Vibration Reduction Effect of Stepped V-Cut Blasting

The aim of this research is to study the vibration reduction effect of stepped V-cut blasting (SV-cut) in tunnel blasting. Firstly, the method for determining SV-cut blasting parameters are provided based on the rock millisecond blasting theory. Secondly, numerical computation models for both traditional vertical V-cut blasting (V-cut) and SV-cut blasting are established using the explicit dynamic finite element program LS-DYNA^3D. Finally, combined with numerical simulation results and engineering practice, in-situ contrast blasting experiments and vibration tests using both V-cut and SV-cut blasting were performed. The results of the study indicate that the peak Von Mises stress and compression damage range at the bottom of the cut cavity for SV-cut blasting are 1.64 times and 1.66 times larger than that for V-cut blasting, respectively, which results in a more complete cut cavity with SV-cut blasting. At the top and back side of the model, the vibration reduction effectiveness of SV-cut blasting is up to 11.53% and 22.45%, respectively; however, the vibration reduction effectiveness is only 0.21% at the lateral side. SV-cut blasting can not only enable perfect blasting drivage but can also reduce the vibration intensity induced by cut hole blasting by at least 30%.