A case study of determining the safety threshold of blasting vibration for tunnel lining

摘要

A method for determining the safety threshold of blasting vibration velocity is proposed, which is based on dynamic response calculating, monitoring analysis, and statistical relationship between the safety evaluation and the peak vibration velocity (PPV) before and after blasting. The simulation results show that the PPV in the blasting frontside is obviously larger than PPV in the blasting backside. The maximum calculated PPV is 10.7 cm/s, and it shows a significant decreasing trend with the increase of rock mass classification index. By comparing the PPV and crack alteration on the lining before and after blasting, it is recommends that the safety threshold should be 10 cm/s for intact lining or B-grade cracked lining and the V-classified surrounding rock tunnel. Alternatively, if the lining crack grade falls between 1 A and B, then the safety threshold of the III-classified and IV-classified surrounding rock tunnel are recommended as 5 cm/s and 6 cm/s, respectively.