Improving the utilization of non-renewable resources takes a crucial position in circular economy. Gob-side entry driving technology has been widely applied in coal mines in China, such as in the Shilawusu mine (Ordos City, Inner Mongolia), here considered as a case study due to its high safety and resource-recovery rate. However, at present the complexity of coal pillar utilization makes it hard to fully master the key technology for coal pillar size design, which leads to huge waste of coal resources. Based on theoretical calculation and numerical simulation, this study analyzed the basic mechanical structure of coal pillar and the characteristics of its weakening failure, providing theoretical reference for efficient recovery of coal resources. In general, results of this study can be helpful in pursuing the efficient, hence sustainable, development of mines with Gob-side entry driving technology.