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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Numerical study on local failures of reinforced concrete slabs against underwater close-in explosions

Abstract: Reinforced concrete (RC) slabs are the primary load-carrying member of underwater facilities. They can suffer severe local failures such as cratering, spalling, or breaching as a result of underwater close-in (UWCI) explosions. In this study, we established a fully validated high-fidelity finite element analysis approach to precisely reproduce the local failures of RC slabs after a UWCI explosion. A recently proposed dynamic constitutive model is used to describe wet concrete. The effects of free water content on the material properties, including the tensile/compressive strength, elastic modulus, strain rate effect, failure strength surface, and equation of state, are comprehensively calibrated based on existing test data. The calibrated material parameters are then verified by a single-element test. A high-fidelity finite element analysis (FEA) approach of an RC slab subjected to a UWCI explosion is established using an arbitrary Lagrangian-Eulerian (ALE) algorithm. Simulating previous UWCI explosion tests on RC orifice targets and underwater contact explosion tests on saturated concrete slabs showed that the established FEA approach could accurately reproduce the pressure-time history in water and damage patterns, including the cracking, cratering, and spalling, of the RC orifice target and saturated concrete slab. Furthermore, parametric studies conducted by simulating an RC slab subjected to a UWCI explosion showed that: (i) the local failure of an RC slab enlarges with increased charge weight, reduced standoff distance, and reduced structural thickness; (ii) compared to a water-backed RC slab, an air-backed RC slab exhibits much more obvious local and structural failure. Lastly, to aid the anti-explosion design of relevant underwater facilities, based on over 90 simulation cases empirical formulae are summarized to predict local failure modes, i.‍e., no spall, spall, and breach, of water- and air-backed RC slabs subjected to a UWCI explosion.

Key words: Reinforced concrete slab (RC); Underwater close-in (UWCI) explosion; Saturated concrete; Failure modes; Numerical simulation

Chinese Summary  <28> 水中近场爆炸下钢筋混凝土板局部破坏模式数值模拟研究

作者:周飞1,李贺东2,吴昊1
机构:1同济大学,结构防灾减灾工程系,中国上海,200092;2浙江理工大学,建筑工程学院,中国杭州,310018
目的:钢筋混凝土板是水下设施的主要承重构件,在水中近场爆炸下可能遭受严重的局部破坏,如开坑、震塌及开裂。本文旨在通过高精度数值仿真方法探讨水中近场爆炸下爆距、炸药质量、结构厚度和结构背面空气/水介质对混凝土板损伤破坏的影响规律,并总结水中近场爆炸下混凝土板破坏模式评估公式。
创新点:1.采用作者前期建立的新型混凝土动态本构模型,系统标定了含水混凝土本构模型参数;2.采用任意拉格朗日-欧拉算法,建立钢筋混凝土板在水中近场爆炸下的高精度模拟方法;3.建立水中近场爆炸下钢筋混凝土板损伤破坏分析模型,开展参数分析并归纳出损伤破坏评估方法。
方法:1.基于现有试验数据,对自由水含量对混凝土的抗拉/抗压强度、弹性模量、应变率效应、强度面和状态方程的影响进行综合标定;2.通过模拟现有混凝土隧洞靶的水中近场爆炸试验和混凝土板的水下接触爆炸试验,对所建立的有限元分析方法再现水中爆炸荷载以及混凝土的开坑、开裂等损伤破坏的能力进行验证;3.通过参数分析,明确爆距、炸药质量、结构厚度和结构背面空气/水介质对混凝土板损伤破坏的影响规律;4.基于大量仿真分析,归纳出水中近场爆炸下混凝土板破坏模式评估公式。
结论:1.系统标定的本构模型参数可准确描述饱和混凝土的动态力学性能;2.建立的高精度数值模拟方法可准确描述近场爆炸作用下混凝土板的开坑、开裂及震塌破坏;3.水中近场爆炸下混凝土板的局部破坏随着炸药质量的增加、爆距的减小和结构厚度的减小而增大;4.与背面水介质相比,背面空气介质的混凝土板损伤破坏显著增加;5.归纳的水中近场爆炸作用下混凝土板损伤评估方法,可用于相关水下设施的抗爆设计。

关键词组:钢筋混凝土板;水中近场爆炸;饱和混凝土;破坏模式;数值仿真


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DOI:

10.1631/jzus.A2300338

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On-line Access:

2024-08-27

Received:

2023-10-17

Revision Accepted:

2024-05-08

Crosschecked:

2024-08-20

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