Review Clogging Behavior by the Modified Gradient Ratio Test Device with Implanted Piezometers

Abstract

A modified implanted Gradient Ratio (GR) test system was proposed in the study. In comparison with the conventional GR test device, all the piezometers are implanted into the soil specimen, and an additional piezometer is installed at soilgeotextile interface, in order to precisely measure the pore pressure variation of the soil-geotextile system. By using the modified GR test apparatus, 120 tests were conducted to study the clogging behavior of soil-geotextile system. Four types of needle-punched nonwoven geotextiles and five gap-graded soil mixtures were used in the program. These soils are the mixture of the Ottawa sand and various percentages of weathered mudstone. Three hydraulic gradients were used in the GR tests. The results of the study indicated that the modified implanted GR test system is able to provide pore pressure head measurement within the test specimen. In general, GR values obtained from the implanted GR test system are greater than those obtained from the conventional GR tests.