Investigation of dynamic effect on soil erosion and ground settlement due to tunnel leakage

Soil erosion and ground settlement are frequently observed due to leakage in in-service subway tunnels, posing significant risks to moving trains and the surrounding environment. In this study, the designated apparatus that allows circumferential joint leakage was manufactured and the moving train load was simulated. The evolution of soil erosion and ground settlement were investigated using model tests, and the effect of vibration loads on leakage was revealed. The prediction model was proposed considering both tunnel leakage and vibration load. Test results show that the evolution of tunnel leakage shows three-stage variation, and the locations of tunnel leakage exhibit different behaviors. Leakage at tunnel invert shows the most severe and unstable soil erosion, and the sand loss was two times that at tunnel crown leakage. The sand loss due to joint leakage increased by 30%–60% with the presence of moving train loads. The ground settlement due to tunnel leakage follows the Gauss's curve. Compared to no-vibration load, ground settlement increased by 10%–35%. A ground settlement prediction model considering tunnel leakage and subway vibration loads was proposed and validated using field data and test results. The findings provide important guidance for assessing soil erosion and ground settlement caused by shield tunnel leakage under moving train loads. • Train vibration is shown to accelerate joint leakage and soil erosion in shield tunnels. • Model tests quantify leakage-induced soil loss and its contribution to ground settlement. • A validated model predicts ground settlement under vibration-seepage-erosion coupling.