Abstract:

To investigate surface movement and deformation characteristics due to continuous mining and continuous backfilling (CMCB)of coal under artificial lakes, laboratory and field coring mechanical tests were conducted on the CMCB area to verify the feasibility of the filling body. Based on the equivalent mining height probability integration method, the surface subsidence of the CMCB area was predicted. The height of the water-conducting fracture zone was analyzed using numerical simulation, and its results were compared with those of the probability integration method. The results show that the strength of the filling body is 5.063 MPa, which is higher than the designed strength of 2.0 MPa, ensuring safe mining.Owing to continuous mining and backfilling in the area, the maximum inclination value of the surface was 0.3 mm/m and the maximum horizontal deformation value of the surface was -0.2 mm/m, respectively, which is less than the range of grade Ⅰ damage to brick and concrete structures. The surrounding surface subsidence was gentle, and there was no safety hazard. The height of the water-conducting fracture zone was about 49.7 m, and the distance from the waterproof layer was about 160.3 m, indicating the safety of underwater coal mining. Results of the FLAC^3D numerical simulation and probability integration method were close, thereby verifying that the CMCB technology can effectively slow down surface movement and deformation.

Key words: continuous mining and continuous backfilling, backfill, surface movement and deformation prediction, probability integration method, numerical simulation