Rapid Assessment of Geotextile Clogging Potential Using the Flexible Wall Gradient Ratio Test

A new test method for clogging potential of geotextile filters by finer grained soils has been developed. The test, called the flexible wall gradient ratio (FWGR) test, is a combination of a flexible wall permeameter and the standard Gradient Ratio test. Because the test allows for backpressure saturation, the time required for stabilization during a clogging test is greatly reduced. Trials were performed using a broadly-graded glacial till with a hydraulic conductivity of about 10^–6 m/s; a variety of geotextiles were used to obtain the range of likely behaviours from piping to clogging. Results showed that the FWGR was able to obtain accurate results within a week, compared with times of two months for the same trials with the conventional gradient ratio test. The FWGR results were consistent and showed good repeatability. The FWGR seems to be an improvement over current test methods for performance testing of geotextile filters in fine-grained soils.