Research on Stability of Gateway Retained Along Goaf in Thin Seam with Hard Roof and Hard Coal

In order to solve high dfficult problem of the gateway retained along the goaf under the condition of the thin seam with hard roof and hard coal, taking Ji angjiawan Mine as a study object, a coordinative yield support was provided to the gateway internally and a compressive and yield combined support was provided to th e gateway sidewalls. A yield curve of a constant yield bolt (anchor) and a mixing ratio between the polymer yield swelling material and the compressive material was pro vided. With the analysis, a support with a 018 mm x2 400 mm yield bolt and a 017. 8 mm x 8 000 mm yield anchor was determined for the gateway internally and a sup port plan with 2 m wide polymer yield sweling material and the compressive material determined for the gateway sidewalls. The application results showed that the max convergence between the roof and floor and the two sidewalls of the gateway was 255 mm and 249 mm individually and a max convergence ratio of the gateway cross section was 1 5%, which could ensure the stability of the gateway retained along the goaf in the thin seam with hard roof and hard coal.