THE INFLUENCE OF THE DRAINAGE PARTICLE CONTACT AREA ON SOIL-NONWOVEN GEOTEXTILE FILTRATION BEHAVIOR

Seepage rate and clogging potential assessments for a soil-geotextile filtration system are presented in this paper. An ASTM Gradient ratio test apparatus was modified to carry out the tests. A drainage layer formed by steel beads was placed at the downstream of a geotextile to simulate the granular drainage layer in the field. The experimental results show: (1) For the steel bead sizes used in the experiment, the lower the opening area, the lower the flow seepage rate. However, the final flow seepage rate was not proportional to the opening in the interface between the geotextile and steel beads. (2) When steel beads were used to form the downstream drainage layer, the clogging potential increased with the reduction in the open area between the geotextile and drainage material, indicating that a 100 % opening underestimates the clogging potential of the filtration system. (3) Beads of different sizes can be formed into drainage layers with the same sized open area; however, the GR values exhibit minor changes when the size of the open area remains the same. For the covering abstract see ITRD E117244.