| The depth of mining is increasing in China,,with the shallow mineral resources facing depletion,deep mineral resources mining has become the norm,the future will be deeper rock formation mining.The main way of deep mining is drilling and explosion,where there is initial ground stress around the deep rock body,and the explosive stress wave will be coupled with it to the rock body.Due to the complex geological effect,according to the results of geostress measurement at home and abroad,horizontal stress is usually 0.5 to 5.5 times vertical stress,most of it is 0.8 to 1.2 times,the maximum value can reach 30 times or even greater,different side pressure has a significant impact on the blasting rock breaking process.In view of the rock breaking process under different side pressure,this paper uses the finite element software ANSYS/LS-DYNA to carry out a numerical simulation of the five-hole blasting rock breaking process under the different side pressure coefficients,and the simulation selects the vertical stress for 20 MPa to simulate the underground depth of 800 m and the 40 MPa model to be underground at 1600 m depth.The side pressure coefficient of 1,0.3,2 and 4 side pressure is selected to analyze the blasting rock breaking process,and the situation where the side pressure coefficient is 4 times affected by ground stress is great,the optimization effect law is simulated by changing the diameter of the gun hole,the spacing of the hole,the hole hole and the delayed blasting of milliseconds.The main work of the thesis is as follows:(1)The destructive effect of the coupling field of explosion stress and initial ground stress on the rock body around the gun hole is analyzed theoretically,the distribution characteristics of the initial ground stress are discussed,the theory of loose ring of the gun hole is introduced,and the initial stress state around the hole is analyzed under ground stress.The theoretical analysis of the cases in which the side pressure coefficient is equal to 1 and the side pressure coefficient is not equal to 1 respectively.(2)A brief description of the numerical simulation of explosives,air material modeland and its state equation,air and gun mud material model,the use of RHT material structure,the introduction of implicit-display simulation of ground stress solution,and the construction of simple models and experiments.(3)The side pressure coefficient of vertical stress of 20 MPa and 40 MPa was simulated in the case of 1,0.3,2 and 4 blasting rock,and the influence of the initial stress state around the gun hole on the evolution of rock damage,the penetration of rock damage,Stress wave propagation and selection units analyze the law of stress change in different directions.The results show that the initial ground stress is inhibited to the blasting rock,the attenuation speed of the stress wave accelerates with the increase of ground stress,and the influence of the initial stress state around the gun hole on the blasting rock increases more and more obvious with the increase of horizontal and vertical ground stress,and the larger ground stress affects the evolution of normal direction damage.The greater the ground stress,the stronger the normal direction damage inhibition,the more concentrated the damage development,the smaller the damage on the ground stress,the degree of depth,the random development of the outside of the gun hole damage,with the increase of ground stress inclination direction damage is also closer to the direction of the ground stress normal.(4)After analyzing the diameter of different gun holes,the spacing of the gun holes,the empty holes and the delayed blasting of milliseconds,it is found that the four methods will have different characteristics of the optimization effect of the blasting effect,with the increase of ground stress and the increase of the gap between the side pressure size,the inhibition effect of ground stress on rock damage gradually increased,and the optimization effect gradually weakened. |
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