Investigation on Tunnel-Induced Successive Surface Displacements during Construction Period at Shallow Depths in Shanghai Soft Ground

The capabilities to evaluate and control the ground movements due to tunneling are very important to ensure the safety of construction and to reduce the project cost. When a tunnel is constructed at shallow depths in soft soils, even small ground movements may cause detrimental effects to the nearby buildings, underground facilities and sensitive municipal pipelines. This paper introduces the successive surface displacements during the construction period due to a large-diameter (D) slurry shield tunnel, which was built at shallow depths in soft soils in Shanghai, China. Ground movements directly above the centerline of the tunnel were monitored before and after shield passage. Field observations showed that the ground response related closely to depths and deviated from those predicted by those empirical techniques. Moreover, it was observed that when the depth is low enough such as 0.75D, the machine's overall weight and its distribution are unneglectable factors to control the ground deformation.