Filtration behaviour of soil-nonwoven geotextile combinations subjected to various loads: Fid-Bau Portal

Filtration behaviour of soil-nonwoven geotextile combinations subjected to various loads

Hong, Yung-Shan / Wu, Cho-Sen

Geotextiles are often subject to different load types in their filtration applications. The load action can cause changes in soil density, geotextile stretching and flow interaction at the soil-geotextile interface. The impact of load type on the filtration behaviour of soil-nonwoven geotextile combinations has been studied through a series of tests using a laboratory test apparatus. Two chemical-bonded nonwoven geotextiles were employed in this study. One of the three load types, namely sustained, pulsatory (0.1 Hz, and a total of 5000 cycles) and a combination of both was applied. After applying this specific type of load on a soil-geotextile combination, water was allowed to flow down through the geotextile from the soil into a drainage layer set at various hydraulic gradients. The flow rates corresponding to elapsed times were measured and the average hydraulic conductivity value was extracted by using Darcy's law to characterize the filtration performance of the entire soil-geotextile combination. The experimental results revealed that the void ratio of soil decreased with the increase of total load. Soil-GT1 combinations exhibited a normal relationship between the average hydraulic conductivity and the normal load applied; the average hydraulic conductivity increased with an increase in the total load. Soil-GT2 combinations exhibited different load-dependent responses to a normal load with the average hydraulic conductivity depending on the magnitude and type of load. Such load-dependent hydraulic conductivity changes are attributed mainly to the geotextile in-plane strain and the pumping action in the combination.