Abstract:

The external load and response of main tunnel of a Tconnected shield tunnel on Ningbo Metro Line No. 3 are analyzed. And then the construction conditions during construction are studied, the external load and convergence deformation of main tunnel are monitored, and the structural internal force is calculated to obtain the structural response and its variation law of the main tunnel. The study results show that: (1) The construction process can be divided according to external load and structural system, and each working condition has obvious different response. (2) The internal forces of shield launching and receiving end are mainly affected by the shield jacking force and the external grouting load, which mainly affects the cutting side; the internal force increment during the cutting process reaches 10%～20%, and that induced by the grouting pressure reaches 50%. (3) The axial force increment of each ring and inner support is below 200 kN, the axial force loss caused by the breakthrough location can be shared by the remaining positions, and the breakthrough location does not require a special overload design.

Key words: shield method, field test, Tconnected tunnel, external load of lining structure, internal force response