Research on gradual optimization of slurry mixture ratio for shield tunnel backfill grouting based on fuzzy mathematics

Abstract

The grouting behind the shield tunnel segment is one of the key procedures in shield tunneling construction. It has a good effect in ensuring the stability of surrounding rocks, controlling the deformation of strata, and effectively inhibiting the floating of segments. The compatibility between the grouting slurry and the target stratum is the core factor affecting its function. This paper proposes a gradual optimization method that combines the fuzzy comprehensive evaluation method, the analytic hierarchy process, and the multiple regression analysis method. Taking the bleeding rate, setting time, 28-day compressive strength, initial fluidity, consistency, consolidation shrinkage rate, and density as evaluation indexes, this paper discusses the influence of different mixture ratios and their interactions on the comprehensive properties of the grouting slurry and determines the optimized mixture ratio of the grouting slurry. Finally, the self-developed experimental device is used to simulate the actual grouting process to verify the effectiveness of the optimization method proposed in this paper and the rationality of the optimization results. The specific values of the optimal mixture ratio of the slurry compatible with the target stratum are finally obtained as follows: water-binder ratio: 0.7, binder-sand ratio: 0.7, bentonite-water ratio: 0.23, and cement-fly ash ratio: 0.6. The optimization method proposed in this paper can provide a reference for selecting the appropriate slurry mixture ratio for strata with different engineering geological parameters.