Design And Construction Of Tunnel Built By Shield Of Rectangular Cross Section

This is a detailed report of construction experience of a tunnel built by a shield of rectangular cross section with reinforced concrete segments. In case of tunneling by a rectangular shield, there were the following problems to be overcom by technical developments; (1) structural joints between segments, (2) complexity in erector handling, (3) exact steering operation of shield and perfect filling of tail void left around the lining erected. Such rectangular shape of cross section has various advantages comparing the conventional circular shape as follows; (1) effective utilization of excavated space, (2) greater overburden depth, (3) stability of lining against unbalanced earth pressure caused by neighbouring construction.