Roof Condition Characteristics Affecting the Stability of Coal Pillars and Retained Roadway

The stability of the retained roadway next to the coal pillar in the long-wall mining system is mainly affected by displacement and rock pressure of the roof rock layers of the coal seam. With the objective of forecasting negative impacts in underground coal mining, this article analyzes the roof structure of the coal seam to illustrate the mechanism that causes instability of roadway retained in different roof conditions. A computer program is then used to simulate and assess the instability of the coal pillars and roadways in various roof variations according to the geological and technical conditions of the Khe Cham mine #11 seam. The results show that lowering and rotation of the console of main roof seriously affect the stability of the protective coal pillars. Vertical stresses distribution on the coal pillar increases significantly when the thickness of the immediate roof rock is very thin and insufficient to fill the goaf. Therefore, corresponding to different roof conditions, there is an effective solution for coal pillar design and roadway support to ensure production safety. This article can be used as a reference to designate technical recommendations in similar geological conditions.