The phenomenon of earthquake fault rupture propagation through overlying soils is quite complex and is not well understood at this time. An improved understanding would assist in siting and in designing critical facilities constructed in regions where soils overlie potentially active faults. For example, a number of earth dams have been constructed over potentially active faults. Furthermore, significant ground movements can occur on subsidiary fault planes several miles from the main fault rupture. The objective of this project is to develop improved models and analytical procedures, suitable for use by practicing engineers investigating the effects of a boundary displacement on overlying particulate media. This investigation integrates knowledge in the fields of geology, seismicity, numerical methods, physical modelling and geomechanics. Well-documented fault rupture case histories, and the results from small-scale model tests, can provide physical evidence of the mechanism whereby a soil mass responds to an underlying tectonic movement. The aim is to develop soil models, incorporating both pre- failure and post-failure soil behavior, for implementation within computational methods. This includes the development of three- dimensional procedures - which can be validated by the three-dimensional physical model tests - to study strike-slip fault movements. Given the inherent shortcomings in applying a continuum-based approach to the analysis of failure in a soil mass, discrete element techniques require further development. Another goal is to support the analytical procedures through an exploration of methods for characterizing critical soil properties, such as the hydraulic conductivity along newly-formed shear fractures in earth materials.
