Study on Construction Blasting Vibration Control and Effect of Space Coupling of the Large Cavern under High Crustal Stress

Taken extremely complex and specific underground chamber excavation of TBM assembly in Jinping Ⅱ Hydropower Station as the background, the research was done on construction blasting vibration effects and control technology in the large cavern under high crustal stress. Combined theoretical analysis with field trials and other methods, chamber controlled blasting program and its parameters of better control of blasting vibrations were set in regard with the geological conditions of TBM assembly chamber, cross-section shape and size, chamber body structure and sequence of construction methods. The blasting vibration test program under complex conditions and measuring points were arranged appropriately. The result is that the blasting vibration attenuation coefficient values and was 1.24 and 0.56. Practice shows that the impact of blasting vibration on rock and underground structures is lesser, therefore the chamber driving speed and construction safety can be ensured by the chamber controlled blasting technology for construction. The blasting vibration attenuation that is deduced from the practice can better reflect the effect of blasting vibration chamber: according to the correlation between dose and level distance of blasting, safe construction blasting can be guided. In addition, there is a greater relevance between blasting vibration control method, materials and strength of underground structures. As blasting dose is the same, with increased age and strength of concrete, its ability to withstand the intensity of blasting vibration is also increased dramatically.