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APPLICATION OF GEOMEMBRANE TO CONTROL PIPING OF SANDY SOIL UNDER CONCRETE CANAL LINING (CASE STUDY: MOGHAN IRRIGATION PROJECT, IRAN)

Fine sandy soils have always been known as one of those problematic soils which will erode rapidly and cause piping due to water flow. This phenomenon has caused the destruction of many concrete canal linings around the world. In the present study, the history of the design, construction and operation of a canal in the Moghan Irrigation and Drainage Network, in north‐west Iran, is reviewed and the main causes of destruction of the concrete lining of the canal are discussed. Based on the results of geotechnical studies, it was found that the canal was constructed on wind‐blown deposits consisting of very fine to fine sand and loess. During operation of the canal, the fine, clean sandy subgrade soil was highly eroded due to water seeping under the canal lining, causing severe piping and consequently destruction of the lining. Following field and laboratory investigations, the main cause of the problem was diagnosed as “physical dispersivity” of the subgrade soil, and application of a geomembrane under the concrete lining was chosen as the most economical and practical measure to remedy the problem. Copyright © 2010 John Wiley & Sons, Ltd.