The strong rockburst disaster in deep tunnels is a difficult issue for the safety of excavation and the efficient application. The design of scientific blasting excavation has become an important technical means for the effective control of strong rockburst disasters. This paper conducts a aseries of numerical simulation and field tests involving the efficiency of the destressing blasting control on the strong rockburst disasters, based on the prevention and the control of frequent strong rockburst disasters with the increase of buried depth and in-situ stresses at diversion tunnels at Jinping Ⅱ hydropower station. The two destressing blasting schemes are demonstrated by numerical simulation. The one is to use twin-row inclined radial drillings in rock walls and the other is to apply vertical advance boreholes on tunnel faces. The results indicate that the relaxation zones appear at the left side wall blasting holes, the central part of the vault, the right side haunch and the spandrel blasting holes, after performing the scheme one. As for the method two, the extended range of relaxation zones occur in front of the tunnel faces by means of destressing blasting and release concentrated stress on tunnel faces. Based on the comparison of the Russenses Rockburst Discrimination Law, the two methods play an important role in the rockburst prevention and control effect. The intensity of rockburst after destressing blasting is reduced and occurs a strong rockburst, such as the left side of the wall between the bottom to the haunch, the right side of the wall ranging from the lower haunch to the vault, the left side of the spandrel and the right side of the bottom wall. Furthermore, the possibility of the rockburst occurrence on the face is also significantly reduced. Field test verification further demonstrates the feasibility and effectiveness of the rapidly released stress based on blasting pressure relief theory to prevent and control rockburst. In addition, the field tests analyze the advantages of the two schemes on blasting relief for preventing and controlling strong rockburst. Based on the comprehensive research and the field application, this paper proposes several rockburst prevention and control measures at diversion tunnels in Jinping Ⅱ hydropower station, which is benefit for the design and construction of blasting excavation in strong rockburst.
