EVALUATION OF TUNNEL FACE FAILURE USING X-RAY CT

The objective of this paper is to evaluate tunnel face failure using model test apparatus with X-ray CT scanning. First of all, a three dimensional face failure was visualized using the results of CT scanning and the failure mechanism in three dimensions was quantified. Then, in order to discuss on the scale effect of model test on 1G condition, a series of centrifuge model test were conducted. Based on the comparison of the results of centrifugal testing with those of CT scanning, it was convinced that the failure mechanism obtained from CT scanning was fairly acceptable to model the failure mechanism for the purpose of stability analysis. Then, a three dimensional model on tunnel face failure was proposed based on the CT results and the stability analysis on the tunnel face failure was conducted using the proposed model. Finally, it was a first time that the stability analysis was done based on a true three dimensional failure mechanism and it was convinced that the effectiveness of the proposed model was validated.