Research On Failure Behavior Of Concrete/reinforced Concrete Subjected To The Penetration Loading

The concrete and reinforced concrete structure which have important strategic value have been reinforced with the development of modern defense system.Besides,the concrete and reinforced concrete structures are also become increasingly thicker and have been transferred from the ground to the underground or inside the mountain.When the concrete and reinforced concrete structures are attacked,the effectively destruction or damage and increasing the protective characteristics of these structures with important strategic value are the hot topic in scholars at home and abroad.Therefore,the research on the penetration problems of concrete and reinforced concrete targets has great significance in military,scientific research,and engineering application.The numerical algorithm of penetration of concrete and reinforced concrete,the failure behavior of concrete and reinforced concrete subjected to the shaped charge and projectile penetration loadings,and the penetration mechanism of rigid projectile normal and oblique perforation of concrete and reinforced concrete target are studied systematically by combining theoretical analysis,numerical simulation and experimental research.The main studies of the thesis are described as follows:(1)A coupled three-dimensional Euler and PIC(particle in cell)algorithm is proposed to solve the numerical analysis problem,that the Euler method cannot track the deformation process of rebar during the penetration process of reinforced concrete.The algorithm adopts particle with a certain volume and influence domain to simulate real material flow.The bidirectional mapping of physical quantities are achieved by the influence domain-weighted average based on the topological relationship between cells and particles.For the complexity of parallel algorithm of hydrocode,the solution of data dependence and the realization of the parallel algorithm are presented.Based on the idea of software engineering,the parallel hydrocode is designed using MPI(Message Passing Interface).Comparisons of numerical results and experimental results of typical explosion and impact problems show that the coupled algorithm combines the advantages of both Lagrange and Euler method and can efficiently calculate the process of large deformation and dynamic damage of the material.The results of the calculation and analysis can provide useful reference for further research on explosion and impact problems.(2)The simulation optimization of shaped-charge structures and the numerical simulation of penetration performance of the shaped-charge penetrating the concrete/reinforced concrete were carried out.Based on the simulation results,the deformation process and the effect of rebar on the anti-penetration process of the reinforced concrete are analyzed.Then,a new charging structure with good penetration performance is designed.The large-size concrete target penetration experiment was carried out,which showed a greater size effect on the concrete target with using larger diameter shaped-charge.Then,the compressive strength tests of the large-size test concrete samples at different parts were carried out.Based on the test results,a dynamic constitutive model considering the damage factor was proposed and added into the developed parallel hydrocode to simulate the damage of concrete target.The size effect of concrete target and the effectiveness of numerical simulation technique are verified by comparing the results of numerical simulation and that of the experiments.(3)The numerical simulations of projectiles penetration of concrete and reinforced concrete targets were carried out,and the influence of initial penetration velocity and the performance parameters of the concrete on the penetration process were obtained.Besides,the experiments of projectiles penetration of the thick concrete and reinforced concrete target were also conducted and verified the effectiveness of the developed algorithm.The developed parallel hydrocode is adopted to simulate the projectile penetration of the infinite thick concrete target,and the relationship between the target speed and penetration depth is obtained.The solving ability of the developed parallel hydrocode is verified by comparing with the experimental results.Furthermore,in order to explore the deformation of rebar during penetration process,the numerical simulation of designed projectile about penetration of the reinforced concrete is carried out.Then,the influences of the impact velocity,concrete compressive strength,and concrete thickness on penetration progress are analyzed.On this basis,the experiments of projectiles penetration of the thick concrete/reinforced concrete were performed,and the damage of concrete and reinforced concrete under different impact velocities was obtained,which are compared with the numerical simulation results to verify the effectiveness of the proposed algorithm.(4)An analytical model of rigid projectile normal and oblique perforation of the concrete and reinforced concrete target is constructed based on energy method,which can predict the residual velocity,ballistic limit and the thickness of the shear plugging after the perforation.However,the current engineering models of perforation can predict the residual velocity and ballistic limit velocity after the perforation.Few analytical models are used to predict the damage area and the depth of the crater on the target back.The energy consumptions of initial cratering and penetration reaming are obtained on the basis of the dynamic cavity expansion theory.For the energy consumption of shear plugging formation,a new method is proposed considering the reinforcement ratio and the tensile strength of reinforcing bars.Based on energy conservation and the principle of minimum potential energy,the explicit equations of residual thickness,ballistic limit and residual velocity are formulated,and then a theoretical analysis model of rigid projectile normal and oblique perforation of concrete and reinforced concrete target is proposed.Moreover,the effects of impact velocity,concrete compressive strength and reinforcement ratio on perforation performance are discussed.