2.4　Construction Technology of Shield Arrival

Compared with the construction of interval tunnel，the arrival of shield has its particularity and importance.The work contents include：formation reinforcement，shield positioning and recheck and measurement of receiving tunnel position，portal treatment and installation of temporary sealing device of portal ring，installation of receiving base，etc.The specific construction flow chart is shown in Fig.2.24.This section takes Nanjing Yangtze River Tunnel as an example and introduces the above aspects.