Blast Performance and Its Assessment on Excavation Damaged Zone of Anisotropic Rock

Abstract:

The 290 level cave is situated in Nanfen Surface Mine, Liaoning, China. Nanfen surface mine is one of the biggest iron ore in Benxi Iron Company. The base line of the pit bottom has reached 346m level in Nanfen surface mine. The importance of in situ assessment of stability of the 290 level cave for next mining design and construction has been met. Investigation at the Nanfen Surface Mine has shown that damage exists around 290 level cave and that the damage develops from the energy imparted to the rock by the excavation method and by redistribution of the in situ stress field around the 290 level cave. Subsequent near-by excavations, removal of loose material from the existing cave and pore pressure changes will all influence the development and extent of rock damage, as does the rock type and its fabric. Based on the engineering characters and rock mechanics, the main characteristics of stress induced brittle failure of the site are introduced. Various evaluation and measures are sought to stabilize the over-stressed rock mass. The induced anisotropic damage process was modeled. The major results from numerical analysis of the cavern are presented and validated by direct comparison with actual monitoring data. Next, an optimization study was conducted with the experimentally validated and adjusted mathematical model, measured with a recorder within such a cave. And the stability of the 290 level cave in Nanfen Surface Mine was analysis. As a result, the model is expected to be a useful tool for simulation, design, and optimization of pasteurization tunnels. A suitable support measure was proposed and taken.