Nonwoven geotextiles are typically subjected to unequal biaxial tension in filtration applications

which changes the pore sizes

and can easily cause the failure of material. This work investigates the analytical solutions for the equivalent pore size and pore size distributions (PSDbi) subjected to unequal biaxial tensile strains. The experimental data collected from two nonwoven geotextiles under equal biaxial tensile strains are compared with the analytical solutions. The analytical variations of the pore size parameters under unequal biaxial tensile strain are calculated. It is concluded that the changes in analytical PSDbi depends on the tensile strains and the directional parameter Ka. The experimental PSD curves under equal biaxial tensile strains correspond with the analytical predictions. For changes in O95

the solution predicts more accurately than the PSDbi solution. The solution predicts more accurately for the thicker nonwoven geotextiles. The same conclusion can be drawn from the results under uniaxial tensile strains in the literatures.