Stability analysis of surrounding rock and pillar design in roadway backfill mining method

Abstract

Over the past few decades, the low recovery of resource coupled with the strong strata behavior has plagued the development of mines in Western China. To address these issues, an emerging and innovative technology- roadway backfill mining method was proposed in this paper on the basis of the compressive properties of backfill materials. A rational composition for backfill materials is obtained and the roadway layout and the backfill mining technology of this method are presented. Once placed, the backfill materials together with the barrier pillar have to satisfy certain mechanical stability requirement to ensure a safe underground working environment. In this respect, a mechanical model of roadway backfill mining method was developed using statics analysis. Formulas for predicting roof subsidence above mined out area and the stress distribution in barrier pillar are obtained. Furthermore, an instability criterion of coal pillars is proposed. Combined with the specific geological and mining conditions of 3101 working face in Changxing Coal Mine, the current study showed that the width of backfill mining roadway to be 7.0 m, the width of unexploited coal pillar to be not less than 3.0 m, and the elastic foundation coefficient of backfill body to be not less than 1.5 × 107 N/m3.