Study On The Rock Breaking Characteristics Of Combined Borehole Induces Unloading And Cutting Pick

With the coal resource exploitation of the growing problems of deep mining has become increasingly prominent and high stress is restricted in deep roadway driving,resulting in high energy consumption of the main factors of cutting.Drilling and unloading induced by deep mining is an effective means to reduce the high stress,decreasing cutting energy consumption and prolong the service life of the cutting teeth.This paper is based on the analysis of deep hard rock unloading characteristics,determines the influence of high ground stress of rock mass;and researches crushing characteristics of single tooth and multi picks cutting deep hard rock after unloading,in drilling induced unloading foundation.This paper plays an important role in the deep hard rock tunneling theory.In this paper,granite as the research object,using Drucker-Prager rock constitutive model,using Explicit module in ABAQUS establishes the unloading rock mass model.It established the different stress(40MPa,45MPa,50MPa,55MPa,60MPa)rock mass model of the unloading,analysis unloading characteristics of different depth(50cm,80cm,120cm,150cm)and different hole diameters(30mm,50mm,80mm、100mm)when single hole drilling is unloaded,unloading different borehole layout(triangle,quadrilateral,hexagonal)and different hole spacing(100mm,150mm,200mm,250mm)when multiholes are unloaded.The results show that the unloading effect is more obvious when the stress is 50MPa,after drilling formation stress concentration zone is maximum,and rock unloading effect is the best when the hole diameter is 80mm the depth of the hole is 120cm,drilling arrangement is quadrangle,the hole spacing is 100mm.In this paper,under the optimal drilling parameters unloading condition of 50MPa stress researches optimal single tooth cutting angle,the optimal cutting speed,the optimal cutting depth of single pick and the tooth spacing of picks based on the analysis of the three direction stress curve and the characteristic value of the three direction stress.Simulation analyses section tooth cutting rules of single tooth with different cutting angle(30°,45°and 60°),different cutting speed(2m/s,2.5m/s,3m/s,3.5m/s),different cutting depth(60mm,65mm,70mm,75mm)of single tooth,and different cutting tooth spacing(70mm,75mm,80mm,85mm)of picks.The results show that when the optimal single tooth cutting angle is 60°,the optimal cutting speed is 2m/s,the optimal cutting depth of 70mm,cutting resistance characteristic value is minimum.When the cutting tooth spacing is 75mm,cutting resistance value is minimum.Compared with the unloaded hard rock cutting stress,the cutting resistance is greatly reduced,and the deep rock can be effectively reduced the three direction stress.An effective method to realize the high efficiency excavation of deep hard rock is based on the combination of drilling induced unloading and cutting.The application of this method has a high reference value and promotion value in the field of coal rock mining,other metal mining and tunnel excavation.