Numerical and experimental investigation of blasting damage control of a high rock slope in a deep valley

The disturbance of a rock mass due to blasting impact and stress redistribution can significantly affect the overall performance of an excavation. Crack formation during presplit blasting was analyzed with a mathematical model, considering the in situ stress. The results clearly indicate that the in situ stress can inhibit crack formation. The linear density of the explosive and blast hole spacing should be adjusted to improve crack formation. The damage distribution produced by different blasting approaches was reproduced with a numerical simulation based on the secondary development of LS-DYNA. The results demonstrate that the damage control effects of conventional presplit blasting or smooth blasting under in situ stress are not ideal. Owing to the combination of blasting load and stress redistribution, crack formation at the lateral sides was inhibited during presplit blasting, while the middle side could not be sufficiently broken during smooth blasting. An optimized method of presplit-smooth blasting was proposed and verified with numerical simulations. Finally, based on excavation of the Baihetan high rock slope, a comparison of the conventional and optimized approaches was conducted with sonic wave tests and roughness monitoring. The results demonstrate that the presplit-smooth blasting approach inherits the advantages of both presplit and smooth blasting, and could significantly improve contour control effects.