L'article suivant donne une description de la methode theorique pour le calcul du danger d'un soulevement du fond d'une fouille cadragee dans l'argile. Terzaghi et Tschebotarioff ont deja donne des formules pour un pareil calcul, mais ces formules ne sont valables que pour des fouilles de petite profondeur. Basee sur les formules de la capacite portante des fondations dans l'argile, une nouvelle solution du probleme de soulevement du fond a ete developpee. La profondeur critique d'une fouille est donnee par : D c = N c . S/γ ou s et γ sont respectivement la resistance au cisaillement et le poids d'unite de l'argile, N c etant un coefficient sans dimension et dependant de la forme de la fouille, c'est-a-dire de la proportion largeur-longueur et de la proportion profondeur-largeur. Les valeurs de N c , identiques aux valeurs donnees par Skempton (1951) pour la capacite portante, sont montrees graphiquement dans la Figure 2. La validite de ces formules a ete examinee par comparaison de quatorze fouilles. Dans sept de ces fouilles, un soulevement total du fond a eu lieu, les coefficients theoriques de securite donnant comme valeur moyenne de 0,96. Quatre fouilles, ou on constatait un soulevement partiel du fond, ont fourni une valeur moyenne des coefficients theoriques de securite de 1,11. Les trois dernieres fouilles ont ete accomplies sans evenement speciaux, mais des observations sur place indiquaient que, avec une profondeur agrandissante, on aurait du craindre un soulevement du fond, la valeur moyenne des coefficients theoriques de securite etant de 1,08. Les resultats obtenus ci-dessus montrent, ainsi, que la methode decrite nous permet d'estimer avec une precision suffisante le danger d'un soulevement du fond d'une fouille dans l'argile, et que la methode suffit pour la plupart des usages pratiques.

Stability of strutted excavations in clay

Experimental investigation of mechanical characteristics for linings of twins tunnels with asymmetric cross-section

Stability analysis of the middle soil pillar for asymmetric parallel tunnels by using model testing and numerical simulations

Damage behaviors, prediction methods and prevention methods of rockburst in 13 deep traffic tunnels in China

Analysis of additional stress for a curved shield tunnel

Numerical analysis of ground displacement and segmental stress and influence of yaw excavation loadings for a curved shield tunnel

Influence of non-associated flow rule on passive face instability for shallow shield tunnels

An analytical model of loosening earth pressure in front of tunnel face for deep-buried shield tunnels in sand

This paper focuses on the ground settlement induced by the construction of a curved shield tunnel. Ground loss and construction loadings are the two factors causing ground settlement, and two corresponding analytical models were developed. First, the ground settlement due to ground loss was analyzed based on 3D image theory. The “integrative gap at shield tail” (IGST) and overcutting gap of a curved tunnel were considered. Second, the ground settlement due to construction loadings was analyzed by modifying Mindlin’s solutions. The additional thrust, frictional force, and grouting pressure were considered. Subsequently, a case study and a parameter analysis were conducted. Finally, the obtained solutions were compared with a classical analytical solution, numerical simulations, and monitored results. The proposed model could effectively predict the ground settlement induced during curved shield tunneling.

Mingju Zhang

Papers

Analysis of additional stress for a curved shield tunnel

Numerical analysis of ground displacement and segmental stress and influence of yaw excavation loadings for a curved shield tunnel

Influence of non-associated flow rule on passive face instability for shallow shield tunnels

An analytical model of loosening earth pressure in front of tunnel face for deep-buried shield tunnels in sand

Analytical solutions to ground settlement induced by ground loss and construction loadings during curved shield tunneling