Time-varying numerical analysis of mode in induction caving roof

New method for handling roof of emptied areas based successive mining is proposed, which is induction caving roof. The effect of induction caving roof is relative to the construct path, the mining method and the order of the induction caving. At the same time, the physical properties of mine and rock are nonlinear material properties (elastoplastic material). The system of induction caving roof is the nonlinear and the time-varying system, The FEM basic equations are built according to the theory of the time-varying mechanics. Then based the geology and the ore characteristic, the 2D FEM time-varying mechanical model is built in the testing stope of the Tongkeng Mine, the technology of the many steps is used to simulate the time-varying mechanical behavior, special the expanding of the plastic zone, the displacement and the safety factor in the tunnel to the two kinds mode of the induction caving roof. The effects are analyzed to the safety of the stope and the influences on the mine technology. The results show that it is advantage to induction caving roof, for which it is the technology the first pre-splitting blasting and the last forced caving. According to the results, it is proposed that the millisecond blasting between the first pre-splitting blasting bolts and the last bolts in the same time.