Fragmentation controlled blasting

破碎控制爆破

基本信息

批准号：
14350529
负责人：
KANEKO Katsuhiko
金额：
$ 7.55万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350529/
关键词：
Blasting Rock fragmentation Fracture Mechanics Crack Fragment size distribution Stress wave Detonation gas Heterogeneous material

项目摘要

(1) The dynamic fracture process in Hopkinson's test was analyzed using proposed finite element method to verify the strain-rate dependency of dynamic tensile strength. It is clarified that the strain-rate dependency is due to the stress concentration and redistribution mechanism in the rock. The rock inhomogenety also contributed to the strain-rate dependency.(2)The fracture process in one free-face rock was analyzed to investigate the fracture pattern and its mechanism. It was cleared that the fracture process as well as the fracture pattern were affected by the applied pressure-rate. The transition between quasi-static and dynamic fracture process can be estimated by the non-dimensional time defined by the propagation velocity, the burden and rise time of the applied pressure.(3)A numerical simulation method, coupled the finite element arid the finite difference calculation, to analyze the multiple fracture propagation due to stress waves and the detonation gas is developed. It is c … More onfirmed that the detonation gas considerably affects the generation and propagation of the fractures and that he numerical gas-propagation velocity along the fractures approximately agrees with that obtained by the laboratory experiments. It is concluded that the gas velocity along the fracture in bench blasting is lower than the air sound velocity except for the vicinity of the blast hole.(4)A method to predict the fragment size distribution in bench blasting using numerical and image analyses was proposed. In this method, the fracture process in bench blasting was analyzed using proposed FEM and fragment size distribution was evaluated by the image analysis of FEM result.(5)Rock fragmentation in bench blasting was examined using proposed method and the influence of blast condition on fragmentation was clarified. It is recognized that the widely spaced blast pattern is effective to reduce the bolder in fragments. Furthermore, it is pointed out that the optimal fragmentation in the field with respect to delay time depends strongly on the gas flow through the fractures caused by the stress wave. Less

(1) 采用所提出的有限元方法对霍普金森试验中的动态断裂过程进行了分析，验证了动态抗拉强度的应变率依赖性，阐明了应变率依赖性是由于岩石中的应力集中和再分布机制造成的。岩石的不均匀性也导致了应变率依赖性。(2)分析了一种自由面岩石的断裂过程，研究了断裂模式及其机制，明确了断裂过程和断裂模式受到影响。由准静态和动态断裂过程之间的转变可以通过由传播速度、载荷和施加压力的上升时间定义的无量纲时间来估计。(3)一种数值模拟方法，耦合了建立了有限元和有限差分计算方法，分析了应力波和爆轰气体引起的多重裂缝扩展，证实了爆轰气体对裂缝的产生和扩展有很大影响，并进行了数值模拟。沿裂缝的气体传播速度与室内实验得到的结果基本一致，得出的结论是，除炮孔附近外，沿裂缝的气体速度低于空气声速。(4)A。提出了利用数值和图像分析预测台架爆破中破片尺寸分布的方法。该方法利用所提出的有限元法分析了台架爆破中的破片尺寸分布，并通过有限元结果的图像分析来评估破片尺寸分布。(5)台架爆破中岩石破碎程度使用所提出的方法进行了检查，并阐明了爆炸条件对破碎的影响，人们认识到，宽间隔的爆炸模式可以有效地减少碎片的粗体，此外，还指出了现场的最佳破碎效果。时间很大程度上取决于应力波引起的通过裂缝的气体流量。