To study the rock breaking method under the free surface induced by disc cutter,the rock breaking simulations were first conducted based on the discrete element method,and the dynamic process of rock breaking under th...To study the rock breaking method under the free surface induced by disc cutter,the rock breaking simulations were first conducted based on the discrete element method,and the dynamic process of rock breaking under the free surface was studied including stressed zone,crush zone,crack initiation and propagation.Then the crack propagation conditions,specific energy,etc.under different free surface distance(S)were also investigated combined with linear cutting experiments.The results show that the rock breaking process under the free surface induced by disc cutter is dominated by tension failure mode.There exists a critical S to promote crack propagation to free surface effectively.And this rock breaking method can improve the rock breaking force and breaking efficiency significantly when proper.展开更多
The tunnel boring machine(TBM)is typically used in hard-rock tunnel excavation.Owing to the unsatisfactory adaptability of TBM to the surrounding rock,when crossing high-strength and high-wear strata,the TBM can easil...The tunnel boring machine(TBM)is typically used in hard-rock tunnel excavation.Owing to the unsatisfactory adaptability of TBM to the surrounding rock,when crossing high-strength and high-wear strata,the TBM can easily cause defects,such as abnormal wear on cutters and overload damage to bearings,thus affecting the construction efficiency and cost.Therefore,high-pressure waterjet technology should be applied to assist in rock breaking for efficient TBM tunneling.In this study,the effects of water pressure,nozzle diameter,and nozzle speed on cutting are investigated via laboratory experiments of cutting hard rock using high-pressure waterjets.The penetration performance of the TBM under different water pressures is investigated via a field industrial penetration test.The results show that high-pressure waterjets are highly efficient for rock breaking and are suitable for industrial applications,as they can accommodate the advancing speed of the TBM and achieve high-efficiency rock breaking.However,during the operation of high-pressure waterjets,the ambient temperature and waterjet temperature in the tunnel increase significantly,which weakens the cooling effect of the cutterhead and decreases the construction efficiency of the TBM.Therefore,temperature control and cooling measures for high-pressure waterjets during their long-term operation must be identified.This study provides a useful reference for the design and construction of high-pressure water-jet-assisted cutterheads for breaking road headers.展开更多
基金Project(2013CB035401)supported by the National Basic Research Program of ChinaProject(2012AA041803)supported by the National High-Technology Research and Development Program of China+2 种基金Project(51475478)supported by the National Natural Science Foundation of ChinaProject(2015GK1029)supported by the Science and Technology Project of Strategic Emerging Industry in Hunan Province,ChinaProject(CX2017B048)supported by the Hunan Provincial Innovation Foundation For Postgraduate,China
文摘To study the rock breaking method under the free surface induced by disc cutter,the rock breaking simulations were first conducted based on the discrete element method,and the dynamic process of rock breaking under the free surface was studied including stressed zone,crush zone,crack initiation and propagation.Then the crack propagation conditions,specific energy,etc.under different free surface distance(S)were also investigated combined with linear cutting experiments.The results show that the rock breaking process under the free surface induced by disc cutter is dominated by tension failure mode.There exists a critical S to promote crack propagation to free surface effectively.And this rock breaking method can improve the rock breaking force and breaking efficiency significantly when proper.
基金the National Natural Science Foundation of China (52204108)the Fundamental Research Funds for the Central Universities (300102251201).
文摘The tunnel boring machine(TBM)is typically used in hard-rock tunnel excavation.Owing to the unsatisfactory adaptability of TBM to the surrounding rock,when crossing high-strength and high-wear strata,the TBM can easily cause defects,such as abnormal wear on cutters and overload damage to bearings,thus affecting the construction efficiency and cost.Therefore,high-pressure waterjet technology should be applied to assist in rock breaking for efficient TBM tunneling.In this study,the effects of water pressure,nozzle diameter,and nozzle speed on cutting are investigated via laboratory experiments of cutting hard rock using high-pressure waterjets.The penetration performance of the TBM under different water pressures is investigated via a field industrial penetration test.The results show that high-pressure waterjets are highly efficient for rock breaking and are suitable for industrial applications,as they can accommodate the advancing speed of the TBM and achieve high-efficiency rock breaking.However,during the operation of high-pressure waterjets,the ambient temperature and waterjet temperature in the tunnel increase significantly,which weakens the cooling effect of the cutterhead and decreases the construction efficiency of the TBM.Therefore,temperature control and cooling measures for high-pressure waterjets during their long-term operation must be identified.This study provides a useful reference for the design and construction of high-pressure water-jet-assisted cutterheads for breaking road headers.
