The Performance of Geotextile Materials Used for Filtration and Separation in Different Structures as an Important Part of Geotextiles Requirements

Abstract

Currently, a water discharge coefficient as an important feature of geotextile materials that affects their filtration capacity in a frozen condition is not included in the geotextiles material specifications. The higher the water discharge coefficient of geotextile materials is, the less ice they contain when frozen. The necessary requirements and corresponding mathematical relations for choosing the appropriate geotextile materials are presented in this study. Geotextile materials used as separating layers in a railway formation should meet the same requirement.The effective diameter of the geotextile material pores (cells) was obtained by sieving through it the fine-grained quartz sand of pre-determined grain-size composition. Nevertheless, as microscopic research showed, particles produced due to the ballast abrasion and bridging (colmating) of the geotextile material have a plate-like shape. Consequently, the curve of their granulometric composition differs from that of the quartz sand.Based on the experimental data, the criteria for the required mathematically calculated filtration flow diameter have been established to ensure that geotextile materials are not colmated during their designed life span. The theoretical, field and laboratory research conducted permitted to formulate the propositions on making amendments to the requirements and their modification boundaries depending on the area of geotextile materials application.