Optimization of the drilling-and-blasting process to improve fragmentation by creating of a preliminary stress in a blockKhalidilla Yussupov, Saifilmalik Myrzakhmetov, Khairulla Aben, Serhii Nehrii and Tetiana NehriiE3S Web Conf., 280 (2021) 08015DOI: https://doi.org/10.1051/e3sconf/202128008015