This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensi...This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensive field measurement program was conducted to determine entry deformation,roof fracture zone,and anchor bolt(cable)loading.The results indicate that GSERC deformation presents asymmetric characteristics.The maximum convergence near roof cutting side is 458 mm during the primary use process and 1120 mm during the secondary reuse process.The entry deformation is closely associated with the primary development stage,primary use stage,and secondary reuse stage.The key block movement of roof cutting structure,a complex stress environment,and a mismatch in the supporting design scheme are the failure mechanism of GSERC.A controlling ideology for mining states,including regional and stage divisions,was proposed.Both dynamic and permanent support schemes have been implemented in the field.Engineering practice results indicate that the new support scheme can efficiently ensure long-term entry safety and could be a reliable approach for other engineering practices.展开更多
The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from en...The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from energy consumption. These ecological costs are incorporated in an iterative ultimate pit optimization algorithm. A case study is presented to demonstrate the influence of ecological costs on pit design outcome. The results show that it is possible to internalize ecological costs in mine designs. The pit optimization outcome shifts considerably to the conservative side and the profitability decreases substantially when ecological costs are accounted for.展开更多
To better design and analyze concrete structures, the mechanical properties of concrete subjected to impact loadings are investigated. Concrete is considered to be a two-phase composite made up of micro-cracks and sol...To better design and analyze concrete structures, the mechanical properties of concrete subjected to impact loadings are investigated. Concrete is considered to be a two-phase composite made up of micro-cracks and solid parts which consist of coarse aggregate particles and a cement mortar matrix. The cement mortar matrix is assumed to be elastic, homogeneous and isotropic. Based on the Moil-Tanaka concept of average stress and the Eshelby equivalent inclusion theory, a dynamic constitutive model is developed to simulate the impact responses of concrete. The impact compression experiments of concrete and cement mortar are also carried out. Experimental results show that concrete and cement mortar are rate-dependent. Under the same impact velocity, the load-carrying capacity of concrete is higher than that of cement mortar. Whereas, the maximum strain of concrete is lower than that of cement mortar. Regardless of whether it is concrete or cement mortar, with the increase in the impact velocity, the fragment size of specimens after experiment decreases.展开更多
基金Project(WPUKFJJ2019-19)supported by the Open Fund of State Key Laboratory of Water Resource Protection and Utilization in Coal Mining,ChinaProject(51974317)supported by the National Natural Science Foundation of China。
文摘This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensive field measurement program was conducted to determine entry deformation,roof fracture zone,and anchor bolt(cable)loading.The results indicate that GSERC deformation presents asymmetric characteristics.The maximum convergence near roof cutting side is 458 mm during the primary use process and 1120 mm during the secondary reuse process.The entry deformation is closely associated with the primary development stage,primary use stage,and secondary reuse stage.The key block movement of roof cutting structure,a complex stress environment,and a mismatch in the supporting design scheme are the failure mechanism of GSERC.A controlling ideology for mining states,including regional and stage divisions,was proposed.Both dynamic and permanent support schemes have been implemented in the field.Engineering practice results indicate that the new support scheme can efficiently ensure long-term entry safety and could be a reliable approach for other engineering practices.
基金Project(50974041)supported by the National Natural Science Foundation of ChinaProject(NCET-11-0073)supported by Program for New Century Excellent Talents in University of Ministry of Education of China+1 种基金Project(201102065)supported by the Natural Science Foundation of Liaoning Province,ChinaProject(2012921075)supported by the Ten Million Talent Project of Liaoning Province,China
文摘The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from energy consumption. These ecological costs are incorporated in an iterative ultimate pit optimization algorithm. A case study is presented to demonstrate the influence of ecological costs on pit design outcome. The results show that it is possible to internalize ecological costs in mine designs. The pit optimization outcome shifts considerably to the conservative side and the profitability decreases substantially when ecological costs are accounted for.
基金The National Natural Science Foundation of China(No. 11162015)the Natural Science Foundation of Ningxia Hui Autonomous Region (No. NZ1106)
文摘To better design and analyze concrete structures, the mechanical properties of concrete subjected to impact loadings are investigated. Concrete is considered to be a two-phase composite made up of micro-cracks and solid parts which consist of coarse aggregate particles and a cement mortar matrix. The cement mortar matrix is assumed to be elastic, homogeneous and isotropic. Based on the Moil-Tanaka concept of average stress and the Eshelby equivalent inclusion theory, a dynamic constitutive model is developed to simulate the impact responses of concrete. The impact compression experiments of concrete and cement mortar are also carried out. Experimental results show that concrete and cement mortar are rate-dependent. Under the same impact velocity, the load-carrying capacity of concrete is higher than that of cement mortar. Whereas, the maximum strain of concrete is lower than that of cement mortar. Regardless of whether it is concrete or cement mortar, with the increase in the impact velocity, the fragment size of specimens after experiment decreases.
