Probabilistic back-analysis of K0 and deformation properties of fine soils found in Line 2 of Santiago Metro, Chile

摘要

Field measurements were taken during construction of a double track tunnel for the northernrnextension of Santiago Metro Line 2 in Chile, between 2004 and 2005. The tunnel was driven through a thickrndeposit of a fine fluvial-lacustrine sediment, consisted mainly by silts and clays with low deformability, withrnconsistency moderate to high and with presence of isolated thin lenses of silty fine sand, gravel and volcanic ash.rnThe monitoring data made possible Bayesian updating of the coefficient of earth pressure at rest (K_0) and of therndistribution of soil deformability with depth, represented by a hyperbolic model that requires knowing the initialrntangent modulus (E_i). The back-analysed values for K_0 and modulus distribution with depth were different fromrnwhat was used for design of Line 2 and were incorporated into the design of the new Line 3 under constructionrnfor Santiago Metro.