Three-imensional Numerical Simulation Of Blasting Damage Of Joint Rock Mass

Joints are common in natural rock masses,which make rock masses exhibit discontinuities,heterogeneity,anisotropy and nonlinearity also make the blast damage of joint rock masses random and complex.Therefore,the study of the spatio-temporal evolution law of blasting damage of joint rock mass has guiding effect and reference significance for rock mass blasting.Based on the finite element numerical simulation method,combined with rock dynamics and stress wave propagation theory,and an ANSYS/LS-DYNA numerical simulation software,the evolution and distribution of blast damage of joint rock mass are systematically studied.The main research contents and conclusions are as follows:Firstly,the RHT model is selected for the numerical simulation test,and the principle and implementation method of fluid structure coupling algorithm are introduced;Then,the parameters of RHT model are selected,and the granite blasting model test results and numerical simulation results are compared to verify the rationality of RHT model and parameter selection.The failure modes of the two results are compared,and the peak stresses at different shot center distances are compared.The coincidence effect is good,It shows that the selected model and parameters can better describe the blasting behavior of rock mass;The fluid structure coupling range of the three-dimensional numerical model is discussed.Combined with the comparison of the stress peak curve,it is determined that the fluid structure coupling range is 10 times of the blast hole radius.Secondly,the three-dimensional numerical model of single hole blasting in jointed rock mass is established.The effects of joint position,joint inclination,joint properties and joint quantity on the damage evolution and distribution of rock mass are discussed.The damage nephogram,stress nephogram,damage radius and stress time history curve are compared.The results show that the barrier effect of joints on the propagation of explosion energy is obvious,and the damage of rock mass after joints is greatly reduced;The existence of joints in rock mass will also reduce the radius of crushing zone and fracture zone of rock mass after blasting,and the reduction range is also affected by the number of joints and filling medium;When the joint surface intersects with the blast hole,there will be strong and weak damage areas around the blast hole.Finally,in order to explore the influence of double hole blasting on the temporal and spatial evolution law of rock mass damage under each joint condition,a three-dimensional numerical model of double hole blasting in jointed rock mass is established.Combined with the change curve of rock mass damage variables between blast holes,it is concluded that the joint between blast holes will reduce the damage range of rock mass between blast holes,and a through fracture zone cannot be formed between two blast holes;When there is a short joint between blast holes,the damage of rock mass will develop towards the end of the joint;When the two parallel joint planes intersect with the blast hole,compared with the intersection of the single joint plane and the blast hole,the damage area of the whole rock mass expands,the radius of the crushing area around the blast hole increases,and the phenomenon of the strong and weak damage area around the blast hole is weaker than that of the single hole blasting;The cross joint between blast holes will weaken the transmission of stress wave,the damage degree of rock mass between cross joints is very low,and the damage range of rock mass around two blast holes is greatly reduced.