The Influence Of Eccentric Uncoupled Charge Structure On The Dynamic Response And Damage Evolution Of Rock Mass

In recent years,blasting engineering has played an indispensable role in the development of construction related industries.It improves the work efficiency of related projects such as tunnels,mines,and slopes,but poses a significant threat to the safe excavation and personal safety of engineering blasting.In actual blasting engineering,due to the self weight of the charge,the relative position of the blast hole is not in a concentric coupling state.Therefore,the study of the impact of eccentric and uncoupled charging structures on the dynamic response of rock blasting and the distribution of rock damage evolution in blasting engineering has made its blasting state more consistent with actual working conditions,providing effective guarantees for safe excavation and personal safety in engineering blasting.The research results have certain guiding significance for practical engineering.Based on the finite element software ANSYS/LS-DYNA and post-processing software LSPREPOST,this paper establishes the eccentric uncoupled charge single-hole blasting model,and discusses the dynamic response of rock mass of HJC model and RHT model.The main contents are as follows:(1)From the macro and micro point of view,the damage factor of rock mass is defined,and the damage radius formula of rock mass with eccentric uncoupled charge structure under blasting load is deduced;Based on the blasting theory,the constitutive state equations of HJC model and RHT model are embedded in ANSYS/LS-DYNA,and solved according to the postprocessing software LS-PREPOST,and the differences between the two models are analyzed.(2)Based on the blasting theory and the finite element numerical simulation calculation,the rock mass blasting model of single hole eccentric uncoupled charge is established,and the corresponding calculation results are obtained;By analyzing the effective stress,pressure and damage nephogram under different eccentric coefficients,it is found that the damage evolution distribution of RHT model can better describe the actual engineering rock blasting process than that of HJC model;The damage radius,effective stress,velocity and pressure ratio of the coupling and uncoupling sides of the blasthole increase with the increase of the eccentricity coefficient.(3)The influence of uncoupling coefficient K on the blasting load of rock mass and the dynamic response of rock mass during blasting are investigated.It is found that the damage radius of the crushing zone is larger than that of the crack zone under the condition of different uncoupling coefficient K;Based on the evolution distribution of rock blasting damage,the variation of seismic wave energy under various working conditions is analyzed.It is found that the peak value of seismic wave energy increases with the increase of uncoupling coefficient K.From the perspective of energy conservation,the parameters of explosives and rock mass are consistent.The smaller the uncoupling coefficient K is,the larger the damage radius of the crushing area is,and the more blasting load energy is consumed,so the smaller the energy converted into seismic wave is.The research results are consistent with the law of conservation of energy.(4)The relationship between the blast center distance l and the damage degree D under different working conditions is explored,the functional relationship between them is established,and the fitting curve and fitting formula under each working condition are obtained by fitting them;Determine the safety threshold of rock mass particle peak vibration velocity vpp under various working conditions,establish the relationship between the safety threshold of vpp and the damage degree D under different uncoupling coefficient K,and fit the two to obtain the prediction formula of the safety threshold of particle peak vibration velocity vpp under different working conditions.(5)The numerical simulation of large section tunnel blasting with and without ground stress is carried out,and the dynamic response and damage evolution of rock mass near the tunnel blasting are studied.By analyzing the results,it is found that the ground stress has a certain inhibiting effect on the vibration speed of rock mass and the development of cracks.