Geomechanical characterization of different lithofacies of the Cuitzeo ignimbrites

摘要

Volcanic rocks, especially ignimbrites exhibit complex mechanical behaviors due to their largernvariation in welding, porosity, textural and granulometrical characteristics. It is well known that the mechanicalrnproperties of rocks (mainly the uniaxial strength) are greatly controlled by variables such as grain and porernsize and their shapes. In order to understand such variations the authors combined field and laboratory studyrnof ignimbrites applying different analyses. The authors studied a well-exposed ignimbrite succession locatedrnat the southern edge of the Cuitzeo lake in Michoacán, México. The distribution of each ignimbrite lithofaciesrnwas spatially and temporally assigned, while only the most representatives ones were physical-mechanicallyrncharacterized. Strength, deformation, as well as the failure behavior of selected lithofacies were directly relatedrnto micro-textural and granulometrical characteristics by a series of uniaxial and pre- and post-failure nondestructivernanalyses, including ultrasonic pulse velocity and X-ray image tomographies. Results were comparedrnand evaluated allowing to explore the variation in the mechanical properties, directly related to the characteristicsrnderived from their diagenesis.The results emphasized the importance of the physical-mechanical characterizationrnof each ignimbrite lithofacies to construct conceptual and numerical models of different slope instabilitiesrnoccurred in the zone, particularly along the Guadalajara-Mexico City highway.