Abstract
The foci of this study are to examine and reduce bugholes on the sidewall of tunnel lining concrete. The experimental investigation prepared a tilting form to simulate the concrete construction, and examined the relation between the concrete angle and bugholes. Comparative tests, such as remover type, vibrating time and form materials, were conducted to confirm the reducing effect of bugholes. The test result shows that bugholes significantly increase in the case of 30 degree or greater. In addition, the fundamental behavior of air-bubbles was observed in the visible test using an acrylic plate. The observation confirms the process that plural small bubbles combine and generate large bugholes.
