Blast wave characteristics of multi-layer composite charge:Theoretical analysis,numerical simulation,and experimental validation

This article investigates the characteristics of shock wave overpressure generated by multi-layer composite charge under different detonation modes.Combining dimensional analysis and the explosion mechanism of the charge,a peak overpressure prediction model for the composite charge under singlepoint detonation and simultaneous detonation was established.The effects of the charge structure and initiation method on the overpressure field characteristics were investigated in AUTODYN simulation.The accuracy of the prediction model and the reliability of the numerical simulation method were subsequently verified in a series of static explosion experiments.The results reveal that the mass of the inner charge was the key factor determining the peak overpressure of the composite charge under single-point detonation.The peak overpressure in the radial direction improved apparently with an increase in the aspect ratio of the charge.The overpressure curves in the axial direction exhibited a multi-peak phenomenon,and the secondary peak overpressure even exceeded the primary peak at distances of 30D and 40D(where D is the charge diameter).The difference in peak overpressure among azimuth angles of 0-90°gradually decreased with an increase in the propagation distance of the shock wave.The coupled effect of the detonation energy of the inner and outer charge under simultaneous detonation improved the overpressure in both radial and axial directions.The difference in peak overpressure obtained from model prediction and experimental measurements was less than 16.4%.

A new method of cut-blasting for vertical shaft excavation and its experimental study

Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cutting effect of central large-diameterblasthole and the method of cutting blast by stage and deck toe space charging for thevertical large-diameter blastholes was put forward and analyzed theoretically.This new cutblasting method is provided with the advantages of high blasthole using ratio, big cavitybulk, low rate of chunk, even lumpiness, and relatively high energy using ratio.The parameterchoices and practical effects of this cutting method were discussed after in situexperiment.It shows that the decked delay time of 75～100 ms is applicable.

EXPERIMENTAL STUDY OF MECHANISM AND TECHNOLOGY OF DIRECTED CRACK BLASTING

The dynamic stress-fields and their distribution characteristics around boreholes in the directed crack blasting were measured with the dynamic photo-elastic laser holography apparatus and the ultradymamic measurement system. The directed crack mechanism and its mechanical model have been analysed and expounded. Through the 43 production experiments using slotted cartridges and the double triangle center cut-holes for directed crack blasting in underground rock drift, the results of which the rates of half-hole marks and efficiency of borehole,and the nonsmooth grades of the cut contours are 96%, 98% and 10cm respectively have been achieved.

Experimental study on stemming effect in rock blasting

基于爆炸理论和压力波浪理论，起源在爆炸的岩石中的起源的材料的机制和运动被分析，起源的长度的计算表示被推出。有不同起源长度的爆炸实验被执行，结果证明理论起源长度，是 0.730.8 次负担，在经验的长度的范围，它是 0.630.88 次负担。有理论起源长度的领域实验的爆炸结果是令人满意的，它显示出理论推导，分析正确、可靠。结果将供应与参数设计的理论大意爆炸的岩石。

Industrial Experiment on Coke Spraying With ZBS Additive in Blast Furnace

In order to improve the thermal properties of coke, an industrial experiment on the coke spraying with ZBS additive solution was carried out at coking plant and No. 6 blast furnace （2 000 m^3 ） of Kunming Iron and Steel Co Ltd. The coke reaction index （CRI） of the coke spraying with ZBS additive solution decreases by 10. 56 %, and the coke strength after reaction （CSR） increases by 7.80% in comparison with those of the un-sprayed coke. During the experiment, the average iron output increases by 66. 69 t/d, and the coke rate is reduced by 5. 21 kg per ton iron, while the fluctuation of furnace temperture is small, and sulphur content in hot metal and 100% of hot metal are acceptable.

STRESS AND ENERGY TRANSFER OF WATER COUPLING BLASTING

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Study on Smooth Blasting Results in Jointed and Fractured Rock

Factors that affect blasting results may be grouped into those factors that can be controlled and those that cannot be controlled. The controllable factors include explosive properties, initiation timing, and blast geometry. The uncontrollable factors comprise the rock’s natural structures, such as joints and fractures, and the properties, such as elastic constants, density and strength. Among these, the influence of rock structural planes often contributes a high degree of variability to blasting results. This paper presents a theoretical analysis of rock structural plane influences on smooth blasting results based on elasticity and stress wave propagation theory with an emphasis on smooth blasting techniques. Two types of simulated experiments in lab (using strain and acoustic emission measurements) are used to verify the theoretical analysis. The results show that it is difficult to achieve smooth blasting results when the angle between the natural rock structural planes and the blast induced fracture planes ranges from 10° to 60°. Among these angles, 30° is the least desirable angle to produce a smooth wall. For angles less than 10° and greater than 60°, the influence of rock structural planes on blasting results can be ignored.

基于知识与数据相结合的高炉炉温融合预测

针对复杂高炉冶炼过程具有大滞后等特点,为提高高炉炉温预测精度,提出一种经验知识与数据相结合的炉温融合预测方法。首先,根据高炉经验知识,分析各变量在高炉内的滞后关系,以及在滞后时间内停留在高炉内部形成的累积关系,累积量对当前炉温造成的影响。通过累积量进行相关性分析,合理地确定输入变量。然后,将铁水温度与铁水硅含量融合来更好地表征炉温。最后,通过神经网络利用累积量作为输入建立经验知识与数据相结合的高炉炉温融合预测模型。实验中使用某钢厂高炉生产数据进行仿真,结果表明累积量模型具有良好的性能,可为高炉炉温预测提供新思路。

水下爆炸冲击下箱型隧道结构破坏试验及数值模拟

针对水下爆炸荷载作用下混凝土隧道结构的动态响应、损伤演化及其破坏问题,本文采取室内模型试验与数值计算相结合的方法,根据东湖水下隧道设计了比尺为40∶1的试件,开展了水下箱型混凝土隧道缩比模型的爆炸试验,通过监测应变信号,比较了不同乳化炸药当量下混凝土隧道试件的动态响应规律,通过测量破坏范围的大小、裂缝扩展的长度,调查了箱型隧道缩比模型试件在水下爆破荷载作用下的破坏形式;采用ANSYS/LSDYNA中S-ALE算法对试验进行了1∶1建模仿真分析,对照试验数据及破坏形态,发现模拟结果与试验结果基本一致,同时对仿真结果进一步分析得到了水下爆炸冲击波的传播完整过程和试件结构的变形规律,通过对测点应变、位移数据的统计分析,揭示了箱型隧道试件在爆炸荷载下的动态响应机理。结果表明:箱型混凝土隧道结构在横向上的应变远大于纵向上应变;隧道破坏位置主要集中在爆源附近区域以及结构转角位置,验证了S-ALE算法能够较为准确的模拟出水下爆炸下结构的动态响应及损伤演化。

露天矿山环保抑尘剂研制及性能研究

针对石灰石露天矿爆破粉尘的防治问题,选取氯化钙、甲基纤维素、脂肪醇聚氧乙烯醚、丙三醇4种单体,采用正交实验法对4种单体进行四因素三水平实验。以pH值、黏度、渗透速率、保水率作为考核指标,采用极差法对实验结果进行分析得到最佳配方的复合抑尘剂(A),将抑尘剂(A)与水稻秸秆粉末纤维素酶解离液进行1∶1复配得到环保抑尘剂(B)。将两类抑尘剂与水进行实验对比,进行润湿性、抗破坏性、抗冻性、抗蒸发性表征,SEM测试和室内抑尘模拟实验。研究结果表明:抑尘剂(B)在抗冻、抗蒸发性及润湿作用上与抑尘剂(A)相似且都明显优于水;抑尘剂(B)固化性能更佳,微观形貌显示具有良好的黏结作用。在室内模拟风机风速为12.8 m/s,时间为20 min的扬尘模拟实验中,水、抑尘剂(A)、抑尘剂(B)的抑尘效率分别为32.22%、71.73%和73.25%。

A rapid approach for isolating a single fungal spore from rice blast diseased leaves

Single spore isolation is a fundamental approach in plant pathology and mycology to isolate and identify plant fungal pathogens from diseased samples.However,routine single spore isolation procedure is time-consuming and has a high risk of contamination by other microorganisms.In this study,we developed a rapid approach for isolating a single spore of the fungal pathogen,Pyricularia oryzae,from rice blast diseased leaves in the paddy field with low potential of contamination.First,rice blast leaves with single lesions were selected in the paddy field,and a single lesion was cut out and pressed and dragged gently across the surface of water agar.Next,a germinated single spore with a barely visible piece of agar was cut out of water agar with a dissecting needle under a stereomicroscope at approximately 120-fold magnification.Last,the germinated single spore with water agar was transferred onto oatmeal tomato agar for growth and preservation.Based on our experience,a skilled technician or student can successfully isolate single spore from over 150 independent diseased samples with nearly no contaminations in a single working day.This approach is also suitable for isolating single spore from other fungal disease samples that produce abundant aerial conidia.

从新冠病毒起源到BLAST工具的正确实践

基本局部比对搜索工具(basic local alignment search tool,BLAST)是核酸或蛋白质序列相似性分析最常用的工具之一。因为程序涉及参数较多,一些学生和研究者有时不根据实际情况也不阅读说明书就直接选择默认参数,可能会得出错误结论。BLAST可以进行核酸、蛋白质序列及其相互间的比对,一些低年级学生会有困惑,不知如何进行程序的选择等问题。鉴于这些情况,笔者尝试用2020年初网络的热议话题"新冠病毒极有可能源于实验室"作为引子吸引学生注意力,通过复现并从理论上初步分析其错误,以及产生错误的原因来达到让本科生快速熟悉BLAST的使用及易错点,达到BLAST理论教学的目的。在实验课中,虚构恐龙基因,即一个小组在基因中插入"密码",由另一小组解开"密码",通过小组间利用BLAST工具进行加密与解密的趣味活动,从而加深对程序正确选择的理解,同时巩固了理论教学内容。此教学设计利用当下新冠病毒起源的热点话题不仅提高了学生的学习兴趣,同时也帮助他们利用该工具解决实际问题,培养了学生利用专业知识进行言论分辨的能力。希望此文能对BLAST工具的正确使用和新医科背景下生物医学教学有所启发和帮助。

钙质砂场地爆炸成坑实验与数值模拟研究

为了建立钙质砂场地爆炸成坑效应的计算方法,首先在开挖出的钙质砂模型场地开展了不同当量、不同埋深的野外爆炸实验,然后基于有限元与光滑粒子流耦合算法建立了适用于钙质砂爆炸成坑计算的数值模型,并分析了炸药形状和土体参数对爆坑形态的影响,最后建立了适用于钙质砂场地中的爆坑计算公式。结果表明:埋置爆下,钙质砂场地爆坑尺寸大于硅质砂土中的爆坑尺寸;光滑粒子流算法能较好地揭示钙质砂场地中爆坑轮廓的形成机理;炸药形状和土体密实度等参数对于钙质砂爆坑形态具有不同程度的影响,拟合得到的钙质砂场地接触爆和埋置爆抛掷型爆坑尺寸计算公式,可较好地预测不同爆炸当量作用下的爆炸成坑尺寸。

混凝土烟囱爆破拆除工程教学的虚拟仿真实验建设

工程爆破教学中,拆除爆破构筑物建模周期长,单次实验费用消耗高,短期内无法重复实验。另外,实验本身瞬态不可逆,且危险性高,不利于近距离观察与学习。针对爆破拆除工程中实验教学的难点问题,从虚拟仿真教学实验的设计方案出发,建立了虚拟仿真教学实验平台系统。首先通过“倾倒方案选择”和“切口设计”两个环节的互动操作,让学习者掌握倾倒方案选择的依据以及爆破切口的设计方法,理解切口形状、导向窗与定向窗等爆破切口设计内容。根据烟囱倾倒的力学原理,分析切口设计要满足应力条件,熟悉受拉区、受压区以及中性轴知识,掌握切口截面应力极值的计算公式以及强度条件的应用;其次,通过“爆破参数设计”让学习者参与炸药单耗、炮孔参数及起爆网路的设计与连线,正确选择孔内外雷管段别;随后,学习者通过“安全校核”与“减震措施布置”两个环节的交互学习,掌握数据采集的步骤,学习安全校核的方法以及设置控制爆破负面效应的措施;最后,学习者进入“爆破现场”模块并亲身体会现场起爆操作过程,通过参与设计、组织施工中的每个步骤,并逐渐建立对爆破作业流程的认知。另外,实验系统对于每个模块都设置有知识介绍,便于学习者自主学习。虚拟仿真实验平台的建设不仅优化了教学方法,而且提高了教学质量,同时丰富了工程爆破实验教学特色与创新思路。

砂泥岩互层岩质边坡爆破振动衰减规律现场试验研究

为保证砂泥岩互层岩质边坡在爆破振动作用下安全稳定,需明确爆破振动在砂泥岩互层岩质边坡中的衰减规律。为此,以平陆运河青年枢纽一期工程为依托,通过开展现场爆破试验,对比分析高程效应修正前后爆破振动衰减模型的拟合结果,深入研究砂泥岩互层岩质边坡的爆破振动衰减规律。结果表明:边坡岩体在爆破振动作用下的最大位移会产生高程放大效应,最终位移可能不为零;考虑高程效应的爆破振动衰减模型较未修正的萨道夫斯基公式的拟合精度更高,岩质边坡的爆破振动衰减规律应考虑高程效应;受层理倾向和倾角的影响,砂泥岩互层岩质边坡的爆破振动衰减规律存在差异,建立不同层理下的爆破振动衰减预测模型是后续重要的研究方向。

台阶爆破模型试验下破碎岩石抛掷速度规律分析

为了研究台阶爆破破碎岩石抛掷速度的主要影响因素与变化规律,采用量纲分析法确定破碎岩石抛掷速度的主要影响因素,并借助高速摄影系统与台阶爆破模型试验研究不同影响因素下破碎岩石抛掷速度的变化规律.结果表明:破碎岩石抛掷速度的主要影响因素为炸药单耗、最小抵抗线与炸药量的关系(W^(3)/Q)和不耦合系数,抛掷速度对炸药单耗最为敏感,W^(3)/Q与不耦合系数次之;高速摄影图像显示,当爆破作用时间为0.5 ms时,台阶自由面岩石出现位移,当爆破作用时间为2.0 ms时,在爆炸应力波作用下,台阶自由面出现裂缝,破碎岩石的运动形态可分为鼓包运动阶段与抛掷运动阶段,二者之间存在明显的过渡阶段;炸药单耗、W^(3)/Q、不耦合系数与抛掷速度间存在明显的非线性关系,抛掷速度随炸药单耗的增加呈指数函数递增,且存在临界炸药单耗使破碎岩石的抛掷速度出现激增,抛掷速度随W^(3)/Q、不耦合系数的增大呈幂函数递减.

露天矿山深孔台阶压渣爆破参数优化研究

为了提高露天矿山深孔台阶爆破质量,通过对某矿区现有台阶爆破参数和大块率进行现场调研,提出压渣爆破技术方案,结合LS⁃DYNA软件仿真分析与理论计算,得到适宜的孔网参数和压渣厚度,并将该参数应用于现场爆破试验。结果表明,压渣厚度5 m、孔间距5 m、抵抗线4 m为适宜爆破参数,该条件下现场爆破试验平均大块率小于7%,取得了良好的爆破效果。

地下水封洞库施工巷道开挖爆破技术研究

以国内某地下水封洞库的建设为例对施工巷道的开挖爆破技术进行了研究。首先,基于施工巷道的地质构造特征提出了合理的加固和支护建议。其次,在巷道口近区开挖阶段,对全断面爆破和台阶爆破的效果进行了对比分析;在巷道主体的开挖阶段,对人工钻爆和机械钻爆两种爆破方案的爆破效果效率进行了统计与对比分析。最后,对爆破作用下施工巷道的沉降变形进行了监测分析。研究结果表明:施工巷道口近区经预加固后,全断面爆破与台阶爆破均能满足设计和规范要求,但全断面爆破的施工速率更高;进入巷道主体后采用全断面爆破;人工钻爆与机械钻爆各有优劣势,人工钻爆的施工效率更高,机械钻爆的安全性更高。开挖爆破诱发的位移和沉降均满足设计和相关规范的要求。

某露天矿山预裂爆破参数优选与试验研究

为了得到确保露天矿山边坡安全稳定的最佳预裂爆破参数组合,采用数值模拟结合相似模型试验的方法,探讨了岩石双孔爆破下裂纹扩展规律,并进行了现场预裂爆破试验。结果表明:裂纹先由炮孔壁产生,且炮孔附近的原岩破坏程度较大;随着不耦合系数由1.33增大至3.00,孔壁所承受的冲击压力显著减小,粉碎区半径逐渐减小。采用极差分析法,研究了不同因素对试验指标的影响程度,根据评价指标确定试验因素的最优组合。模型试验结果表明:孔距与孔径之比为9、不耦合系数为3.00、起爆延期时间为12 ms、最大单响药量为5.4 g(三孔一响)的组合条件下,模型试件预裂成缝效果最佳。根据数值模拟及相似模型试验结果,结合理论计算,选取孔距为0.8 m(孔距与孔径之比约为9)、不耦合系数为3.00、延期时间为12 ms、最大单响药量为11.25 kg(三孔一响)的预裂爆破参数进行现场试验,取得了良好的预裂效果。研究结果可以为露天矿山现场预裂爆破参数的设计提供参考,对于实现精确控制爆破、确保露天矿山边坡安全稳定具有重要意义。

松软煤层底板岩层控制爆破诱发煤层增透模拟试验研究

针对松软煤层深孔预裂爆破增透时存在的爆破效果差、裂隙闭合快、增透时效短等问题,开展了底板深孔控制爆破试验研究。通过理论分析,建立了深孔底板爆破力学传播模型,分析了应力波在煤、岩体的传播过程,和控制孔诱导爆破裂隙的定向扩展效应。以淮南矿区C-13煤层为对象,利用相似模拟实验与数值模拟计算研究了有、无控制孔对爆破效果的影响。结果表明,当应力波作用于煤岩交界面时会因煤、岩体波阻抗不同反射形成拉伸应力波,加剧煤岩交界面的损伤程度,而岩体损伤所形成的弱面,引导了爆生应力波向此方向扩展,最终在松软煤体形成损伤裂纹,从而实现了松软煤层底板爆破诱发煤层增透。而控制孔提供的自由面效应会使应力波在控制孔附近发生应力集中,使裂隙朝控制孔方向定向发育。研究成果对松软高瓦斯煤体定向爆破增透有一定的参考意义。