Geosynthetic capillary barriers: current state of knowledge

TLDR

The study compiles theoretical background, laboratory and full‑scale data, and evaluates the current knowledge of porous geosynthetics’ hydraulic properties to inform the design of unsaturated geosynthetic capillary barriers. It analyzes water retention curves, hydraulic conductivity functions, and the mechanisms by which water is stored at interfaces between fine‑grained soils and nonwoven geotextiles. Experimental results demonstrate that geosynthetic capillary barriers outperform soil‑only barriers, underscoring that designs must incorporate nonwoven geotextiles beneath fine‑grained soils to achieve enhanced performance.

Abstract

ABSTRACT: This paper provides theoretical background, laboratory data and full-scale measurements useful in understanding the interaction between soils and geosynthetics under unsaturated conditions. It also includes an evaluation of the current state of knowledge regarding the hydraulic properties of porous geosynthetics under unsaturated conditions relevant for geosynthetic capillary barrier design. These properties include the water retention curve and the hydraulic conductivity function. In addition, the mechanisms involved in the development of capillary barriers are evaluated to explain the storage of water at the interface between materials with contrasting hydraulic conductivity (e.g. a fine-grained soil and a nonwoven geotextile). Finally, specific applications are presented to illustrate new opportunities and applications that may result from a better understanding of the unsaturated hydraulic properties of geosynthetics. Experimental data are provided illustrating that geosynthetic capillary barriers are superior to soil-only capillary barriers. Based on this observation, it is emphasized that no capillary barrier should be designed without consideration of the enhanced performance offered by the inclusion of nonwoven geotextiles under the fine-grained soil component of the cover.