Abstract
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.
Highlights
Because of the advantages of high efficiency, simple operation, and low cost, the drilling and blasting method has always been the main method in rock excavation engineering such as mining, tunneling, and underground space development
In the process of cut blasting, the prime cut hole takes the empty holes as the free surface and swelling space, so the corresponding burden rock is subjected to high degree of constriction [1]
The objective of this study is to analyze the relationship between cut parameters and damage zones by using the numerical simulation method
Summary
Because of the advantages of high efficiency, simple operation, and low cost, the drilling and blasting method has always been the main method in rock excavation engineering such as mining, tunneling, and underground space development. The cut parameters were optimized based on numerical results and verified by field tests These models have some inherent drawbacks, for example, the TCK model only considers the tension damage [14]. The damage evolution mechanisms of rock blasting have been studied by many researchers, little work has been conducted on the investigation of cut blasting For this case, Xie and Lu [23] investigated the influence of in situ stress on damage evolution to rock mass under the Swedish cut model; further, a burden optimization was conducted for burn cut in the deep tunnel. In order to study the influence of cut parameters that include the burden and the diameter of the empty hole and prime cut hole on rock damage evolution, a simplified cut numerical model is established in LS-DYNA. The blasting damage induced by gas pressure is not considered in this study
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