Damage is one of the most important characteristics of rock failure.Studying the damage mechanism of rock blasting under the guiding effect of the water jet slot and revealing the mechanism of controlled blasting with...Damage is one of the most important characteristics of rock failure.Studying the damage mechanism of rock blasting under the guiding effect of the water jet slot and revealing the mechanism of controlled blasting with water jet assistance are crucial.In this study,a rock-like material was chosen as the research object for the calibration experiment of the numerical model.The numerical simulation models were then established by ANSYS/LS-DYNA,and the blastinduced damage mechanism under the guiding effect of the water jet slot was analyzed according to the blasting theory.The results indicated that explosive energy accumulates toward the direction of the slot as the guiding effect of the water jet slot,which allows the rock mass in the direction of the slot bear more damage.Meanwhile,the rock mass in the middle of the connection line between two blast-holes bears more damage under the combination of the effect of the explosion stress wave and guiding effect of water the jet slot on the detonation gas during double-slotted borehole blasting,which results in the formation of a gourd-shaped blast-induced damage area.In addition,the influence of the water jet slot on blast-induced damage varies depending on the blasting-process stage.展开更多
Tunnel though coal seam is one of the most difficult tunnels since its risk of coal and gas outburst and the complex geological conditions.According to the directional cutting of water jet and the characteristic of th...Tunnel though coal seam is one of the most difficult tunnels since its risk of coal and gas outburst and the complex geological conditions.According to the directional cutting of water jet and the characteristic of the coal seam and rock mass,this paper presents a new method of tunnelling though coal seam assisted by water jet slotting,which can be divided into improving permeability of coal seam and directional cracking in the rock mass.The mechanism of improving permeability of coal seam was stated,and the crack criterion of rock during blasting was established based on fracture theory.Then,the evolution law of pressure wave and the crack propagation were simulated by FEM software ANSYS/LS-DYNA,the results show that the shape of the crush zone formed by stress wave is different between the normal borehole blasting and the slotted borehole blasting,and the tension is the main factor which let crack propagation.What is more,for normal borehole blasting,the tension concentration occurred along the direction of 45 degrees and let crack expand,while for slotted borehole blasting the tension concentration occurred along the direction of 0 degrees and 90 degrees,and the maximum tension along the direction of 0 degrees is larger than the maximum tension along the direction of 90 degrees,and the main crack expand along the direction of 0 degrees,which prove that the existence of the slot play a good role of orientation for directional cracking.展开更多
基金support for this work was provided by the Sichuan Natural Science Foundation Project(Youth Science Foundation Project)(No.2022NSFSC1089)the Natural Science Foundation of Southwest University of Science and Technology(No.18zx7124).
文摘Damage is one of the most important characteristics of rock failure.Studying the damage mechanism of rock blasting under the guiding effect of the water jet slot and revealing the mechanism of controlled blasting with water jet assistance are crucial.In this study,a rock-like material was chosen as the research object for the calibration experiment of the numerical model.The numerical simulation models were then established by ANSYS/LS-DYNA,and the blastinduced damage mechanism under the guiding effect of the water jet slot was analyzed according to the blasting theory.The results indicated that explosive energy accumulates toward the direction of the slot as the guiding effect of the water jet slot,which allows the rock mass in the direction of the slot bear more damage.Meanwhile,the rock mass in the middle of the connection line between two blast-holes bears more damage under the combination of the effect of the explosion stress wave and guiding effect of water the jet slot on the detonation gas during double-slotted borehole blasting,which results in the formation of a gourd-shaped blast-induced damage area.In addition,the influence of the water jet slot on blast-induced damage varies depending on the blasting-process stage.
基金Financial support for this work,provided by the National Basic Research of China(2014CB239203)the National Natural Science Foundation of China(51474158)+1 种基金also supported by Program for New Century Excellent Talents in University(NCET-12-0424)The authors would like to thank the State Key Laboratory of Coal Mine Disaster Dynamics and Control and Hubei Key Laboratory of Waterjet Theory&New Technology.
文摘Tunnel though coal seam is one of the most difficult tunnels since its risk of coal and gas outburst and the complex geological conditions.According to the directional cutting of water jet and the characteristic of the coal seam and rock mass,this paper presents a new method of tunnelling though coal seam assisted by water jet slotting,which can be divided into improving permeability of coal seam and directional cracking in the rock mass.The mechanism of improving permeability of coal seam was stated,and the crack criterion of rock during blasting was established based on fracture theory.Then,the evolution law of pressure wave and the crack propagation were simulated by FEM software ANSYS/LS-DYNA,the results show that the shape of the crush zone formed by stress wave is different between the normal borehole blasting and the slotted borehole blasting,and the tension is the main factor which let crack propagation.What is more,for normal borehole blasting,the tension concentration occurred along the direction of 45 degrees and let crack expand,while for slotted borehole blasting the tension concentration occurred along the direction of 0 degrees and 90 degrees,and the maximum tension along the direction of 0 degrees is larger than the maximum tension along the direction of 90 degrees,and the main crack expand along the direction of 0 degrees,which prove that the existence of the slot play a good role of orientation for directional cracking.