A simple application of probabilistic concepts as an indicator of tunnel face instability in sequential tunnels by settlement estimation
Many of sequential tunnels constructed in urban areas passes through areas where influence of excavation produces negligible consequences on near buildings or infrastructures. Under these circumstances major attention is given to the ground conditioning through a face stability analysis and too few is given to the settlements that the excavation might produce. The following paper is presented with the goal to provide an estimation of ground settlement to use as an indicator of tunnel face instability by a simple application of probabilistic concepts. Based on the classical Gaussian profile, a methodology for elaborating a settlement model that updates through monitoring measures is proposed. Basic probabilistic concepts are used to build the settlement model and also some directives for reliability analysis are indicated. Finally, a case study of a construction of a sequential tunnel for a metro system is presented in order to give a better understanding on the use of the present concept.