Liaison with Australian State Road Authorities in recent years has been the impetus for reviewing current accepted drainage practice, with tested, technically advanced, cost effective products now readily available in Australia. Premature pavement failure commonly caused by slow drainage response has benefited from design methods incorporating geocomposite panel drains, giving improved drainage response times, high flow infiltration, efficient filtration and economical installation. Pipe stiffness test results highlight the difference in service performance to show that geocomposite panel drains are superior in structural capacity whilst their rigidity compliments efficient installation. Comparison of factors affecting inflow capacity and outflow discharge identify the optimum flow performance of panel drains. Inflow considerations can be shown to be a more relevant criteria than design for discharge capacity of 1/3 height flow. Geotextile filtration performance is an integral part of geocomposite drainage systems with research highlighting assessment of insitu conditions critical to efficient long term drainage inflow. Type of backfill used, permeability rates for insitu soil, rock and pavement materials control inflow play an integral part in overall design. Design practice should consider location of the system, permeability rates for insitu materials and geotextile filtration along with drainage inflow and discharge capacity. (a) For the covering entry of this conference, please see ITRD abstract no. E217099.
Abstract