PERMEABILITY TESTS OF SELECTED FILTER FABRICS FOR USE WITH A LOESS-DERIVED ALLUVIUM

Permeability tests on six nonwoven and two woven geotextiles with a silty-clay alluvium indicate that all of the fabrics tested will prevent piping of the soil, regardless of the state of compaction. When a discontinuity (such as a hole) was introduced into the soil, some soils were observed to pipe. The range of permeabilities of soil-fabric systems was observed to be narrow, even though the range of fabric permeability was wide and the soil compaction varied. A theoretical analysis shows that the permeability of the soil is the controlling factor in permeability testing of the soil-fabric system. A piping test similar to the test for dispersive clays is suggested as an alternative to permeability testing of soils and filter fabrics. (Author)