Abstract
Enlargement of shield tunnel for the connecting section, has been executed by NATM. In order to establish a safe and economical enlargement method, it is necessary to clarify the behavior of various supporting measures, such as shield segment, shotcrete and of course ground itself. However, it is very difficult to estimate their behavior during enlargement, because the supporting system changes along with the complicated enlargement process. Detailed field measurement and numerical analysis were carried out, and the behavior of supportings is discussed. Obtained informations are useful for the planning of further enlargement of shield tunnel.
