In the process of blasting operation, the shock waves, stress waves, and earthquake waves subsequently develop. Due to the existence of these waves, the internal structure of the rock mass is inevitably influenced. When the vibration velocity exceeds a critical value, it can induce the formation of internal cracks in the rock mass, thus causing potential harm to the structure protected . In some complicated geological conditions, the path of blasting excavation has limitation, and then the blasting source is close to some special protective structures which have strict requirements for blasting vibration. In such condition, to prevent the potential harm of internal crack formation resulting from the blasting vibration, the blasting excavation methods need to be optimized. Consequently, the optimized blasting method can be used to reduce blasting vibration in the complicated geological conditions, which provides reference for better application of the drilling and blasting method in the engineering construction.
When the phase II underground powerhouse is being excavated, to develop a certain width cracks in the position of predesigned contours, the presplit blasting is performed to buffer and reflect the blasting vibration waves, consequently, the damage to the retaining rock mass can be effectively controlled. The maximum vibration velocity of the phase I underground powerhouse is 0.22 cm/s in the presplitting blasting of deep hole. As to presplitting blasting of shallow hole, its maximum vibration velocity is 0.16 cm/s, and all of them are located at 6# set. Therefore, the presplitting blasting of shallow hole can be applied to effectively reduce the vibration velocity induced in the phase I underground powerhouse. 153554b96e