Simulaton Study Of Blasting Failure Process Of Jointed Rock Mass With PFC Code

At present,blasting is a very common method in rock mass excavation engineering.According to the characteristics of rock mass excavated by blasting,study on the rock mass blasting effect can improve not only the efficiency of blasting engineering,but also the safety and stability.Based on Particle Flow Code(PFC)2D,the simulation and analysis of rock blasting process and millisecond blasting are carried out in this disseratation.The following research contents are carried out from four aspects.1.The fundamental principle of the PFC theory is introduced in detail.By the uniaxial compression test,the influence of the mesoscopic parameters of the particle on the macroscopic mechanical properties of the model is obtained,which provides a reference for the calibration of the mesoscopic parameters.2.A numerical model of rock mass is built by PFC2 D.Blasting action is simulated by blasting point in the hole wall.The introduction of the establishment method of the PFC numerical model divided into five parts,including the formation of the particle aggregation,the setting of joints,the calibration of the model parameters,the application of the nonreflective boundary and the setting of the damping parameters.3.Through the treatment of blasting load,mesoscopic parameters,boundary condition and damping form of numerical model,a numerical calculation model capable of simulating blasting can be obtained in PFC2 D,and the feasibility of simulating rock mass blasting by PFC2 D is verified.A numerical model of intact rock mass is established.The results show that the blasting process has undergone three processes: surface uplift,crack propagation and rock mass throwing,which verify the feasibility of PFC2 D simulation of rock mass blasting.4.With PFC2 D,the models of the intact and jointed rock mass are built respedtively,and the blasting load is applied to study the blasting damage characteristics of the jointed rock mass.Through the analysis of the blasting process of the intact rock mass and the jointed rock mass,it is concluded that the joints will affect the crack propagation during the rock mass blasting,and the key joints have a decisive influence on the effect of the rock mass blasting.The results show that the preset joints will be penetrated preferentially and continue to expand along the joints.The larger the joint spacing is,the more obvious the working condition is;the smaller the length of joints,the smaller the impact on the blasting effect.