Numerical simulation of blasting at tunnel contour hole in jointe rock mass

摘要

Generally rock blasting is evaluated more economically and efficiently than mechanical excavation. But if damage zone gets large by poor blasting, the cost of reinforcement would be larger than mechanical excavation. Especially when blasting in tunnel, over-break affects tunnel stability, cost and terms of construction, therefore, blasting design is important to control over-break. The elements affecting rock blasting are drilling length and diameter, over-burden, the factor about explosive characteristic, rock mass strength and characteristics of discontinuity. Among them, the orientation and spacing of discontinuity are the most affectable factors for the failure of the blasting mechanism due to propagation of Shockwave and expansion of gas. In this study, simulation of tunnel contour hole blast is performed by using conventional program particle flow code 2 dimension (PFC2D) developed by Itasca Ltd.