Gangue from underground separation of coal can directly be used for filling mined out areas, saving transport capacity and reducing the amount of waste polluting the environment above the ground. We introduced a struc...Gangue from underground separation of coal can directly be used for filling mined out areas, saving transport capacity and reducing the amount of waste polluting the environment above the ground. We introduced a structure and operating principle of an underground direct-impact sieving device by which a separation experiment was carried out. By means of high speed conveyer belts, coal and gangue impacted the breaking board at high speeds ranging from 6 to 14 m/s. Given the differences of hardness between coal and gangue, after selective crushing, the gangue with the higher hardness was crushed less and coal with lower hardness crushed more, which could be separated by a 50 mm sieving plate. The material above the sieving plate was disposed of as gangue and the material below as coal. The results indicate that the crush ratio below the 50 mm sieving plate increases linearly with an increase in impact velocity and decays exponentially with an increase in hardness. Employing this equipment to separate coal and gangue, the hardness of coal f should be <2. This separation device provides relatively good effect in separating coal and gangue with a relatively wide difference of hardness.展开更多
A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recover...A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recovering high quality safety coal pillars and deep mining of the Suncun Coal Mine （SCM）, Xinwen Coal Group, Shandong are resolved. The physical-chemical properties of coal gangue, optimized proportion of materials, backfilling system and craft in the SCM were studied in the laboratory and then an industrial test was carried out on high quality coal pillars under a town. The results show that finely crushed kaolinized and fresh gangue with granularity less than 5 mm can be used as aggregate with fly ash to replace part of the cement and a composite water reducer as an additive, accounting for 1.0%-1.5% of the total amount of cement and fly ash. The recommended proportion is l（cement）：4（fly ash）： 15（coal gangue）, with a mass fraction of 72%-75%, rheoiogical paste-like properties and a strength of more than 0.7 MPa at 7 d. The sequence of adding cement, fly ash, water reducer and then coal gangue ensures that the suspended state of the slurry, reducing the wear and jam of pipelines. The working face is advancing continuously by the alternating craft of building block walls with coal gangue and backfilling mined-out gobs with paste-like slurry. The recovery rate is as high as 90% with a backfilling cost of 36.9 YuarffL good utilization of coal gangue and no subsidence on the surface. This technology provides a good theoretical basis and application experience for coal mines, cement backfilling with paste-like slurry.展开更多
The increasing anthropogenic CO2 emission and global warming has challenged the China and other countries to seek new and better ways to meet the world’s increasing need for energy while reducing greenhouse gas emiss...The increasing anthropogenic CO2 emission and global warming has challenged the China and other countries to seek new and better ways to meet the world’s increasing need for energy while reducing greenhouse gas emissions.The overall proposition of this research is to develop a brand-new CO2 physical and chemical sequestration method by using solid waste of coal mining and cementitious material which are widely used for goaf backfilling in coal mining.This research developed a new testing system(constant temperature pressurized reaction chamber(CTPRC))to study the effects of different initial parameters on mineral carbonation such as different initial water-binder ratio,initial sample porosity and initial carbon dioxide pressure.The experimental results show that the CO2 consumption ratio is 15%,10%and 7%higher with relatively high initial water-binder ratio,initial sample porosity and initial CO2 pressure within 48 h.In addition,some physical and chemical evidence was found through the electron microscope scanning and XRD test to further explain the above test results.This proposed research will provide critical parameters for optimizing CO2 sequestration capacity in this cementitious backfilling material with forming agent.展开更多
To investigate the creep and instability properties of a cemented gangue backfill column under a highstress area,the uniaxial compression creep tests were conducted by single-step and multi-step loading of prismatic s...To investigate the creep and instability properties of a cemented gangue backfill column under a highstress area,the uniaxial compression creep tests were conducted by single-step and multi-step loading of prismatic samples made of cemented gangue backfill material(CGBM)under the high stressstrength ratio.The creep damage was monitored using an electrical resistivity device,ultrasonic testing device,and acoustic emission(AE)instrument.The results showed that the CGBM sample has a creep hardening property.The creep failure strength(CFS)is slightly larger than the uniaxial compressive strength(UCS),ranging in ratio from 108.9%to 116.5%.The instantaneous strain,creep strain,and creep rate increase with increasing stress-strength ratio in the single-step loading creep tests.The instantaneous strain and creep strain decrease first and then increase during the multi-step loading creep process.The axial creep strain of the CGBM column can be expressed by the viscoelastic-plastic creep model.Creep instability is caused by the accumulation of strain energy under multi-step loading and the continuous lateral expansion at the unconstrained middle position during the creep process.The creep stability of a CGBM column in a high-stress area can be monitored based on the variation of electrical resistivity,ultrasonic pulse velocity(UPV),and AE signals.展开更多
Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affecte...Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affected by leaching from the gangue. This can has an impact on the application of the water for agricul- tural irrigation or use as drinking water. Therefore, it is of great significance to understand the effect coal gangue has on the shallow groundwater of a reclaimed area. We studied the effect of coal gangue on fluo- rine, arsenic, mercury, and lead levels in the shallow groundwater of a reclamation area by testing the water and the coal gangue. One well near the reclamation area was used as a control well and element levels in water from this well and from the soil next to the well were also measured. The results show that the levels of these elements are increasing in the reclamation area over time. The increase in fluorine, arsenic, mercury, and lead in monitor wells varies from 7.42% to 8.26%, from 7.13% to 7.90%, from 4.85% to 6.48%, and from 4.69% to 6.42%, respectively. Fluorine and arsenic levels are lower in monitor wells than in the control water. The other elements are found in greater concentration than in the control. The Nemerow index also indicates that the shallow groundwater in the reclamation area I is moderately affected by the back-filling coal gangue, while the shallow groundwater in the reclamation area II and III are slightly affected by the back-filling coal gangue. This shallow groundwater could be used for agri- cultural irrigation or for drinking.展开更多
Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this ...Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this study,a mining technology of continuous driving and gangue backfilling(CDGB)was proposed.The technology,which can not only alleviate ground subsidence and gangue discharge,but also release the above-mentioned coals,contributes to green and efficient sustainable development of mining.The stability of the system of the solidified body-reserved coal pillar combination(S-C combination)is crucial to the CDGB technology.Therefore,it is of great significance to explore the mechanical and damage characteristics of S-C combination in the synergistic bearing process.First,four sets of differentshaped S-C combination specimens were fabricated and a S-C combination bearing structure in CDGB was constructed to explore the differences in mechanical characteristics and damage modes of different-shaped S-C combination specimens during CDGB.Subsequently,their surface strain field evolutions and acoustic emission(AE)response characteristics in the load-bearing process were obtained with the aid of the digital image correlation technique and the AE signal monitoring system.Furthermore,a damage evolution model based on AE parameters and mechanical parameters was established to clarify the damage evolution law.The following results were obtained:(1)The free area of S-C combination can serve as a quantitative index to evaluate the stability of the overburden control system;(2)The concept of critical value k of the free area was first proposed.When the free area exceeds the critical value k(free area ratio greater than 1.13),the deformation resistance and the free area changes becomes negatively correlated;(3)As the free area expands,the failure of the S-C combination specimen evolves from tensile failure to shear failure.The distribution characteristics of the axial strain field also verified such a change in the failure mode;(4)When the free area expands,the peak AE count gradually changes from“double peaks”to“a single peak”.In this process,the expansion of free area shortens the time for accumulating and releasing energy during loading.Micro cracks generated in the specimen change from a phased steep growth to a continuous increase,and the process in which micro cracks develop,converge,intersect and connect to form macro cracks accelerates.The damage evolution law concluded based on AE parameters and mechanical parameters can well characterize the damage evolution process of S-C combination,providing certain reference for the study on the synergistic bearing of S-C combination during CDGB.展开更多
By using the steady-state seepage method, a patent seepage device together with the MTS815.02 Rock Mechanics Test System is used to test the seepage properties of non-Darcy flow in a granular gangue with five differen...By using the steady-state seepage method, a patent seepage device together with the MTS815.02 Rock Mechanics Test System is used to test the seepage properties of non-Darcy flow in a granular gangue with five different grain sizes during the compaction. The experimental results show that the seepage properties are not only related to the stress or displacement level, but also to the grain size, the pore structure of the granular gangue, and the current porosity The permeability and the non-Darcy flow coefficient can be fitted respectively by the cubic polynomials and the power functions of the porosity, Formally, the flow in granular gangue satisfies the Forchheimer＇s binomial flow, but under the great axial and confining pressure and owing to the grain＇s crushing, the flow in granular gangues is different from that in rock-fills which are naturallv oiled un. As a result, the non-Darer flow coefficient may be negative.展开更多
We analyzed the deformation characteristics of overlying stratum in backfilling with fully-mechanized and retaining roadways along the gob area coal mining technology, and established a mechanical model for the roof k...We analyzed the deformation characteristics of overlying stratum in backfilling with fully-mechanized and retaining roadways along the gob area coal mining technology, and established a mechanical model for the roof key stratum of retaining roadways along gob under the conditions of backfilling and fully- mechanized coal mining technology. Using Winkler elastic foundation theory, we analyzed a part of the key stratum under the action of elastic foundation coupling problem, and derived deflection analyt- ical expressions. Combined with specific conditions, we obtained the deflection curves for the roof key stratum of retaining roadways along gob under the conditions of backfilling and fully-mechanized coal mining technology. On this basis, we adopted the Coulomb's earth pressure theory to solve the problem of lateral pressure of the gangue filling area on the supporting wall beside the roadway and to provide the theoretical basis for reasonable selection of the distance between gangue concrete wall and roof and fur- ther discussion on the supporting stability of roadway.展开更多
Based on the Particle Flow Code(PFC^(2D)) program,we set up gangue backfill models with different gangue contents and bond strength,and studied the stress-strain behaviours,the pattern of shear band and force chains,m...Based on the Particle Flow Code(PFC^(2D)) program,we set up gangue backfill models with different gangue contents and bond strength,and studied the stress-strain behaviours,the pattern of shear band and force chains,motion and fragmentation of particles under biaxial compression.The results show that when the bond strength or contents of gangue are high,the peak strength is high and the phenomena of post-peak softening and fluctuation are obvious.When gangue contents are low,the shape of the shear band is symmetrical and most strong force chains transfer in soil particles.With an increase in gangue content,the shape of the shear band becomes irregular and the majority of strong force chains turn to transfer in gangue particles gradually,most of which distribute along the axial direction.When the gangue content is higher than 50%,the interconnectivity of strong force chains decreases gradually:at the same time,the strong force chains become tilted and the stability of the system tends to decrease.With an increase in external loading,the coordination numbers of the system increase at first and then decrease and the main pattern of force chains changes into columnar from annular.However,after the forming of the advantageous shear band,the force chains external to the shear band maintain their columnar shape while the inner ones bend obviously.As a result,annular force chains form.展开更多
Broken gangue has been extensively used in rockfill dams,subgrade,embankment,foundation cushion and other engineering construction.The deformation characteristics of broken gangue under the bearing compression play a ...Broken gangue has been extensively used in rockfill dams,subgrade,embankment,foundation cushion and other engineering construction.The deformation characteristics of broken gangue under the bearing compression play a decisive role in the firmness,stability and safety of these structures(buildings),and the meso-fabric change of broken gangue under the bearing compression significantly affects its macro deformation.In this study,the transparent characterization and quantitative analysis of 3D fabric of broken gangue under the bearing compression were performed through CT scanning test,image processing and 3D reconstruction technology,and the influence mechanism of internal fabric of broken gangue on its macro deformation was revealed.The results show that:In the loading stage of 0–2 MPa,the sharp corners,thin edges on the blocks and the bar-shaped and blade-shaped blocks with poor regularity are broken first under the bearing compression;in the loading stage of 2–8 MPa,a large number of larger particles in the sample are crushed in the mode of fragmentation;in the loading stage of 8–10 MPa,the breakage degree of samples is relieved.The axial displacement of the block inside the sample occurs,as well as the lateral displacement of the block converging to the central axis of the sample.In the rapid deformation stage,the macro deformation of the broken gangue is mainly caused by the rearrangement and adjustment of the block structure and the breakage of the block;in the slow deformation stage,it is mainly caused by the breakage of the block;in the stable deformation stage,it is mainly caused by the optimization and adjustment of the bearing skeleton in the sample.展开更多
After five years research, a totally new technology for producing a rapid-hardening cement containing bigh content of coal gangue is proposed’ In the technology, a specially designed rotary kiln is used as the calciu...After five years research, a totally new technology for producing a rapid-hardening cement containing bigh content of coal gangue is proposed’ In the technology, a specially designed rotary kiln is used as the calciulng equipmeut, whose structure is more like a conventional clinker cooler than a conventional rotary kiln. A fluidized bed furnace fueled by coal gangue is designed as its heater. With this technology, the quality of the cement yielded can be guaranteed; besides, no high grade coal is needed,no wastes are produced; furthermore, the investment is greatly lowered as compared with a traditional one. So it is a new viable method for disposing coal gangue’展开更多
基金the Natural Science Foundation of Jiangsu Province (No.BK2009098)
文摘Gangue from underground separation of coal can directly be used for filling mined out areas, saving transport capacity and reducing the amount of waste polluting the environment above the ground. We introduced a structure and operating principle of an underground direct-impact sieving device by which a separation experiment was carried out. By means of high speed conveyer belts, coal and gangue impacted the breaking board at high speeds ranging from 6 to 14 m/s. Given the differences of hardness between coal and gangue, after selective crushing, the gangue with the higher hardness was crushed less and coal with lower hardness crushed more, which could be separated by a 50 mm sieving plate. The material above the sieving plate was disposed of as gangue and the material below as coal. The results indicate that the crush ratio below the 50 mm sieving plate increases linearly with an increase in impact velocity and decays exponentially with an increase in hardness. Employing this equipment to separate coal and gangue, the hardness of coal f should be <2. This separation device provides relatively good effect in separating coal and gangue with a relatively wide difference of hardness.
基金Projects 2006BAB02A03 supported by the National Key Technology Research and Development ProgramProjects 2006BA02B05 by the 11th Five Year Key Program for Science and Technology Development of China
文摘A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recovering high quality safety coal pillars and deep mining of the Suncun Coal Mine （SCM）, Xinwen Coal Group, Shandong are resolved. The physical-chemical properties of coal gangue, optimized proportion of materials, backfilling system and craft in the SCM were studied in the laboratory and then an industrial test was carried out on high quality coal pillars under a town. The results show that finely crushed kaolinized and fresh gangue with granularity less than 5 mm can be used as aggregate with fly ash to replace part of the cement and a composite water reducer as an additive, accounting for 1.0%-1.5% of the total amount of cement and fly ash. The recommended proportion is l（cement）：4（fly ash）： 15（coal gangue）, with a mass fraction of 72%-75%, rheoiogical paste-like properties and a strength of more than 0.7 MPa at 7 d. The sequence of adding cement, fly ash, water reducer and then coal gangue ensures that the suspended state of the slurry, reducing the wear and jam of pipelines. The working face is advancing continuously by the alternating craft of building block walls with coal gangue and backfilling mined-out gobs with paste-like slurry. The recovery rate is as high as 90% with a backfilling cost of 36.9 YuarffL good utilization of coal gangue and no subsidence on the surface. This technology provides a good theoretical basis and application experience for coal mines, cement backfilling with paste-like slurry.
基金the National Natural Science Foundation of China(No.51304207)the Fundamental Research Funds for the Key Laboratory of Coal-based CO2 capture and geological storage,China University of Mining and Technology(No.2016A03).
文摘The increasing anthropogenic CO2 emission and global warming has challenged the China and other countries to seek new and better ways to meet the world’s increasing need for energy while reducing greenhouse gas emissions.The overall proposition of this research is to develop a brand-new CO2 physical and chemical sequestration method by using solid waste of coal mining and cementitious material which are widely used for goaf backfilling in coal mining.This research developed a new testing system(constant temperature pressurized reaction chamber(CTPRC))to study the effects of different initial parameters on mineral carbonation such as different initial water-binder ratio,initial sample porosity and initial carbon dioxide pressure.The experimental results show that the CO2 consumption ratio is 15%,10%and 7%higher with relatively high initial water-binder ratio,initial sample porosity and initial CO2 pressure within 48 h.In addition,some physical and chemical evidence was found through the electron microscope scanning and XRD test to further explain the above test results.This proposed research will provide critical parameters for optimizing CO2 sequestration capacity in this cementitious backfilling material with forming agent.
基金supported by the National Natural Science Foundation of China(No.51974192)Shanxi Province Postgraduate Education Innovation Project(No.2020SY567)+2 种基金the Applied Basic Research Project of Shanxi Province(No.201801D121092)Distinguished Youth Funds of National Natural Science Foundation of China(No.51925402)Shanxi Science and Technology Major Project(No.20201102004)。
文摘To investigate the creep and instability properties of a cemented gangue backfill column under a highstress area,the uniaxial compression creep tests were conducted by single-step and multi-step loading of prismatic samples made of cemented gangue backfill material(CGBM)under the high stressstrength ratio.The creep damage was monitored using an electrical resistivity device,ultrasonic testing device,and acoustic emission(AE)instrument.The results showed that the CGBM sample has a creep hardening property.The creep failure strength(CFS)is slightly larger than the uniaxial compressive strength(UCS),ranging in ratio from 108.9%to 116.5%.The instantaneous strain,creep strain,and creep rate increase with increasing stress-strength ratio in the single-step loading creep tests.The instantaneous strain and creep strain decrease first and then increase during the multi-step loading creep process.The axial creep strain of the CGBM column can be expressed by the viscoelastic-plastic creep model.Creep instability is caused by the accumulation of strain energy under multi-step loading and the continuous lateral expansion at the unconstrained middle position during the creep process.The creep stability of a CGBM column in a high-stress area can be monitored based on the variation of electrical resistivity,ultrasonic pulse velocity(UPV),and AE signals.
基金The project was funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affected by leaching from the gangue. This can has an impact on the application of the water for agricul- tural irrigation or use as drinking water. Therefore, it is of great significance to understand the effect coal gangue has on the shallow groundwater of a reclaimed area. We studied the effect of coal gangue on fluo- rine, arsenic, mercury, and lead levels in the shallow groundwater of a reclamation area by testing the water and the coal gangue. One well near the reclamation area was used as a control well and element levels in water from this well and from the soil next to the well were also measured. The results show that the levels of these elements are increasing in the reclamation area over time. The increase in fluorine, arsenic, mercury, and lead in monitor wells varies from 7.42% to 8.26%, from 7.13% to 7.90%, from 4.85% to 6.48%, and from 4.69% to 6.42%, respectively. Fluorine and arsenic levels are lower in monitor wells than in the control water. The other elements are found in greater concentration than in the control. The Nemerow index also indicates that the shallow groundwater in the reclamation area I is moderately affected by the back-filling coal gangue, while the shallow groundwater in the reclamation area II and III are slightly affected by the back-filling coal gangue. This shallow groundwater could be used for agri- cultural irrigation or for drinking.
基金the National Natural Science Foundation of China(Nos.U21A20108,52322403,52174108,and 51974105)the Support Plan for Science&Technology Innovation Talents in Universities of Henan Province(No.21HASTIT024)+1 种基金the Scientific and technological innovation research team of Henan Polytechnic University(No.T2021-5)the Henan Excellent Youth Science Foundation(No.222300420045).
文摘Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this study,a mining technology of continuous driving and gangue backfilling(CDGB)was proposed.The technology,which can not only alleviate ground subsidence and gangue discharge,but also release the above-mentioned coals,contributes to green and efficient sustainable development of mining.The stability of the system of the solidified body-reserved coal pillar combination(S-C combination)is crucial to the CDGB technology.Therefore,it is of great significance to explore the mechanical and damage characteristics of S-C combination in the synergistic bearing process.First,four sets of differentshaped S-C combination specimens were fabricated and a S-C combination bearing structure in CDGB was constructed to explore the differences in mechanical characteristics and damage modes of different-shaped S-C combination specimens during CDGB.Subsequently,their surface strain field evolutions and acoustic emission(AE)response characteristics in the load-bearing process were obtained with the aid of the digital image correlation technique and the AE signal monitoring system.Furthermore,a damage evolution model based on AE parameters and mechanical parameters was established to clarify the damage evolution law.The following results were obtained:(1)The free area of S-C combination can serve as a quantitative index to evaluate the stability of the overburden control system;(2)The concept of critical value k of the free area was first proposed.When the free area exceeds the critical value k(free area ratio greater than 1.13),the deformation resistance and the free area changes becomes negatively correlated;(3)As the free area expands,the failure of the S-C combination specimen evolves from tensile failure to shear failure.The distribution characteristics of the axial strain field also verified such a change in the failure mode;(4)When the free area expands,the peak AE count gradually changes from“double peaks”to“a single peak”.In this process,the expansion of free area shortens the time for accumulating and releasing energy during loading.Micro cracks generated in the specimen change from a phased steep growth to a continuous increase,and the process in which micro cracks develop,converge,intersect and connect to form macro cracks accelerates.The damage evolution law concluded based on AE parameters and mechanical parameters can well characterize the damage evolution process of S-C combination,providing certain reference for the study on the synergistic bearing of S-C combination during CDGB.
基金Projects 50225414 and 50574090 supported by National Natural Science Fund for Distinguished Young Scholars, and 105024 supported by the Key Projectof Educational Ministry
文摘By using the steady-state seepage method, a patent seepage device together with the MTS815.02 Rock Mechanics Test System is used to test the seepage properties of non-Darcy flow in a granular gangue with five different grain sizes during the compaction. The experimental results show that the seepage properties are not only related to the stress or displacement level, but also to the grain size, the pore structure of the granular gangue, and the current porosity The permeability and the non-Darcy flow coefficient can be fitted respectively by the cubic polynomials and the power functions of the porosity, Formally, the flow in granular gangue satisfies the Forchheimer＇s binomial flow, but under the great axial and confining pressure and owing to the grain＇s crushing, the flow in granular gangues is different from that in rock-fills which are naturallv oiled un. As a result, the non-Darer flow coefficient may be negative.
基金supported by the National Natural Science Foundation of China (Nos. 51074163 and 50834005)the Ministry of Education Support Program for New Century Excellent of China(No. NCET-08-0837)the Fundamental Research Funds for the Central Universities of China
文摘We analyzed the deformation characteristics of overlying stratum in backfilling with fully-mechanized and retaining roadways along the gob area coal mining technology, and established a mechanical model for the roof key stratum of retaining roadways along gob under the conditions of backfilling and fully- mechanized coal mining technology. Using Winkler elastic foundation theory, we analyzed a part of the key stratum under the action of elastic foundation coupling problem, and derived deflection analyt- ical expressions. Combined with specific conditions, we obtained the deflection curves for the roof key stratum of retaining roadways along gob under the conditions of backfilling and fully-mechanized coal mining technology. On this basis, we adopted the Coulomb's earth pressure theory to solve the problem of lateral pressure of the gangue filling area on the supporting wall beside the roadway and to provide the theoretical basis for reasonable selection of the distance between gangue concrete wall and roof and fur- ther discussion on the supporting stability of roadway.
基金supported by the Fundamental Research Funds for the Central Universities(Nos.2010QNB25 and 2012LWB66)the National Natural Science Foundation of China(Nos.51323004,51074163 and 50834005)+1 种基金the Trans-Century Training Programme Foundation for the Talents by the State Education Commission(No.NCET-08-0837)the"Six Major Talent"Plan of Jiangsu Province and the Graduate Innovation Fund Project of Jiangsu Province(No.CXZZ13_0924)
文摘Based on the Particle Flow Code(PFC^(2D)) program,we set up gangue backfill models with different gangue contents and bond strength,and studied the stress-strain behaviours,the pattern of shear band and force chains,motion and fragmentation of particles under biaxial compression.The results show that when the bond strength or contents of gangue are high,the peak strength is high and the phenomena of post-peak softening and fluctuation are obvious.When gangue contents are low,the shape of the shear band is symmetrical and most strong force chains transfer in soil particles.With an increase in gangue content,the shape of the shear band becomes irregular and the majority of strong force chains turn to transfer in gangue particles gradually,most of which distribute along the axial direction.When the gangue content is higher than 50%,the interconnectivity of strong force chains decreases gradually:at the same time,the strong force chains become tilted and the stability of the system tends to decrease.With an increase in external loading,the coordination numbers of the system increase at first and then decrease and the main pattern of force chains changes into columnar from annular.However,after the forming of the advantageous shear band,the force chains external to the shear band maintain their columnar shape while the inner ones bend obviously.As a result,annular force chains form.
基金supported by the National Natural Science Foundation of China(Nos.52104103,52022107,52174128)the Natural Science Foundation of Jiangsu Province(Nos.BK20210499,BK20190031)。
文摘Broken gangue has been extensively used in rockfill dams,subgrade,embankment,foundation cushion and other engineering construction.The deformation characteristics of broken gangue under the bearing compression play a decisive role in the firmness,stability and safety of these structures(buildings),and the meso-fabric change of broken gangue under the bearing compression significantly affects its macro deformation.In this study,the transparent characterization and quantitative analysis of 3D fabric of broken gangue under the bearing compression were performed through CT scanning test,image processing and 3D reconstruction technology,and the influence mechanism of internal fabric of broken gangue on its macro deformation was revealed.The results show that:In the loading stage of 0–2 MPa,the sharp corners,thin edges on the blocks and the bar-shaped and blade-shaped blocks with poor regularity are broken first under the bearing compression;in the loading stage of 2–8 MPa,a large number of larger particles in the sample are crushed in the mode of fragmentation;in the loading stage of 8–10 MPa,the breakage degree of samples is relieved.The axial displacement of the block inside the sample occurs,as well as the lateral displacement of the block converging to the central axis of the sample.In the rapid deformation stage,the macro deformation of the broken gangue is mainly caused by the rearrangement and adjustment of the block structure and the breakage of the block;in the slow deformation stage,it is mainly caused by the breakage of the block;in the stable deformation stage,it is mainly caused by the optimization and adjustment of the bearing skeleton in the sample.
文摘After five years research, a totally new technology for producing a rapid-hardening cement containing bigh content of coal gangue is proposed’ In the technology, a specially designed rotary kiln is used as the calciulng equipmeut, whose structure is more like a conventional clinker cooler than a conventional rotary kiln. A fluidized bed furnace fueled by coal gangue is designed as its heater. With this technology, the quality of the cement yielded can be guaranteed; besides, no high grade coal is needed,no wastes are produced; furthermore, the investment is greatly lowered as compared with a traditional one. So it is a new viable method for disposing coal gangue’
