The most important objective of blasting in open pit mines is rock fragmentation.Prediction of produced boulders(oversized crushed rocks) is a key parameter in designing blast patterns.In this study,the amount of boul...The most important objective of blasting in open pit mines is rock fragmentation.Prediction of produced boulders(oversized crushed rocks) is a key parameter in designing blast patterns.In this study,the amount of boulder produced in blasting operations of Golegohar iron ore open pit mine,Iran was predicted via multiple regression method and artificial neural networks.Results of 33 blasts in the mine were collected for modeling.Input variables were:joints spacing,density and uniaxial compressive strength of the intact rock,burden,spacing,stemming,bench height to burden ratio,and specific charge.The dependent variable was ratio of boulder volume to pattern volume.Both techniques were successful in predicting the ratio.In this study,the multiple regression method was superior with coefficient of determination and root mean squared error values of 0.89 and 0.19,respectively.展开更多
Experimental investigation was conducted to characterize the responses of high performance concrete(HPC) subjected to multiaxial compressive stresses. The HPC specimens were prepared with three different mix proportio...Experimental investigation was conducted to characterize the responses of high performance concrete(HPC) subjected to multiaxial compressive stresses. The HPC specimens were prepared with three different mix proportions, which corresponds to three different uniaxial compressive strengths. The cubic specimens with size of 100 mm for each edge were tested with servo-hydraulic actuators at different stress ratios. The principal stresses and strains of the specimens were recorded, and the failure of the cubic specimens under various stress states was examined. The experimental results indicated that the stress states and stress ratios had significant influence on the strength and deformation of HPC under biaxial and triaxial compression, especially under triaxial compression. Failure criteria were proposed for the HPC specimens under biaxial and triaxial compressive loading. The test results provided a valuable reference for obtaining multi-axial constitutive law for HPC.展开更多
文摘The most important objective of blasting in open pit mines is rock fragmentation.Prediction of produced boulders(oversized crushed rocks) is a key parameter in designing blast patterns.In this study,the amount of boulder produced in blasting operations of Golegohar iron ore open pit mine,Iran was predicted via multiple regression method and artificial neural networks.Results of 33 blasts in the mine were collected for modeling.Input variables were:joints spacing,density and uniaxial compressive strength of the intact rock,burden,spacing,stemming,bench height to burden ratio,and specific charge.The dependent variable was ratio of boulder volume to pattern volume.Both techniques were successful in predicting the ratio.In this study,the multiple regression method was superior with coefficient of determination and root mean squared error values of 0.89 and 0.19,respectively.
基金supported by the National Natural Science Foundation of China(Grant No.51278118)the National Basic Research Program of China("973"Project)(Grant No.2009CB623200)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Experimental investigation was conducted to characterize the responses of high performance concrete(HPC) subjected to multiaxial compressive stresses. The HPC specimens were prepared with three different mix proportions, which corresponds to three different uniaxial compressive strengths. The cubic specimens with size of 100 mm for each edge were tested with servo-hydraulic actuators at different stress ratios. The principal stresses and strains of the specimens were recorded, and the failure of the cubic specimens under various stress states was examined. The experimental results indicated that the stress states and stress ratios had significant influence on the strength and deformation of HPC under biaxial and triaxial compression, especially under triaxial compression. Failure criteria were proposed for the HPC specimens under biaxial and triaxial compressive loading. The test results provided a valuable reference for obtaining multi-axial constitutive law for HPC.
