Abstract: A model test system comprising a model rig and a noncontact measurement system is designed for investigating the deformation law of the stratum caused by tunnel construction. In this system, dry sand is used as a filler. The stratum deformation and settlement upon the tunnel, which is due to the invert arch deformation caused by a long stop time of shield, is simulated by motor towing. The results of investigating the settlement pattern of the stratum under various buried depths of the tunnel, stratum loss rates, and soil compactness conditions show that: (1) The failure modes of the stratum are roughly similar, but exactly similar to the shape of a funnel under various conditions; the ground settlement decreases as the distance from the tunnel increases, but the ground settlement curves under various conditions are consistent with the Gaussian distribution function. (2) The width coefficient of the ground settlement trough is related to the tunnel radius, shear strength parameters of soil, and buried depth of the tunnel. The modified formula of the settlement trough width coefficient is obtained by a quantitative analysis of the test results. Finally, the modified formula is compared with that in current research and the measured data to verify its reasonableness. In conclusion, the formula can be used to predict the ground settlement in sandy soil areas.

Key words: tunnel engineering, ground settlement, model test, particle image velocimetry technique, sliding angle