This chapter covers the cushioning or puncture protection function of nonwoven needlepunched geotextiles. After the introduction, the chapter briefly reviews the stress–strain behavior of different types of geomembranes and geotextiles and various types of puncture test methods and index properties of cushion geotextiles. Three types of design methods are presented that can be used to select a cushion geotextile for a specific project: theoretical, empirical, and experimental. Because most of the published literature and data relate to high-density polyethylene geomembranes, a section is presented on designing cushion geotextiles for flexible geomembranes. References at the end of the chapter give additional sources of information for each important topic covered in the chapter.
