Influence of Air Overpressure induced by Blasting Excavation of Phase Ⅱ Diversion Upper Horizontal Adit of Meizhou Pumped Storage Power Station on Accident Gate

Air overpressure generated from the blasting excavation may affect the safety of surrounding structures. The blasting operation area of the horizontal tunnel of the second phase of Meizhou Pumped storage power station is only 81 m away from the steel accident gate of the upper drainage tunnel of the second phase project, which has been built and put into the operation in the first phase. However, the blasting may affect the operation stable of the accident gate. Therefore, taking the blasting excavation of the horizontal hole above the water diversion of the second phase of Meizhou pumped storage power station as the object, the field monitoring of blasting air overpressure was carried out. The distribution rule of blasting air overpressure and its influence on the safety of the emergency gate in the upper reservoir of Meizhou pumped storage power station were analyzed, which provided support for analyzing the influence of blasting air overpressure on the safety of the emergency gate in the upper reservoir. The blasting air overpressure monitoring data show that the air overpressure level in front of the accident gate about 80 m away from the blasting master surface is distributed at 0.63~3.46 kPa, which is much smaller than the suggested corresponding blasting safety control standard of 100 kPa. The protective facilities before the gate can effectively reduce the air overpressure at the gate position, and the measured air overpressure in the fourth and fifth blasting is reduced by more than 55%. When the single and total charge volume are effectively controlled, the measured air overpressure value is much smaller than the suggested control standard value. Besides, there is no abnormality in the field macro investigation and other detection data, the blasting construction does not affect the safe operation of the accident gate on the reservoir.