Investigation On The Mechanisms And Engineering Modeling Of Confined Concrete Against Penetration

Concrete is a widely used building material in both military and civil engineering fields,and its performance and mechanism against penetration are of great significance.Confined concrete has an advantage over the concrete without confinement in resisting penetration.In order to make up the shortage of present research on confined concrete,this paper studies its anti-penetration problem using a combination of theoretical analysis and numerical simulation method.This paper can provide theoretical support for the design of protective structure such as shielding layer and protective wall;therefore,it has great academic value and military application.The main work can be summarized as follows:1.An engineering model for predicting the penetration depth of semi-infinite concrete target is developed.This paper builds a new quasi-static finite cavity expansion model by assuming that the materials in the comminuted region obey the Hoek-Brown yield criterion,which can better describe the feature of concrete than the Mohr-Coulomb and the Griffith yield criterion.Based on this model,a penetration depth predicting model for infinite concrete target is developed.The comparison results with common penetration depth predicting formulas shows that the predicting model in this paper can be used in most penetration cases.2.New cylindrical and spherical cavity expansion models for confined concrete are obtained.The paper gives the analytical calculation formulas of the cavity stress in models with different response regions,and then discusses the cavity expansion process and some influence factors.The results shows that the lower the concrete strength,the stronger the confinement effect.3.The mechanism of confined concrete against long rod projectile is studied.This paper carries out numerical simulation of a rigid long rod projectile penetrating concrete target using ANSYS/LS-DYNA.By changing the projectile velocity and the dimensions of targets,the anti-penetration mechanism of confined concrete target is analyzed.The simulation results show that increasing the confinement of target can decrease its penetration depth,and this decrease has a limit which is related to steel tube wall thickness and the target size.Also,in second stage of penetration,the penetration resistance trends to be a constant.4.Engineering models for predicting the penetration depth of confined concrete against hard core bullet and long rod projectile are built.The calculation results show that these engineering models are reasonable and feasible.