VIBRATION PROPAGATION OF TUNNEL BLASTING IN GRANITE AREAS

Qingdao is the typical granite region, which uses the drill and blast method to the excavate tunnel. Firstly, the article analyzes the measured blasting data of 3 work site which belong to Qingdao Metro Line 3 using field measurement and statistical analysis. The correlation between vibration velocity of surface and neighboring buildings and the frequency characteristics caused by blasting of blasting distance and dose were researched. The empirical formula including the above factors was concluded by regression analysis. The numerical modeling method was used to research the influence of blast to surface and neighboring buildings, and the simulate particle vibration data was compared with the measured by numerical simulation. The main conclusions are as follows：(1)with the increase of blasting distance, the maximum vibration velocity of surface particle decreases in the form of index attenuation.(2)the vibration frequency caused by blasting is distributing randomly with scaled distance, therefore it is unable to establish the mathematical model between them, and the dominant frequency mostly ranges from 20 to 70 Hz.(3)with the stories increase, the maximum vibration velocity of three-vectors has the magnifying trend. The maximum vibration velocity of the particle inside the building is generally less than the particle closing to the building exterior surface.