Centrifuge Modeling of Tunnel Excavation over an Existing Perpendicular Tunnel

Nowadays, tunnels are constructed in an increasing rate due to rapid development in urban areas. Consequently, soil-structure interaction problems due to tunnelling have become a major concern. Limited studies are conducted on twin tunnel interaction considering only two-dimensional tunnel excavation and simulating the effect of volume loss only. Therefore, the stress transfer mechanism caused by multi-stage tunnel advancement and weight loss on an existing tunnel was not fully understood. When a new tunnel is excavated above an existing tunnel, effect of weight loss caused by removal of soil weight inside the new tunnel lining should be considered. In this study, a three-dimensional centrifuge model test is conducted to investigate the effects of volume and weight losses on the interaction between perpendicularly crossing tunnels. Three-dimensional stress ground displacement, deformation of the existing tunnel and bending moment induced on tunnel lining are reported and discussed