The stress strength factor, length and opening degree of cracks around boreholes as well as movement regularity Of blockage with the smooth blasting by water coupling are calculated out according to the theories of fr...The stress strength factor, length and opening degree of cracks around boreholes as well as movement regularity Of blockage with the smooth blasting by water coupling are calculated out according to the theories of fracture mechanics and explosion dynamics, and the relation between the pressure in holes and the change of hoIe volume is pointed out, thereby the distance between boreholes is worked out in this paper. For limestone, when uncoupling coefficient is 3,diameter of holes is 100 mm, the hole distance of water coupling smooth blasting is 2. 3 m. The result is consistent with practice.展开更多
Factors that affect blasting results may be grouped into those factors that can be controlled and those that cannot be controlled. The controllable factors include explosive properties, initiation timing, and blast ge...Factors that affect blasting results may be grouped into those factors that can be controlled and those that cannot be controlled. The controllable factors include explosive properties, initiation timing, and blast geometry. The uncontrollable factors comprise the rock’s natural structures, such as joints and fractures, and the properties, such as elastic constants, density and strength. Among these, the influence of rock structural planes often contributes a high degree of variability to blasting results. This paper presents a theoretical analysis of rock structural plane influences on smooth blasting results based on elasticity and stress wave propagation theory with an emphasis on smooth blasting techniques. Two types of simulated experiments in lab (using strain and acoustic emission measurements) are used to verify the theoretical analysis. The results show that it is difficult to achieve smooth blasting results when the angle between the natural rock structural planes and the blast induced fracture planes ranges from 10° to 60°. Among these angles, 30° is the least desirable angle to produce a smooth wall. For angles less than 10° and greater than 60°, the influence of rock structural planes on blasting results can be ignored.展开更多
Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for...Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for achieving an excellent smooth blasting effect.In this paper,the Riedel-Hiermaier-Thoma(RHT)model was employed to study rock mass damage under smooth blasting.Firstly,the parameters of the RHT model were calibrated by using the existing SHPB experiment,which were then verified by the existing blasting experiment results.Secondly,the influence of different charge structures on the blasting effect was investigated using the RHT model.The simulation results indicated that eccentric charge blasting has an obvious pressure eccentricity effect.Finally,to improve the blasting effect,the smooth blasting parameters were optimized based on an eccentric charge structure.The overbreak and underbreak phenomena were effectively controlled,and a good blasting effect was achieved with the optimized blasting parameters.展开更多
文摘The stress strength factor, length and opening degree of cracks around boreholes as well as movement regularity Of blockage with the smooth blasting by water coupling are calculated out according to the theories of fracture mechanics and explosion dynamics, and the relation between the pressure in holes and the change of hoIe volume is pointed out, thereby the distance between boreholes is worked out in this paper. For limestone, when uncoupling coefficient is 3,diameter of holes is 100 mm, the hole distance of water coupling smooth blasting is 2. 3 m. The result is consistent with practice.
文摘Factors that affect blasting results may be grouped into those factors that can be controlled and those that cannot be controlled. The controllable factors include explosive properties, initiation timing, and blast geometry. The uncontrollable factors comprise the rock’s natural structures, such as joints and fractures, and the properties, such as elastic constants, density and strength. Among these, the influence of rock structural planes often contributes a high degree of variability to blasting results. This paper presents a theoretical analysis of rock structural plane influences on smooth blasting results based on elasticity and stress wave propagation theory with an emphasis on smooth blasting techniques. Two types of simulated experiments in lab (using strain and acoustic emission measurements) are used to verify the theoretical analysis. The results show that it is difficult to achieve smooth blasting results when the angle between the natural rock structural planes and the blast induced fracture planes ranges from 10° to 60°. Among these angles, 30° is the least desirable angle to produce a smooth wall. For angles less than 10° and greater than 60°, the influence of rock structural planes on blasting results can be ignored.
基金Projects(11802058,52074262)supported by the National Natural Science Foundation of ChinaProjects(BK20170670,BK20180651)supported by the Jiangsu Youth Foundation,China+2 种基金Project(2020QN06)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(SKLGDUEK1803)supported by the State Key Laboratory for Geomechanics and Deep Underground Engineering,ChinaProject supported by the Mass Entrepreneurship and Innovation Project of Jiangsu,China。
文摘Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for achieving an excellent smooth blasting effect.In this paper,the Riedel-Hiermaier-Thoma(RHT)model was employed to study rock mass damage under smooth blasting.Firstly,the parameters of the RHT model were calibrated by using the existing SHPB experiment,which were then verified by the existing blasting experiment results.Secondly,the influence of different charge structures on the blasting effect was investigated using the RHT model.The simulation results indicated that eccentric charge blasting has an obvious pressure eccentricity effect.Finally,to improve the blasting effect,the smooth blasting parameters were optimized based on an eccentric charge structure.The overbreak and underbreak phenomena were effectively controlled,and a good blasting effect was achieved with the optimized blasting parameters.
基金Project(2022YFC2903901)supported by the National Key R&D Project of ChinaProjects(52274249,52334003)supported by the National Natural Science Foundation of China+1 种基金Project(2020-24)supported by the Key Science and Technology Project of Guangxi Transportation Industry,ChinaProject(2023ZZTS0516)supported by the Fundamental Research Funds for the Central Universities,China。
