Support crushing and water inrush when mining under an unconsolidated confined aquifer in the Qidong Coal Mine was prevented by roof pre-blasting.The mechanism and applicable conditions for this method have been studi...Support crushing and water inrush when mining under an unconsolidated confined aquifer in the Qidong Coal Mine was prevented by roof pre-blasting.The mechanism and applicable conditions for this method have been studied.The results show that when an overburden structure that may cause support crushing and a water inrush accident exists the weakening of the primary key stratum,which thereby reduces its weighting step,roof pre-blasting is both feasible and effective.If the position of the primary key stratum can be moved upward to exceed 10 times the mining height the possibility of support crushing and water inrush disaster caused by key stratum compound breakage will be lowered.The overburden structure of the number 7121 working face was considered during the design of a technical proposal involving roof pre-blasting.After comprehensively analyzing the applicability of roof pre-blasting the resulting design prevented support crushing and water inrush disasters from happening at the number 7121 working face and laid a solid foundation for mining safely.展开更多
Horizontal section top-coal(HSTCC)caving offers a powerful method to efficiently excavate rude coal in steep and thick seams,and pre-blasting weakening has a profound effect on pursuing great production,high efficienc...Horizontal section top-coal(HSTCC)caving offers a powerful method to efficiently excavate rude coal in steep and thick seams,and pre-blasting weakening has a profound effect on pursuing great production,high efficiency and good benefit under particular conditions like a small-scale working face with large-scale sectional caving height.+564-level HSTCC working face in B3–6coal seams of Jiangou Colliery in Urumqi was taken as study case for in situ industrial experiment.Total thickness of seams in the study case is about 50.0 m and average angel here is over 83°.In the industrial experiments,at first we adopted continuous charge machine and emulsion matrix explosive to substitute for traditional blasting schemes for specific geological settings in the study case.Hybrid analyses and assessments with blasting crack propagation analysis,abutment pressure monitoring prediction and economical benefit assessment were attributed to be able to attest pre-blasting weakening effects practically.Meanwhile crack propagation analysis after pre-blasting weakening showed that in all triple monitoring bore holes rock masses of top-coal would be fallen into three stages from the bottom up:fracture zone,plastic zone and elastic zone generally,and fracture toughness respectively in correspondent zones was calculated by the analytical formula:0.5616–0.8806,0.6403–0.9541 and0.7535–1.1900 MPa m1/2after pre-blasting weakening.Pressure monitoring prediction and economical benefit assessment also indicated that it was necessary to introduce the pre-blasting weakening with predominant blasting scheme from both views.For excavation in extremely steep and thick coal seams,relevant results would be a useful tool to study the mechanism of pre-blasting weakening both qualitatively and quantitatively.展开更多
Major mineral hazard identifications should consider perilous types of fatal accidents in collieries from its definition, and then set existent hazardous objects and their relevant amount as referenced factors. Elimin...Major mineral hazard identifications should consider perilous types of fatal accidents in collieries from its definition, and then set existent hazardous objects and their relevant amount as referenced factors. Eliminating hazards in systems and decreasing risks are their essential purposes with help of hazard identification, risk evaluation and management. By pre-control on major hazards, fatal accidents are avoided, stuffs＇ safety and healthy are protected, levels of safe management are enhanced, and perpetual systems are built up finally. However, choosing the proper identification and evaluation is a problem all along. Based on specific condition in Jiangou Coal Mine, method of LEC was applied for hazard identification and evaluation in the pre-blasting process within horizontal section top-coal mechanized caving of steep seams. And control measures to of each hazard were put forward. The identification method combining qualitative and quantitative analysis. So, it is practical and operable for the method to develop the given scientific research and has a distinctive impact on high efficiency and safety products for pre-blasting in horizontal section top-coal mechanized caving of steep seams.展开更多
The pre-blasting zones have a significant influence on the coal broken and the recovery rate of the top coal caving mining.This paper explores the coal movement mechanism in the top coal with pre-blasting zones based ...The pre-blasting zones have a significant influence on the coal broken and the recovery rate of the top coal caving mining.This paper explores the coal movement mechanism in the top coal with pre-blasting zones based on the geological parameters of Jiangcang No.1 mine in the western of China.The steeply inclined ultra-thick coal seam was mined by using the sublevel top-coal caving mining method.The geo-image process system(GIPS)software was used to track the mark points on the coal and roof.The support was used to record the load on the top of the support during the caving mining process.The results show that the horizontal coal is moved to the shield window and the vertical coal is moved downward in the first level,while that in the second level shows consistency for the integrity of the coal.The vertical displacements of the corresponding points in the first level are lairger than that in the second level.However,the load on the top of the support in the first level is smaller than that in the second level.It indicated that the pre-blasting zones will give a more loosen top-coal and a small degree of difficulty in the top coal caving.展开更多
基金the National Natural Science Foundation of China(No.50974116)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(SZBF2011-6-B35)for their financial support
文摘Support crushing and water inrush when mining under an unconsolidated confined aquifer in the Qidong Coal Mine was prevented by roof pre-blasting.The mechanism and applicable conditions for this method have been studied.The results show that when an overburden structure that may cause support crushing and a water inrush accident exists the weakening of the primary key stratum,which thereby reduces its weighting step,roof pre-blasting is both feasible and effective.If the position of the primary key stratum can be moved upward to exceed 10 times the mining height the possibility of support crushing and water inrush disaster caused by key stratum compound breakage will be lowered.The overburden structure of the number 7121 working face was considered during the design of a technical proposal involving roof pre-blasting.After comprehensively analyzing the applicability of roof pre-blasting the resulting design prevented support crushing and water inrush disasters from happening at the number 7121 working face and laid a solid foundation for mining safely.
基金provided by the National Natural Science Foundation of China (No.11002021)the Doctoral Subject,Foundation of the Ministry of Education of China (No.20070008012)+1 种基金the National High Technology Research and Development Program of China (No.2008AA062104)Team Program for Key Scientific and Technological innovation,Shaanxi Province of China (No.2013KCT-16)
文摘Horizontal section top-coal(HSTCC)caving offers a powerful method to efficiently excavate rude coal in steep and thick seams,and pre-blasting weakening has a profound effect on pursuing great production,high efficiency and good benefit under particular conditions like a small-scale working face with large-scale sectional caving height.+564-level HSTCC working face in B3–6coal seams of Jiangou Colliery in Urumqi was taken as study case for in situ industrial experiment.Total thickness of seams in the study case is about 50.0 m and average angel here is over 83°.In the industrial experiments,at first we adopted continuous charge machine and emulsion matrix explosive to substitute for traditional blasting schemes for specific geological settings in the study case.Hybrid analyses and assessments with blasting crack propagation analysis,abutment pressure monitoring prediction and economical benefit assessment were attributed to be able to attest pre-blasting weakening effects practically.Meanwhile crack propagation analysis after pre-blasting weakening showed that in all triple monitoring bore holes rock masses of top-coal would be fallen into three stages from the bottom up:fracture zone,plastic zone and elastic zone generally,and fracture toughness respectively in correspondent zones was calculated by the analytical formula:0.5616–0.8806,0.6403–0.9541 and0.7535–1.1900 MPa m1/2after pre-blasting weakening.Pressure monitoring prediction and economical benefit assessment also indicated that it was necessary to introduce the pre-blasting weakening with predominant blasting scheme from both views.For excavation in extremely steep and thick coal seams,relevant results would be a useful tool to study the mechanism of pre-blasting weakening both qualitatively and quantitatively.
基金Supported by the National Natural Science Foundation of China （1100202 l） the Doctoral Subject Foundation of the Ministry of Education of China （20070008012） the National High Technology Research and Development Program （2008AA062104）
文摘Major mineral hazard identifications should consider perilous types of fatal accidents in collieries from its definition, and then set existent hazardous objects and their relevant amount as referenced factors. Eliminating hazards in systems and decreasing risks are their essential purposes with help of hazard identification, risk evaluation and management. By pre-control on major hazards, fatal accidents are avoided, stuffs＇ safety and healthy are protected, levels of safe management are enhanced, and perpetual systems are built up finally. However, choosing the proper identification and evaluation is a problem all along. Based on specific condition in Jiangou Coal Mine, method of LEC was applied for hazard identification and evaluation in the pre-blasting process within horizontal section top-coal mechanized caving of steep seams. And control measures to of each hazard were put forward. The identification method combining qualitative and quantitative analysis. So, it is practical and operable for the method to develop the given scientific research and has a distinctive impact on high efficiency and safety products for pre-blasting in horizontal section top-coal mechanized caving of steep seams.
基金This research was supported by the National Natural Science Foundation of China(Grants 51674264 and 51574244)the National Key Research and Development Program of China(Grants 2017YFC0603002 and 2018YFC0604501).
文摘The pre-blasting zones have a significant influence on the coal broken and the recovery rate of the top coal caving mining.This paper explores the coal movement mechanism in the top coal with pre-blasting zones based on the geological parameters of Jiangcang No.1 mine in the western of China.The steeply inclined ultra-thick coal seam was mined by using the sublevel top-coal caving mining method.The geo-image process system(GIPS)software was used to track the mark points on the coal and roof.The support was used to record the load on the top of the support during the caving mining process.The results show that the horizontal coal is moved to the shield window and the vertical coal is moved downward in the first level,while that in the second level shows consistency for the integrity of the coal.The vertical displacements of the corresponding points in the first level are lairger than that in the second level.However,the load on the top of the support in the first level is smaller than that in the second level.It indicated that the pre-blasting zones will give a more loosen top-coal and a small degree of difficulty in the top coal caving.
