Seepage velocity and piping resistance of coir fiber mixed soils

In the context of sustainable watershed management, natural fibers mixed with soil have applications in irrigation and drainage projects such as river levees, contour bunds, temporary canal diversion works, temporary check dams, soil structures, stream restoration, etc., for controlling seepage. In this study, a number of experiments were carried out for determining the seepage velocity and piping resistance of different types of soils mixed randomly with coir fibers. Three types of soils are used in this study. The experiments were carried out for various hydraulic heads, fiber contents, and fiber lengths. Discharge velocity and seepage velocity of flow of water through soil is calculated in each case and compared with plain soil. It is observed that fibers reduce the seepage velocity of plain soil considerably and thus increase the piping resistance of soil. Regression equations based on experiments are developed for quantifying the seepage velocity and piping resistance considering hydraulic gradient, fiber contents, and fiber lengths. Suitability of coir fibers for field applications with typical examples is also highlighted. The results show that coir fiber mixed soil can be used to increase the piping resistance and reduce seepage velocity in the above mentioned applications.