Abstract: It is important to evaluate the interaction between the twin large tunnels in close space to facilitate its economical and safe design and construction. The paper mainly involves the field monitoring on interaction between the twin large diameter slurry shield tunnels in close space—East Fuxing Road Tunnels across the Huangpu River. Firstly, it introduces the origin and background of the subject, the engineering situation. Then, it introduces the field monitoring including horizontal displacement of deep soil, settlements of ground surface and deep soil, three-dimensional displacements and deformation of the north tunnel, the water-soil load acting on the north tunnel, internal force of the north tunnel, the excess pore water pressure in soil. Through analyzing the field monitoring data, the rule that the constructing shield affects the settlement of ground surface, the displacement of deep soil, the excess pore water pressure, the displacement and deformation and internal force of the existing tunnel, are obtained. Obviously, the interaction is very more than estimated. And the actual internal force could be much than the adopted for the design.

Key words: close space, shield, tunnel, interaction