Coarse arches are a common issue in caving mines where large fragments are expected. These arches interrupt ore flow in drawpoints, decreasing available draw area, and also increasing the possibility of non-uniform draw, which can increase fine migration, mud-rush risk, and induced stress in the caved column. Moreover, hang-up removal is operationally complex and dangerous. The literature on gravity flow indicates that coarse arches are mainly influenced by the ratio between the rock fragments and the size of the opening and stresses, but some key variables have not been quantified. Here, the influence of fragment-size distribution and drawbell geometry on hang-up formation is analyzed through controlled laboratory experiments in a physical model. Results show that drawbell parameters, such as length, width and angle are relevant parameters in hang-up events. In particular, the ratios DL/d80 and DW/d80 as well as VDB/Vp are key to hang-up events, the probability of which will decrease when these ratios increase.

中文翻译：

---

拉铃几何形状对洞穴矿山应用中悬吊影响的试验研究

在预计会有大碎片的崩落矿山中，粗拱是一个常见问题。这些拱在拉拔点中断了矿石流动，减少了可用的拉拔面积，也增加了不均匀拉拔的可能性，这会增加精细运移、冲泥风险和塌陷柱中的诱导应力。此外，挂断移除在操作上是复杂且危险的。关于重力流的文献表明，粗拱主要受岩石碎片比例与开口大小和应力的影响，但一些关键变量尚未量化。在这里，通过物理模型中的受控实验室实验分析了碎片大小分布和拉铃几何形状对挂起形成的影响。结果表明，拉铃参数，如长度、宽度和角度是挂断事件中的相关参数。特别是DL/d80和DW/d80比值以及VDB/Vp比值是挂断事件的关键，当这些比值增加时，挂断事件的概率会降低。