natural Science Foundation of China(Grant Nos.52174080 and 51974160)Science Foundation of Tiandi Technology Co.,Ltd.(2022-2-TD-ZD016).
文摘During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadway.Therefore,studying the mechanical properties and energy evolution rules of coal samples containing holes and filled structures has certain practical significance for achieving coordinated control of coal mine rockburst disasters and the stability of roadway surrounding rocks.To achieve this aim,seven types of burst-prone coal samples were prepared and subject to uniaxial compression experiments with the aid of a TAW-3000 electro-hydraulic servo testing machine.Besides,the stress–strain curves,acoustic emission signals,DIC strain fields and other data were collected during the experiments.Furthermore,the failure modes and energy evolutions of samples with varying drilled hole sizes and filling materials were analyzed.The results show that the indexes related to burst propensity of the drilled coal samples decline to some extent compared with those of the intact one,and the decline is positively corelated to the diameter of the drilled hole.After hole filling,the strain concentration degree around the drilled hole is lowered to a certain degree,and polyurethane filling has a more remarkable effect than cement filling.Meanwhile,hole filling can enhance the strength and deformation resistance of coal.Hole drilling can accelerate the release of accumulated elastic strain energy,turning the acoustic emission events from low-frequency and high-energy ones to high-frequency and low-energy ones,whereas hole filling can reduce the intensity of energy release.The experimental results and theoretical derivation demonstrate that hole filling promotes coal deformability and strength mainly by weakening stress concentration surrounding the drilled holes.Moreover,the fillings can achieve a better filling effect if their elastic modulus and Poisson’s ratio are closer to those of the coal body.
基金supported by the Major State Basic Research Development Program of China (No. 2014CB046302)
文摘Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project "Technical Revolution in Ecological and Efficient Coal Mining and Utilization & Intelligence and Diverse Coordination of Coal-based Energy System," initiated by Chinese Academy of Engineering, puts forward three stages(3.0, 4.0 and 5.0) of China's coal industry development strategy. Aimed at "reduced staff,ultra-low ecological damage, and emission level near to natural gas," breakthroughs should be achieved in the following three key technologies during the China Coal Industry 3.0 stage(2016–2025): including intelligent coal mining, ecological mining, ultra-low emission and environmental protection. This paper focuses on the development trends of the China Coal Industry 3.0 and its support for China Coal Industry 4.0 and 5.0 is analyzed and prospected as well, which may offer technical assistance and strategy orientation for realizing the transformation from traditional coal energy to clean energy.
基金This work was supported by the National Natural Science Foundation of China(NSFC,Grant No.51874175)the China Coal Technology&Engineering Group Foundation(Grant Nos.2018RC001,KJ-2018-TDKCZL-02).Comments from two anonymous reviewers and the editor are also greatly appreciated.
文摘The evolution of mining-induced stress field in longwall panel is closely related to the fracture field and the breaking characteristics of strata.Few laboratory experiments have been conducted to investigate the stress field.This study investigated its evolution by constructing a large-scale physical model according to the in situ conditions of the longwall panel.Theoretical analysis was used to reveal the mechanism of stress distribution in the overburden.The modelling results showed that:(1)The major principal stress field is arch-shaped,and the strata overlying both the solid zones and gob constitute a series of coordinated load-bearing structures.The stress increasing zone is like a macro stress arch.High stress is especially concentrated on both shoulders of the arch-shaped structure.The stress concentration of the solid zone in front of the gob is higher than the rear solid zone.(2)The characteristics of the vertical stress field in different regions are significantly different.Stress decreases in the zone above the gob and increases in solid zones on both sides of it.The mechanical analysis show that for a given stratum,the trajectories of principal stress are arch-shaped or inverselyarched,referred to as the‘‘principal stress arch’’,irrespective of its initial breaking or periodic breaking,and determines the fracture morphology.That is,the trajectories of tensile principal stress are inversely arched before the first breaking of the strata,and cause the breaking lines to resemble an inverted funnel.In case of periodic breaking,the breaking line forms an obtuse angle with the advancing direction of the panel.Good agreement was obtained between the results of physical modeling and the theoretical analysis.
文摘In this article an attempt to determine the influence of mining factors on the seismic activity during the longwall mining of the upper layer of coal seam no.405/2 in one of the Polish hard coal mines in the Upper Silesian Coal Basin was conducted.Two longwall panels were mined in analogous geological conditions and based on the same mining system and technology.However,there was significant difference with regards to the mining factors,which was reflected in the observed seismic activity.Some tools used in mining seismology were applied to illustrate the aforementioned influence of mining factors,e.g.the frequency-energy distribution,the frequency-magnitude distribution,the 2 D distribution of released seismic energy,the relationship between released seismic energy and the volume of mined coal,the Benioff strain release,and the Gutenberg-Richter(GR)b coefficient distribution(b is the proportion between high and low energy tremors).Concerning the Benioff strain release,a new solution,based on the slope of a fitted line in a moving time window,is proposed.
文摘Methods of exploitation drainage, which is presently applied in polish hard coal mines in Upper Silesian Coal Basin(Poland), are not effective enough, high risk of methane hazard can be observed, and production capacity of the mining plant is not fully used. Methane hazard, which may occur during planned coal exploitation, is presented in this paper. Following parameters are taken into consideration in the forecasts: coal extraction parameters, geological and mining conditions, deposit's methane saturation degree and impact of coal exploitation on the degasification coefficient of the seams, which are under the influence of relaxation zone. This paper presents the results of the analysis aiming to verify applicability of drainage ahead of mining of the coal seams by using surface directional wells. Based on the collected data(coal seams' structural maps, profiles of the exploratory wells, geological cross-sections), the lab tests of drilling cores and direct wells' tests, static model of the deposit was constructed and suitable grid of directional wells from the surface was designed. Comparison of forecasted methane emission volume between the two methods is investigated. The results indicated the necessity of performing appropriate deposit's stimulations in order to increase effectiveness of drainage ahead of mining.
文摘Mining-induced seismicity is a reflection of rock geomechanical evolution of geological environment in the natural and man-made systems and in the mining-technical systems. In order to predict and prevent mining-induced seismicity, it is necessary to research geodynamics and stress state of intact rock mass, to determine possible deformations and additional stresses as a result of large-scale rock extraction, conditions of accumulated energy release. For that a geodynamical monitoring is required on every stage of deposit development and a closing. The report considers principal influencing factors of preparation and occurrence of mining-induced earthquakes. Also it estimates precursors and indicators of rock mass breaking point, and experience concerning prediction and prevention of mining-induced seismicity in the Khibiny apatite mines in the Murmansk region, which is the largest mining province.
基金This work has been supported by the National Key Research and Development Program(Grant No.2017YFC0603000)which was jointly completed by the Coal Mining Research Branch of CCRI,China University of Mining and Technology(Xuzhou and Beijing),Henan Polytechnic UniversityXinji Energy Company Limited of China Coal Energy Group.This work was also supported by the National Natural Science Foundation of China(Grant No.51927807)。
文摘This paper reviews the major achievements in terms of mechanical behaviors of coal measures,mining stress distribution characteristics and ground control in China’s deep underground coal mining.The three main aspects of this review are coal measure mechanics,mining disturbance mechanics,and rock support mechanics.Previous studies related to these three topics are reviewed,including the geo-mechanical properties of coal measures,distribution and evolution characteristics of mining-induced stresses,evolution characteristics of mining-induced structures,and principles and technologies of ground control in both deep roadways and longwall faces.A discussion is made to explain the structural and mechanical properties of coal measures in China’s deep coal mining practices,the types and dis-tribution characteristics of in situ stresses in underground coal mines,and the distribution of mining-induced stress that forms under different geological and engineering conditions.The theory of pre-tensioned rock bolting has been proved to be suitable for ground control of deep underground coal roadways.The use of combined ground control technology(e.g.ground support,rock mass modification,and destressing)has been demonstrated to be an effective measure for rock control of deep roadways.The developed hydraulic shields for 1000 m deep ultra-long working face can effectively improve the stability of surrounding rocks and mining efficiency in the longwall face.The ground control challenges in deep underground coal mines in China are discussed,and further research is recommended in terms of theory and technology for ground control in deep roadways and longwall faces.
基金CCTEG Coal Mining Research Institute(No.TDKC-2022-MS-01)the National Natural Science Foundation of China(No.52274123)the Mining Education Australia(MEA),Collaborative Research Grant Scheme(No.RS-59041).
文摘Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.
文摘The Cheria region in Northeastern Algeria has been facing aquifer overexploitation by the agricultural sector and prolonged droughts,resulting in a considerable decline in groundwater levels.This study investigates the feasibility of implementing artificial recharge techniques to replenish the Eocene aquifer which serves as the primary water source in the Cheria region.A 3D transient numerical model,based on the finite difference method,was used to simulate groundwater flow from 2021 to 2031 using Visual MODFLOW Flex.During the modelling process,three scenarios were considered:(1)including pumping without a recharge,(2)recharge of the entire area through efficient infiltration without pumping,and(3)artificial recharge using river water infiltration basins at two sites,Draa Douamis sinkholes and Eocene limestone outcrops.The simulation results showed that aquifer exploitation without recharge caused significant drawdowns,which were 3 m to 7 m in the north-eastern part and 8 m to 12 m in the central and southern parts.In contrast,the second scenario,involving recharge without pumping,showed a rise in groundwater levels of 2 m to 2.7 m in the north-eastern part and 3 m to 3.62 m in the central and southern parts.The third scenario,employing artificial recharge,indicated a positive response to artificial recharge,with increased piezometric levels at the proposed sites,signifying a beneficial impact on the aquifer.These findings underline the potential of artificial recharge as a promising approach to address the groundwater depletion and environmental issues in the Cheria Basin.
基金We acknowledge the combined support from the National Natural Science Foundation of China(Grant Nos.52039007 and 42102325)Tiandi Science and Technology Co.,Ltd.(Grant No.2022-2-TD-MS012).
文摘Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,it is always challenging to accurately measure rock mass properties.In this study,a three-dimensional(3D)microseismic(MS)data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is proposed.It is a 3D finite element model that takes seepage,damage and stress field effects into account jointly.Multiple factors(i.e.joints,water and microseismicity)are used to optimize the rock mass mechanical parameters at different scales.The model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground mining.It is found that the damage pattern is mostly controlled by the structure,water and rock mass parameters.The damage pattern is evidently different from the two-dimensional result and is more consistent with the field observations.This difference is caused by the MS-derived damage acting on the rock mass.MS data are responsible for gradually correcting the damage zone,changing the direction in which it expands,and promoting it to evolve close to reality.For the crown pillar,the proposed model yields a more trustworthy safety factor.In order to guarantee the stability of the pillar,it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.
