The National Institute for Occupational Safety and Health (NIOSH) conducted a comprehensive monitoring program in a room-and-pillar mine located in Southern Virginia. The deformation and the stress change in an instrumented pillar were monitored during the progress of pillar retreat mining at two sites of different geological conditions and depths of cover. The main objectives of the monitoring program were to better understand the stress transfer and load shedding on coal pillars and to quantify the rib deformation due to pillar retreat mining; and to examine the effect of rib geology and overburden depth on coal rib performance. The instrumentation at both sites included pull-out tests to measure the anchorage capacity of rib bolts, load cells mounted on rib bolts to monitor the induced loads in the bolts, borehole pressure cells (BPCs) installed at various depths in the study pillar to measure the change in vertical pressure within the pillar, and roof and rib extensometers installed to quantify the vertical displacement of the roof and the horizontal displacement of the rib that would occur during the retreat mining process. The outcome from the monitoring program provides insight into coal pillar rib support optimization at various depths and geological conditions. Also, this study contributes to the NIOSH rib support database in U.S coal mines and provides essential data for rib support design.

美国国家职业安全与健康研究所 (NIOSH) 对位于弗吉尼亚州南部的一个房柱式矿井进行了全面的监测计划。在不同地质条件和覆盖深度的两个地点进行矿柱后退采矿过程中，对仪表矿柱的变形和应力变化进行了监测。监测计划的主要目标是更好地了解煤柱上的应力传递和负荷脱落，并量化由于煤柱后退开采造成的肋变形；并检验肋地质和覆盖层深度对煤肋性能的影响。两个地点的仪器包括用于测量带肋螺栓锚固能力的拉拔测试、安装在带肋螺栓上用于监测螺栓中诱发载荷的称重传感器、安装在研究支柱不同深度处用于测量的钻孔压力传感器 (BPC)。支柱内垂直压力的变化，以及安装的顶板和肋板引伸计，用于量化在后退采矿过程中可能发生的顶板垂直位移和肋板水平位移。监测计划的结果提供了对不同深度和地质条件下煤柱肋支撑优化的深入了解。此外，这项研究还为美国煤矿的 NIOSH 肋骨支撑数据库做出了贡献，并为肋骨支撑设计提供了必要的数据。