Abstract: Abstract: The parameters designation of roadside backfill body is the key to control surrounding rock in gob-side entry retaining. Among which strength and width of backfill body are the main influencing factors. Yangdong Mine is chosen as the analysis object in this paper,through theoretical calculation, the most reasonable strength grade of backfill concrete is determined to be C20. FLAC3D numerical simulation software is used to study the deformation law of surrounding rock in different width of backfill body, and the optimal width of backfill body is determined to be 1m. Field practice shows that the two-sided displacement and convergence between roof and floor are all in the controllable range after using this design parameters to build roadside backfill body, which verifies the rationality of the parameter designation.

Key words: Key words: thin coal seam, gob-side entry retaining, roadside backfill, numerical simulation