This study investigates the factors affecting the rock-breaking efficiency of the TBM disc cutter in deep rock excavation,including confining pressure,penetration,cutter spacing,and revolution speed.The finite element...This study investigates the factors affecting the rock-breaking efficiency of the TBM disc cutter in deep rock excavation,including confining pressure,penetration,cutter spacing,and revolution speed.The finite element method is employed to formulate a rock-breaking model of the rotary disc cutters and a numerical simulation is also implemented.The rock breaking effect,rock breaking volume,and rock breaking specific energy consumption under different combinations of the factors are investigated.An orthogonal test of four factors at four levels was constructed.Based on the test results and range analysis in the process of deep rock mass breaking,the order of sensitivity of each influencing factor with respect to the rock breaking specific energy for the disc cutter is cutter spacing>revolution speed>penetration>confining pressure.By constructing a numerical simulation comparison scheme,the orthogonal test results are analyzed and corroborated,and the rock breaking law and rock breaking efficiency under different influencing factors are derived.Finally,the sensitivity of different influencing factors on the rock-breaking efficiency is verified.展开更多
The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard formations.Percussive drilling is the most potential approach to increase rock-breaking e...The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard formations.Percussive drilling is the most potential approach to increase rock-breaking efficiency and ROP.However,the rock-breaking mechanism of percussive drilling is still unclear enough,especially the micro-fracture mechanism of rock under confining pressure(under lateral pressure and hydraulic pressure).In this paper,the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact(PDC)cutters are carried out using a drop-weight impact testing machine and an acoustic emission(AE)recording system,the influence of parameters such as cutter shape,rake angle,and impact energy on rock-breaking are systematically analyzed.This study includes a numerical simulation to examine the process of crack initiation,propagation,and cuttings formation during the impact process with the consideration of confining pressure.The results show the conicalshaped cutter is the most aggressive with high breaking efficiency.The penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the cutter.There exists critical impact energy makes the rock breaking efficiency the highest.The critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°.The rock mainly failed in tensile mode,and the inter-grain crack is the main crack.Hydraulic pressure can inhibit the formation of horizontal cracks,while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile cracks.The research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.展开更多
基金Project(51979156)supported by the National Natural Science Foundation of ChinaProject(tsqn202103087)supported by the Young Taishan Scholars,ChinaProject(2019KJG015)supported by the Youth Innovation Technology Project of Higher School in Shandong Province,China。
文摘This study investigates the factors affecting the rock-breaking efficiency of the TBM disc cutter in deep rock excavation,including confining pressure,penetration,cutter spacing,and revolution speed.The finite element method is employed to formulate a rock-breaking model of the rotary disc cutters and a numerical simulation is also implemented.The rock breaking effect,rock breaking volume,and rock breaking specific energy consumption under different combinations of the factors are investigated.An orthogonal test of four factors at four levels was constructed.Based on the test results and range analysis in the process of deep rock mass breaking,the order of sensitivity of each influencing factor with respect to the rock breaking specific energy for the disc cutter is cutter spacing>revolution speed>penetration>confining pressure.By constructing a numerical simulation comparison scheme,the orthogonal test results are analyzed and corroborated,and the rock breaking law and rock breaking efficiency under different influencing factors are derived.Finally,the sensitivity of different influencing factors on the rock-breaking efficiency is verified.
基金supported by the National Natural Science Foundation of China(Grant No.52034006,No.52004229,No.52225401,No.52274231)Regional Innovation Cooperation Project of Sichuan Province(2022YFQ0059)+2 种基金Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(2020CX040301)Natural Science Foundation of Sichuan Province(23NSFSC 2099)Science and Technology Strategic Cooperation Project between Nanchong City and Southwest Petroleum University(SXHZ004).
文摘The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard formations.Percussive drilling is the most potential approach to increase rock-breaking efficiency and ROP.However,the rock-breaking mechanism of percussive drilling is still unclear enough,especially the micro-fracture mechanism of rock under confining pressure(under lateral pressure and hydraulic pressure).In this paper,the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact(PDC)cutters are carried out using a drop-weight impact testing machine and an acoustic emission(AE)recording system,the influence of parameters such as cutter shape,rake angle,and impact energy on rock-breaking are systematically analyzed.This study includes a numerical simulation to examine the process of crack initiation,propagation,and cuttings formation during the impact process with the consideration of confining pressure.The results show the conicalshaped cutter is the most aggressive with high breaking efficiency.The penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the cutter.There exists critical impact energy makes the rock breaking efficiency the highest.The critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°.The rock mainly failed in tensile mode,and the inter-grain crack is the main crack.Hydraulic pressure can inhibit the formation of horizontal cracks,while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile cracks.The research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.
