Residual coal pillars play an important role in mining the adjacent coal seam safely, managing the gobs and maintaining the stability of abandoned coal mines. The height to diameter ratio (H/D) affects the stability of residual coal pillars. In this study, uniaxial compressive tests of coal specimens with five H/D (2.0, 1.5, 1.0, 0.8 and 0.6) were performed, and the stress, strain and acoustic emission (AE) were monitored. Results show that the uniaxial compressive strength (UCS) and peak strain increase with H/D decreasing. An empirical equation is proposed to calculate the UCS based on the H/D. The AE activities during coal failure process can be separated into four periods. The span of quiet period and rapid decline period shorten with H/D decreasing. The smaller the H/D is, the more complicated the failure characteristics of coal will be. The failure form of coal with H/D of 2.0, 1.5, and 1.0 is primarily shear failure, while splitting failure along the axial direction is the mainly mode when H/D is 0.8 or 0.6. The initiation, expansion, aggregation and connection of micro-cracks can be reflected by the real-time spatial evolution of AE event points.

残煤柱对邻近煤层的安全开采、采空区的管理和废弃煤矿的稳定发挥着重要作用。高径比（H/D）影响剩余煤柱的稳定性。在本研究中，对具有五个H/D（2.0、1.5、1.0、0.8 和 0.6）的煤试样进行了单轴压缩试验，并对应力、应变和声发射 (AE) 进行了监测。结果表明，单轴抗压强度 (UCS) 和峰值应变随着H/D 的减小而增加。提出了一个经验公式来计算基于H/D的 UCS. 失煤过程中的AE活动可分为四个时期。静默期和快速下降期的跨度随着H/D 的减小而缩短。H/D越小，煤的破坏特性就越复杂。H/D为2.0、1.5、1.0的煤体破坏形式以剪切破坏为主，H/D为0.8或0.6时以轴向劈裂破坏为主。AE 事件点的实时空间演化可以反映微裂纹的萌生、扩展、聚集和连接。