Numerical Simulation Of Rock Blasting Damage Evolution Based On HJC Constitutive Model

The evolution law of rock blasting damage and safety assessment of related projects have always been the focus of attention in the field of geotechnical engineering.Due to the high cost and poor controllability of blasting test,the numerical method can make up for the lack of real-time monitoring of all-round information of rock blasting process,so it has gradually become one of the important means of blasting theory research.At present,the fluid-solid coupling method is widely used and relatively mature in rock blasting simulation based on traditional finite element method,while new meshless methods such as Smoothed Particle Hydrodynamics?SPH?method are still in the preliminary stage of development.Herein,the determination of the coupling range in the rock blasting simulation by the fluid-solid coupling method and the simulation of rock blasting damage evolution based on the Holmquist-Johnson-Cook?HJC?constitutive model were studied orderly.In addition,the parameter determination of the Riedel-Hiermaier-Thoma?RHT?model developed from the HJC model and the application of SPH-FEM coupling method were studied.The main research contents and conclusions are as follows:Firstly,the fluid-solid coupling method was used to simulate the rock single-hole blasting,and the effects of the fluid-solid coupling range under different charge radius,uncoupling coefficient and mesh precision on the simulation results were explored.The convergence of peak stress attenuation curve,stress nephogram and stress-time history curve of rock element was analyzed.Considering the calculation cost,it is concluded that the reasonable value of the fluid-solid coupling range of general rock drilling blasting is 5-10 times of the charge radius.Then,based on the fluid-solid coupling method and HJC constitutive model,the blasting damage of rock and jointed rock mass was simulated.The results show that with the increase of decoupling coefficient of charge,the range of each damage zone decreases,and the reduction range of crushing zone is smaller than that of fracture zone.The distribution characteristics of rock blasting damage in the radial direction of borehole can be characterized by the Logistic function.The difference of rock lithology will significantly affect the range of crushing zone and the transition boundary between the crushing zone and fracture zone.The existence of joints will have a significant impact on the propagation of explosive wave in rock mass,and will produce unique damage evolution path and local damage enhancement and inhibition zones.Finally,the parameters determination of the RHT model and the application of SPH-FEM coupling method in rock blasting simulation were studied.Through the basic experiments and theoretical derivation,a set of parameters were determined,and the parameters were corrected with the parameter sensitivity analysis.The sensitive parameters were identified as ?₀,?_s,p_e,G,f_c,B,M and F_G.In addition,it is found that the SPH-FEM coupling method can vividly simulate the phenomena of rock blasting pitting and cracking,but there are still some shortcomings in the treatment of the interface coupling between SPH and FEM.