Abstract: To investigate the effects of grouting pressure, slurry properties, and grouting diffusion range on the model responses (surface settlement and ground loss) of shallow tunnels, an innovative model test device is developed. This device can simulate the variation of lining segment of the shallow tunnels during grouting. The device includes systems of tunnel convergence, loading-unloading, grouting, and sample preparation. The originality of this device is that the model lining can move freely in the vertical direction during the grouting process, which is more in line with the engineering reality. The experimental results show the following: (1) The slurry pressure evolution pattern under allowable tunnel displacement is different from that of conventional model with fixed conditions. To be specific, the peak value of the slurry pressure under the allowable tunnel displacement is about 5 times that under the conventional tunnel model with fixed conditions. (2) With increasing grouting pressure, a higher peak value of the slurry pressure is obtained and the surface volume loss rate is reduced by up to 0.71% in the present study. (3) With increasing grouting volume, the trend of the slurry pressure turns different and the ground loss ratio is reduced by up to 0.67%. (4) When using different grouting methods, the form of the slurry diffusion becomes different and the ground loss ratio decreases by up to 0.44%.

Key words: shield tunnel, grouting behind lining, slurry pressure evolution, surface settlement, model test