GEOSYNTHETICS – A REVIEW OF THE TRANSMISSIVITY IN GEOTEXTILES UNDER ORTHOGONAL IN-PLANE FLOW DIRECTIONS.
Is
very importante know the real position of the geotextile in drainage applications.
Typical geothecnicals laboratories that realized hydraulics tests with
geosynthetics have generals knowledgement that
transmissivity tests values can`t be adequate to expand for design parameters. Many factors can prove it, that are: manufacture process, fiber types, porous distribuition, fiber distribuition, etc.
Common tests like ASTM D 4716 procedures, sometimes, don't put in order critical and field conditions, limiting tests to fabric and standart characterization. These situations turns to critical if don’t have a good safety control for the manufactured samples.
A little study of in-plane flows of needle-punched geotextiles with two samples of the same mass per square unit, varing collections points in geotextile warp was ralized to measure differents in-plane flow in many directions. These tests are realized on transmissivity apparatus, based on ASTM D 4716, that some geotextile samples are tested as in parallel as orthogonal manufacture direction.
The results shows that the in-plane flow is very influenced to direction manufacture. More studies will be necessary to avaliate and simulate field applications with geosynthetic fabrics, that homogeneity parâmeters may to be avalliate to good behavior of hidraulic functions (drainage and filtration applications).
Paper sended to Geotechnique Journal, London-UK, 2001.
Marcelo Ferreira dos Santos is a Doctor Science in Geotechnical Engineering at Viçosa Federal University (Viçosa City, Minas Gerais State, Brazil)