Unified solution of earth pressure at the end of shallow buried shield at different driving angles

Abstract

This study develops a three-dimensional sliding block model for estimating average face pressure in shield tunneling, considering three distinct driving directions based on limit equilibrium theory. The sliding surfaces initiate from the horizontal planes at both tunnel sides. The geometric dimensions of the sliding blocks beneath both tunnel sides are correlated with the shield tunneling direction angle β. Through independent mechanical analyses of soil masses above and below the tunnel arch, equilibrium equations are established to obtain a unified solution for the average face pressure influenced by β. Comparative validation against existing horizontal shield tunneling data confirms the model's rationality and methodological validity. Results demonstrate significant correlations between face pressure and three key parameters: tunneling angle, depth-to-diameter ratio, and soil shear strength. At specific burial depths, different shear strength parameters exhibit varying influence intensities on face pressure. Particularly, face pressure vanishes when critical combinations of tunneling angle and shear strength parameters are achieved, indicating natural stabilization of tunnel face soil masses.

Keywords: 3D slider; Driving angle; Earth pressure at the end; Limit equilibrium; Unified solution.