ABSTRACT
A tunnel face tester (TFT exploration) is developed a forward facing exploration system based on reflection method elastic wave exploration using excavation blasting as a vibration source in mountain tunnel construction. In this study, an algorithm for estimation of velocity behind tunnel face is developed and implemented in this system. The algorithm is based on the ratio between the amplitude of forward going wave and reflecting wave. In addition, it was applied to the actual tunnel site, compared with the actual excavation results, and good results were obtained.
