Rock fracturing by explosive energy: review of state-of-the-art

A study of the dynamic rock fracture initiation and propagation due to explosive energy is presented through a detailed state-of-the-art review. Explosive energy dissipation in crushing and fracturing is examined and the various means to enhance the explosive energy utilization for dynamic rock fracturing are reviewed. The study highlights the need for a better understanding of the dynamic fracturing process particularly in the presence of in situ stresses in the rock mass.     

X射线荧光测井的井液效应及其校正

本文从Ｘ射线的性质，以及Ｘ射线与物质作用的机理出发，对井液效应进行了研究，并对其影响过程进行模拟。在理想井液模型上，推导出Ｘ射线活度与钻孔参数的数理关系。在此基础上，进一步研究得到了能适应野外多变情况的井液效应校正公式（ＣＢＷＥ）和方法。     

An innovative priming system - emulsion-based booster

The mineral industry is leading towards a technology driven optimization process. Drilling and blasting are such unit operations in a mine, which can alter the balance sheet of the mine if not planned properly. The development, improvement and utilization of innovative technologies in terms of blast monitoring instruments and explosives technology are important for cost effectiveness and safety of mineral industries.

The ever-growing demand for minerals has compelled the industry to adopt large opencast projects using heavy equipment. This has necessitated use of a few hundred tonnes of explosives in each blast. The bulk delivered fourth generation explosives have solved the problem of explosive loading to a large extent as it provides improved safety in manufacturing, transportation and handling. Bulk delivered emulsion is non-explosive until gasification is complete and a large quantity of explosive can be transported and loaded into blast holes efficiently and with safety. The priming of bulk delivered explosives in Indian mines uses the conventional PETN/TNT-based boosters. The conventional booster possesses safety problems in terms of handling and use, so Indian Explosives Ltd has developed an emulsion-based booster (Powergel Boost).

This paper explores the potential of an emulsion-based booster used as a primer to initiate bulk delivered emulsion explosives used in mines. An attempt has been made at a comparative study between the conventional booster and the emulsion-based booster in terms of the initiation process developed and their capability of developing and maintaining a stable detonation process in the column explosives. The study has been conducted using a continuous velocity of detonation (VOD) measuring instrument, the VODMate two channel system manufactured by Instantel Inc. of Canada. During this study three blasts were monitored. In each blast two holes were selected for study, the first hole was initiated using a conventional booster while the other one used an emulsion-based booster. The findings of the study advocates that the emulsion-based booster is capable of the efficient priming of bulk delivered column explosive with a stable detonation process in the column.     

On size and boundary effects in scaled model blasts spatial problems

This paper addresses size and boundary effects on wave propagation, fracture pattern development and fragmentation in small scale laboratory-size specimens for model blasting. Small block type specimens are centre-line loaded by linear explosive charges and supersonically detonated. Using elastic wave propagation theory and fracture mechanics it is shown that the type of boundary conditions which prevail at the outer boundary of the cylinder control the extension of bore-hole cracking and fragmentation within the body of the cylinder. In the case of a composite block where a cylindrical core of different material is embedded, the level of fracturing and fragmentation is controlled by the separation of the interface which in turn depends on the relative dimensions of the core and the block. The most important parameter is the ratio between the length of the pulse (space-wise or time-wise) and the characteristic dimensions of the models, i.e. in this case the dimensions of the core and the mantel. Stress wave superposition effects occur in the corner sections of the mantel. Theoretical results are in good agreement with recent experimental findings.     

Mechanism of loading on plates due to explosive detonation

This paper investigates the various mechanisms and parameters that are responsible for delivering impulse to a vehicle that is unfortunate enough to detonate a buried mine. Small scale tests are used to examine the effects of air blast or ejected sand in imparting impulse to a plate that is located above the surface of the saturated soil that contains the explosive. Parameters such as confinement, stand off distance, depth of burial of the explosive, density of the soil, and saturation level of the soil are also examined.     

Type Ia supernovae: An explosion in the regime of a convergent delayed detonation wave

The model of a presupernova’s carbon-oxygen (C-O) core with an initial mass of 1.33 M _⊙, an initial carbon abundance X _C ⁽⁰⁾ =0.27, and a mean rate of increase in mass of 5 × 10^?7 M _⊙ yr^?1 through accretion in a binary system evolved from the central density and temperature ρ_c=10⁹ g cm^?3 and T _c=2.05 × 10⁸K, respectively, by forming a convective core and its subsequent expansion to an explosive fuel ignition at the center. The evolution and explosion equations included only the carbon burning reaction ¹²C+¹²C with energy release corresponding to the complete conversion of carbon and oxygen (at the same rate as that of carbon) into ⁵⁶Ni. The ratio of mixing length to convection-zone size α_c was chosen as the parameter. Although the model assumptions were crude, we obtained an acceptable (for the theory of supernovae) pattern of explosion with a strong dependence of its duration on α_c. In our calculations with sufficiently large values of this parameter, α_c=4.0 × 10^?3 and 3.0×10^?3, fuel burned in the regime of prompt detonation. In the range 2.0×10^?3≥α_c≥3.0×10^?4, there was initially a deflagration with the generation of model pulsations whose amplitude gradually increased. Eventually, the detonation regime of burning arose, which was triggered from the model surface layers (with m ? 1.33 M _⊙) and propagated deep into the model up to the deflagration front. The generation of model pulsations and the formation of a detonation front are described in detail for α_c=1.0 × 10^?3.     

初动在核爆监测中的应用及分析

核爆炸与地震相比,围绕爆炸源的初动具有更多的向上记录和更高的振幅周期比,初动可以作为核爆与地震的一个识别标志。某些核爆炸的向下记录。或许是由于低信噪比的原因,记录到的是初至波的第二个半周;其余的也许是由于近P波走时曲线的反射波造成。     

西太平洋副热带高压中期变化的数值试验 Ⅱ.热带西太平洋热源的作用

用一个全球谱模式作数值试验,研究了１９７９年６月中旬一次西太平洋副热带高压西伸北进的中期天气过程中热带西太平洋地区理想热源的作用。结果表明：理想热源的作用大约在４天以后可以影响我国东部的副热带高压和中高纬度的环流;理想热源在热带洋面上产生的扰动首先沿副高南边的东风气流向西北方向传播,到中纬西风带后分为两支,一支继续向西北方向传播,另一支转向东北偏东方向传播,两支扰动的共同作用,导致了副热带高压和西风带环流的变化。     

高产水稻理想株型的灰色关联度分析

应用灰色关联分析方法 ,分析了 6个水稻品种 2 1个株型性状对单株产量的影响。结果表明 :单株产量与 2 1个株型性状的关联序依次为 :剑叶厚 >倒二叶厚 >剑叶宽 >倒二叶宽 >倒二叶鞘长 >剑叶鞘长 >倒二叶弦长 >倒三叶宽 >倒三叶厚 >倒三叶鞘长 >剑叶长 >倒二叶长 >倒三叶长 >剑叶弦长 >倒三叶弦长 >倒三叶基夹角 >倒三叶叶开角 >剑叶叶开角 >剑叶基夹角 >倒二叶基夹角 >倒二叶叶开角。     

Characteristics of the Seismic Waves from a New Active Source Based on Methane Gaseous Detonation

Active seismic sources are critical for obtaining high resolution images of the subsurface. For active imaging in urban areas, environment friendly and green seismic sources are required. In present work, we introduce a new type of green active source based on the gaseous detonation of methane and oxygen. When fired in a closed container, the chemical reaction, i.e. gaseous detonation, will produce high pressure air over 150MPa. Seismic waves are produced when high pressure air is quickly released to impact the surroundings. The first field experiment of this active source was carried out in December, 2017 in Jingdezhen, Jiangxi Province, where a series of active sources were excited to explore their potential in mine exploration. In current work, we analyzed the seismic waves recorded by near-field accelerators and a dense short-period seismic array and compared them with those from a mobile airgun source, another kind of active source by releasing high pressure air into water. The results demonstrate that it can be used for high resolution near surface imaging. Firstly, the gaseous detonation productions are harmless CO₂ and water, making it a green explosive source. Secondly, the dominant seismic frequencies are 10-80Hz and a single shot can be recorded up to 15km, making it suitable for local structure investigations. Thirdly, it can be excited in vertical wells, similar to traditional powder explosive sources. It can also act as an additional on-land active source to airgun sources, which requires a suitable water body as intermediate media to generate repeating signals. Moreover, the short duration and high frequency signature of the source signals make it safe with no damage to nearby buildings. These make it convenient to excite in urban areas. As a new explosive source, the excitation equipment and conditions, such as gas ratio, sink depth and air-releasing directions, need further investigation to improve seismic wave generation efficiency.