Experimental and numerical study on blast-induced rock damage and fragmentation under low temperatures

• Blast-induced rock fragmentation under different low temperatures is compared. • Fractal dimension of blast-induced low-temperature rock fragmentation is obtained. • Blast-induced damage of multi-gradient low-temperature rock is identified. • Different multi-gradient low-temperature rock blasting performances are analyzed. Low temperatures in cold regions have significant effects on rock blasting performance, e.g., blast-induced rock fragmentation. However, very limited study has explored the influences of sub-zero temperatures on blast-induced rock response. The present study employs experimental tests and numerical simulation to examine the damage and fragmentation of rock subjected to blasting under low-temperature conditions. The small-scale blasting tests of rocks at room temperature (i.e., 20 °C) and different low temperatures (i.e., from −10°C to −40°C) are first conducted to examine low temperatures’ effects on blast-induced rock fragmentation by using the three-parameter Generalized Extreme Value (GEV) function and fractal theory. The findings indicate that the average sizes of blast-induced rock fragments first increase and then fall as the rock temperature drops from 20 °C to − 40 °C, and the least uniform fragment size distribution is presented at −30 °C. Moreover, the numerical models of a full-scale deep borehole are established to examine the effects of different low-temperature gradient characteristics in rock mass on the damage and fragmentation of rocks caused by blasting. It is observed that the blast-induced damage of the multi-gradient low-temperature rock mass first decreases and then increases with rock depths approaching the ground surface. In addition, it is noted that rock damage and fragmentation induced by blasting can significantly differ with changing multi-gradient low-temperature conditions in a rock mass (e.g., different multi-gradient low-temperature ranges, multi-gradient low-temperature depths in rock mass, and numbers of multi-gradient low-temperature layers). The findings can be used as a reference for fine rock blasting design under low-temperature conditions.