Numerical Simulation Of Influence Of Joint On Blasting Opening And Lumpiness Of Rock Mass

Rock blasting fragmentation directly affects the construction cost and progress of rock excavation engineering.Complex joint fissures of different scales are developed in natural rock mass,which will have a significant impact on the blasting cracking mode and blasting fragmentation distribution of rock mass.Therefore,it is of great significance to study the blasting cracking law and block distribution of jointed rock mass for improving the blasting crushing effect of rock mass and realizing green blasting.In this paper,the propagation characteristics of explosion stress wave in jointed rock mass and the influence of joints on blasting cracking of rock mass are studied by means of theoretical analysis and numerical simulation.The effects of joint geometric parameters and physical and mechanical parameters on explosion stress wave propagation and rock blasting cracking are analyzed.Aiming at the multi-hole blasting of jointed rock mass,the influence of joint geometric parameters,physical and mechanical parameters and charge structure on the distribution of blasting rock fragmentation is analyzed.The main research results are as follows :(1)Based on the theoretical analysis of the propagation characteristics of stress wave in jointed rock mass,the influence mechanism of joint on the propagation of explosion stress wave is studied by using ANSYS / LS-DYNA numerical simulation of single hole blasting in jointed rock mass.The results show that joints play a role in blocking and reflecting the propagation of explosion stress wave.With the increase of joint spacing,the barrier effect of joints on explosion stress wave is enhanced,and the reflection effect of joints on explosion stress wave increases first and then decreases.The stress at the joint end is mainly concentrated on its lower side,and the tensile stress at the lower side of the joint end decreases first and then increases.In addition,the width,number of layers and density of joints also affect their barrier and reflection effects.(2)ANSYS / LS-DYNA was used to simulate the single-hole blasting process of jointed rock mass,and Image J was used to count the area of rock mass blasting cracking area,and the influence of joints on rock mass blasting cracking was studied.The results show that with the increase of the distance between the joint and the blast hole,the crack area between the joint and the blast hole increases,the crack propagation range at both ends of the joint decreases,and the crack at both ends of the joint cracks.