AbstractDuring earthquakes, emergence of a fault rupture has always been a major threat to the safety of critical structures, as it is very difficult to predict the exact location and magnitude of the fault rupture. Until recently , work concentrated largely on the effect of faulting on lifeine systems (e.g. pipelines) and highways. Recent advancements in the field of fault rupture-infrastructure interaction revealed subtle interactions with surface infrastructure, esepcially for shallow foundations, and suggested that appropriate foundation design could protect buildings from significant damage.
The focus of this research is to imrpove understanding of the effects of earthquake fault propagation through soil and its interaction with shallow foundations. Physical modelling was carried out using the geotechnical centrifuge at the Universtiy of Dundee, where models of soil-foundation systems were subjected to reverse faulting. Fountainbleau sand was used in all the tests for its well-classified properties and a reverse fault with dip angle, a = 60º propagated upward through the soil interacting with the overlying foundation.
A series of free-field reverse fault tests were carried out, investigating the effects of soil depth on rupture propagation and the 'modelling of models' (grain size effects) during reverse faulting. The development of fault localisation through soil is observed to be progressive, gradually decreasing its dip angle while approaching the soil surface. Further tests were performed investigating the effects of foundation position on the interaction of a reverse fault with shallow strip foundation. The response of the foundation was found to be very sensitive to the exact position of the fault. For a fault throw of 4m, rotation varied between 1.1º and 15.1º in the strip foundation tests, which were otherwise identical except for their position. Further tests were performed investigating interactin of reverse fault ruptures and a single or row of rectangular shallow foundations. Isolated (widely spaced) foundations were found to be more vulnerable to damage than a closely spaced row of foundations. Single square footing tests show an increase in roation as the orientation changed from being parallel to 16º and 30º to the line of strike of the fault rupture emergence.
Reverse fault rupture propagation through soil and its interaction with rigid shallow foundations were successfully modelled in the centrifuge. The findings of the research have imrpoved the understanding of soil-structure interaction in near-fault zones and provided hope that structures with shallow foundations can be designed to withstand significant structural damage.
|Date of Award||2011|
|Sponsors||University of Peshawar|
|Supervisor||Jonathan Knappett (Supervisor), Ian Mackie (Supervisor) & Mark Bransby (Supervisor)|