Simplified Prediction Method for Ground Surface Displacement Caused by Full‐Process Excavation of Quasi‐Rectangular Shield Tunnels

ABSTRACT In order to explore the surface displacement law caused by the entire process of rectangular shield tunneling, the effects of the additional cutterhead thrust ( p 1 ) of the cutterhead, the shield shell friction ( p 2 ), the additional grouting pressure ( p 3 ) at the tail of the shield, and ground loss caused by the quasi‐rectangular shield tunneling were considered. The traditional integration method for the above four factors was simplified, and a simplified calculation method for surface displacement values was proposed. Based on the Zhengzhou Metro Line 8 project, the surface displacement values caused by each factor were calculated. The simplified method calculation values were compared and verified with the integration method calculation values and measured data. The influence of parameter changes on the accuracy of displacement calculation values and simplified methods was further analyzed. The results show that the surface displacement values calculated by the simplified method are in good agreement with the values calculated by the integral method and the measured data. The Poisson's ratio of soil ( μ ), the internal friction angle ( φ ), and the depth‐to‐diameter ratio ( H d ) are the main parameters that affect the accuracy of the simplified method. The conditions that need to be met to control the calculation error of surface displacement within 5%, 10%, and 20% are given, and the applicable working conditions of the simplified method are summarized.