The foundation pit of Longcao Road Station of Shanghai Metro Line 12 passes through beneath the viaduct of operating Metro Line 3

so that the pier located in the middle of foundation pit needs protection to ensure the safety of Metro Line 3. Based on the project above

the piers response of viaducts due to unloading is analyzed with combination of 3D numerical method

laboratory test and field test. It is shown that the piers in soft soil rises due to unloading

which agrees well with numerical estimation. The horizontal displacement of piers develops toward the unloading side with significant fluctuations during the process

and the final deformation is consistent with numerical simulation. Unloading leads to a slight loss of ultimate bearing capacity of piles

but it does not threaten the safety of viaduct. Upheaval of piers recovers partly under semi-surrounding unloading condition

and it does not recover under surrounding unloading condition.