Abstract
Japan Highway Public Corporation has been gathering several data which measured or observed under tunnel construction by NATM, and the data have saved on the Data Base system since 1981. This study attempts to show the tendency of the rock mass behavior during tunnel excavation. Mean volumes of the deformation were shown and discussed for each rock mass condition and employed support. The accuracy of some regression models for the maximum displacement estimation using displacements in early stage after excavation of the working face is verified. Lastly, the possibility to predict occurrences of some accidents using displacements in early stage is discussed. In this study, the order statistic concept is employed in order to avoid influence of outliers in the data set.
