Geocomposite Drainage Systems: Highway Edge Drains and Retaining Wall Sheet Drains

摘要

The project has focused on geocomposite drainage systems made from various types and configurations of polymeric drainage cores covered by polymeric geotextile filters. The cores are available in a wide variety of shapes; for example, columns, nubs, cuspations, meshes, dimples, etc. The geotextile filters are bonded directly into the cores. The first application is that of highway edge drains in which the drainage cores are generally 12 in. or 18 in. high and completely surrounded by the geotextile filter. They are placed vertically in the ground immediately adjacent to highway pavement base courses for the purpose of accepting lateral drainage. The second application is that of retaining wall drainage in which the drainage system completely covers the backfilled side of the wall with the geotextile filter attached to the side of the core facing the backfilled soil. Their purpose is to drain the backfill soil thereby relieving hydrostatic pressure against the back of the wall. Each of the two application areas were addressed in an identical manner: a literature review, design calculations (regarding core strength, core flow rate, geotextile permeability, geotextile opening size and geotextile strength), testing of various commercial products and a generic specification.