High-steep waste dumps in open-pit mines frequently demonstrate complex particle-size distributions and fractal characteristics along their slopes,which have a significant impact on slope stability.This study takes th...High-steep waste dumps in open-pit mines frequently demonstrate complex particle-size distributions and fractal characteristics along their slopes,which have a significant impact on slope stability.This study takes the Dasuji South waste dump in Inner Mongolia as a case to quantify the fractal dimensions of soil-rock mixtures at various slope heights,and to clarify how these fractal properties govern shear strength and deformation behavior under overlying stress,thereby affecting the overall stability of the waste dump slope.Field sampling and laboratory tests were conducted to determine the particle-size composition and fractal dimensions while direct shear tests were conducted and revealed that lower fractal dimensions indicating coarser particle assemblages significantly enhance shear resistance.Complementary PFC_(2)D discrete element simulations demonstrate that slopes composed of lower-fractaldimension materials deform less and contain localized deformation zones,whereas higher-fractal-dimension slopes experience more extensive displacement and a heightened risk of landslides.These findings refine our understanding of the relationship between fractal grain-size distribution and slope stability,providing a robust theoretical basis for improved stability assessment and optimized support strategies in deep open-pit mining waste dumps,and ultimately aiding in more effective disaster prevention within geotechnical engineering.展开更多
Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump mate...Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes.In this study,pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an insitu field investigation.Spatial heterogeneity is simulated through use of the random finite element method(RFEM)and the random limit equilibrium method(RLEM)and a comparative study is presented.Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope.Seismic performances of the slope have been reported through the probability of failure and reliability index.It was observed that the RLEM approach overestimates failure probability(P_(f))by considering seismic stability with spatial heterogeneity.The P_(f)was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials.Further,it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.展开更多
With the rapid growth of China's economic strength,the demand and market share are also constantly increasing.The number ofcars is rapidly increasing,and a large amount of fuel is consumed as a result.The massive ...With the rapid growth of China's economic strength,the demand and market share are also constantly increasing.The number ofcars is rapidly increasing,and a large amount of fuel is consumed as a result.The massive release of vehicle exhaust seriously damages the natural environment,and the environmental crisis is becoming increasingly serious.This article follows the principles of improving fuel efficiency,reducing emissions,andenhancing vehicle performance.Using NX 12.0 software,a three-dimensional model of a certain type of dump truck frame is constructed based on actual parameters.ANSYS Workbench is used to simplify the geometric model,mesh division,and material definition,and a finite element model is constructed.Obtain the structural performance and natural vibration characteristics of the original chassis under four typical working conditions:bending,torsion,lifting,and unloading,through static analysis and modal analysis.On this basis,the dimensions of the components that bear less load on the original frame were optimized,and the topology of the second crossbeam and rear end corner of the subframe that bear less load on the original frame was optimized to obtain a new frame.The new frame of the dump truck underwent secondary static analysis and modal analysis,and it was found that the weight of the new frame decreased by 41.03 kg,successfully reducing the weight of the frame by 4.38%,improving the vehicle's handling and stability,and extending its service life.展开更多
Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated prim...Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated primarily by human activities and urbanization.The problem of waste littering and dumping in developing countries like Nigeria is increasingly affecting environmental resources such as air and water.Several studies have revealed alarming levels of heavy metals that exceed the World Health Organization(WHO)standards.Plastic waste represents a substantial portion of litter,affecting water quality.Pollution results in the depletion of aquatic ecosystems and an increase in water-related diseases.This review aims to assess the impact of waste littering and dumping on surface water quality in Nigeria.In this review,the findings of various studies on surface water bodies in Nigeria,particularly those under the influence of urbanization and waste disposal,were compiled.This review compared numerous physical and chemical parameters like pH,dissolved oxygen,and heavy metals,and microbiological properties such as total coliforms.The water quality index(WQI)was also computed in these studies to ascertain the suitability of the water samples for human consumption.Review results showed that numerous water bodies in Nigeria have significantly diverse water quality levels,with some samples meeting or exceeding the WHO guidelines for microbiological,chemical,and physical characteristics.Notably,levels of heavy metals,turbidity,and pH frequently exceeded permissible limits,pointing to contamination from agricultural and industrial sources.The WQI results for multiple locations revealed that the majority of surface water sources were classified as“bad”to“very bad”,meaning they were unfit for human consumption.The results emphasized the critical need for immediate action to prevent further harm and deterioration of surface water bodies in Nigeria.Recommendations include strengthening waste management policies,promoting recycling initiatives,fostering collaborations among stakeholders,developing littering penalties and enforcing fines to curb the challenge,and raising educational awareness from the primary level.This review emphasizes the need for proactive measures to protect the environment and surface water quality in Nigeria.展开更多
Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often ...Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often involves tedious and risky field work.To this end,this study demonstrated the use of periodically acquired unmanned aerial vehicle(UAV)-based images over a coal mine spoil dump in New South Wales,Australia.A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers.Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved.The two-dimensional classification outcome was then transformed into three-dimensional(3D)block models using a point-based interpolation approach for stability analysis.The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches,which treat the entire dump as a uniform category.This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments,thereby enhancing the safety and efficiency of mining operations.展开更多
Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic cha...Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic changes and the influencing factors of the soil reinforcement effect of plant species after artificial vegetation restoration under different recovery periods.We selected dump areas of the Delni Copper Mine in Qinghai Province,China to study the relationship between the shear strength and the peak displacement of the root-soil composite on the slope during the recovery period,and the influence of the root traits and soil physical properties on the shear resistance characteristics of the root-soil composite via in situ direct shear tests.The results indicate that the shear strength and peak displacement of the rooted soil initially decreased and then increased with the increase of the recovery period.The shear strength of the rooted soil and the recovery period exhibited a quadratic function relationship.There is no significant function relationship between the peak displacement and the recovery period.Significant positive correlations(P<0.05)exists between the shear strength of the root-soil composite and the root biomass density,root volume density,and root area ratio,and they show significant linear correlations(P<0.05).There are no significant correlations(P>0.05)between the shear strength of the root-soil composite and the root length density,and the root volume ratio of the coarse roots to the fine roots.A significant negative linear correlation(P<0.05)exists between the peak displacement of the rooted soil and the coarse-grain content,but no significant correlations(P>0.05)with the root traits,other soil physical property indices(the moisture content and dry density of the soil),and slope gradient.The coarse-grain content is the main factor controlling the peak displacement of the rooted soil.展开更多
Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the ra...Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.展开更多
In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are e...In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.展开更多
The plug-in hybrid vehicles(PHEV)technology can effectively address the issues of poor dynamics and higher energy consumption commonly found in traditional mining dump trucks.Meanwhile,plug-in hybrid electric trucks c...The plug-in hybrid vehicles(PHEV)technology can effectively address the issues of poor dynamics and higher energy consumption commonly found in traditional mining dump trucks.Meanwhile,plug-in hybrid electric trucks can achieve excellent fuel economy through efficient energy management strategies(EMS).Therefore,a series hybrid system is constructed based on a 100-ton mining dump truck in this paper.And inspired by the dynamic programming(DP)algorithm,a predictive equivalent consumption minimization strategy(P-ECMS)based on the DP optimization result is proposed.Based on the optimal control manifold and the SOC reference trajectory obtained by the DP algorithm,the P-ECMS strategy performs real-time stage parameter optimization to obtain the optimal equivalent factor(EF).Finally,applying the equivalent consumption minimization strategy(ECMS)realizes real-time control.The simulation results show that the equivalent fuel consumption of the P-ECMS strategy under the experimentally collected mining cycle conditions is 150.8 L/100 km,which is 10.9%less than that of the common CDCS strategy(169.3 L/100 km),and achieves 99.47%of the fuel saving effect of the DP strategy(150 L/100 km).展开更多
The dump diffuser is an important component in advanced annular combustor, and its performance affects greatly the fluid field and pressure loss of the combustor. This paper presents the characteristics of the total p...The dump diffuser is an important component in advanced annular combustor, and its performance affects greatly the fluid field and pressure loss of the combustor. This paper presents the characteristics of the total pressure loss. Experiments and numerical simulations, keeping the inlet March number of prediffuser constant ( Ma =0 20), are carried out to obtain the regularity of the total pressure loss. It varies with the relative dump gap ( δ =1 2～3 0)by changing the position of prediffuser and combustor liner, respectively. Research shows that there exists the minimum total pressure loss ( σ *=1 6%～1 75%) when relative dump gap δ is about 1 8.展开更多
基金supported by the National Key Research and Development Program of China(2024YFC2909500)State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering(SDGZ2505)National Natural Science Foundation of China(42377148)。
文摘High-steep waste dumps in open-pit mines frequently demonstrate complex particle-size distributions and fractal characteristics along their slopes,which have a significant impact on slope stability.This study takes the Dasuji South waste dump in Inner Mongolia as a case to quantify the fractal dimensions of soil-rock mixtures at various slope heights,and to clarify how these fractal properties govern shear strength and deformation behavior under overlying stress,thereby affecting the overall stability of the waste dump slope.Field sampling and laboratory tests were conducted to determine the particle-size composition and fractal dimensions while direct shear tests were conducted and revealed that lower fractal dimensions indicating coarser particle assemblages significantly enhance shear resistance.Complementary PFC_(2)D discrete element simulations demonstrate that slopes composed of lower-fractaldimension materials deform less and contain localized deformation zones,whereas higher-fractal-dimension slopes experience more extensive displacement and a heightened risk of landslides.These findings refine our understanding of the relationship between fractal grain-size distribution and slope stability,providing a robust theoretical basis for improved stability assessment and optimized support strategies in deep open-pit mining waste dumps,and ultimately aiding in more effective disaster prevention within geotechnical engineering.
基金the financial support provided by MHRD,Govt.of IndiaCoal India Limited for providing financial assistance for the research(Project No.CIL/R&D/01/73/2021)the partial financial support provided by the Ministry of Education,Government of India,under SPARC project(Project No.P1207)。
文摘Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes.In this study,pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an insitu field investigation.Spatial heterogeneity is simulated through use of the random finite element method(RFEM)and the random limit equilibrium method(RLEM)and a comparative study is presented.Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope.Seismic performances of the slope have been reported through the probability of failure and reliability index.It was observed that the RLEM approach overestimates failure probability(P_(f))by considering seismic stability with spatial heterogeneity.The P_(f)was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials.Further,it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.
文摘With the rapid growth of China's economic strength,the demand and market share are also constantly increasing.The number ofcars is rapidly increasing,and a large amount of fuel is consumed as a result.The massive release of vehicle exhaust seriously damages the natural environment,and the environmental crisis is becoming increasingly serious.This article follows the principles of improving fuel efficiency,reducing emissions,andenhancing vehicle performance.Using NX 12.0 software,a three-dimensional model of a certain type of dump truck frame is constructed based on actual parameters.ANSYS Workbench is used to simplify the geometric model,mesh division,and material definition,and a finite element model is constructed.Obtain the structural performance and natural vibration characteristics of the original chassis under four typical working conditions:bending,torsion,lifting,and unloading,through static analysis and modal analysis.On this basis,the dimensions of the components that bear less load on the original frame were optimized,and the topology of the second crossbeam and rear end corner of the subframe that bear less load on the original frame was optimized to obtain a new frame.The new frame of the dump truck underwent secondary static analysis and modal analysis,and it was found that the weight of the new frame decreased by 41.03 kg,successfully reducing the weight of the frame by 4.38%,improving the vehicle's handling and stability,and extending its service life.
基金support received by the University of South Africa for a conducive research environment。
文摘Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated primarily by human activities and urbanization.The problem of waste littering and dumping in developing countries like Nigeria is increasingly affecting environmental resources such as air and water.Several studies have revealed alarming levels of heavy metals that exceed the World Health Organization(WHO)standards.Plastic waste represents a substantial portion of litter,affecting water quality.Pollution results in the depletion of aquatic ecosystems and an increase in water-related diseases.This review aims to assess the impact of waste littering and dumping on surface water quality in Nigeria.In this review,the findings of various studies on surface water bodies in Nigeria,particularly those under the influence of urbanization and waste disposal,were compiled.This review compared numerous physical and chemical parameters like pH,dissolved oxygen,and heavy metals,and microbiological properties such as total coliforms.The water quality index(WQI)was also computed in these studies to ascertain the suitability of the water samples for human consumption.Review results showed that numerous water bodies in Nigeria have significantly diverse water quality levels,with some samples meeting or exceeding the WHO guidelines for microbiological,chemical,and physical characteristics.Notably,levels of heavy metals,turbidity,and pH frequently exceeded permissible limits,pointing to contamination from agricultural and industrial sources.The WQI results for multiple locations revealed that the majority of surface water sources were classified as“bad”to“very bad”,meaning they were unfit for human consumption.The results emphasized the critical need for immediate action to prevent further harm and deterioration of surface water bodies in Nigeria.Recommendations include strengthening waste management policies,promoting recycling initiatives,fostering collaborations among stakeholders,developing littering penalties and enforcing fines to curb the challenge,and raising educational awareness from the primary level.This review emphasizes the need for proactive measures to protect the environment and surface water quality in Nigeria.
基金supported by the Australian coal industry's research(Grant No.C29048).
文摘Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often involves tedious and risky field work.To this end,this study demonstrated the use of periodically acquired unmanned aerial vehicle(UAV)-based images over a coal mine spoil dump in New South Wales,Australia.A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers.Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved.The two-dimensional classification outcome was then transformed into three-dimensional(3D)block models using a point-based interpolation approach for stability analysis.The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches,which treat the entire dump as a uniform category.This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments,thereby enhancing the safety and efficiency of mining operations.
基金supported by the Project of Qinghai Science&Technology Department(Grant No.2021-ZJ-956Q).
文摘Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic changes and the influencing factors of the soil reinforcement effect of plant species after artificial vegetation restoration under different recovery periods.We selected dump areas of the Delni Copper Mine in Qinghai Province,China to study the relationship between the shear strength and the peak displacement of the root-soil composite on the slope during the recovery period,and the influence of the root traits and soil physical properties on the shear resistance characteristics of the root-soil composite via in situ direct shear tests.The results indicate that the shear strength and peak displacement of the rooted soil initially decreased and then increased with the increase of the recovery period.The shear strength of the rooted soil and the recovery period exhibited a quadratic function relationship.There is no significant function relationship between the peak displacement and the recovery period.Significant positive correlations(P<0.05)exists between the shear strength of the root-soil composite and the root biomass density,root volume density,and root area ratio,and they show significant linear correlations(P<0.05).There are no significant correlations(P>0.05)between the shear strength of the root-soil composite and the root length density,and the root volume ratio of the coarse roots to the fine roots.A significant negative linear correlation(P<0.05)exists between the peak displacement of the rooted soil and the coarse-grain content,but no significant correlations(P>0.05)with the root traits,other soil physical property indices(the moisture content and dry density of the soil),and slope gradient.The coarse-grain content is the main factor controlling the peak displacement of the rooted soil.
基金funded by the National Key R&D Program of China (Grant No. 2021YFB3901402)the Fundamental Research Funds for the Central Universities (Project No. 2022CDJKYJH037)。
文摘Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.
基金Ho Chi Minh City University of Technology(HCMUT)Vietnam National University Ho Chi Minh City(VNU-HCM)for supporting this study。
文摘In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.
文摘The plug-in hybrid vehicles(PHEV)technology can effectively address the issues of poor dynamics and higher energy consumption commonly found in traditional mining dump trucks.Meanwhile,plug-in hybrid electric trucks can achieve excellent fuel economy through efficient energy management strategies(EMS).Therefore,a series hybrid system is constructed based on a 100-ton mining dump truck in this paper.And inspired by the dynamic programming(DP)algorithm,a predictive equivalent consumption minimization strategy(P-ECMS)based on the DP optimization result is proposed.Based on the optimal control manifold and the SOC reference trajectory obtained by the DP algorithm,the P-ECMS strategy performs real-time stage parameter optimization to obtain the optimal equivalent factor(EF).Finally,applying the equivalent consumption minimization strategy(ECMS)realizes real-time control.The simulation results show that the equivalent fuel consumption of the P-ECMS strategy under the experimentally collected mining cycle conditions is 150.8 L/100 km,which is 10.9%less than that of the common CDCS strategy(169.3 L/100 km),and achieves 99.47%of the fuel saving effect of the DP strategy(150 L/100 km).
文摘The dump diffuser is an important component in advanced annular combustor, and its performance affects greatly the fluid field and pressure loss of the combustor. This paper presents the characteristics of the total pressure loss. Experiments and numerical simulations, keeping the inlet March number of prediffuser constant ( Ma =0 20), are carried out to obtain the regularity of the total pressure loss. It varies with the relative dump gap ( δ =1 2～3 0)by changing the position of prediffuser and combustor liner, respectively. Research shows that there exists the minimum total pressure loss ( σ *=1 6%～1 75%) when relative dump gap δ is about 1 8.
