Coal mine roadway junctions in bord and pillar mining, in particular, are more vulnerable to roof fall due to the excavation induced stresses as well as general stress loading pattern inherent to the typical cross section achieved in practice. Roof fall incidences are generally more in junctions of development galleries and a cause of concern as they provide access to faces in different directions (dip/rise). The CMRI-ISM rock mass classification system, popularly known as Rock Mass Rating (RMR), is being used for the design of support system in underground coal mines for the last 30 years in India. In spite of the well-defined guidelines, it has been observed that roof failures are still a major concern in many underground coal mines. In this research, an attempt has been made to develop a new rock load prediction model for junctions of bord and pillar workings based on the geoengineering investigations carried out in 63 coal mines. After analysis of failure and stable cases, a best suited rock load predictor equation was developed. Analysis indicated that the maximum roof failure cases occurred for RMR values in between 30 and 45, and this zone is considered as highly unstable zone. Assessment of stable and unstable class is also done with respect to rock load for varied RMR. A general support design has also been suggested as per the RMR and severity of the roof fall. The suggested approach can help designing a rational support system for underestimated and overestimated zones thus minimising the roof fall cases leading to improved safety and productivity in underground coal mines.

由于开挖引起的应力以及实践中所实现的典型横截面固有的一般应力加载模式，特别是在博尔德和柱子开采中的煤矿巷道交界处更容易遭受顶板坠落的影响。屋顶跌落的发生率通常更多地出现在开发画廊的交界处，这是一个令人担忧的问题，因为它们提供了进入不同方向（倾斜/上升）的面的通道。在过去的30年中，印度使用CMRI-ISM岩体分类系统（俗称“岩体额定值”（RMR））来设计地下煤矿的支撑系统。尽管有明确的指导方针，但已经发现，屋顶破裂仍然是许多地下煤矿中的主要问题。在这项研究中 基于对63个煤矿进行的地球工程研究，已经尝试开发一种新的岩石载荷预测模型，用于博德和支柱工作交界处。在分析了故障和稳定情况之后，开发了最适合的岩石载荷预测器方程。分析表明，最大的屋顶破坏案例发生在RMR值介于30到45之间的区域，该区域被认为是高度不稳定的区域。还针对各种RMR对岩石载荷进行了稳定和不稳定等级的评估。还建议根据RMR和屋顶跌落的严重程度设计总体支撑设计。建议的方法可以帮助为低估和高估区域设计合理的支持系统，从而最大程度地减少屋顶崩塌的情况，从而改善地下煤矿的安全性和生产率。