Discontinuous Deformation Analysis Method for Deformation Response of Hidden Resources in Collapse Area under Blasting Excavation

Aiming at the safety problem of hidden resources mining in collapse area of underground metal mines, the discontinuous deformation analysis (DDA) is used to address the deformation response of hidden resources in collapse area under blasting dynamic load. The calculation process of DDA method is stated using the minimization principle of potential energy and plane strain assumption. Meanwhile, free field boundary is inserted in the DDA model and the tangential free damper and normal free damper of boundary units are used to discuss the deformation response of blasting excavation after grouting reinforcement near the collapse area. Results show that the input wave in the DDA model is characterized by obvious hysteresis, and the wave propagation velocity computed considering the hysteresis is consistent with the measured results. Modelling results after excavation indicate that the deformation under the slip line of collapsed zone is clearly less than that above the slip line, which is consistent with the actual monitoring results after excavation. Moreover, the velocity amplification coefficient of monitoring points in the collapsed zone increases with increasing distance from blasting source. Therefore, it is reliable to introduce free-field boundaries and the free dampers of boundary units into the DDA model to study the deformation response of stopes at the edge of collapse area under blasting dynamic load. © 2020, Editorial Department of Journal of Southwest Jiaotong University. All right reserved.