Catastrophe stability analysis for shallow tunnels considering settlement

Abstract

Limit analysis of the stability of geomechanical projects is one of the most difficult problems. This work investigates the influences of different parameters in NL failure strength on possible collapsing block shapes of single and twin shallow tunnels with considering the effects of surface settlement. Upper bound solutions derived by functional catastrophe theory are used for describing the distinct characteristics of falling blocks of different parts in twin tunnels. Furthermore the analytical solutions of minimum supporting pressures in shallow tunnels are obtained by the help of the variational principle. Lastly, the comparisons are made both in collapsed mechanism and stability factor with different methods. According to the numerical results in this work, the influences of different parameters on the size of collapsing block are presented in the tables and the limit supporting loads are illustrated in the form graphs that account for the surface settlement.