Meikuang Anquan (Oct 2023)
Research of stress wave and crack propagation superposition effect of double-hole blasting in coal and rock mass
Abstract
Aiming at the problems of hole spacing and blasting scheme selection in coal rock loosening blasting construction, the distance between the holes in the fracture zone of the double hole blasting is calculated based on rock dynamics and blasting theory, and LS-DYNA is used to analyze the influence of stress wave and crack propagation superposition effect on the spacing of blasting holes and blasting plan in double hole blasting. The research results indicate that: when two holes blasting simultaneously and the spacing between the holes is 3.4 m (twice the crack radius of a single hole blasting), the crack areas between the holes cannot be fully connected; when the hole spacing is 2.5 m, the fracture zone between the holes can be fully penetrated; and in millisecond blasting, when the spacing between the blast holes is 3.4 m, due to the obvious secondary expansion of cracks in the crack area around the first blast holes under the superposition of stress waves in the later blast holes, the crack areas between the blast holes can be basically connected. However, when the spacing between the blast holes is 3.0 m, the crack areas between the blast holes can be fully connected and cover the entire range of the drill holes. When loosening blasting is carried out on the excavation surface on site, the spacing between blast holes should generally be less than twice the crack radius of a single hole blasting (approximately 70% of the estimated spacing between blast holes for simultaneous blasting and 90% of the estimated spacing between blast holes for millisecond blasting) to ensure the effectiveness of loosening blasting. Compared with simultaneous blasting, millisecond blasting can not only guarantee the blasting effect, but also reduce the number of holes and the amount of blasting materials, so it is the preferred blasting scheme.
Keywords
