Evaluation of ground disturbance behavior during articulated shield tunneling on small radius curved routes in clays

Abstract

Current theoretical works on excavation-induced ground settlement in clays for small radius curve tunnels typically treat the shield as a continuous entity, neglecting the influence of the articulation device. Consequently, the accurate assessment of over-excavation effects resulting from changes in the small curvature shield excavation route is impossible. As regards the articulation and geometric relationship between the shield machine and tunnel excavation route, this paper develops formulae for calculating soil over-excavation amount and articulation angle at different positions during tunnel excavation. The clay soil settlement affected by multiple factors during the construction of an articulated shield is resolved via the mirror image method and Mindlin's solution, which takes into account articulation impacts. Additionally, the on-site monitoring data is utilized for comparison and verification with the proposed theoretical solution. It is demonstrated that the solution for small curvature excavation settlement involving the articulation effect achieves good conformance in predicting soil deformation. Finally, the parametric analyses are conducted to estimate the impact of the articulation device on the predicted ground settlement values in clay soil.