Abstract:

In order to simultaneously get long distance and better precision of tunnel seismic prediction(TSP), the combined blasting method was adopted to ameliorate trigger modes of seismic signals in the TSP advanced geological preeiction. The empirical formula of the center distance between the trigger boreholes was brought forward.In addition, when the time delay errors of instantaneous detonators were  controlled under several micro-seconds or even several tenths of one micro second, and the measuring instrument was introduced to measure the  time delay error, the errors of seismic travel time information and geological predictions could be reduced. By means of the combined blasting method, seismic waves with the characteristic of both highenergy and high frequency, as well as long distance and better precision of predictions could be obtained at the same time. This method was successfully applied at the Yunwushan tunnel of the Yiwan Railway, and the Qiyueshan Tunnel and the Longtan tunnel of the Hu-Rongxi Expressway.

Key words: combined blasting, tunnel seismic prediction(TSP), seismic wave, advanced geological prediction, time delay error