Geosynthetics are versatile materials that can be used in a variety of applications in tunnel construction. One of the most common uses of geosynthetics in tunnel construction is as a filter and separator. This involves placing geotextiles between layers of soil to prevent the mixing of different soil types and to allow water to pass through. Nonwoven and woven geotextiles are effective in this application because they are able to filter out fine particles while allowing water to pass through.