Understanding the classification of rock mass blastability is an important basis for determining reasonable blasting parameters and improving engineering efficiency. Combined with the practice of bench blasting in Weijiamao mining area, the protodyakonov coefficient and the tensile strength of rock samples are obtained according to the engineering geological data of the mining area, on the basis of site investigation and sampling. The density and acoustic wave velocity of the rock samples on the exposed step surface are measured and analyzed by wax sealing density tests and acoustic wave tests. According to the four indexes obtained, the rock mass blastability in the mining area is studied based on the principle of weighted cluster analysis. The research shows that there are coarse sandstone, medium sandstone, fine sandstone, sandy conglomerate and argillaceous sandstone in the Wejiamao mining area. The density of the marl sandstone is the highest, which is 2.75 g/cm³. The density of the coarse sandstone is the lowest, 2.01 g/cm³, while the density of the sandy conglomerate, fine sandstone and medium sandstone lies between the marl sandstone and the coarse sandstone. In the acoustic wave test, the longitudinal wave velocity of the rock in the 1064 platform is the highest, which is 2.615 km/s, while that in the 1096 platform is the lowest, which is 2.029 km/s. According to the distribution of the rock samples at the corresponding platform, the blastability of the rock mass in Weijiamao mining area gradually decreases from 1112 platform to 1064 platform. Among them, the 1112 platform is mainly sandy conglomerate with a medium blastability. The 1096 platform is mainly coarse sandstone with an easy blastability. The 1080 platform is medium sandstone with a medium blastability. The 1064 platform is mainly composed of fine sandstone with a difficult blastability.

In deep hole bench blasting, the classification of rock mass under different geological conditions according to its blastability is the premise for determining and optimizing blasting parameters. It is of great significance to improve blasting efficiency and effect and reduce blasting costs. Combined with the actual blasting excavation of Changtan open-pit coal mine, relevant indexes of rock mass blastability classification were obtained through on-site single-hole blasting crater tests, rock mass acoustic wave tests and laboratory rock mechanical tests. Furthermore, the blastability of stripped rock mass in Changtan open-pit coal mine was classified and evaluated based on the combination weighting(CWM) and cloud model(CM). The results show that the blastability of gray-green coarse sandstone at the 1130 platform is grade Ⅲ(medium). The blastability of yellow-green medium sandstone at the 1115 platform is grade Ⅱ(more difficult to be broken by blasting). The blastability of purple-red sandy mudstone at the 1100 platform is grade Ⅰ(difficult to be broken by blasting). The blastability of purple mudstone at the 1145 platform is grade Ⅲ(medium).