Abstract: There are many problems of shield tunneling through railway station, i.e. limited space, no reserved hoisting holes on shield and insufficient clearance of station. As a result, a dismountable shield is adopted to cross underneath Cangsong Road Overpass of Liuxi StationNingbo Railway Station Section on Ningbo Metro Line No. 4. Firstly, the necessity of creative application of dismountable shield and the effectiveness of partitioning design of shield cutterhead are presented. And then the strength of shield cutterhead is studied by numerical simulation, and the stability of construction for pile cutting of dismountable shield is analyzed based on monitoring results of surface settlement. The results show that the disassembling scheme of 3 pieces (1 big and 2 small) of cutterhead can meet the requirements of the structural strength in the construction of pile cutting by shield. Finally, the settlement monitoring on the overpass deck pavement and ground surface is carried out with shield tunneling control. The monitoring results show that the final cumulative settlement values of the surface range from -5 mm to 2 mm, which do not reach the warning value, indicating that the settlement value is within a controllable range during the construction.

Key words: dismountable shield, pile cutting, construction control, numerical simulation, safety assessment