Performance of Geotextile Materials Installed Adjacent to Filters Beds in a Drainage System

The geotextile materials, initially used for soil conservation practices, have found a new application as ready-made filters in subsurface drainage projects. As clogging decreases the efficiency of filters, this phenomenon has to be investigated in detail before the widespread utilization of such materials take place. Necessary instruments were designed and manufactured to apply the modified ASTM-5101 standards to investigate the clogging potential of 300 and 500 gm-1 polyester fabric. Soil samples were placed on these fabrics underlain with gravel, concrete blocks, a supporting steel screen, uniform-sized steel beads, and a steel plate uniformly perforated. Infiltration tests were conducted under 1 and 4 hydraulic gradients. It was observed that the type and magnitude of contact between the geotextile and the substrata affects the drainage system. The direct contact between the granular particles or concrete blocks and the geotextile influences the cross-sectional area through which drainage takes place, and the clogging potential increases with the reduction in this area. Of these substrata only the steel beads and the perforated plate were used to simulate drainage under laboratory conditions.