Strata Behaviors and Roof Monitor of Room-and-Pillar System

Based on field observations and theoretical analyses, the characteristic of periodic caving of immediate roof and main roof in a room and pillar system was analyzed. The research shows that the first caving distance of main roof is larger in a room and pillar system than in a longwall system, and main roof also has the feature of periodic caving. Its strata behaviors are violent and affected by pillar robbing sequence. From the actual condition, the method combining the analysis of roof caving distance with the dynamic observation of roof was used in the monitor of roof stability and has obtained better effects in practice.