Reusing Fine Silty Sand Excavated from Slurry Shield Tunnels as a Sustainable Raw Material for Synchronous Grouting

Using the Nanjing Dinghuaimen Yangtze River Tunnel project as a case study, we proposed method to reuse excavated silty-fine sand by adjusting proportion of waste replace commercial sand. This would address issue recycling significant amount generated when slurry shield passes through stratum. Moreover, have evaluated grout indicators such density, fluidity, consistency, bleeding rate, volumetric shrinkage, setting time, and unconfined compressive strength examined how particle size distribution affected grout’s performance. The findings show that replacement ratio increases, rate gradually increase; meanwhile, shrinkage increases initially before decreasing; time decreases gradually; increasing. key factor altering performance is less than 50% weakening adsorption effect fine particles on water due increase in sand’s fineness modulus. When it greater 50%, tends be distributed nonuniformly fill voids between larger particles, thus contributing changes properties.