A Pore Size Distribution-based Microscopic Model for Evaluating the Permeability of Clay

Abstract

This work aimed to propose a semi-empirical model that predicts the permeability of saturated clay using the data of mercury intrusion porosimetry (MIP). First, the pore size distribution (PSD) curve obtained from an MIP test was regarded as a discrete probability function of pore diameters; thus, its shape could be characterized by probability parameters (e.g., the expected value and the standard deviation). Subsequently, these probability parameters, combined with the microporosity calculated from the volume of intruded mercury, were correlated with the permeability of clay based on Hagen-Poiseuille's equation. Next, the performance of the proposed permeability model was verified using data reported in the literature. Thereafter, the model was applied to estimate the permeability of normally consolidated (NC) and overconsolidated (OC) kaolin subjected to various triaxial loading. The results highlighted that the proposed model is capable of characterizing the sensitive variation of kaolin permeability under different overconsolidation ratios (OCRs), stress paths, and stress levels.