ABSTRACT
In order to demonstrate the applicability of the proposed constitutive equation to back analyses for assessing the stability of tunnels from measured displacements, a physical model test was carried out. Excavation was simulated by reducing the airbag pressure systematically until collapse of the tunnels occurred. The objective of the back analysis is to determine the values of the anisotropic parameter that correctly simulate the deformational behaviour observed in the physical model tests. In order to verify the applicability of the constitutive equation proposed for back analyses, measured displacements around the two parallel tunnels in the physical model tests were used as input data for back analyses. The deformation of the pillar zone is well simulated with that observed in the laboratory model test. Considering these results, it can be concluded that back analysis based on the proposed constitutive equation is highly applicable to practical problems.
