Study on the Influence of Blasting Construction of Double-Layer Superimposed Primary Support Arch Cover Method on the Surrounding Environment

To study the impact of blasting construction of double-layer superimposed primary support arch cover method, relying on the station construction project of Dalian Metro Line 5, the disturbance of blasting on high-rise buildings, surrounding strata, adjacent pilot tunnels and the arch structure is analyzed based on numerical simulation and field monitoring results. At the same time, research is carried out on the blasting excavation footage of pilot tunnels. The results show that there will be a certain "elevation amplification effect" (EAE) on high-rise buildings during the blasting construction using the method. The peak particle velocity (PPV) of adjacent tunnels decreases gradually with the increase of the distance from the explosion centers. For the adjacent pilot tunnel, the main influence area is within the range of - 5 to 5 m from the pilot tunnel face. For adjacent buildings, the main influence stage is within the range of - 2 to 2 m from the pilot tunnel face. Blasting operations significantly intensify the plastic yield of surrounding rocks around the station. Blasting excavation footage can be used as the optimization parameter in the construction process, and the blasting excavation footage of pilot tunnel 4 can be adjusted from 1.0 to 1.5 m. The formation of the arch structure composed of double-layer superimposed primary support and secondary lining effectively reduces the impact of rock blasting on the whole station and high-rise buildings.