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Design and Application of Blasting Parameters for Presplitting Hard Roof with the Aid of Empty-Hole Effect

机译：空洞效应辅助预裂硬顶的爆破参数设计与应用

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摘要

Theoretical calculation and numerical simulation were performed to analyze the mechanism of rock fracturing between holes in deep-hole presplit blasting, crack evolution under the synergistic action of dynamic and static loads, and the mechanism of fracture movement guided by tangential stress concentration of empty holes. The pattern and characteristic zones of main and wing cracks across a cross section were identified. Combined with blast dynamics, the scope of stress-induced cracks around blast holes and the maximum length of secondary cracks induced by detonation gas was calculated. It was found that the initiation and extension of cracks were oriented predominantly along the line passing through the hole centers (LPTHC). Moreover, the maximum length of the tensile crack zone induced by reflected stress waves was obtained. The effects of emptyhole diameter and charge coefficient on crack propagation were analyzed, and the proper blast-hole spacing was determined. Later, a LS-DYNA(3D) blast model was used to illustrate von Mises stress propagation, strain variation, and evolution of main and wing cracks between holes. The scope of strain failure, fracture pattern, and crack characteristic zones in the rock mass was determined. The results demonstrate that the hole spacing, at 3.2 m, is reasonable. Furthermore, blasting parameters were determined for 8939 working face at Xinzhouyao Mine and then deep-hole blasting was implemented to presplit the hard roof. After presplitting, the working resistance of supports was significantly reduced, thereby achieving effective control on the hard roof.
机译：进行了理论计算和数值模拟，分析了深孔预裂爆破中孔间岩石破裂的机理，动静载荷协同作用下的裂纹扩展以及空孔切向应力集中指导的裂缝运动机理。确定了横断面上主裂纹和机翼裂纹的图案和特征区域。结合爆炸动力学，计算了爆破孔周围应力诱发裂纹的范围和爆炸气体诱发的二次裂纹的最大长度。发现裂纹的产生和扩展主要沿着穿过孔中心（LPTHC）的线定向。此外，获得了由反射应力波引起的拉伸裂纹区域的最大长度。分析了空孔直径和装药系数对裂纹扩展的影响，并确定了合适的爆破孔间距。后来，使用LS-DYNA（3D）爆炸模型来说明von Mises应力传播，应变变化以及孔之间主裂纹和机翼裂纹的演变。确定了岩体中的应变破坏，断裂模式和裂缝特征区域的范围。结果表明，孔距为3.2 m是合理的。此外，确定了新洲窑矿8939工作面的爆破参数，然后进行了深孔爆破以预裂硬顶。预分叉后，支架的工作阻力大大降低，从而实现了对硬顶的有效控制。

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  • 来源
    《Shock and vibration》 |2018年第8期|8749415.1-8749415.16|共16页
  • 作者

    Chen Baobao; Liu Changyou; Yang Jingxuan;

  • 作者单位

    State Key Lab Coal Resource & Mine Safety, Xuzhou 221116, Jiangsu, Peoples R China;

    China Univ Min & Technol, Sch Mines, Minist Educ China, Key Lab Deep Coal Resource Min, Xuzhou 221116, Jiangsu, Peoples R China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
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