Interaction of multiple tunnels has become more important in recent years due to an increase in number of tunnels constructed in urban areas. When investigating multi-tunnel interaction problems, previous studies mainly focused on circular tunnels. However, the influence of tunnel shape on crossing-tunnel interaction is still not fully understood. In this study, two sets of three-dimensional centrifuge tests were interpreted to investigate the interactions between perpendicularly crossing tunnels with different shapes of the existing tunnel (circular and horseshoe) in dry sand. To gain further insight into stress transfer in each test, three-dimensional numerical back-analyses were carried out using PLAXIS 3D. Unlike a conventional elastic-perfectly plastic soil model, the advanced hypoplasticity constitutive model with small-strain stiffness was adopted. Results from interaction tests of crossing tunnels are reported and discussed. The influence of tunnel shape on the multi-tunnel interaction is explained.
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