Experimental Investigation on Shock Wave Characteristics of Aluminized Explosives in Air Blast

To investigate the shock wave characteristics of RDX-based aluminized explosives,air blast tests were conducted for measuring the parameters of 10 kg aluminized explosives which contained 0-40% aluminum.The results showed that with the increasing of aluminum content,the overpressures and impulses increase at first and then decrease within 7 m or 5 m,which reached the maximum when aluminum content was 20% or 30%.Power exponential formulas are used to fit the shock wave parameters vs scaled distance,where an equal weight of TNT is used to calculate the scaled distance.The overpressures of HL0 and TNT in tested locations not only conform to the similar law,but also conform to the same attenuation law after gaining the scaled distances of equal TNT mass.The pre-exponential factors of overpressure and impulse,kp and kI,decrease along with the increasing of Al content and keep the same pace as the calculated PCJ）.The attenuation coefficients a_P and aIincrease at first and decrease later with the increasing of aluminum content,and they reached the maximal values with30% Al containing,which keeps the same pace as the calculated QV.

Simulation of Airblast Load and Its Effect on RC Structures

In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented.

Particle Swarm Approach for Structural Optimization of Battleship Strength Deck Under Air Blast

This paper presents the implementation and application of a modified particle swarm optimization(PSO) method with dynamic adaption for optimum design of a battleship strength deck subjected to non-contact explosion. The numerical simulation process is modified to be more computationally efficient so that the task is realizable. The input variables are the thickness of plates and the dimensions of stiffeners, and the total structural mass is chosen as the fitness value. In another case, the response surface method(RSM) is introduced and combined with PSO(PSO-RSM), and the results are compared with those obtained by the traditional PSO approach. It is indicated that the PSO method can be well applied in the optimum design of explosion-loaded deck structures and the PSO-RSM methodology can rapidly yield optimum designs with sufficient accuracy.

Physical Properties of Crushed Air-cooled Blast Furnace Slag and Numerical Representation of Its Morphology Characteristics

Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag （SCR） and crushed limestone （LCR） were comparatively investigated. The shape, angularity, surface texture and internal pore structure of aggregate particles for different size and gradation were numerically represented by sphericity （ψ） and shape index （SI）, angularity number （AN）, index of aggregate particle shape and texture （IAPST）, porosity and pore size, respectively. The results show that SCR is a porous and rough aggregate. Apparent density, void, water absorption and smashing index of SCR are obviously higher than those of LCR with the same gradation, respectively. However, bulk density of SCR is lower than that of LCR with the same gradation. SI, AN, IAPST and porosity of SCR are obviously higher than those of LCR with the same gradation, respectively. The smaller particle size of SCR, the larger of its AN, IAPST and porosity.

Application of Air-cooled Blast Furnace Slag Aggregates as Replacement of Natural Aggregates in Cement-based Materials：A Study on Water Absorption Property

The influence of air-cooled blast furnace slag aggregates as replacement of natural aggregates on the water absorption of concrete and mortar was studied, and the mechanism was analyzed. The interface between aggregate and matrix in concrete was analyzed by using a micro-hardness tester, a laser confocal microscope and a scanning electron microscope with backscattered electron image mode. The pore structure of mortar matrixes under different curing conditions was investigated by mercury intrusion porosimetry. The results showed that when natural aggregates were replaced with air-cooled blast furnace slag aggregates in mortar or concrete, the content of the capillary pore in the mortar matrix was reduced and the interfacial structure between aggregate and matrix was improved, resulting in the lower water absorption of mortar or concrete. Compared to the concrete made with crushed limestone and natural river sand, the initial absorption coefficient, the secondary absorption coefficient and the water absorption capacity through the surface for 7 d of the concrete made from crushed air-cooled blast furnace slag and air-cooled blast furnace slag sand were reduced by 48.9%, 52.8%, and 46.5%, respectively.

Optimization of the Air Deck Blasting Parameters on the Basis of the Holmquist-Johnson-Cook Constitutive Model

The present study considers the so-called air deck blasting,one of the most commonly used techniques for the improvement of blasting efficiency in mining applications.In particular,it aims to improve the operating conditions of large-scale equipment,increase the efficiency of the slope enlarging process,and reduce the mining cost.These objectives are implemented through a two-fold approach where,first,a program for slope enlarging based on the middle air-deck charge blasting-loosening technology is proposed,and second,the physical mechanism responsible for the stress wave attenuation in the rock is analyzed in the framework of a Holmquist–Johnson–Cook constitutive model.Field test results verify that the proposed approach is highly efficient and economical when used in medium-hard rock blasting and thus provides a basis for the practical implementation of slope enlargement for high benches in Open-Pit Mines.

Effect of Crushed Air-cooled Blast Furnace Slag on Mechanical Properties of Concrete

Morphology characteristics of mix aggregates with crushed air-cooled blast furnace slag（SCR） and crushed limestone（LCR） with 5-20 mm and 20-40 mm gradation were represented by numerical parameters including angularity number（AN） and index of aggregate particle shape and texture（IAPST）.The effect of mix aggregates containing SCR on compressive strength and splitting tensile strength of concrete was investigated.Fracture characteristics of concrete,interfacial structure between aggregates and matrix were analyzed.The experimental results show that porous and rough SCR increases contact area with matrix in concrete,concave holes and micro-pores on the surface of SCR are filled by mortar and hydrated cement paste,which may increase interlocking and mechanical bond between aggregate and matrix in concrete.SCR can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with LCR.The increase of AN and IAPST of aggregate may enhance mechanical properties of concrete.

Effects of content and particle size of TiH2 powders on the energy output rules of RDX composite explosives

In order to improve the detonation characteristics of RDX,a RDX-based composite explosive with TiH_(2)powders was prepared.The effects of content and particle size of TiH_(2)powders on thermal safety,shock wave parameters and thermal damage effects of RDX-based composite explosive were studied with the C80 microcalorimeter,air blast experiment system and colorimetric thermometry method.Experimental results showed that TiH_(2)powders could enhance the thermal stability of RDX-based composite explosive and increase its ultimate decomposition heat.The content and particle size of TiH_(2)powders also had significant effects on the thermal safety,detonation velocity,shock wave parameters,fireball temperature and duration of RDX-based composite explosives.Furthermore,the differences of TiH_(2)and Ti powders on the detonation energy output rules of RDX-based composite explosives were also compared,showing that TiH_(2)powders had better influences on improving the explosion power and thermal damage effect of RDX-based composite explosives than Ti powders,for the participation of free H_(2)released by TiH_(2)powders in the detonation process.TiH_(2)powders have important research values as a novel energetic additive in the field of military composite explosives.

武钢4号高炉炉缸温度异常升高的机理分析

武钢4号高炉炉缸侧壁温度异常升高,主要原因是炉缸碳砖与炉壳之间存在气隙,煤气串入导致热传导变差,再加上铁口区域渣铁环流加剧,碳砖热面渣铁壳的脱落,使渣铁水直接接触碳砖,导致碳砖温度急剧升高。通过灌浆,治理了串煤气,渣铁凝结层逐渐形成,炉缸温度恢复正常。

基于动爆冲击波演化规律的超压计算模型

为建立动爆冲击波超压的工程计算模型,开展了球形装药动爆试验和数值模拟研究,获取了动爆冲击波场演化历程图像,定量分析了装药速度对冲击波波阵面传播速度的影响。结果表明:在装药速度影响下爆轰产物各向膨胀速度不再相同,爆轰产物膨胀速度的变化使得冲击波强度和空间位置分布发生了相应的变化,正向冲击波强度更高,更早与爆轰产物相分离。在静爆冲击波演化模型的基础上,通过引入含有角度和传播时间的修正因子,建立了静动爆关联的球形装药动爆冲击波超压计算模型。采用该模型计算得到的不同速度、不同药量球形装药冲击波压力与试验结果吻合较好,模型具有一定普适性。

连接方式对蜂窝夹芯结构抗爆性能的影响规律研究

目的旨在探究近场空爆载荷作用下蜂窝夹芯结构面板与芯层的连接方式对抗爆性能的影响。方法分别设计了由激光选区熔化技术打印制备的316L不锈钢一体式蜂窝夹芯结构和分离式蜂窝夹芯结构2种构型,并进行了50 mm爆距的爆炸冲击实验。后又结合数值模拟方法对比分析了一体式、分离式、胶接式和焊接式4种连接方式在爆炸载荷作用下的动态响应过程,并分别从各层结构变形失效、背板最大残余挠度及吸能等角度联合揭示了抗爆性能差异及其影响规律。结果一体式蜂窝夹芯结构背板最大残余挠度为17.5mm,相比分离式、胶接式和焊接式,分别减少了47.3%、43.0%、28.3%。爆炸冲击结束后,一体式蜂窝夹芯结构的总塑性应变能和背板应变能占比分别为866.9J、13.3%,与焊接式蜂窝夹芯结构的相近,但其总塑性应变能较分离式、胶接式分别低4.1%、16.6%,而背板应变能占比则较二者分别低13.8%、14.3%。结论通过实验与仿真研究,证明了连接强度对蜂窝夹芯结构抗爆性能具有显著的影响,其中一体式结构抗爆性能表现最佳,且连接强度越高,其运动速度越小,响应时间也越短,对其提升防护结构的减震效果具有重要作用。

深孔轴向多段间隔装药孔壁冲击压力分布

为确定地下垂直长深孔爆破时合理的空气间隔长度,基于爆轰波理论,分析了多段间隔装药爆破条件下孔壁冲击压力随间隔长度变化的内在分布规律函数;依据Mises准则,得出了不同岩性时合理的间隔长度参考值,并通过数值模拟和现场爆破试验进行了验证。结果表明,空气间隔段孔壁冲击压力沿炮孔轴线从两端向中间骤降,但在中点周围略微增大,压力曲线呈两端大、中间小、中点周围略微凸起的“W”形对称分布。

侧面爆破粉尘时空分布模拟分析

从开放性细颗粒物污染治理角度出发,建立建筑物拆除爆破产尘的几何计算模型,运用计算流体力学(CFD)工具,对给定环境风速下的建筑物周围压力场和速度场进行了模拟分析,并对侧面折叠爆破粉尘按R-R(Rosin-Rammler)分布,使用气流-粒子双向耦合的DPM模型研究了爆炸粉尘的时空分布。结果表明,下风侧因建筑物存在导致风速、压力急剧变化而产生涡流,涡流是影响爆破粉尘时空分布的关键因素之一。在时间上,爆破粉尘有气流拖曳运动状态和扩散态;在空间上,因重力作用致下部空间的粉尘浓度较大。

近距空爆载荷作用下高韧钢的抗爆性能及影响因素研究

为探讨高韧钢的抗爆性能及其影响因素,结合空爆试验,对高韧钢平板和加筋板的动响应过程进行了数值模拟,并与相同厚度的高强钢进行了对比。首先,开展了高韧钢和高强钢平板的空爆试验,对比分析了2种材料平板的变形和破坏试验结果。随后,采用LS-DYNA非线性有限元程序对高韧钢平板在近距空爆载荷作用下的变形/失效过程进行了数值模拟,并与试验结果进行了对比,验证了数值模拟方法的合理性。在此基础上,通过数值模拟进一步分析了高韧钢平板和加筋板结构的动态响应过程和失效机理。研究结果表明,在TNT药量为1200 g、爆距为100 mm的近距空爆载荷作用下,10 mm厚的高韧钢平板仅发生拉伸大变形,而10 mm厚的高强钢平板中部出现大破口。高韧钢平板的抗爆性能明显优于同等厚度下的高强钢平板。近距离空爆载荷作用下,高韧钢平板的主要变形模式为整体拉伸变形,而高韧钢加筋板结构的主要破坏模式为沿加筋部位的剪切破坏。随着载荷强度的增大,高韧钢加筋板结构呈现出3种不同的失效破坏模式;随着加筋高度的增大,面板沿加筋的局部剪切应力更大,高韧钢加筋板的抗爆性能反而会劣化。研究结果展示了高韧钢的抗爆优势,可为高韧钢在舰船防护结构中的潜在应用提供技术支撑。

风冷高炉矿渣的超细粉磨与化学激发联合活化研究

风冷高炉矿渣水化活性低,某企业工业试验中使用风冷高炉矿渣作混合材生产复合水泥时,矿粉在水泥中的掺量通常低于30%。本文提出超细粉磨和化学激发联合活化的技术思路,改造粉磨工艺实现风冷高炉矿渣超细粉磨,并探究了粉磨工艺参数对矿粉粒径和活性指数的影响,当矿粉比表面积为650 m^(2)/kg时,28 d活性指数为88.4%,比原生矿粉提高了26.2%。在化学激发方面则研究了激发剂种类、掺量以及多元复配对矿粉活性的影响,最终以硫酸钠、硫酸铝钾和三乙醇胺为主要成分制备了一款复合激发剂,矿粉粉磨过程引入1.5%复合激发剂即可使7 d活性指数提高16.9%。

高炉重矿渣在高速公路路基工程中的应用研究

采用包钢高炉重矿渣铺筑了路基试验段,测试分析了重矿渣的矿物组成、稳定性、及其作为填筑材料的黏聚力、压缩系数、回弹模量和承载比等性能,研究了粒径大小对最大干密度、最佳含水率的影响规律及施工工艺.结果表明:重矿渣稳定性好,含有C 3S硅酸三钙、C 2S硅酸二钙等硅酸盐材料,具有一定的胶凝活性,有利于提高承载力;重矿渣填筑料压缩系数为0.05 MPa-1,属于低压缩性土,回弹模量为86.7 MPa,黏聚力为13.66 kPa,承载比能满足路基不同深度的强度设计要求.随着重矿渣9.5 mm通过率的减小,其重击实试件的最大干密度和最佳含水率逐渐降低.重矿渣路基试验段的松铺系数为1.1,最佳碾压方式为2遍静压加6遍动压,压实参数满足规范要求,平整度平均值小于20 mm,路用性能优良.

梅蓄电站二期上引水洞爆破开挖诱发空气超压对上库事故闸门的影响分析

爆破开挖过程中产生的空气超压可能会影响周边建构筑物的安全。梅州抽水蓄能电站二期引水平洞的爆破作业区,距离在一期工程中已建好并投入运行的二期工程引水上平洞上库钢质事故闸门仅81 m,爆破作业可能会影响事故闸门的稳定运行。为此,以梅州抽水蓄能电站二期引水上平洞的爆破开挖为对象,开展了爆破空气超压现场监测工作,分析了爆破空气超压的分布规律及其对梅州抽水蓄能电站上库事故闸门的安全影响,为分析爆破空气超压对上库事故闸门的安全影响提供了支撑。现场的爆破空气超压监测数据表明:距离爆破掌子面约80 m的事故闸门前的空气超压水平分布在0.63~3.46 kPa,远小于建议的相应的爆破安全控制标准100 kPa;闸门前使用胶帘等防护设施可以有效减小闸门位置的空气超压,实测的第4次和第5次爆破空气超压减小了55%以上;单段装药量及总装药量得到有效控制时,实测的空气超压值远低于建议的控制标准;现场宏观调查及其他检测数据也未见异常,爆破施工未影响上库事故闸门的安全运行。

质量参数对空爆荷载梁构件振动位移的影响

为研究质量参数对空爆荷载梁构件振动位移的影响,以等效单自由度法为基本方法,理论推导了柔性及刚性2类梁构件含质量参数在弹性、塑性各阶段的振动位移解,选择矩形截面、圆截面为梁构件典型截面,设计并计算了质量参数在1.00~1.20范围内的13种典型工况。结果表明:对于空爆荷载柔性及刚性2类梁构件,增大其截面面积后,仅考虑质量参数计算振动位移时误差较大,应按质量参数及产生的附加刚度参数耦合效应分析;对于矩形截面梁构件,采用质量参数与刚度参数耦合计算时,其最大弹性位移、最大弹塑性位移和残余变形降低幅度分别约为仅采用质量参数计算结果的4.75、3.28和2.96倍;对于圆截面梁构件,则分别为3.57、2.56和2.32倍;该结论在柔性梁构件及刚性梁构件均适用且无明显差异。

爆炸空气冲击波作用下埋地输气管道响应分析与减振思路设想

近些年来,爆炸源近区的天然气输气管道安全问题受到广泛关注。以某案例为背景,在爆炸空气冲击波作用下,对一埋地输气管道的减振结构进行数值模拟。采用有限元软件LS-DYNA分析爆炸后空气冲击波对管道的动力响应,计算管道是否能正常安全运行;在其他条件不变的条件下,通过调整回填土密度,进一步研究回填土密度为1600、1700kg/m3时对管道位移和振动影响情况。此外,对原来减振模型进行了调整,并对新的减振模型效果进行了分析模拟。结果表明:在原减振结构下管道振动峰值响应速度为13.80cm/s,满足小于14cm/s的规范安全建议值。增加管道周围回填土密度可使振动速度减小,但效果不明显;调整过后的减振模型,大幅减小了管道的位移和振动速度响应,考虑到施工便利性及经济性,新减振模型项目实际应用还有待进一步分析。这2种减振结构都能保证埋地管道更好地保持安全运行,为今后类似工程提供了参考。

基于能量守恒的气枪主动震源激发实验震级计算

分别运用Baker公式、Kinney公式、Broad公式计算甘肃刘家峡气枪主动源一次常规实验激发所释放的能量,并利用能量与震级之间的经验公式,估算一次常规实验产生地震的震级。通过分析刘家峡主动源实验场附近固定数字测震台站记录的单次激发数据发现,气枪激发时所释放的能量并未完全转换为地震波,如气枪主气室在爆破瞬间并非完全绝热,有部分能量随着热量传递而散失,故通过能量守恒方法计算的震级略大。实验结论与Kinney公式计算结果的一致性较好,符合实验实际工况条件。