An interpretation of ground movements recorded during construction of the Donkin-Morien tunnel

A tunnel excavated by a tunnel boring machine was monitored extensively by means of extensometers installed near the tunnel face. Consequently, the three-dimensional state existing at the time of installation must be considered for the interpretation of the monitoring data. Results from three-dimensional finite element simulations are used to back-calculate rock mass strength and deformation properties. The purpose of this study was to establish and test various approaches of back-analysis. Results are compared with field and laboratory measurements. On the basis of these analyses, the paper provides guidance on how field data can be used for back-analysis purposes even when the ground behaves in a nonelastic manner. Key words: tunnelling, monitoring, tunnel boring, back-analysis, nonlinearity.