Abstract: The laws of strata movement and surface subsidence during downward backfill mining of gently inclined medium thick orebody were studied. Typical exploration line profiles were numerically determined via FLAC3D. The river sand and cementing agent were adopted as the materials of the aggregate and barite powder to peform large-scale similar material model tests. The model test results were verified and analyzed via the numerical analysis software-3DEC. The results showed that the strata movement and surface subsidence can be effectively restrained by the method of backfill mining， and cause to the surface subsidence area to concentrate on the top of the orebody and move to the center of the orebody along with the downward mining process. It was also indicated that the mining of deep-buried orebody has less influence on the movement range of overlying strata than that of the shallow-buried orebody. The angle of strata movement and subsidence first decreased and then increased with the increase of the mining depth.The final settlement is mainly found to be cylindrical subsidence.

Key words: gently inclined medium thick orebody, backfill mining, strata movement, similar material, numerical simulation