The influence of geotechnical variability in the subsidence caused by urban tunnel excavation

Abstract

Initially, the subsidence geometry due to tunnelling is described using an empirical Gaussian function. Then, an analytical expression for estimating the displacement field is discussed, considering the effects of ovalization and pure contraction of the tunnel. The Random Field Theory is briefly introduced in order to characterize statistically the geotechnical parameters, taking into account the ground variability and its spatial correlation properties. Subsequently,two software tools are developed to analyze the settlements caused by tunnelling. The first one is based on the Monte Carlo method and is applied to statistical analysis of subsidence basins. The second one is based on the generation of spatially correlated random fields and allows assessing the influence of the ground spatial variability on the dispersion of surface settlements. Finally, the numerical results are compared with observational results from a real tunnel