Research On Dynamic Response And Blasting Characteristics Of Deep Rock Mass Blasting

In recent years,with the rapid development of underground tunnel construction,underground chamber excavation,deep mineral resources mining and other rock projects,deep rock blasting and excavation projects have increased dramatically.The deep rock masses are mostly in high in-situ stress environment,and the blasting excavation is subject to the joint action of in-situ stress and blasting load,which makes the blasting environment complex.Therefore,the research on blasting dynamic response and blasting characteristics of deep rock masses has important theoretical and practical engineering significance for rock blasting.This paper uses the finite element software ANSYS/LS-DYNA and the post-processing software LS-PREPOST to establish a single-hole blasting model of deep rock masses and conduct numerical simulation research on the blasting process of rock masses under different in-situ stress conditions;and different modeling methods and damage models are used to establish rock blasting models to explore the application of numerical simulation respectively.The main research contents are as follows.(1)Integrate a variety of theories to explore the mechanism of the action of the blasting load on the rock mass,the formula for calculating the radius of the fractured zone of the deep blasting rock mass is determined,and the rock mass damage factor is defined from the macroscopic and mesoscopic perspectives.(2)Using finite element software,the single-hole blasting damage model of the rock under different in-situ stress conditions is established.The effective stress,pressure and damage clouds of the rock under different working conditions are analyzed,and it is found that the in-situ stress has a suppressive effect on the size of the effective stress and pressure action area.The radius of crushing zone of rock mass is also related to the in-situ stress.In this paper,the radius of rock mass crushing zone is 7～8 times of charge radius and the radius of fracture zone is 40～50 times of charge radius under the condition of no in-situ stress;when there is influence of in-situ stress,the lateral pressure coefficient is certain and the radius of rock mass damage zone decreases with the increase of horizontal in-situ stress.(3)Based on the numerical calculation results of the rock mass under different working conditions,the time-history curve of the effective stress,pressure,velocity and main crack tip velocity of the rock mass is analyzed.The fluctuation trend of the physical properties of the rock mass is particularly violent;in addition,by calculating the seismic wave energy of the rock mass under different working conditions,it is found that the lateral pressure coefficient remains unchanged,and the seismic wa ve energy decreases with the increase of the horizontal in-situ stress.(4)The relationship between damage degree D,blasting center distance l and peak particle velocity PPV is investigated respectively,and the D-l functional relationship and PPV-l functional relationship are established,as well as the safety criterion PPV threshold for rock vibration under different working conditions is determined,the magnitude of which would be inhibited by the in-situ stress.(5)Four rock blasting damage models are established by using the SPH-FEM coupling method,the FEM method,the RHT model and the HJC model through the control variable method.Comparing the calculated results of the model with the measured values of the test data,it is found that the error of the dat a obtained by the SPH-FEM coupling method is the smallest,and the RHT model can better comprehensively reflect the mechanical properties of the rock mass.