Research Of Building Response To Tunnelling

The construction of underground tunnels in soft ground in urban areas involves the potentialfor ground movements caused by the tunnelling to aect existing surface structures. Masonrystructures are at particular risk of crack damage. Conventional empirical building assessmentsdo not fully capture all aspects of this soil-structure interaction situation. Numerical methodsare increasingly used for such problems. It is common practice in empirical and numericalmethods to model a building as an elastic beam in2D. The objective of this thesis is thedevelopment of a new approach to the numerical modelling of masonry buildings usingsurface beams in3D.In phase one of this project, fnite element analyses of elastic and masonry facades areundertaken and the traditional beam method of modelling them is assessed. New equivalentelasticsurface beams are developed, the properties of which account for the dimensions andopenings in facades which were found to infuence the response to settlements. Equivalentmasonry beams are also developed which have a constitutive model that accounts for thediferent response of masonry buildings in hogging and sagging. Timoshenko beams arechosen to model the facades and these beams were implemented into the OXFEM fniteelement program with full3D capability along with the new constitutive beam models.Example masonry structures were modelled in3D using the new surface beams in phase two.Tunnel construction was simulated under the buildings and the response of the beamscompared to a full masonry building model. Example analyses included buildings bothsymmetric and oblique to the tunnel. Results showed that the equivalent elastic beamsaccurately simulate full masonry building response in sagging regions. Parametric studies confrmed the choice of equivalent beam parameters and the impact of diferent relative stinesses.The equivalent masonry beams displayed the same good agreement in sagging but were lessaccurate in hogging.In phase three, fnite element models are used to compare ground movements and structuralresponse of buildings using the3D equivalent masonry beam method and observed data fromthe construction of the London Underground Jubilee Line Extension. The surface beamsshowed good agreement with the observed building responses in both sagging, where thebuilding response was essentially rigid and in hogging where a more fexible response wasobserved.