Brief Introduction of Synchronous Grouting Model Test Based on Quasi-Rectangular Shield Tunnel

During the construction of quasi-rectangular shield tunnel, the pressure distribution around tunnel is important for effective synchronous grouting to support ground strata. Due to the special shape of quasi-rectangular tunnel, the grouting may silt up on the top of the segment, which influences the grouting fluxion and filling and leads to the non-uniform distribution of the grout. A large model test of quasi-rectangular tunnel was carried out to simulate the process of synchronous grouting. By measuring the grouting pressure and surveying the final grouting shape under different working cases, the pressure distribution in toroidal direction and changing law of grouting were analyzed. Finally, by measuring the displacements of different points in designated sections, the results of settlement and upheaval in different positions are analyzed. As a result, the grouting ratio of 6:4 (up:down) is the most effective one among the three cases designed in this experiment.