Abstract: It is a new technique of mining with subsequent backfilling that the artificial false roof of reinforced concrete is in large exposure span and high stope height. However， the false roof of reinforced concrete costs high， so it is necessary to determine the reasonable parameters of strength， thickness， and reinforcement ratio of the false roof. In view of the technical features of the false roof with large exposure span and high stope height at high-stage subsequent backfilling stoping in a lead-zinc mine of Inner Mongolia， the mechanical models of false roof of reinforced concrete was simplified into thin plate and simply supported beams theory models， obtaining that the safety ratio of false roof of reinforced concrete increases in polyno-mials with the increase of the thickness of false roof of reinforced concrete. The laws between the strength of concrete， the safety ratio， and the thickness of false roof were revealed. Using economic reinforcement ratio theory and FLAC3D software， the optimum thickness of the false roof of reinforced concrete is determined as 1.5 m， the strength as 20.0 MPa ，and the reinforcement parameter as [?]25 mm×95 mm. The research result showed that the reinforced concrete false roof can be in a stable state under the action of its self weight and the upper filling body， which verify the reasonabilty of the thickness of the false roof and the reinforcement parameters. It guides the design of false roof of reinforced concrete in underground mine.

Key words: Subsequent backfill, Thickness of false roof with reinforced concrete, Theory of thin plates, Theory of simply supported beams, Numerical simulation, Economic reinforcement ratio