Geotextile filter design guide

Filter Performance and Design for Highway Drains

“…It has been observed that a number of failures of geotextiles occur during installation and construction rather than in service. This problem was addressed by AASTO and FHWA through a Task 2.7.1 FHWA Criteria Holtz, 1985 andChristopher et al, 1995) 33 2.7.2 Geosyntec Group Criteria (Luettich et al, 1992 (Lafleur, 1999 Table 2-1 Capability of selected geosynthetic filter design criteria to predict filter field performance, based on observation of exhumed samples at sites investigated by Koerner et al (1996) (after Wilson-Fahmy et al, 1996) Figure 6-12 Distributions of piping and clogging particle masses in RRT of NP filters, different in AOS and thickness with 50% wt and 100% wt soils (Thickness and AOS increase from L125 to L350 GT, see Figure 6-13 Distributions of piping and clogging particle masses in RRT of NP filters, different in AOS and thickness (Thickness and AOS increase from L125 to L350 GT, see 1. Introduction…”

“…the apparent opening size, AOS 1 , according to ASTM-D4751) are being compared (e.g. Carroll, 1983, Giroud, 1988, Luettich et al, 1992. To satisfy the last requirement, survivability, the selected geotextile must have adequate mechanical and chemical characteristics, given the anticipated construction and site conditions (AASHTO, 1991).…”

“…This would require appropriate testing methods be developed. From this standpoint, plastic soils are problematic in the case of dispersive clay which can be identified by the conditions, DHR > 0.5 and PI > 5 (Luettich et al, 1992) where DHR is the double hydrometer ratio. Clay deflocculating is influenced by several factors such as, electrolyte concentration, ion valence, temperature, dielectric constant, size of hydrate ion, pH and anion adsorption of clay and water system (Lambe and Whitman, 1979).…”

“…More specific design methods take into account the hydraulic conditions or additional geotextile and soil properties (Luettich et al, 1992). Extensive reviews of geotextile retention criteria can be found elsewhere (e.g.…”

“…Filters at 41 edge drain locations were examined for soil retention, permeability and geotextile clogging assessment. Then, these observations were confronted to several current design methods including those proposed by Giroud (1982), the French Committee of Geotextiles and Geomembranes (1986), Fischer et al (1990), Luettich et al (1992) and Christopher and Holtz (1985) for the FWHA. Results of this comparative study are presented in Table 2.1.…”