| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a tunnel construction method which is not affected by geological conditions and is excellent in economic efficiency, and to provide a tunnel constructed by the construction method. <P>SOLUTION: A new tunnel 1 comprises a widened tunnel portion 4 constructed by widening an existing tunnel 3, and a branch tunnel portion 5 branching from the widened tunnel portion 4. The widened tunnel portion 4 comprises a first zone M whose cross sectional size is constant, and a second zone N whose cross sectional size becomes gradually larger. The branch tunnel portion 5 is constructed so as to branch from the inside of the widened tunnel portion 4 at a predetermined angle toward the deep portion of the natural ground E from a predetermined point 6 located at the end of the widened tunnel portion 4. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
