Selection of backfill grouting materials and ratios for shield tunnel considering stratum suitability

In shield tunnel engineering, there is no uniform standard for the selection of backfill grouting materials and ratios. In this study, to facilitate the selection of a grout, the applications of grout types, materials, and ratios were summarized based on a statistical analysis of engineering cases. Through laboratory tests and range analysis, the relationships among the basic grout performance and ratios were examined. The reference values of the grout ratios and performance requirements in different strata were obtained using statistical methods and by regression analysis. The results showed that the grout type used in engineering is mainly a single-component grout; in strata with groundwater, the usage rate of modified grouts is significantly high. The singlecomponent grout ratio for clay is the most affected by groundwater; for all strata, the change in the B/S ratio is the most significant. The W/B ratio is the most important factor affecting the basic grout performance, and the demand for compressive strength varies the most in all strata.