The use of impermeable linings to protect canal beds from erosion and prevent seepage from the bottom or side of a canal is common. When the groundwater table is high, these linings are vulnerable to a range of problems, including damage caused by uplift pressure. As a result, a drainage system beneath the canal's hard lining is needed to relieve water pressure, especially when the canal is empty at the end of the operation season. When low (or no) demand periods combine with a high groundwater table, concrete lined canals are particularly vulnerable. Reducing uplift force in lined canals is prevalent in gravity dams, but there is a significant gap with similar concerns in lined irrigation canals, and thus a significant opportunity for identifying and addressing the gap through irrigation canal uplift pressure reduction. The performance of a drainpipe with a filter envelope beneath the canal bed is evaluated in this study. The solution approach uses the finite element method to analyse and minimise uplift force. Drain diameters, envelop thicknesses, drain depths under the canal invert, and groundwater surfaces are all considered in various combinations. The groundwater surface lowers and the uplift force reduces as the drain diameter and depth under the canal bed increase, according to the modelling results. The use of a filter envelope around the drainpipe to reduce hydrostatic pressure has been proven to be effective. For forecasting the pressure head in the canal bed centerline, linear and nonlinear regression formulae are offered.
Author(s) Details:
Farzin Salmasi,
Department of Water Engineering, Faculty of Agriculture, University of
Tabriz, Tabriz, Iran.
John Abraham,
University of St. Thomas, Minnesota, School of Engineering 2115 Summit
Avenue St. Paul, Minnesota 55105, USA.
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