Permeability of needle-punched nonwoven geotextiles subjected to uniaxial tensile strains

Abstract

During service life, needle-punched nonwoven geotextiles are frequently subjected to uniaxial tensile strains, which may impact their permeability behavior. The basic model of the permeability coefficient in nonwoven geotextiles is extended to the uniaxial tensile strain condition. The influence of the fiber orientation distribution was considered. The model is expressed as the functions of the tortuosity fractal dimension, pore size characteristics, fiber orientation, physical parameters, and tensile strain. To address the errors in the results of traditional permeability tests attributed to the inhomogeneity and multiple layers of specimens, in-situ X-ray computed tomography (CT) was employed to acquire three-dimensional images of the geotextile during stretching. The three-dimensional imaging technique was employed to extract the microstructure, facilitating fluid flow simulations for determining the permeability of two nonwoven geotextiles, thereby validating the theoretical method. It is shown that the simulated permeability coefficient decreases slightly and then increases with increasing uniaxial tensile strain and necking ratio. The permeability theoretical model exhibits a decreasing trend and then increases around 0.3% strain. The theoretical model can accurately predict the permeability values and rate of change of geotextiles subjected to specific uniaxial tensile strains, thereby offering valuable insights and tools for their effective utilization in various engineering applications.