Long-term behaviour prediction of the Bangkok MRT tunnels using simplified finite-element modelling

Abstract

The existing Bangkok MRT Blue Line has been operating almost 10 years and its extension is now under construction. It is the first highlight underground construction project in Bangkok involving many excavations and tunnelling works. The long-term tunnel behaviour is identified by many influential factors such as the magnitude and distribution of excess pore pressure generated during construction, compressibility and permeability of soil as well as relative soil-lining permeability. This paper focuses on the long-term behaviour of the underground tunnels based on the finite element analysis. The work deals with the deformation analyses of the Bangkok MRT tunnels. The soil constitutive models adopted herein were the hardening soil model for soft and stiff clays and the Mohr-Coulomb for sand. The parameters selected were calibrated against the laboratory testing results. The short-term analysis results were calibrated and compared with the field measuring data during the construction phase. For long-term analysis, a coupled consolidation analysis based on Biot's theory was adopted. The long-term behaviours of the Bangkok MRT tunnels from the finite-element simulation were reported.