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One-step raise excavation with burn cut is a kind of technology which use the drilling and blasting method to excavate the raise quickly. Due to the limitation of the free surface in burn cut, determination of cut parameters such as the length of burden and diameters of empty hole and charge hole is important to achieve a good effect of cut blasting. Meanwhile, the choice of the cut model is also crucial to form a proper opening. In this study, a modified Holmquist-Johnson-Cook (HJC) model, in which the tension-compression damage model and tension-compression strain rate effect model are considered, is embedded in the LS-DYNA software to investigate the damage evolution of rock in cut blasting. A simplified numerical model of burn cut is built in the LS-DYNA. The numerical results indicate that there is a threshold value of the burden length to maximize the opening. The empty hole has the effect of transferring blasting energy, and the effect becomes more obvious with the increase of the hole size. Moreover, the linear charge density of the prime cut hole can affect the compression and tension damage. Further, the comparison among four typical burn cut models are conducted based on numerical results. It demonstrates that triangular prism cut and doliform cut, which have more empty holes arrangement surrounding the prime cut hole, are better than spiral cut and diamond cut that with less empty holes locating one side of the prime cut hole in terms of energy efficiency and damage zone control. [ABSTRACT FROM AUTHOR]

Numerical models of a deep and inverted-U-shaped roadway were established by a particle flow code (PFC2D), and four numerical tests were performed with different blasting locations. The dynamic response characteristics of the deep roadway under blasting disturbance were thoroughly analyzed. According to the failure patterns resulting from the simulations, the dynamic stability of the arch was stronger than that of the vertical wall. The effect of the blasting location on the blasting vibration was assessed, and the diffraction start region and diffraction end region of the stress wave were obtained. The radial stress wave and tangential stress wave around the deep roadway were obtained during the blasting. The results show that the diffraction start region and diffraction end region of the stress wave were related to the fluctuation of stress wave. The effect of depth on the dynamic stability of roadways were analyzed. The results show that the damage around the borehole will be inhibited in the deeper stratum, and the vicinity of the roadway are more prone to break in the deeper stratum. • The dynamic stability of the arch was stronger than that of the vertical wall. • The blasting vibration characteristics of surrounding rock are closely related to the blasting position. • The diffraction start region and diffraction end region of the stress wave are related to the fluctuation of stress wave. • High in-situ stress can weaken the dynamic stability of roadway but inhibit the damage of surrounding rock of a borehole. [ABSTRACT FROM AUTHOR]