Abstract: A tunnel in Shanxi Province is over two layers of the mined areas. Although the mined areas are filled and grouted, the deformations within the surrounding rock mass have occurred and its impact on the proposed tunnel construction has to be evaluated. This effects of the underlying two layers of mining extraction and backfill process are simulated by using three dimensional finite element to obtain deformation field of the rock mass above the mined cavern and the residual deformation of the same area after the backfill and grouting operation. Combined with numerical analysis results, test boring and geophysical survey information, the vertical deformation zones above the mined area and their dimensions can be divided: caving zone, fractured zone and transitional deformation zone. The stability of the tunnel construction in these zones can therefore be evaluated. 

Key words: Coal Mined Area, Tunnels, Global Stability, Three Dimensional Finite Element Analysis