Study on efficient mining of the steep incline and fractured ore-bodies in Yongshaba mine of Guizhou Kailin Group shows that ore-body is fractured and difficult to support the roadways in-vein.After research of the ac...Study on efficient mining of the steep incline and fractured ore-bodies in Yongshaba mine of Guizhou Kailin Group shows that ore-body is fractured and difficult to support the roadways in-vein.After research of the actual conditions about the ore-bodies,we have made the initial decision to adopt reconstruction of roof downward sublevel cut-and-fill mining.The men work safely under the false roof supporting the top plate.However,the difficult problem is how to determine the strength of the false roof.In this case,the method based on reliability theory has been put forward.Combined with elastic mechanics and field practice,when practical value of reliable probability is 90 %,the value of the false roof strength has been calculated,and the study shows that stope span greatly influences the false roof strength.With the strength of artificial roof,the reasonable reinforcement design ensures the false roof which can supply the demand of strength under large span and load.展开更多
This paper investigates the strength and deformation characteristics of reinforced normal and high-strength concrete rectangular beams which failed in shear and repaired by external bonding of carbon fiber and steel p...This paper investigates the strength and deformation characteristics of reinforced normal and high-strength concrete rectangular beams which failed in shear and repaired by external bonding of carbon fiber and steel plate. Five simply supported reinforced concrete beams with shear reinforcement are tested, three of which are made with NSC （normal-strength concrete） and the other two with HSC （high-strength concrete）. The span of the simply supported beams is 0.9 m with 100 mm wide by 200 mm deep cross section. All five beams are tested under four-point bending. Careful repair process is adopted and proved successful. The aim is to restore or increase shear strength of these beams and to monitor their post-repair load-deflection behavior. The effect of concrete compressive strength on the behavior and strength of beams before and after repair is also investigated. Shear cracks patterns and their evolution are observed and discussed.展开更多
基金"973 " Subjects (No. 2010CB732004)National Natural Science Foundation Project (No.50934006)
文摘Study on efficient mining of the steep incline and fractured ore-bodies in Yongshaba mine of Guizhou Kailin Group shows that ore-body is fractured and difficult to support the roadways in-vein.After research of the actual conditions about the ore-bodies,we have made the initial decision to adopt reconstruction of roof downward sublevel cut-and-fill mining.The men work safely under the false roof supporting the top plate.However,the difficult problem is how to determine the strength of the false roof.In this case,the method based on reliability theory has been put forward.Combined with elastic mechanics and field practice,when practical value of reliable probability is 90 %,the value of the false roof strength has been calculated,and the study shows that stope span greatly influences the false roof strength.With the strength of artificial roof,the reasonable reinforcement design ensures the false roof which can supply the demand of strength under large span and load.
文摘This paper investigates the strength and deformation characteristics of reinforced normal and high-strength concrete rectangular beams which failed in shear and repaired by external bonding of carbon fiber and steel plate. Five simply supported reinforced concrete beams with shear reinforcement are tested, three of which are made with NSC （normal-strength concrete） and the other two with HSC （high-strength concrete）. The span of the simply supported beams is 0.9 m with 100 mm wide by 200 mm deep cross section. All five beams are tested under four-point bending. Careful repair process is adopted and proved successful. The aim is to restore or increase shear strength of these beams and to monitor their post-repair load-deflection behavior. The effect of concrete compressive strength on the behavior and strength of beams before and after repair is also investigated. Shear cracks patterns and their evolution are observed and discussed.
