Soil/geotextile filter compatibility: a geometrical, experimental and micro-structural approach

The paper focuses on the evaluation of the long term behaviour of geotextile filters in contact with cohesionless soils. The clogging, blinding and piping levels of the filtering systems have been evaluated analysing the results of long term filtration tests, and of geometrical and micro-structural analyses. The geometrical approach was based on the comparison between geotextile pore size distribution and soil grain size distribution, also taking into consideration the critical diameter of suffusion. Scanning electron microscope images of geotextiles before and after filtration tests provided useful information about blinding and clogging phenomena and about variation of the geotextile internal structure (fibres and voids). Moreover, in order to predict the geotextile filtration opening size, an existing mathematical model was modified to take into account the variation of the geotextile final porosity due to the agglomeration of particles around geotextile fibres or within geotextile pores. The geometrical, experimental and micro-structural approach allowed the Authors to better evaluate the soil/ geotextile filter compatibility also in the complex case of geotextile in contact with internally unstable soils. This procedure could be a useful tool in geotextile filter design under critical/severe conditions.