Influence of building geometry on bending and shear deformations of buildings subject to tunnelling subsidence: experimental testing

Tunnelling-induced settlement damage to pre-existing buildings is a result of bending and shear deformations, which typically occur simultaneously. However, widely accepted methods to assess building damage caused by tunnelling subsidence focus only on the mode of deformation (i.e. shear or bending) that is assumed to govern the onset of building damage. Furthermore, building damage assessment methods typically relate the dominant mode of deformation to the length to height ratio, L/H, of the structure, while more recent research reported that facade openings significantly affect the dominant deformation mode. This paper presents a series of centrifuge tests that explore bending and shear effects on surface structures that are affected by a shallow tunnel excavation in sand. The tests were performed on 3D printed building models with varying L/H ratio and facade openings. The response of these building models to the ground movements caused by the tunnelling operation is monitored using digital image correlation (DIC). Results show that bending deformations increase with the L/H ratio while shearing becomes dominant as the amount of facade openings increases. It is also shown that shearing and bending occur simultaneously and therefore should be combined in future damage assessment methods. The obtained experimental results provide essential benchmark data for computational modelling of tunnelling-induced settlement damage on surface structures, as presented in the companion paper