Numerical investigation of granular filter under the bed of a canal

Abstract

Abstract To protect canal beds against erosion and to prevent seepage from the bottom or side of a canal, impermeable linings are often used. These linings can suffer from several problems including damage due to uplift pressure when the groundwater table is high. Thus, it is necessary to provide a drainage system under the hard lining of the canal to reduce the water pressure, especially at the end of the operation season, when the canal is empty. This work evaluates the performance of a drainpipe with a filter envelope located under the bed of canal. The solution method uses the finite element method to analyze and minimize uplift force. Various combinations of drain diameters, envelop thicknesses, depths of drain under the canal invert, and groundwater surfaces are considered. Simulation results indicate that with increasing drain diameter and depth of drain under the bed of canal, the groundwater surface declines and the uplift force is reduced. The use of a filter envelope around the drainpipe for decreasing hydrostatic pressure is found to be effective. Linear and nonlinear regression equations for predicting the pressure head in canal bed centerline are provided.

Keywords

• Canal
• Drainage system
• Granular filter
• Groundwater head
• Uplift