Seismic Behaviour of Shallow Tunnelling Method Tunnels Accounting for Primary Lining Effects

The shallow tunnelling method (STM) is usually used to construct shallow tunnels buried in soft ground. It consists of primary lining and secondary lining (tunnel). In the seismic design of STM tunnels, it is usually assumed that the secondary lining (tunnel) is resistant to all seismic effects. However, the soil–primary–secondary lining system may generate complex interaction phenomena during ground shaking. Compared with the case where the primary lining is not considered, the existence of the primary lining alters the seismic response of the secondary lining (tunnel). The paper attempts to investigate this complex interaction, focusing on the response of the secondary lining (tunnel). The full dynamic time history analysis is adopted to investigate the interaction in the transversal direction. A case history of the Hohhot (China) arched STM tunnel buried in a stratified soil deposit has been analyzed. Two tunnel configurations for a two-dimensional plane strain model of STM tunnels in Hohhot are studied and compared, including a model with primary lining and one without primary lining. A numerical parametric analysis was conducted to elucidate critical response characteristics of STM tunnels. Salient parameters that may affect the dynamic response of the tunnel were studied, including the characteristics of ground motion, the characteristics of contact interface, the characteristics of the soil, and the characteristics of the tunnel lining. The response characteristics of the tunnel are compared and discussed, including horizontal acceleration, deformation mode, lining internal force, and lining damage. The results show that the primary lining has a significant influence on the magnitude and distribution of the seismic response, especially considering the nonlinearity of the soil and the nonlinear characteristics of the tunnel lining. The effect of primary lining on the seismic response is about 5%–35 %.