A Numerical Study of an Irrigation Canal Constructed on Expansive Soils

Abstract

Irrigation and drainage trapezoidal hydraulic canals constructed on unsaturated expansive soils are susceptible to cracking and uplift due to water content variations in expansive soil. Canal lining and rehabilitation project aim to reduce swelling of expansive soil, distribute water, reduce losses, and to ensure the water reaches the ends of the canals. Expansive soils in Egypt are found in several areas, such as Aswan, Assiut, Edfu, New Cairo, Madinat-Nasr, Alshrouk City and the New Valley. In the present study, expansive soil has been ivcestigated under the lower Al-kharit irrigation canal in Aswan Governorate, Egypt, using field observations and numerical modeling. The numerical model is performed using SIGMA/W 2007 software, which is part of the Geo-Studio software package, to simulate the irrigation canal constructed on expansive soil. The results of analysis showed that the effect of canal rehabilitation can reduce the heave of expansive soil and increase the slope stability of irrigation canal. Additionally, a comparison of two engineering programs PLAXIS-GeoStudio gives acceptable accuracy of using numerical model that use independent solutions or field measurements. It is studied the effect of thickness of the rehabilitated layer with cobbles through a series of simulations to determine the safe design and minimum cost.