US-France Cooperative Research: Damage and Localization in Rocks

Northwestern University, Evanston IL

Investigators

Abstract

0338463 Rudnicki This three-year award supports U.S.-France cooperative research on localization and damage in rocks. The U.S. and French investigators, John Rudnicki at Northwestern University and Yves Gueguen at the Ecole Normale Superieure in Paris, will conduct axisymmetric compression experiments on three rock types: sandstone (typical of hydrocarbon reservoirs), shale (being considered for the French nuclear waste repository) and limestone (to examine the effects of the calcite phase). In addition, the simultaneous measurements of elastic wave speeds will provide information about the relation of macroscopic stress strain behavior and the evolution of microstructural damage. These experimental observations provide the basis for modeling to predict both shear and compaction localization of rocks. The U.S. investigator brings to the project expertise in engineering and deformation of and failure of rocks. This is complemented by the French investigator's work in modeling transport properties of rocks. The onset and evolution of localized deformation remains a fundamental problem in understanding the behavior of the earth's crust. Localized deformation, in the form of faults and shear zones for example, control the mechanical strength of the crust and strongly affect the transport of fluids. The project will further understanding of mechanisms that produce weakening and eventually failure in geomaterials. This has implications for understanding faults in the earth's crust and the mechanics of earthquakes. The project is jointly supported by the National Science Foundation (NSF) and the Centre National de la Recherche Scientifique (CNRS). NSF provides support for visits to France by the U.S. investigator and students. The CNRS covers expenses for travel to the United States.