To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions...To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions of acoustic emission(AE)events become very different as lateral pressure coefficients change.The combined effect of static stress and dynamic disturbance causes the damage around the tunnel,and initial stress conditions control the damage morphology.The blast disturbance cannot fundamentally change the damaged area but will deepen the extent of damage and accelerate the failure speed.The more significant the difference between the vertical and horizontal stresses is,the higher the impact on the tunnel by the dynamic disturbance is.The AE activity recovers to a relatively stable state within a short time after the blast and conforms to power-law characteristics.展开更多
Surface mines continue to implement highwalls for several reasons, such as increasing recovery, improving margins, and justifying higher stripping ratios. Highwall stability is a complex issue that is dependent upon a...Surface mines continue to implement highwalls for several reasons, such as increasing recovery, improving margins, and justifying higher stripping ratios. Highwall stability is a complex issue that is dependent upon a variety of mining and geologic factors, and a safe design is necessary for a successful surface operation. To improve highwall stability, it is important to understand the connection between local geology and blasting. Explosives are employed throughout the mining industry for primary rock breakage. There are a number of controlled blasting techniques that can be implemented to improve highwall stability.These include line drilling, smooth wall blasting, trim blasting, buffer blasting, air decking, and presplitting. Each of these techniques have associated advantages and disadvantages. Understanding local geology is necessary for selecting the appropriate controlled blasting technique. Furthermore, understanding the limitations and conditions for successful implementation of each technique is necessary. A discussion of the impact of geologic conditions on highwall stability is provided. Additionally, discussion is provided for the successful incorporation of the controlled blasting techniques listed above, and the associated mining and geologic factors that influence the selection and design of controlled blasting plans.Finally, a new methodology is proposed.展开更多
Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surfac...Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.展开更多
基金Project(2017YFC0602904)supported by the National Key Research and Development Program of ChinaProject(51974059)supported by the National Natural Science Foundation of ChinaProject(N180115010)supported by the Fundamental Research Funds for the Central Universities,China。
文摘To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions of acoustic emission(AE)events become very different as lateral pressure coefficients change.The combined effect of static stress and dynamic disturbance causes the damage around the tunnel,and initial stress conditions control the damage morphology.The blast disturbance cannot fundamentally change the damaged area but will deepen the extent of damage and accelerate the failure speed.The more significant the difference between the vertical and horizontal stresses is,the higher the impact on the tunnel by the dynamic disturbance is.The AE activity recovers to a relatively stable state within a short time after the blast and conforms to power-law characteristics.
文摘Surface mines continue to implement highwalls for several reasons, such as increasing recovery, improving margins, and justifying higher stripping ratios. Highwall stability is a complex issue that is dependent upon a variety of mining and geologic factors, and a safe design is necessary for a successful surface operation. To improve highwall stability, it is important to understand the connection between local geology and blasting. Explosives are employed throughout the mining industry for primary rock breakage. There are a number of controlled blasting techniques that can be implemented to improve highwall stability.These include line drilling, smooth wall blasting, trim blasting, buffer blasting, air decking, and presplitting. Each of these techniques have associated advantages and disadvantages. Understanding local geology is necessary for selecting the appropriate controlled blasting technique. Furthermore, understanding the limitations and conditions for successful implementation of each technique is necessary. A discussion of the impact of geologic conditions on highwall stability is provided. Additionally, discussion is provided for the successful incorporation of the controlled blasting techniques listed above, and the associated mining and geologic factors that influence the selection and design of controlled blasting plans.Finally, a new methodology is proposed.
文摘Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.
