The Buoyancy of the Tunnel Segmental Lining in the Surrounding Filling Material and its Effects on the Concrete Stress State

Abstract Segmental lining is subject to significant upward buoyancy forces when a grouting material (slurry), initially fluid, adopted fill the gap between its external profile and wall of tunnel excavated with TBM machine. The analysis effects these important in order correctly dimension segmental avoid damage subsequent costly maintenance restoration actions. Given complexity behavior consisting rings circular joints that alternate longitudinal direction tunnel, specific numerical model has been implemented, adopting Finite Element Method (FEM). This able obtain development vertical displacements starting from tail, together bending moments shear induced inside it. developed assess risks breaking damaging concrete steel bolts are used connect at joints; therefore, it represents useful design tool for being also relation produced by appearance considerable around it, due presence fluid filling material. proposed was applied real case (Ningbo metro tunnel) allowed satisfactory results comparison calculated situ measurements. Some sensitivity analyzes on studied have made possible detect which influencing parameters greatest impact forces.