CESS Seminar: Soil sorptive potential: unitary definition of matric potential
Event details
| Date | 08.11.2019 |
| Hour | 12:15 › 13:00 |
| Speaker | Professor Ning Lu, Colorado School of Mines, Colorado, USA |
| Location | |
| Category | Conferences - Seminars |
Abstract:
Despite the widely accepted notion that matric suction is the most fundamental variable for describing soil–water interactions in soil under unsaturated conditions, it is unable to describe several basic soil properties and behaviors such as pore-water pressure, soil water density, and phase changes of soil water. A variable with greater explanatory power, sorptive potential, is conceptualized as the origin of matric suction or matric potential and pore-water pressure. The soil sorptive potential is the sum of the locally varying electromagnetic potentials comprising van der Waals attraction, electrical double-layer repulsion, and surface and cation hydration. Local thermodynamic energy equilibrium dictates that the sorptive potential is always transformed or equal to matric potential minus the pressure potential within a representative elementary volume of matric potential. Limited verification was demonstrated by reducing the sorptive potential to the two well-established concepts of disjoining pressure and osmotic swelling pressure. Soil sorptive potential can be experimentally determined by the soil water retention curve. A parametric study was conducted to illustrate how soil and pore-fluid properties affect sorptive and pressure potentials, indicating that the pore-water pressure under unsaturated conditions can be as high as 0.6 GPa. Such locally high pore-water pressure is induced by the sorptive potential and provides an explanation for phenomena such as abnormally high soil water density, supercooling, and decreased cavitation observed in fine-grained soils.
Bio:
Ning Lu is professor of civil and environmental engineering at Colorado School of Mines (CSM) and the director of the joint CSM/US Geological Survey Geotechnical Research Laboratory in Golden, CO. He is a recipient of the ASCE 2007 Norman Medal, of the ASCE 2010 Croes Medal, of the ASCE 2017 Ralph B. Peck Award, and of the ASCE 2017 Maurice Biot Medal, as well as a fellow of ASCE, Engineering Mechanics Institute, and Geological Society of America. His primary research interests are flow and stress laws in multiphase porous media, rainfall-induced instability of natural and engineered slopes, geologic hazards, energy storage in porous media, and subsurface nuclear waste isolation. He is the senior author of the widely used textbook Unsaturated Soil Mechanics (John Wiley and Sons, 2004) and the textbook Hillslope Hydrology and Stability (Cambridge University Press, 2013).
Despite the widely accepted notion that matric suction is the most fundamental variable for describing soil–water interactions in soil under unsaturated conditions, it is unable to describe several basic soil properties and behaviors such as pore-water pressure, soil water density, and phase changes of soil water. A variable with greater explanatory power, sorptive potential, is conceptualized as the origin of matric suction or matric potential and pore-water pressure. The soil sorptive potential is the sum of the locally varying electromagnetic potentials comprising van der Waals attraction, electrical double-layer repulsion, and surface and cation hydration. Local thermodynamic energy equilibrium dictates that the sorptive potential is always transformed or equal to matric potential minus the pressure potential within a representative elementary volume of matric potential. Limited verification was demonstrated by reducing the sorptive potential to the two well-established concepts of disjoining pressure and osmotic swelling pressure. Soil sorptive potential can be experimentally determined by the soil water retention curve. A parametric study was conducted to illustrate how soil and pore-fluid properties affect sorptive and pressure potentials, indicating that the pore-water pressure under unsaturated conditions can be as high as 0.6 GPa. Such locally high pore-water pressure is induced by the sorptive potential and provides an explanation for phenomena such as abnormally high soil water density, supercooling, and decreased cavitation observed in fine-grained soils.
Bio:
Ning Lu is professor of civil and environmental engineering at Colorado School of Mines (CSM) and the director of the joint CSM/US Geological Survey Geotechnical Research Laboratory in Golden, CO. He is a recipient of the ASCE 2007 Norman Medal, of the ASCE 2010 Croes Medal, of the ASCE 2017 Ralph B. Peck Award, and of the ASCE 2017 Maurice Biot Medal, as well as a fellow of ASCE, Engineering Mechanics Institute, and Geological Society of America. His primary research interests are flow and stress laws in multiphase porous media, rainfall-induced instability of natural and engineered slopes, geologic hazards, energy storage in porous media, and subsurface nuclear waste isolation. He is the senior author of the widely used textbook Unsaturated Soil Mechanics (John Wiley and Sons, 2004) and the textbook Hillslope Hydrology and Stability (Cambridge University Press, 2013).
Practical information
- Informed public
- Free
Organizer
- Profs Brice Lecampion & Alexandre Alahi
Contact
- Prof. Lyesse Laloui