Limit Analysis of Stability of Twin Shallow Tunnels Considering Surface Settlement

Abstract

This work conducts the plane-stain stability analysis of unlined dual shallow-buried tunnel roof with considering settlement. By taking account of the nonlinearity of soils, nonlinear analysis with Power-Law failure criterion is conducted to describe the ground deformation around twin tunnels on the basis of the superposition technique. Due to the geomechanical difference between different parts of twin tunnels, analytical expressions of the two different shape curves which describe two different parts of neighborhood tunnels are obtained with the variation calculus, which are verified by numerical modelling. The dimensionless solutions for the stability number of twin tunnels are obtained by virtual work equations and also compared with those calculated by other collapse mechanisms. The stability number is derived to examine the effects of spacing between tunnels on the stability of tunnels. The parameter sensitivity analysis is carried out to explore the scope of failure soil block and the upper bound limit supporting load in twin tunnels.