Assessment of Ground Movement for a Deep Excavation in Soft Marine Clay

This paper compares the results of finite element analysis of ground movements and measured ground movements during construction of immersed tube tunnel. The tunnel consists of three 102 m immersed tunnel (IMT) elements. The... [ view full abstract ]

This paper compares the results of finite element analysis of ground movements and measured ground movements during construction of immersed tube tunnel. The tunnel consists of three 102 m immersed tunnel (IMT) elements. The entrances to the IMT sections will be formed initially by a trough structure and then two 100 m cut and cover tunnels on each side of the river.
Tunnel site is located in the southern part of a River valley. Along the tunnel alignment there is a relatively homogeneous soft clay overlying bedrock. The soil behaviour in finite element models were described using hardening soil model with small strain stiffness (HS-Small). The input parameters of HS-Small model were calibrated against laboratory tests such as triaxial compression, triaxial extension, Oedometer and direct shear tests. Then, the calibrated parameters were used to predict the movements under loading and unloading of the soil during several construction phases.
Displacement and pore water pressure changes were monitored during the construction. The measured values were compared to the predicted displacements by finite element analysis. The monitored data showed a reasonable match with predicted displacements.