Effect of Coagulant Materials on the Setting Time of Synchronous Grouting

In order to eliminate the unfavorable influence of the long setting time of ordinary synchronous grouting on the construction of the shield, a new type of synchronous grouting was formed by adding coagulant materials (AB materials) to the ordinary synchronous grouting. The influence of the amount of AB materials on the setting time of synchronous grouting slurry was studied to achieve the optimal proportion of the new synchronous grouting slurry. The microstructure of hardening synchronous grouting was observed by polarized light microscope,and the influence of AB on microstructure of synchronous grouting was analyzed. The common synchronous grouting slurry and the optimal proportion of new synchronous grouting slurry were applied to the right line of tunnel from the Yichao section of Hefei Metro Line 4. The results show that the setting time of synchronous grouting slurry with AB materials is greatly reduced, and the optimum dosage of each materials is 410 kg/m³ water, 220 kg/m³ cement, 330 kg/m³ fly ash, 850 kg/m³ sand, 60 kg/m³ bentonite, 20 kg/m³ A materials and 25 kg/m³ B liquid. The surface structure of hardening synchronous grouting is compact and its permeability is improved by adding AB materials. Compared with the common synchronous grouting slurry, the new synchronous grouting slurry can effectively reduce the floating amount of the shield segment by 70.5%.