【作者】 李锐；

【导师】 徐世烺； 李庆华；

【作者基本信息】 浙江大学 ， 建筑与土木工程， 2020， 硕士

【摘要】 近些年来,恐怖主义袭击频率不断提高,大规模工业爆炸频频发生,对现有防护结构提出了严峻的挑战。普通混凝土抗爆结构会在爆炸荷载下产生严重的震塌现象。超高韧性水泥基复合材料(Ultra-High Toughness Cementitious Composite,UHTCC)具有优异的韧性和吸能效果,超高性能混凝土(Ultra-High Performance Concrete,UHPC),具有很高的抗压强度。采用UHTCC和UHPC材料制成的功能梯度板结合了二者优势,具有优越的抵抗爆炸冲击性能。随着计算机技术的发展,数值模拟方法可以准确地预测材料在爆炸、冲击等荷载下的动态力学性能,提高科研效率,节约科研成本。为了系统地研究UHTCC材料在爆炸荷载下的损伤规律,设计出性能优良的防护结构,本文利用LS-DYNA软件对UHTCC功能梯度板在爆炸荷载下的动态响应进行了数值模拟。本文主要工作及成果如下:(1)结合动、静态力学试验和理论计算,得到了适用于UHTCC和UHPC材料的HJC本构模型参数。通过接触爆炸试验对比了 UHTCC、UHPC、UHTCC/UHPC、NSC四种靶体的抗爆效果,并建立了相应的爆炸有限元模型,验证了数值模型的有效性。(2)采用数值模拟方法系统地研究了 U/P/U功能梯度抗爆板在接触爆炸下的动态响应。讨论了炸药量、板厚、配筋、保护层厚度等变量以及多次爆炸对结构抗爆性能的影响。结果表明:同等炸药量下,U/P/U功能梯度板的开坑深度比单独使用UHTCC材料小41.6%,其对于爆炸冲击波的吸收能力是是普通混凝土的50倍。增加板厚、配筋以及合理设置UHTCC能量吸收层厚度均能有效提高功能梯度板的抗爆炸效果。(3)进一步对UHTCC功能梯度板的浅埋爆炸进行了数值模拟,对炸药量、埋置深度、板厚等因素进行了参数分析,给出了 UHTCC功能梯度板的损伤等级评定方法。当比例距离大于0.28,靶体轻微损伤,当比例距离介于0.18和0.28之间,靶体中度损伤,当比例距离小于0.18,靶体严重损伤并贯穿。更多还原

【Abstract】 In recent years,the frequency of terrorist attacks has continuously increased and large-scale industrial explosions occurred frequently,which poses severe challenges to the existing protective structure.Ordinary concrete anti-explosion structure will produce serious collapse under explosion structure.Ultra-High Toughness Cementitious Composite(UHTCC)has excellent performance in toughness and energy absorption.Ultra-High Performance Concrete(UHPC)has extremely high compressive strength.The functional gradient slabs made of UHTCC and UHPC materials combine the advantages of both,which presents superior performance to resist blast loading.With the development of computer technology,numerical simulation method can accurately predict the dynamic mechanical properties of materials under explosion,impact and other loads,so as to improve the efficiency of scientific research and save the cost.Targeting at investigating the damage law of UHTCC material under explosion load systematically,a protective structure with excellent performance was designed.The dynamic response of UHTCC functionally graded plate under explosion load was numerically simulated by LS-DYNA software.The main work and achievements of this paper include:(1)The parameters of the HJC constitutive model for UHTCC and UHPC materials were obtained through dynamic and static mechanical tests,as well as theoretical calculation.The anti-explosion properties of UHTCC,UHPC,UHTCC/UHPC,NSC slabs were compared by contact explosion test,and the corresponding finite element models were established to verify the effectiveness of the numerical model.(2)The dynamic response of U/P/U functionally gradient slabs under contact explosion was systematically studied by numerical simulation method.The variables of explosive content,thickness of slabs,reinforcement,protective layer thickness,as well as effects of multiple explosions on anti-explosion property of structure were discussed.Results show that the pit depth of U/P/U functional gradient slab is 41.6%less than that of UHTCC slab under the same explosive content,and its ability to absorb explosive shock waves is 50 times that of normal concrete.Specially,the anti-explosion effect can be effectively improved by increasing thickness and reinforcement of the slabs,furthermore rationally setting the thickness of energy absorption layer.(3)Furthermore,the shallow buried explosion of UHTCC functionally graded slabs was numerically simulated,and the parameters of explosive content,buried depth,thickness of slabs were analyzed,the damage level assessment method of UHTCC functionally graded slabs was determined.When the scaled distance is greater than 0.28,the target is slightly damaged,when the scaled distance ranges between 0.18 and 0.28,the target is moderately damaged,when the scaled distance is less than 0.18,the target is severely damaged and penetrated.更多还原