Investigation of Performance of Geocomposite Filter-Drains Under Canal Lining Considering Weight of Concrete Lining

Cracking, uplifting and displacement of concrete canal lining would increase loss of water, decrease conveyance efficiency and produce tremendous economical damages to irrigation projects. This may be greatly due to high uplift pressure under concrete lining in areas where the groundwater level is high. Thus, provision of a filter-drainage system in such conditions is vital. In recent years, application of synthetic drainage materials in the form of geocomposite, as a replacement for conventional granular drainage materials have been considered. In the present study, performance of geocomposite as a filter-drainage material under concrete canal lining has been investigated in a laboratory model. The results of the investigations showed that a geocomposite layer of sufficient thickness is able to successfully reduce uplift pressure under the canal lining. As the weight of the concrete lining may itself cause some deformations and reduction in the thickness of geocomposite layer, such effect was also investigated. The results showed that weight of concrete lining would reduce the thickness of drainage layer, causing a substantial reduction between 2 to 8 percent in drainage capacity. Therefore, it was concluded that the effect of overburden pressure caused by the weight of lining must be considered when application of synthetic drainage layers is considered.