混凝土动态力学性能和抗侵彻行为的准细观尺寸效应与相似律研究

The research on dynamic properties of concrete and its anti-penetration behavior is one of the hot and key topics in impact mechanics field. However, the size of aggregates in concrete has notable influence on dynamic properties and anti-penetration behavior of concrete. That is, which has obvious quasi-mesoscale size effect. In this work, the dynamic testing methods were improved, and a new three dimensions quasi-mesoscale structure model for concrete was developed. Using large-scale experimental investigation, quasi-mesoscale numerical simulation, mesoscale observation and theoretical analysis, the multi-scale research were carried out. The dynamic properties experiments and quasi-mesoscale numerical simulations of concrete with different dimensionless sizes of aggregates were conducted. And the transformation characteristics of concrete from material to structure were studied. The threshold dimensionless sizes of aggregates were proposed. And the corresponding quasi-mesoscale size effect and its mechanism were revealed. The dynamic properties experiments and quasi-mesoscale numerical simulations of concrete with different sizes of specimens and same dimensionless sizes of aggregates were conducted. And the corresponding quasi-mesoscale similarity law and its mechanism were revealed. And then, the criteria for extracting the representative volume element from practical concrete work and preparing the scaling specimens for dynamic properties were put forward. The dynamic properties tests and quasi-mesoscale numerical simulations of penetrating concrete with different sizes of aggregates and projectiles were carried out. And the corresponding quasi-mesoscale similarity law and its mechanism were revealed. And then, the criteria for preparing the scaling testing for penetrating concrete were presented. The study results can provide theoretical foundation for the follow-up researches related to concrete dynamic properties, and which have important scientific significance and practical reference value.

混凝土动态性能与抗侵彻行为是冲击动力学领域的研究热点也是重难点之一，然而，粗骨料尺寸对混凝土动态性能和抗侵彻行为具有较大影响，即其具有明显的准细观尺寸效应。本项目改进动态测试手段和方法，发展一种混凝土三维准细观结构模型；以宏观试验为核心、准细观仿真为辅助、细观观测为参考，结合理论分析，开展多尺度研究。对不同粗骨料尺寸的混凝土开展动态性能试验和准细观仿真研究，分析混凝土从材料到结构特性转变的行为特征，给出其无量纲临界尺寸，揭示其准细观尺寸效应及机理；开展骨料/试件尺寸等缩比的混凝土缩比试验与准细观仿真研究，揭示其动态性能的准细观相似律及机理；建立混凝土特征单元提取与试件制备的科学标准。开展不同粗骨料和杆弹尺寸的混凝土抗侵彻试验与准细观仿真研究，揭示其抗侵彻行为的准细观相似律及机理，建立混凝土抗侵彻缩比试验的设计标准。项目成果为混凝土动态响应相关研究奠定理论基础，具有重要的科学意义和应用价值。

混凝土材料是一种以粗骨料与砂浆为基体的复合材料，其动态力学性能与抗侵彻行为是冲击动力学领域的研究热点也是重难点之一。一般混凝土工事以及对应的攻坚弹（含钻地弹）尺寸远大于粗骨料，则混凝土可近似为均质材料；然而，在材料力学性能试验特别是动态力学性能试验以及混凝土抗侵彻缩比试验中，试件和模型弹直径与粗骨料粒径相近，此时混凝土结构特征不可忽视。如何利用小尺寸试件或缩比试验来准确地标定大尺寸混凝土工事的抗侵彻性能与特征，是当前新型攻坚弹、高性能混凝土防护工事以及相关毁伤效能评估等研究中亟待解决的问题。.针对研究目标，围绕三个关键科学问题，项目开展了混凝土试件三维准细观结构模型、动态力学性能及其抗侵彻行为的准细观尺寸效应与相似律等五个方面内容的研究。建立了整形片参数对入射波形上升沿影响的无量纲函数关系，提出了混凝土类材料相对精确SHPB试验与数据处理方法，给出了强度应变率效应校正方法。提出了混凝土三维随机准细观仿真模型的建立方法，揭示了砂浆和粗骨料对混凝土强度的影响规律。研究发现：混凝土的抗压强度小于对应的砂浆强度，但其应变率强化系数均大于对应的砂浆材料，且随着粗骨料无量纲尺寸的增大，混凝土压缩强度应变率强化因子呈现先增大后减小的趋势；当粒径系数小于0.34时，混凝土试件的异质性并不明显，否则混凝土试件力学性能测试结果离散性极大。揭示了混凝土材料抗刚性弹侵彻问题的维像相似律规律：在研究范围内，当弹体直径约大于粗骨料粒径的3倍以上时，刚性卵形弹对混凝土靶板的侵彻近似满足几何相似律；否则侵彻深度受到粗骨料的分布影响比较明显而不满足维像几何相似律。但在本研究中，若在缩比模型中考虑粗骨料粒径与弹径同比放大或缩小时，混凝土材料动态力学性能及其抗侵彻问题皆近似满足几何相似律。.项目成果为混凝土类材料动态力学性能精细化试验研究以及混凝土材料抗侵彻缩比设计与试验结果校正提供科学依据，具有一定的理论意义与实用参考价值。