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.