94 D19. Quaternary Geology I

Tuesday, 27 October 2020
5:30 PM - 8:00 PM
Meeting Rooms

CALCULATING CAPILLARITY IN GRANULAR SOILS AS A FUNCTION OF GRAIN-SIZE PARAMETERS AND PACKING

Paper number: 94-2
Program: Technical Sessions
Time: 5:35 PM – 5:50 PM

Authors

Abstract

Capillarity of a soil is known to be a function of the diameters of the pores, with the largest systematic pores limiting the capillarity of the total soil. Using the log-normal distribution of grain sizes in granular soils to guide sampling, a Monte Carlo simulation based on Soddy circular and spherical geometries was used to numerically determine the pore throat and pore body size distributions within 4-grain tetrahedra as a function of volumetric mean and standard deviation of the source soils. Using a log2 base, Dpt = Ds -2.684 - 0.0281 σgr + 0.155 σgr2 – 0.0129 σgr3, where Ds = Dgr – ln(2) σgr2 (= the grain size mean for total surface area), Dpt and Dgr are the logarithmic mean pore throat and grain diameters, and σgr is the logarithmic standard deviation of grain sizes. Dpb = Ds – 2.152 – 0.0311 σgr - 0.054 σgr2 + 0.004527 σgr3, where Dpb is the logarithmic diameter of the pore body.

These values provide the parameters for understanding the sizing of the 4-grain tetrahedra that form the structural matrix of the soils. Assuming structural integrity of the soils, the pore body diameters within the less regular intervening system of larger pores can be closely constrained from the sizes of these tetrahedra and the packing density of the soils. It is these larger pores that control the capillarity of the soils. The mean diameters of the large pores decrease with increasing standard deviations and packing values, resulting in higher capillarity of the soils.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-358654

© Copyright 2020 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.