Numerical Simulation Research Of Rock Blasting Under Different Confining Pressure

Due to the shrinking of the resources of the shallow stratum and engineering demond,resources exploitation have to deep into the underground.Deep rock mass are often in high initial geostress,rock crack under the joint action of explosion load and confining pressure,which is very complex.The theory of shallow rock mass cannot used to this process.Therefore,rock blasting process in confining pressure is necessary to be analyzed.Under the condition of confining pressure,the dynamic response of the rock under explosion impact load is simulated:(1)The process of rock blasting are analyzed theoretically.In combination with rock blasting process,explosion load and the initial stress superposition is study.(2)ANSYS/LSDYNA is used to simulate the center hole block of confining pressure loading.In two-dimensional case,the influence of grid density on prestress is researched,the result shows that the nonlinear relationship between grid density and the calculation accuracy.In the calculation model of this paper,when the grid size is two-thirds mm,calculation results of prestress has minimum error compared with the analytical solution and relatively sparse or dense grid would decrease the calculation accuracy.(3)The implicit-explicit method and ANSYS/LSDYNA dynamic relaxation method is used to simulate confining pressure load,so as to study the simulation of different loading methods.The results show that the dynamic relaxation method is more convenient and the results and the theoretical solution is closer.(4)ANSYS/LSDYNA is used to simulate the blasting process of center hole under the condition of confining pressure.One-way confining pressure,the equivalent two-way confining pressure,the equivalent numerical simulation are simulated respectively under confining pressure.The results show that the confining pressure of explosion stress wave propagation have little impact,and confining pressure of blast crack and the influence of confining pressure around the hole.There was a significant association formed the stress concentration area.Confining pressure suppresses blast crack extension,the confining pressure of Y direction obviously inhibit the crack propagation of X direction.and closer between the confining pressure and explosion load,the more obvious effects on explosion crack.(5)Through the establishment of experimental platform,not equivalent bidirectional confining pressure of rock blasting model experiment,using high speed camera,analysis of rock surface strain contours.The strain concentration area as a numerical simulation of crack formation in the area,through the comparative analysis further proved the accuracy of the numerical calculation.