Ground response to the construction of Shanghai Metro Tunnel-Line 2

This paper presents the results of a detailed field instrumentation program conducted on an Earth Pressure Balanced (EPB) shield driven tunnel for the construction of the Shanghai Metro Tunnel-Line 2 in China. A twin 6.2 m diameter precast, concrete-segmental tunnel system was constructed in a soft silty clay, which is compressible, sensitive, saturated and with low permeability. In order to study the response of the soft clay and the ground movement during and after the advance of the tunneling machine, the surface and subsurface ground displacements, pore water pressure changes, and earth pressure development around the concrete lining were monitored during construction. Based on the field results, the influences of tunnel construction control processes on the resulting ground responses are interpreted and discussed in this paper. Correlation between the ground response and surface settlement are developed taking into consideration the control factors in the excavation process as well as the grouting process. Particular attention is also given to the development of correlations between the construction control processes and the associated tunnel performance under both short-term and long-term conditions.