A Fundamental Study on Suction and Hysteresis of Soil-Water Characteristic Relation of Cohesive Soil

Johns Hopkins University, Baltimore MD

Investigators

Abstract

This grant provides funding for fundamental study on the capillary effects in a volume of partially saturated clayey soils. Specifically, the magnitude and molecular sources of soil suction, and curvature and contact angles of air-water capillary meniscus between clay particles are of interest. The studies on these topics will provide answers to outstanding fundamental questions concerning the sources of very high suction in clayey soils (as high as 100 times the atmospheric pressure) and the sources of hysteresis of soil-water characteristic relation. The study will be conducted with the aid of numerical and experimental methods. In regard to the numerical methods, a particle-based modeling technique known as the discrete element method and an atom-based modeling technique known as the molecular dynamics will be used. Concerning the experimental methods, the pressure-plate suction testing method, Fourier Transform Infrared spectroscopic method and Environmental Scanning Electron Microscopic method will be employed. The numerical studies are computationally intensive. The difficulty of obtaining unlimited and readily-available computational power has hindered such computationally intensive studies in the past. The recent developments in the use of Graphic Processing Units (GPUs) for computational purposes make possible having teraflop-computational power (basically a parallel supercomputer) right on an office workstation at an affordable price. The confluence of the above recent developments (the advancements in discrete element modeling, molecular dynamics and GPU-based computing) provides an opportunity for tackling the challenging fundamental research of interest in this study. If successful, the study will lead to fundamental scientific knowledge and methodologies needed for designing geotechnical structures involving unsaturated fine-grained soils. For example, the study will lead to rational methods for controlling landslides occurring on partially saturated mountainous slopes triggered by torrential rain and/or earthquakes.