Transmissivity behavior of layered needlepunched nonwoven geotextiles

Needlepunched nonwoven geotextiles contain considerable void space that is available for liquid transmission. Compressing a geotextile reduces its in- plane and cross-plane liquid flow because it alters the fabric's pore struc ture. In this study, we investigate single-fiber and layered needlepunched nonwoven geotextiles as a function of various needlepunching parameters and fiber linear density. We also evaluate the transmissivity parameter beta, which describes the transmissivity property of needlepunched nonwoven geote xtiles. Experimental results indicate that these transmissivities decrease to a constant value with increasing normal stress. The transmissivity behav ior of needlepunched nonwoven geotextiles depends on raw material character istics, needlepunching parameters, and normal stress. This study also propo ses relationships to predict the transmissivity behavior of two needlepunch ed nonwoven geotextiles in parallel.