ABSTRACT
We report the results of research concerning 163 concrete cores sampled in order to clarify the condition within tunnel concrete and to grasp the mechanism about the tunnel concrete fall in Osaka Municipal Subway. Formally, there are two methods, observation and sounding, to judge whether tunnel concrete parts fall. However, these two methods don’t clarify condition within tunnel concrete. Therefore, we adopted core sampling of tunnel concrete. We obtained the directions and depths of cracks and cold joints (joints separated by delayed concrete placing), the depth and size of honeycomb and void, the neutralization depths, alkali-aggregate reaction, and amount of salinity.
