Ph.D. Dissertation Front Matter

Abstract

The research described in this thesis investigated the soil deformation due to the interac­tion of two neighbouring buildings founded on soft clay. The study involved small-scale 1 g physical modelling in which mitigation of the interaction was studied by inserting a model sheet pile wall between two footings. The results were used to validate finite ele­ment analyses that were then extended to simulate a prototype of two buildings with raft foundations constructed on Singapore clay. In the physical models, two 100 mm wide strip footings were placed on a 200 mm thick bed of preconsolidated kaolin in a rigid chamber with a transparent front wall. Tests were conducted without a wall between the footings, with a 100mm long floating wall, and with a vertically restrained (fixed) 100 mm long wall. The footings were loaded in turn and the second footing was only loaded after the consolidation, due to loading on the first footing or subsequent wall insertion, was completed. The soil and footing displacements were photographed through the transparent chamber wall and measured using a combination of Particle Image Velocimetry (PIV ) and close range photogrammetry. A stiffer soil response was observed beneath the second footing than beneath the first. Some additional settlement of the first footing was induced by the loading on the second footing and this was not significantly mitigated by a floating wall. In contrast, with a fixed wall, the settlement of the footing was substantially reduced. Overall, the tilting in the tests with a floating wall was comparable to that in the tests without a wall. The tilting of the first footing, though not the second, was effectively mitigated when a fixed wall was used. Plane strain finite element analyses with the BRICK constitutive soil model were per­formed to simulate the physical models. In general, the observed behaviour patterns were well reproduced, although the finite element analyses tended to exaggerate the stiffness of the soil response under the second footing relative to that under the first when a wall was present. The simulated prototype comprised two 10 m wide, 800 mm thick concrete rafts sep­arated by 2 m resting on 40m of clay. The analyses were similar to those conducted for the physical model simulations. In addition to modelling the effects of installing a float-