PRACTICES FOR CONSTRUCTION OF SUSTAINING HARD CANAL LININGS ON DEFORMABLE GRADES

摘要

Conveyance and distribution of water is an integral part of any irrigation project. Irrigation canals constitute a considerable portion of irrigation systems worldwide. Therefore, improvement of performance for small and large canals would contribute to productivity of available water. This article focuses on hard canal lining practice in Iran. Most of modern irrigation canals constructed in Iran utilize cement concrete linings, and a major concern regarding them is to maintain transmission performance where subsoil is problematic and deformable. In the first part of the paper, an idealized lining segment on a deformable soil is analyzed for minimum properties that would prohibit lining failure. The second part, lists some case histories of hard linings and checks applicability of analyses results to them. It is concluded that for a hard lining to remain functional on deformable soils, the designer has to take into account expected leakage rate from the canal. Integrating leakage rate and leakage pattern into lining design is initially motivated by our readily-acknowledged, short-term goals of preserving initial shape and transmission capacity of canals. Incidentally, it also means more productivity of total transmitted water, which is favorable to our longterm and sometimes less-acknowledged, goal: sustainable usage of water resources.