Performance Evaluation of Fiber Reinforced Concrete for Lining of Hydraulic Tunnels in Water Rich Sand and Gravel Formations
In order to improve the durability of concrete materials used for lining construction of hydraulic tunnels in sand and gravel bearing strata in water rich areas, steel fiber and polypropylene fiber were mixed as hybrid fibers, and the effects of single fiber and hybrid fiber addition on the mechanical and impermeability properties of concrete materials used for lining hydraulic tunnels were evaluated. The results showed that under the same mix ratio conditions, the larger the content of steel fibers and polypropylene fibers, the higher the relative flexural strength and impermeability of concrete specimens, while the compressive strength first increased and then decreased. The addition of hybrid fibers could better improve the mechanical and impermeability properties of concrete used for lining hydraulic tunnels, with a significant synergistic effect. Taking into account the compressive strength, flexural strength, and impermeability of the concrete used in the target project, it was recommended that the optimal dosage of steel fiber in the hybrid fiber was 40 kg·m-3 while the optimal dosage of polypropylene fiber was 4 kg·m-3. The research results suggest that the addition of steel fibers and polypropylene fibers can effectively improve the mechanical and impermeability properties of concrete structures used for lining hydraulic tunnels in sand and gravel bearing strata in water rich areas, thereby improving the quality of hydraulic tunnel construction.
Rich water areasHydraulic tunnel liningHybrid fiber reinforced concreteMechanical propertiesImpermeability performanceReunionComposite material