Experimental Study On Response Characteristics Of Drilling Coal And Rock

In recent years,the mining depth of coal mine is gradually increasing,and the occurrence of rock burst disaster is more and more frequent.Because the occurrence of rock burst is sudden and violent,when the rock burst occurs,the underground workers and mining equipment are not withdrawn in time,which will lead to serious casualties and serious damage of coal mining machinery,The occurrence of rock burst in coal mine has greatly threatened the underground workers and mining equipment.Therefore,it is particularly important to effectively predict the local rock burst disaster.According to the principle of "see the big from the small",the small diameter coal drill pipe is used to drill into the coal seam,and the drilling is equivalent to the reduced size of the roadway.The drill pipe is affected by the coal stress in the drilling process,which is similar to the stress state of the underground coal mining equipment when mining in the working face.Then the stress distribution state of the underground coal body is deduced by the response value of the drilling parameters.In this paper,the mechanical model,drill pipe energy model and drill pipe vibration model of drill pipe drilling are established,and the relationship between propulsive force,torque,rotational speed,energy,vibration displacement and coal stress of drill pipe is obtained.The response parameters of drill hole in the process of drilling coal and rock are collected by using the drilling multi parameter acquisition system made by the research group,and the drilling energy of drill pipe is calculated.The transverse,longitudinal and torsional vibration models of the drill pipe are established.The modal analysis of the drill pipe is carried out by using the finite element analysis software.The results show that the larger the drill pipe diameter is,the lower the natural frequency of the drill pipe is;The longer the length of the drill pipe,the lower the natural frequency of the drill pipe.The critical speed of the drill pipe is calculated to provide a reference for the selection of the drill speed.The results show that the propulsive force and torque of drill pipe are positively correlated with the coal stress,and the rotation speed of drill pipe is negatively correlated with the coal stress.By analyzing the energy conversion relationship during coal and rock breaking,it is found that the energy required for coal and rock breaking is related to the stress state of coal body,and the drill pipe energy during drilling is calculated,and the vibration displacement of drill pipe changes regularly with the increase of hole depth.Through the variation of the above parameters with the hole depth,the change of the coal stress in front of the underground working face is determined,and the position of the peak stress concentration point is determined,which provides a reference for the prediction of local rock burst in coal seam.Through the drilling cuttings method,the validity of the variation law of each response parameter of the borehole is verified,and the feasibility of predicting the local rock burst underground is verified.This thesis has 41 figures,19 tables and 67 references.