Researchers from the National Institute for Occupational Safety and Health (NIOSH) are developing a coal pillar rib rating (CPRR) technique to measure the integrity of coal ribs. The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs. The CPRR utilizes four parameters: rib homogeneity, bedding condition, face cleat orientation with respect to entry direction, and rib height. All these parameters are measurable in the field. A rib data collecting procedure and a simple sheet to calculate the CPRR were developed. The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth. CPRR calculations were conducted for 22 surveyed solid coal ribs, mainly composed of coal units. Based on this study, the rib performance was classified into four categories. A preliminary minimum primary rib support density (PRSD) line was obtained from these surveyed cases. Two sample cases are presented that illustrate the data collection form and CPRR calculations.

美国国家职业安全与健康研究所（NIOSH）的研究人员正在开发一种煤柱肋骨等级（CPRR）技术，以测量煤肋骨的完整性。CPRR表征肋骨成分，并评估其对煤肋骨固有稳定性的影响。CPRR利用四个参数：肋骨均匀性，铺垫条件，相对于进入方向的面防滑钉方向以及肋骨高度。所有这些参数都可以在现场进行测量。开发了肋骨数据收集程序和用于计算CPRR的简单表格。所开发的CPRR可用作地下煤矿中的肋骨质量测绘工具，并确定与覆盖层深度相关的局部肋骨不稳和支撑要求的潜在可能性。CPRR计算是针对22个被调查的实心煤肋进行的，主要由煤炭单位组成。根据这项研究，肋骨性能分为四类。从这些调查的病例中获得了初步的最小初级肋骨支撑密度（PRSD）线。给出了两个示例案例，这些案例说明了数据收集形式和CPRR计算。