Evaluation of predictions of nonwoven geotextile pore size distribution under confinement

Geotextiles are commonly used as filters in geotechnical and geoenvironmental works. For a proper design of a geotextile, filter pore dimensions and gradation are necessary and the equivalent diameter of these pores depends on the confining vertical stress acting on the geotextile layer. This paper investigates the dependency of the geotextile pore size distribution curve on confinement, and addresses the accuracy and calibration of two well-known methods for the estimate of pore dimensions. Five nonwoven geotextiles, made of polyester, were tested in Bubble Point test equipment under unconfined and confined (vertical stresses up to 1000 kPa) conditions. The study aimed mainly to calibrate and expand the applicability of two well-known methods to estimate geotextile pore size distribution based on results from Bubble Point tests. Several hypotheses were addressed to back-analyse parameters relevant for the accuracy of such methods. The results obtained showed that these solutions predicted satisfactorily the pore size distribution curves of the products tested when appropriate values of relevant parameters were employed.