ABSTRACT
Constructing tunnels with branching structures is an effective way to build lifeline networks. To construct a tunnel having a T-shaped branch in a single operation, a branch shield method is adopted. A main shield carries a smaller shield, which can be launched from the main shield at a right angle to drive a branch tunnel. After the separation, the main shield and branch shield can be driven further and simultaneously to complete a T-branch tunnel. With this method, a starting shaft is can be saved at the branch, and the construction can be completed more quickly at lower cost with less impact on the surrounding environment compared to the conventional underground methods that require auxiliary measures. This report introduces an outline of the branch shield method and records of its past use.
