Influence of Small Radius Curve Shield Tunneling on Settlement of Ground Surface and Mechanical Properties of Surrounding Rock and Segment

Compared with straight tunnels, over-excavation occurs on the inner side of curved section during shield construction small radius and disturbance to ground surface mechanical properties surrounding rock segment are more severe. This paper establishes numerical models curve tunnels study characteristics deformation caused by excavation influence parameters settlement, deformation, force. The maximum error between simulation results measured settlement is 7.3%, which in good agreement. show that: (1) value tunnel appears inside section, decrease radius, increases, distance peak point center larger. (2) When smaller, lateral displacement moves farther side, range soil mass also wider. (3) Increasing heading face pressure grouting can reduce but should not exceed 350 kPa, 250 kPa. (4) stress