9416510 Kropp This project addresses the damage resulting from the 1994 Northridge Earthquake to houses built on fill slopes. "Wedge" fills are often used to form cut/fill level building sites on hillsides. Numerous houses build on wedge fills experienced substantial (though seldom catastrophic) damage as a result of the earthquake; this, in the absence of any apparent large-scale shear failure in the fill soils or building foundation materials, such as landsliding or bearing capacity failure. The damage appears to have resulted from a combination of differential ground shaking between the cut and fill portions of the building pads, and from shaking-induced settlement and lateral ground movements in the fill soils. A primary objective of the project is to document the seismic performance of "wedge" fills, especially recent fills constructed to modern standards. In order to gain further insight into the patterns of stresses and strains developed in the fills under earthquake excitation, numerical tools for dynamic response analysis of two-dimensional soil systems are used to model the behavior of typical "wedge" fill sections during the Northridge Earthquake. The validity of these analyses are verified by comparison with typical damage patterns observed following the Northridge event. Following completion of this work, promising mitigation schemes will be identified; such as the use of geosynthetic layers within the fills, the use of over-excavation and thick blanket fills at the top of the embankment, and the development of guidelines for setbacks of structures from the cut/fill interface. ***
