Abstract: Discrete multi-freedom-degree dynamic response model of vertical gob group was developed. Based on structural modal， a new method analyzing gob group blasting response was presented. In combination with a typical engineering problem， verification and discussion were made for the method. Results indicate that the method can directly reflect gob group rock mass response law of displacement and velocity， and describe its blasting response characteristics. The results are in accordance with that of numerical simulation. For internal damping， rock mass vibration damping， the amplitude decays to zero gradually. Rock mass where the blasting loads act on has the strongest response strength. With an increase in the distance between rock mass and the blasting position， response strength of rock mass weakens. The method can greatly decrease computation time and increase calculation efficiency and it provides a new direction for dynamic response analysis of rock mass.

Key words: gob group, structural modal, dynamic response, model, blasting load