Seismic Response of Tunnels in Soft Soil—Status and Future Prospects

For the safe functioning of tunnels, dynamic loading conditions, such as earthquakes, must be considered for design. The main idea here is to review tunnel responses under soft soil conditions and emphasize work done to date toward the seismic response of tunnels. Specifically, various parameters influencing tunneling, effects on tunnel structure, and ground failure due to seismic excitations are discussed. After that, a review of different closed-form solutions used for the transverse and longitudinal analysis of the response of tunnel structures is presented. Next is the study of various numerical models of tunnel systems with adjacent structures, both above and near the ground surface, like buildings, bridges, and buried pipelines. Here, the discussions are based on the different computational modeling procedures adopted by researchers and the effect of soil–tunnel structure interaction arising during seismic events. Subsequently, a review of interactions between underground tunnels and adjacent ground structures is also presented. The paper discusses the effects of segmental jointed tunnels under earthquake loads and the seismic vulnerability of tunnels. Finally, the article tries to stimulate ideas for new work in these areas for the researchers. Thus, emphasis is given to the identification of current gaps in understanding the seismic response of tunnels in soft soil.