冲击下混凝土试样应变率效应和惯性效应探讨  

On strain-rate and inertia effects of concrete samples under impact

作　　者：袁良柱 苗春贺 单俊芳[1] 王鹏飞[1] 徐松林[1,2] YUAN Liangzhu;MIAO Chunhe;SHAN Junfang;WANG Pengfei;XU Songlin(CAS Key Laboratory for Mechanical Behavior and Design of Materials,University of Science and Technology of China,Hefei 230027,Anhui,China;United Laboratory of High-Pressure Physics and Earthquake Science,Institute of Earthquake Science,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国科学技术大学中国科学院材料力学行为和设计重点实验室,安徽合肥230027 [2]中国地震局地震预测研究所高压物理与地震科技联合实验室,北京100036

出　　处：《爆炸与冲击》2022年第1期15-27,共13页Explosion and Shock Waves

基　　金：国家自然科学基金(11672286,11872361);中央高校基本科研业务费专项(WK2480000008);中石油与中科院重大战略合作项目(2015A-4812);高压物理与地震科技联合实验室开放基金(2019HPPES01)。

摘　　要：结合混凝土试件的真三轴静载冲击实验结果,分别运用考虑应变率效应的Holmquist-Johnson-Cook(HJC)模型和考虑静水压效应的Drucker-Prager(DP)模型进行数值分析,以探讨研究混凝土试样应变率效应和惯性效应的方法。在探究混凝土的应变率效应和横向惯性效应的关系时,使用HJC模型的数值模拟结果来拟合DP准则的各个参数。结果表明:随着应变率的升高,混凝土的强度会提高,并且这种强度的提高,也有一部分原因是第一应力不变量I_(1)的增大所导致的。因此,混凝土试件的应变率效应和横向惯性约束具有较强的耦合作用。理论和数值分析了冲击下试样内部的横向应力分布特征与应变率、静水压和试样尺寸的关系,结果发现:试样内部横向应力的幅值随着应变率、静水压的升高而增大,但随着试样尺寸的增大而减小。为了探讨横向惯性带来的强度提升效果,提出了一个有关冲击方向最大应力σ_(x)和等效应力σ_(e)的参数ξ,且ξ=(σ_(x)−σ_(e))/σ_(x)。此参数具有尺寸效应、应变率效应和静水压效应,但是此参数与应力三轴度的关系表现出应变率无关特性,可为应变率效应的研究提供新的思路。Based on the dynamic experimental results of concrete specimens under true triaxial confinement,the Holmquist-Johnson-Cook(HJC)model considering the strain rate effect and the Drucker-Prager(DP)model considering the hydrostatic pressure effect were employed for numerical analysis to explore the methods for studying the strain rate effects and inertia effects.In order to explore the relationship between the strain rate effect and the lateral inertia effect of concrete,the numerical simulation results of the HJC model were used to fit the parameters of the DP criterion,and the values of the parametersαand k at four strain rates were obtained.The relationship between the DP criterion parameters and the strain rate and hydrostatic pressure was comprehensively analyzed.The results of numerical analysis show that with the increase of strain rate,the strength of concrete increases,and this strength increase is partly due to the increase of the first stress invariant I_(1).It can be concluded that the strain rate and lateral inertia constraint of concrete specimens have a strong coupling effect.The relationship between the distribution characteristics of the transverse stress and the strain rate,hydrostatic pressure and specimen size under impact are analyzed theoretically and numerically.The results show that the amplitude of the transverse stress increases with the strain rate and hydrostatic pressure,but decreases with the sample size.In order to investigate the effect of lateral inertia on the strength improvement,a parameterξrelated to the maximum stressσ_(x) and the equivalent stress σ_(e) in the impact direction,defined asξ=(σ_(x)−σ_(e))/σ_(x),was proposed.The relationship between the strain rate,hydrostatic pressure,specimen size and the parameterξwas analyzed by the HJC model.It is found that this parameter has evident size effect,strain rate effect and hydrostatic pressure effect.However,the relationship between the parameterξand the stress triaxiality shows a strain rate independent characteristic.

关 键 词：冲击动力学 混凝土 应变率效应 惯性效应 应力三轴度 

分 类 号：O382[理学—流体力学]