An experimental study of the isolation performance of trenches on ground-borne vibration from underground tunnels

This paper presents a study of the isolation performance of trenches on train-induced ground-bore vibration from underground tunnels. A series of model tests was conducted to perform the study. Both train loads and sinusoidal sweep loads were applied to the model tunnel invert by a shaker. The response of the soil at the surface of the ground was measured by accelerometers. Three types of isolation trenches, i.e., an open trench, an expanded Polystyrene (EPS)-filled trench, and a Duxseal-filled trench, were modelled in the experiment. The results showed that the open trench and the EPS-filled trench increased the dynamic response of the surface soil in front of the trench, but the Duxseal-filled trench had little effect on the dynamic response of the soil on the surface in this area. Although all three types of isolation trenches reduced the response of the soil behind the trench, the open trench and the Duxseal-filled trench were clearly more effective. The test results also showed that, as the excitation frequency increased, the vibration isolation trench was more effective in the near field. The effects of the width, depth, and position of an open trench on isolation performance also were examined in the tests.