Current theoretical studies of ground settlement induced by small radius curved tunnelling mostly consider the shield as a continuous whole and do not consider the effect of shield articulation. Therefore

the over-excavation gap caused by the change of excavation path of small curvature shield cannot be correctly evaluated. Firstly

based on the shield articulation position and the geometric position relationship between the shield and the small curvature tunnel excavation path

the calculation formulas were obtained for the over-excavation gap and articulated angle at different articulation positions of the shield machine during the excavation of the small curvature tunnel. Then

the mirror image method and Mindlin solution were used to solve the ground settlement caused by the combined effect of over-excavation ground loss

shield tail ground loss

excavation face uneven thrust

shield shell uneven friction and slurry pressure at the shield tail during articulated shield. Finally

engineering monitoring data were used to compare and verify with the theoretical solution of this paper

and good agreement was obtained. In addition

parametric analysis was carried out for the tunnel turning radius

front shield length

shield articulation angle and over-excavation gap. The analysis results show that ignoring the effect of shield articulation will overestimate the ground loss and result in large predictions of ground settlement. As the turning radius decreases

length of the front shield

shield articulation angle and over-excavation gap increases

the ground settlement increases

but the change of its value has a small effect on the settlement in front of the excavation face and a larger effect on the settlement behind the excavation face. Behind the excavation face

the longitudinal surface settlement tends to increase and then decrease as the distance from the excavation face increases

when the turning radius is taken to be small and the front shield length

shield articulation angle and over-excavation gap are taken to be large.