For prefabricated horizontal drains, the water flow path must be provided to have drainage and filtration functions properly. It is permitted to flow from the soil mass under the surcharge to appropriate drainage and filtration points. Thus the drains can provide stability of embankment and traffic ability of equipment. Good quality of sands, however, is being exhausted. The problems such as low permeability of sand cause unstability of embankment and low consolidation rate. Expensive raw materials such as sand used for drains prevent cost effective construction. In this study, theoretical studies have been performed for drainage and filtration characteristics, low consolidation rate of sandmat and prefabricated horizontal and vertical drains. These prefabricated horizontal drains were adopted to substitute for sandmat in domestic highway construction sites and test instrumentation was installed to investigate the drainage and filtration capacities of these materials. Finally, discussion on quality control and methodology, cost analysis for sandmat and prefabricated horizontal drains were performed.
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