Deformations and pore pressures in the vicinity of a precast, segmented, concrete-lined tunnel in clay

During construction of a 2.16 m diameter tunnel in a soft to firm clay deposit in Thunder Bay, Ontario, an initial array of instrumentation to provide data indicating overall performance and a second array to provide detailed spatial deformation and pore-water pressure distribution were installed. The tunnel lining consisted of unbolted rings composed of four trapezoidal, unreinforced concrete sections assembled within the tailpiece of the tunnel boring machine. This paper presents and discusses detailed observations of soil deformation, pore-water pressure changes, and total pressure on the lining obtained from the second array of instrumentation. The soil stratigraphy was similar to that at the first array and the data obtained are compared with the earlier data. Monitoring of the instruments is continuing and data from the first year of observations are presented.Lors de la construction d'un tunnel de 2.16 m de diam\ue8tre dans un d\ue9p\uf4t d'argile molle \ue0 ferme \ue0 Thunder Bay, Ontario, une premi\ue8re s\ue9rie d'instruments a \ue9t\ue9 install\ue9e pour obtenir des indications sur le comportement g\ue9n\ue9ral de l'ouvrage et une deuxi\ue8me s\ue9rie a \ue9t\ue9 install\ue9e pour mesurer en d\ue9tail la distribution des pressions interstitielles et des d\ue9formations. Le rev\ueatement du tunnel \ue9tait constitu\ue9 d'anneaux non boulonn\ue9s, form\ue9s par quatre sections trap\ue9 zoidales de b\ue9ton arm\ue9, assembl\ue9es \ue0 l'arri\ue8re d'une machine-tunnel. Cet article pr\ue9sente les observations d\ue9taill\ue9es de d\ue9formations du sol, de variations de pressions interstitielles et de contraintes totales sur le rev\ueatement, obtenues \ue0 l'aide de la deuxi\ue8me s\ue9rie d'instruments. La stratigraphie du sol \ue9tant semblable \ue0 celle pr\ue9valent \ue0 proximit\ue9 de la premi\ue8re s\ue9rie; les donn\ue9es obtenues sont compar\ue9es. On continue \ue0 faire le relev\ue9 des instruments, et les donn\ue9es relatives \ue0 premi\ue8re ann\ue9e d'observation sont pr\ue9sent\ue9es.Peer reviewed: YesNRC publication: Ye