Abstract: To provide theoretical basis to analyze the stability of the surrounding rocks in working face to recover the room mining standing pillars with backfilling, the rock mechanical structure consisting of backfilling materials and pillars has been researched by means of theoretical analysis and mathematical derivation. The results have shown that elastic foundation coefficient of pillars k p , compression ratio of backfilling materials φ, flexural rigidity of roof EI and load of the roof q are the key factors to control the stability of the pillars. Based on the elastic foundation beam theory, the deflection equation of the roof rock beam has been obtained; the calculation of the elastic foundation coefficient of pillars and backfilling materials developed; equations for calculation of the effect of compression ratio of backfill- ing materials on the press on pillars, roof subsidence and characteristics of stress distribution have been deduced; and in the end the assessing formula of pillar stability has been developed in the paper.

Key words: backfilling, room mining standing pillars, stability of the pillars, elastic foundation, compression ratio of backfilling material