ABSTRACT
The most important functions of the grout material injected to fill the void behind the segment rings in soft ground tunneling are to prevent the segment rings from settling downwards or floating upwards (generate a foundation), ensure overlapping of segment gaskets (minimize gasket rupturing), minimize surface settlement and prevent water ingress into the tunnel. In order to fulfill these functions, the tender documents require the grout material to provide certain physical and mechanical properties such as uniaxial compressive strength, gelling time, and sedimentation height. In this study, a theoretical method, which already exists in the literature, is proposed to estimate the short-term (~6 hours and ~12 hours) uniaxial compressive strength of the hardened backfill grout for tunnels passing through stable cohesive soils and soft rocks. In this method, loads acting inside the tunnel, elasticity properties of soil and segment ring and geometric properties of tunnel and segment ring are taken into account. The validity of the method is well verified by checking functionality of the two-component grout used in the Mahmutbey–Bahcesehir–Esenyurt Metro Project.
