In order to optimize gob-side entry in fully-mechanized working face in moderate-thick-coal seams, we adopt a new attempt to pack roadside by pumping ordinary concrete, which is very important for the development of g...In order to optimize gob-side entry in fully-mechanized working face in moderate-thick-coal seams, we adopt a new attempt to pack roadside by pumping ordinary concrete, which is very important for the development of gob-side entry technology. The concrete has a long initial setting time and a low initial strength. So it is difficult to control the surrounding rock. In this paper, we analyze the effect of using roadside cable to reinforce supporting in gob-side entry surrounding rock controlling based on elas-tic-plastic and material mechanics knowledge. And then we propose a scheme that cable is used to reinforce roadside supporting and a single hydraulic prop is used as the temporary supporting in gob side. Using the numerical simulation software FLAC2D, we numerically simulated supporting scheme. Results of both the 2D modeling and the industrial test on No.3117 face in Jingang Mine prove that the scheme is feasible. The results show that the technology of protecting the roadway in gob-entry retained efficiently make up the deficiency of roadside packing with ordinary concrete, effectively control the roof strata and acquire a good result of retaining roadway.展开更多
The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the stope.In this paper,the stress distribution characteristics are analyzed via the ...The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the stope.In this paper,the stress distribution characteristics are analyzed via the numerical calculation with the account of OCP presence or absence.In addition,this study revealed the joint effect of side pressure relief area of the goaf and stress concentration in OCP on the final stress distribution.Furthermore,the rules of abutment stress distribution affected by three influencing factors,namely horizontal-vertical distances between OCP and working face and buried depth of OCP,are analyzed.The functional model linking the peak stress of surrounding rock with the above influencing factors is developed.The field application of the above results proved that the rib spalling and deformation of a 2.95 m-high and 5.66 m-wide roadway could be efficiently controlled by rationally adjusting working states of the support,and adopting the hydraulic prop coordinated with the p type metal beam and anchor cable to strengthen the surrounding rock of working face and roadway,respectively.The proposed measures are considered appropriate to satisfy the safe operation requirements.展开更多
Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation chara...Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.展开更多
Fully mechanized mining with large mining height(FMMLMH)is widely used in thick coal seam mining face for its higher recovery ratio,especially where the thickness is less than 7.0 m.However,because of the great mining...Fully mechanized mining with large mining height(FMMLMH)is widely used in thick coal seam mining face for its higher recovery ratio,especially where the thickness is less than 7.0 m.However,because of the great mining height and intense rock pressure,the coal wall rib spalling,roof falling and the instability of support occur more likely in FMMLMH working face,and the above three types of disasters interact with each other with complicated relationships.In order to get the relationship between each two of coal wall,roof,floor and support,and reduce the occurrence probability of the three types of disasters,we established the system dynamics(SD)model of the support-surrounding rock system which is composed of"coal wall-roof-floor-support"(CW-R-F-S)in a FMMLMH working face based on the condition of No.15104 working face in Sijiazhuang coal mine.With the software of Vensim,we also simulated the interaction process between each two factors of roof,floor,coal wall and the support.The results show that the SD model of"CW-R-F-S"system can reveal the complicated and interactive relationship clearly between the support and surrounding rock in the FMMLMH working face.By increasing the advancing speed of working face,the support resistance or the length of support guard,or by decreasing the tipto-face distance,the stability of"CW-R-F-S"system will be higher and the happening probability of the disasters such as coal wall rib spalling,roof falling or the instability of support will be lower.These research findings have been testified in field application in No.15104 working face,which can provide a new approach for researching the interaction relationship of support and surrounding rock.展开更多
The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking un...The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.展开更多
基金support from the National Nature Science Foundation of China (No50874124)
文摘In order to optimize gob-side entry in fully-mechanized working face in moderate-thick-coal seams, we adopt a new attempt to pack roadside by pumping ordinary concrete, which is very important for the development of gob-side entry technology. The concrete has a long initial setting time and a low initial strength. So it is difficult to control the surrounding rock. In this paper, we analyze the effect of using roadside cable to reinforce supporting in gob-side entry surrounding rock controlling based on elas-tic-plastic and material mechanics knowledge. And then we propose a scheme that cable is used to reinforce roadside supporting and a single hydraulic prop is used as the temporary supporting in gob side. Using the numerical simulation software FLAC2D, we numerically simulated supporting scheme. Results of both the 2D modeling and the industrial test on No.3117 face in Jingang Mine prove that the scheme is feasible. The results show that the technology of protecting the roadway in gob-entry retained efficiently make up the deficiency of roadside packing with ordinary concrete, effectively control the roof strata and acquire a good result of retaining roadway.
基金supported by the Special Funding Projects of Sanjin Scholars” Supporting Plan (No. 2050205)the National Key Research Projects (No. 2016YFC0600701)Ordinary University Graduate Student Scientific Research Innovation Projects of Jiangsu Province of China (No. KYLX16_0564)
文摘The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the stope.In this paper,the stress distribution characteristics are analyzed via the numerical calculation with the account of OCP presence or absence.In addition,this study revealed the joint effect of side pressure relief area of the goaf and stress concentration in OCP on the final stress distribution.Furthermore,the rules of abutment stress distribution affected by three influencing factors,namely horizontal-vertical distances between OCP and working face and buried depth of OCP,are analyzed.The functional model linking the peak stress of surrounding rock with the above influencing factors is developed.The field application of the above results proved that the rib spalling and deformation of a 2.95 m-high and 5.66 m-wide roadway could be efficiently controlled by rationally adjusting working states of the support,and adopting the hydraulic prop coordinated with the p type metal beam and anchor cable to strengthen the surrounding rock of working face and roadway,respectively.The proposed measures are considered appropriate to satisfy the safe operation requirements.
基金Financial support for this work was provided by the National Natural Science Foundation of China(Nos.51474005,51004002)
文摘Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.
基金Financial support for this work,provided by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.SZBF2011-6-B35)the Research Fund for the Doctoral Program of Higher Education of China(No.20120095120017)the National High Technology Research and Development Program of China(No.2012AA062101)
文摘Fully mechanized mining with large mining height(FMMLMH)is widely used in thick coal seam mining face for its higher recovery ratio,especially where the thickness is less than 7.0 m.However,because of the great mining height and intense rock pressure,the coal wall rib spalling,roof falling and the instability of support occur more likely in FMMLMH working face,and the above three types of disasters interact with each other with complicated relationships.In order to get the relationship between each two of coal wall,roof,floor and support,and reduce the occurrence probability of the three types of disasters,we established the system dynamics(SD)model of the support-surrounding rock system which is composed of"coal wall-roof-floor-support"(CW-R-F-S)in a FMMLMH working face based on the condition of No.15104 working face in Sijiazhuang coal mine.With the software of Vensim,we also simulated the interaction process between each two factors of roof,floor,coal wall and the support.The results show that the SD model of"CW-R-F-S"system can reveal the complicated and interactive relationship clearly between the support and surrounding rock in the FMMLMH working face.By increasing the advancing speed of working face,the support resistance or the length of support guard,or by decreasing the tipto-face distance,the stability of"CW-R-F-S"system will be higher and the happening probability of the disasters such as coal wall rib spalling,roof falling or the instability of support will be lower.These research findings have been testified in field application in No.15104 working face,which can provide a new approach for researching the interaction relationship of support and surrounding rock.
基金financial support provided by the Xinjiang Uygur Autonomous Region Key R&D Project Task Special-Department and Department Linkage Project(No.2022B01051)Major Project of Regional Joint Foundation of China(No.U21A20107)+1 种基金Hunan Provincial Natural Science Foundation of China(No.2024JJ4021)the Xinjiang Uygur Autonomous Region Tianchi Introduction Plan(No.2024XGYTCYC03)。
文摘The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.
