Based on the field test of environmental vibration characteristics of subway tunnel millisecond delay blasting, considering the irregular characteristics of blasting load, a modified Davidenkov constitutive model based on asymmetric loading and unloading criterion is used to describe the dynamic nonlinear characteristics of the site soil. The transient air shock wave generated by the internal explosion on the surface of cylindrical blast hole is simulated by improving the Friedlander equation. And a three-dimensional refined finite element model of ground-blast-source system, involving the blast wave input and finite/infinite element coupling boundary, is realized. The effectiveness of the model method is verified by comparing with in-situ testing data. The environmental vibration features induced by 50 ms delay blasting and instantaneous blasting are numerically simulated.
It is found that millisecond delay blasting can not only effectively reduce the surface peak vibration velocity, but also significantly change the frequency spectrum characteristics of surface vibration. The frequency band of surface vibration produced by millisecond delay blasting is relatively concentrated, which has a significant effect on dispersing blasting vibration energy. Moreover, the main frequency of surface velocity response is higher, which is far away from the natural frequency of building structure, it can significantly reduce the structural vibration level of adjacent buildings caused by blasting construction. The research results reveal the vibration characteristics and vibration reduction mechanism of millisecond delay blasting environment, which can provide scientific basis and reference for blasting construction of subway tunnel in complex urban environment.