Dynamic Damage Evolution And Fracture Simulation Of Macro Porous Rock Based On Peridynamic Theory

Under explosive loading,the transmission law of stress wave,energy accumulation and release mechanism,dynamic damage evolution mechanism have always been hot issues in rock mass engineering.In this paper,the dynamic damage evolution and crack propagation of macro porous rock mass are main study line.Using Monte Carlo method to randomly cast the pores and generate the macro pore model.Combined with the peridynamic theory and self-compiled numerical calculation program,the dynamic damage evolution and crack propagation of macro porous rock mass are studied by combining theoretical analysis,experiment and numerical simulation.The following work has been accomplished.Firstly,uniaxial compression test and numerical simulation were carried out on the porous specimen,it is clear that the porosity has a significant effect on the mechanical properties of macro porous rock materials.With the increase of porosity,the density,compressive strength,elastic modulus and longitudinal wave velocity of the sample decrease.Besides,the size of pore size has a significant impact on the mechanical properties of rock mass.In order to explore the regular pattern of crack germination and propagation of macro porous rock under dynamic loading,the damage distribution of macro porous rock under explosion load is calculated by self-compiled numerical calculation program.Secondly,investigating the dynamic damage and crack propagation of porous rock mass under borehole blasting,both PD numerical simulation and experiment show that:the reasonable pore size and porosity ensure the strength of the medium and help to consume the explosion energy and the number and length of main fractures.Finally,in geotechnical blasting engineering,obtaining a smooth excavation surface and maintain the stability of the excavated rock mass,it is necessary to control the generation and propagation direction of blasting crack.Based on the PD theory numerical simulation and related experiments,the effects of porous blasting,prefabricated crack inclination,macro pores and other factors on crack initiation angle and crack propagation length are analyzed.The results show that:in single hole blasting,when the incidence angle is less than 75 °,the angle of initiation of wing crack derived from crack tip increases with the increase of incidence angle.In the double hole blasting,when the angle of the prefabricated crack is less than 90 °,with the increase of the prefabricated crack angle,the main crack propagates to the prefabricated crack and tends to be parallel to the connecting line of the two holes,and the smooth pulley profile can be obtained.When porosity and pre cast fracture act on crack growth,porosity plays a important role in crack growth.