Hydraulic conductivity of geotextiles under typical operational conditions

Abstract

It is well known that granular backfill can account for more than 50% of the total construction cost for typical geosynthetic-reinforced soil structures. It is therefore desirable to investigate the possibility of using low-quality onsite soil, which may be cohesive and near saturated, as backfill. A geosynthetic that possesses adequate drainage capability in addition to having high tensile stiffness and strength would be highly suitable for this purpose. This study was conducted to investigate the cross-plane and inplane hydraulic conductivities of such geotextiles under typical operational conditions. Two types of geotextile, namely, a nonwoven and a woven-nonwoven composite geotextile, were tested by using different methods of confinement in their virgin state. Samples of the geotextiles retrieved from the field were also tested, and the results were compared with the hydraulic conductivity of virgin specimens. An equation is proposed to include the effect of confining stresses on the hydraulic conductivity of geotextiles. A reduction factor, termed the degree of retention (DOR), is introduced to express the long-term reduction in hydraulic conductivity due to soil-particle retention. In addition, a simple performance test is proposed for investigating the flow behavior of a soil-geotextile composite under its typical operational conditions.