Numerical Investigation for Reduction of Uplift Forces by Drain Pipes under the Bed of a Canal

Impermeable linings are frequently used to protect canal beds from erosion and to prevent seepage from the bottom or side of a canal. These linings are susceptible to a variety of issues, including damage caused by uplift pressure when the groundwater table is high. As a result, a drainage system beneath the canal's hard lining is required to reduce water pressure, particularly at the end of the operation season when the canal is empty. Concrete lined canals are particularly vulnerable when low (or zero) demand periods coincides with high groundwater table. Reducing the uplift force under lined canals is common in gravity dams but there is a considerable gap with similar problems for lined irrigation canals and hence a considerable scope for identifying and dealing with the gap through reducing uplift pressure in irrigation canals. This study assesses the performance of a drainpipe with a filter envelope located beneath the canal bed. To analyze and minimize uplift force, the solution method employs the finite element method. Various combinations of drain diameters, envelop thicknesses, drain depths under the canal invert, and groundwater surfaces are taken into account. The simulation results show that as the drain diameter and depth under the canal bed increase, the groundwater surface decreases and the uplift force decreases. It has been discovered that using a filter envelope around the drainpipe to reduce hydrostatic pressure is effective. There are linear and nonlinear regression equations provided for predicting the pressure head in the canal bed centerline.