| 摘要 |
<p>PROBLEM TO BE SOLVED: To make accurately evaluatable and predictable a slack in front of the facing of a tunnel. SOLUTION: In a method for predicting a slack, a plurality of electrodes 12 for measuring specific resistances are installed on a facing surface 10. On the facing surface 10, three horizontal lines 1-3 for installing the electrodes 12 are set, and the electrodes 12 are fixed and arranged at an equal interval on the horizontal measuring lines tracks 1-3. When the arrangement of the electrodes 12 is completed, the specific resistance of the rock bed of the facing surface 10 is successively measured. The specific resistance of the rock bed changes according to water content or the like contained in the rock bed. When there is a slack, the specific resistance at that part generally increases since a gap rate is extremely high as compared with a part without any slack. Therefore, by evaluating the level of the obtained specific resistance, the slack of the front geological features of the facing surface 10 can be predicted.</p> |
