Geomaterial behavior and testing

A complete characterization detailing the intricate and complex response of geomaterials remains a challenging task that can only be realized on a partial basis via a careful drilling and sampling program coupled with detailed laboratory testing and comprehensive series of in-situ tests and field geophysics. As now evidenced from results reported from over 60 international geotechnical experimentation sites at worldwide locations, such extensive efforts directed at a particular soil formation take decades of time and considerable funding for completion. For a practical approach in routine site characterizations, the minimal standard of work should be seismic piezocone tests (SCPTu) or seismic flat dilatometer tests (SDMT), as up to 5 separate measurements of soil behavior are captured during a single sounding. These results should be supplemented with sampling and laboratory testing directed at defining parameters within a rational effective stress framework, and in particular, critical state soil mechanics (CSSM). Even then, a number of challenges remain, including the appreciation of rate effects, fabric, particle breakage, weathering, and diagenesis. Furthermore, nontextbook geomaterials (e.g., silty sands, carbonate clays, diatomaceous earth, peats, organic silts) will require a considerably higher level of testing and investigative effort because of greater uncertainty in understanding their anomalous behavior. Also, the characterization of geosynthetics, often used to complement or replace the function of earthen materials in many structures (e.g., reinforcement, drainage) requires the characterization of product-specific hydraulic, mechanical, and rheological properties. © 2009 IOS Press.