Abstract In order to improve the effect of smooth blasting in tunnelling, this paper proposes the blasting technology with water bags in notched holes. It also analyzes the blasting effect based on the rock damage induced by radial decoupling charge and spaced charge, the blasting efficiency in radial and axial directions, the radial pressure on the hole wall and mark rate of perimeter holes at site, the rock fragmentation, and the overbreak and underbreak of the tunnel. The results show that: (1) The change of radial decoupling coefficient has an effect on the axial and radial blasting effects, and the change of spaced charge coefficient only has an effect on the axial and inter-hole blasting effects; (2) when Kd=1.25, rock damage is concentrated in zones between the explosive holes, and axial rock damage zones are relatively small; when Kd =1.75, excessive water bags would induce an energy dissipation, and the rock damage zones are smaller; and (3) the blasting technology with water bags in notched holes can produce smooth tunnel contour profile, with more finely broken rock mucks, and the optimal charging factors are Kr= 1.5 and Kd=1.5.
Abstract：
In order to improve the effect of smooth blasting in tunnelling, this paper proposes the blasting technology with water bags in notched holes. It also analyzes the blasting effect based on the rock damage induced by radial decoupling charge and spaced charge, the blasting efficiency in radial and axial directions, the radial pressure on the hole wall and mark rate of perimeter holes at site, the rock fragmentation, and the overbreak and underbreak of the tunnel. The results show that: (1) The change of radial decoupling coefficient has an effect on the axial and radial blasting effects, and the change of spaced charge coefficient only has an effect on the axial and inter-hole blasting effects; (2) when Kd=1.25, rock damage is concentrated in zones between the explosive holes, and axial rock damage zones are relatively small; when Kd =1.75, excessive water bags would induce an energy dissipation, and the rock damage zones are smaller; and (3) the blasting technology with water bags in notched holes can produce smooth tunnel contour profile, with more finely broken rock mucks, and the optimal charging factors are Kr= 1.5 and Kd=1.5.
.Numerical Simulation and Field Experiment of the Blasting Technology with Water Bags in Notched Holes[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(2): 150-158
2022, Vol. 59 