Analysis on the excavation management system of slurry shield TBM in permeable sandy ground

Slurry shield TBMs with full-face mechanized excavation and active face support using slurry suspension are increasingly being employed for the construction of underwater tunnels. When tunneling in permeable sandy ground, the choice of suitable excavation management system and volume calculation method is extremely important to prevent security emergencies such as face collapse, water inflow and ground deformation. However, this subject has not attracted adequate attention in previous studies. Until now, there is still a lack of reliable methods to calculate geomaterials excavated from the tunnel face in permeable sandy ground. In the present study, shortcomings of traditional calculation method have been analyzed. Improved calculation method considering the effect of slurry filtration loss and ground water displacement has been proposed to evaluate the performance of excavation management system in permeable sandy ground. A case study of Sutong GIL Yangtze River Crossing Cable Tunnel has been carried out. The results indicate that the calculation error based on the improved method is smaller than that based on the traditional method. The improved method is much more suitable for permeable sandy ground.