An investigation of surface deformation after fully mechanized, solid back fill mining

The surface deformation after fully mechanized back filling mining was analyzed. The surface deformation for different backfill materials was predicted by an equivalent mining height model and numerical simulations. The results suggest that: (1) As the elastic modulus, E, of the backfill material increases the surface subsidence decreases. The rate of subsidence decrease drops after E is larger than 5 GPa; (2) Fully mechanized back fill mining technology can effectively control surface deformation. The resulting surface deformation is within the specification grade I, which means surface maintenance is not needed. A site survey showed that the equivalent mining height model is capable of predicting and analyzing surface deformation and that the model is conservative enough for engineering safety. Finally, the significance of establishing a complete error correction system based on error analysis and correction is discussed.