Three dimensional Numerical and Analytical Solutions of Limit Support Pressure at Shield Tunnel Face

Abstract:

The elasto plasticity finite element method was used to study the face stability of shield tunnel in three dimensional condition, the relationship between the limit support pressures and the tunnel depth to diameter ratio and soil strength was obtained. The limit support pressure was rewritten as the summation of cohesion, overlying surcharge load and soil weight multiplied by their corresponding influence coefficients. The varying characteristics of influence coefficients with the friction angle of soil and tunnel depth to diameter ratio were obtained. A comparison with the numerical results validated the 3D wedge limit equilibrium model. Results show that the influence coefficient of soil weight obtained from 3D wedge model agrees well with numerical results, while the influence coefficients of soil cohesion and surcharge load deviate from the numerical results slightly.

Key words:shield tunnel; face stability; limit support pressure; numerical simulation; limit equilibrium