【作者】 王靖；

【导师】 师燕超；

【作者基本信息】 天津大学 ， 结构工程， 2017， 硕士

【摘要】 相较于远距离爆炸,近距离爆炸事件更容易发生且造成的破坏和损失更大,严重威胁着人员的生命财产安全。为了研究钢筋混凝土板在近距离爆炸下的破坏机理和响应模式,探究有效的数值模拟手段用以发展损伤评估工具,研究爆炸产生的混凝土碎片分布,为近距离爆炸下钢筋混凝土板抗爆规范的制定提供思路,本文研究了以下内容并得出了相应结论:(1)开展了五组钢筋混凝土板近距离野外爆炸试验,研究了近距离爆炸下钢筋混凝土板的破坏形态,对板迎爆面和背爆面的破坏模式进行了对比分析,测量了各试验工况下板破坏区域的范围及贯穿洞口的尺寸、形状及对称性。试验结果表明,相较于远距离爆炸下发生的整体弯曲或剪切破坏,钢筋混凝土板在近距离爆炸下的破坏模式有显著差异,主要以压碎破坏、贯穿破坏和剥落破坏等局部破坏为主,这主要是因为近距离爆炸下作用在钢筋混凝土板上的荷载分布与远距离爆炸工况下不同。(2)研究了近距离爆炸下混凝土碎片的抛射分布、尺寸分布、质量分布、抛射速度和形状分布等内容。研究发现:碎片的整体抛射区间为扇形,碎片抛射造成的威胁主要来自纵向,超过50%质量的碎片分布在板前2m范围内;尺寸区间10~30mm的碎片所占比例最大,随着比例距离减小,小尺寸碎片的质量比例增加;碎片累计质量比例服从Weibull分布;抛射速度和碎片形状的研究结果表明,爆炸造成了大量高速抛射的大尺寸尖锐碎片。(3)使用有限元软件LS-DYNA对钢筋混凝土板在近距离爆炸下的破坏形态进行了数值模拟研究。建立了空气,炸药和钢筋混凝土板的数值模型,采用了精细的材料模型和恰当的材料定义,同时为了避免网格扭曲,采用了侵蚀算法,对侵蚀判据进行了合理取值。将数值模拟与野外现场试验进行了对比分析,结果比较一致。更多还原

【Abstract】 Compared with distance explosions,close-in explosions are more likely to happen and will bring greater damage and more lost,which have brought serious threat to human life and property safety.In order to study the failure mechanism and response mode of the reinforced concrete slab under close-in explosion,explore effective numerical simulation ways for the development of damage assessment tools,study distribution of fragments produced by explosion and provide some suggestions for the development of antiknock specification,research was mainly carried out by the following three aspects in this article:(1)Five groups of field tests about reinforced concrete slabs under close-in explosion were conducted,the failure mode and mechanism of reinforced concrete slabs under close-in explosion were studied,the damage conditions on the rear face and front face of the slabs were analyzed and compared,the size,shape and symmetry of the holes generated in the explosions were measured,and the overall failure mode of the slabs were observed and measured.Results show that,compared with whole bending or shear failure of reinforced concrete slabs under distance explosion,the damage model of slabs under close-in explosions is significantly different.Local failure modes such as penetration and crushing damage,fragments spalling and ejection are mainly happen in close-in explosion.This is mainly because the distribution and characteristics of blast loadings acted on the reinforced concrete slabs under close-in explosion are different from distance explosion.(2)Fragments generated by explosion in the five groups were collected,screened,weighed and classified,the ejection distribution,size distribution,mass distribution,projectile velocity and shape of the fragments were studied.It found that: the total projectile interval of the fragments is fan-shaped,and the threat of fragments ejecting mainly comes from the longitudinal direction;the proportion of small-sized fragments increases with the decrease of the proportional distance,and the proportion of fragments with size range of 10~30mm is the largest;The cumulative mass fraction of fragments obeys the Weibull distribution;the mass of the fragments in the area of 2m of the slab is more than half of the total mass;the explosive caused a large number of large-size sharp fragments ejecting at high speed.(3)The failure mode and dynamic response of the reinforced concrete slab under close-in explosion were studied using finite element software LS-DYNA.Simulation model including air,explosive and reinforced concrete slab was built,accurate material model and scientific material definition were adopted,and erosion criterion was also adapted in LS-DYNA to avoid the mesh distortion.The comparison of numerical and test results of damage pattern of reinforced concrete slab demonstrates validity and reliability of numerical simulation.更多还原