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Long duration blast loading and debris distribution of complex masonry panel structures

复杂砌体板结构的长持续爆炸荷载和碎片分布

基本信息

批准号：
EP/M009254/1
负责人：
Simon Clubley
金额：
$ 12.03万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FM009254%2F1
关键词：
Long duration blast loading debris

项目摘要

Blast loading and its interaction with structures is a complex phenomenon even in the simplest of urban settings. Modelling the effect of air blast and coupled structural response is a non-trivial task. The difficulty is increased when considering long duration blast due to the considerable drag loads imparted by the dynamic pressure phase. Long duration blast loading is defined here as an explosive event in which the positive phase duration, clearly exceeds 100msec; conventional explosives have a positive phase duration of less than 50msec. These types of load cases are most commonly associated with chemical vapour cloud detonation, e.g. 2005 Buncefield Disaster (between 150-250 tonnes TNT equivalence). Academic literature presents both researcher and practitioner with little understanding pertaining to the long duration blast response of commonplace masonry or segmental structures. Knowledge gaps exist in the methods available, principally: (a) we cannot currently calculate the amount of rubble or debris blockage that will prevent emergency services providing life saving assistance, (b) we do not have accurate tools to predict resulting casualties or net damage and, (c) current calculation methods are flawed and cannot model real structures beyond crude approximations. To solve this key gap in knowledge, the latest techniques in advanced computational modelling are required coupled with instrumentation intensive national test facility sponsored experiments. By their nature, long duration blast loads transmit large magnitude impulse and the non-negligible effects of drag loads make interactions with structures complex to model; intrinsically more so than a conventional explosive source. When modelling structural collapse, the reliability of readily available numerical methods (e.g. Finite Element Analysis) fail in the discrete phase, particularly for brittle systems susceptible to particulate fragmentation. Newer adaptive techniques in blast effects research such as the Applied Element Method, overcome these limitations through the use of continuum decoupling techniques and collision detection algorithms. It is now possible to model complex segmental, jointed arrangements and determine a reliable debris field distribution following breakage. Preliminary research has shown that pressure equalisation on the rear structural face in the long duration case can reduce net loading by 25-30%. These effects are further complicated by dynamic pressures entraining broken fragments. Importantly for long duration blast, incident and reflected impulses are at least one order of magnitude greater leading to rapid over-matching of comparatively smaller structures. This research proposal will use advanced computational techniques in conjunction with comprehensive experimental trials conducted in the UK, Ministry of Defence Air Blast Tunnel to derive breakage algorithms and debris fragmentation profiles. Precise mapping using mass distribution grids, 3D laser scanning and high speed video will allow the comparison of analytical and trial results. The effects of blast clearing and net pressure effects across individual panels will be examined carefully. This will form the reference benchmark for the analysis of complex interlinked structural geometries. Linking breakage algorithms to the current limited guidance for conventional small explosive exclusion zones will be a key objective.

即使在最简单的城市环境中，爆炸荷载及其与结构的相互作用也是一个复杂的现象。模拟空气爆炸和耦合结构响应的影响是一项艰巨的任务。由于动压阶段所传递的相当大的阻力载荷，在考虑长时间爆破时，难度增加了。长持续时间爆炸载荷在这里定义为正相持续时间明显超过100msec的爆炸事件；常规炸药的正相持续时间小于50毫秒。这些类型的载荷案例通常与化学蒸汽云爆炸有关，例如2005年Buncefield灾难（150-250吨TNT当量）。学术文献表明，研究人员和从业人员对普通砌体或节段结构的长时间爆炸反应知之甚少。现有的方法存在知识空白，主要是：(a)我们目前无法计算妨碍紧急服务提供救生援助的瓦砾或碎片堵塞的数量，(b)我们没有准确的工具来预测由此造成的伤亡或净损失，以及(c)目前的计算方法有缺陷，不能模拟真实结构，只能进行粗略的近似。为了解决这一关键的知识差距，需要先进的计算建模的最新技术与仪器密集的国家测试机构赞助的实验相结合。由于长持续时间的爆炸荷载传递的冲击幅度较大，且阻力荷载的影响不可忽略，使得与结构的相互作用难以建模；本质上比传统的爆炸源更强。当模拟结构坍塌时，现成的数值方法（例如有限元分析）的可靠性在离散阶段失效，特别是对于易受颗粒破碎影响的脆性系统。在爆炸效应研究中，应用单元法等较新的自适应技术通过使用连续体解耦技术和碰撞检测算法克服了这些限制。现在可以对复杂的分段、节理排列进行建模，并确定破碎后可靠的碎片场分布。初步研究表明，在长时间的情况下，后结构面的压力均衡可以减少25-30%的净载荷。这些影响由于夹带破碎碎片的动态压力而进一步复杂化。重要的是，对于长时间爆炸，入射脉冲和反射脉冲至少要大一个数量级，导致相对较小的结构快速过匹配。这项研究计划将使用先进的计算技术，结合在英国国防部空气爆炸隧道进行的综合实验试验，得出破碎算法和碎片破碎剖面。利用质量分配网格、3D激光扫描和高速视频进行精确测绘，可以对分析结果和试验结果进行比较。爆破清理和净压力对各个面板的影响将被仔细检查。这将成为分析复杂互连结构几何形状的参考基准。将破损算法与目前有限的常规小爆炸禁区指南联系起来将是一个关键目标。