Evaluation of ground loss ratio with moving trajectories induced in double-O-tube (DOT) tunnelling

This paper investigates the influence of moving trajectories on ground loss ratio (GRL) due to the double-O-tube (DOT) tunnelling method. DOT tunnelling has three moving trajectories: pitching, yawing, and rolling, which have different behaviours during tunnel construction compared with those from single circular shield tunnelling. These moving trajectories cause overexcavation during tunnelling. The calculation method of gap area between the DOT shield machine and linings is evaluated in this research. Based on the superposition concept, the modification equation of GLR is proposed, which takes both moving trajectory and grouting volume into consideration. A field DOT tunnelling case is analysed to determine the correlation between moving trajectories and ground settlement. The influence of tail grouting is discussed by adjusting the grouting volume in different periods. The finite element method is also employed by setting the modified ground loss ratio (GLR') as the contraction increment of linings. Results from both the measured and simulated settlements verify the reasonability of the proposed equation and the effect of moving trajectories on ground loss. Key words: double-O-tube tunnelling, modified ground loss ratio, finite element method, ground settlement. Cette recherche analyse l'influence des trajectoires en mouvement sur le rapport de perte aux terres (GRL) du a la methode de tunnelisation a double tube O (DOT). La tunnelisation DOT a trois trajectoires mobiles : le tangage, le lacet et le roulis, qui ont un comportement different lors de la construction du tunnel par rapport a ceux d'une tunnelisation a bouclier circulaire unique. Ces trajectoires mobiles provoquent une surexcavation lors du percement du tunnel. La methode de calcul de la zone d'ecart entre la machine de protection DOT et les revetements est evaluee dans cette recherche. Base sur le concept de superposition, l'equation de modification du GLR est proposee, qui prend en compte a la fois la trajectoire de deplacement et le volume de jointoiement. Un cas de tunnelisation DOT sur le terrain est analyse pour determiner la correlation entre les trajectoires mobiles et le tassement aux terres. L'influence de l'injection de queue est discutee en ajustant le volume de coulis a differentes periodes. La methode des elements finis est egalement utilisee en fixant le rapport modifie de perte aux terres (GLR') comme l'increment de contraction des revetements. Les resultats des reglements mesures et simules verifient le caractere raisonnable de l'equation proposee et l'effet des trajectoires mobiles sur la perte aux terres. Mots-cles: tunnelisation a double tube, rapport de perte modifie de la terre, methode des elements finis, tassement de la terre.
Introduction Shield tunnelling has been widely used in the construction of metro tunnels due to its advantages with respect to safety, reduced environmental disturbance, and increased construction efficiency (Lee and [...]