Examining Fundamental Problems of APC Canal Concrete Lining and Strategies to Solve them

Background/Objectives: In this research, various reasons of creation of crack irrigation canals, uplift, and failure of concrete lining, and coping strategies with these problems were investigated. Methods/Statistical Analysis: In the main APC canal, the primary type of the canal trapezoid section includes executing a filter at the bottom of the canal, executing soil-cement mixture, and then executing a concrete lining at the walls of the canal. The final type of the canal trapezoid section reformed executing a filter in the bottom and walls of the canal, executing a lean concrete, and then executing the main concrete lining at the bottom and walls of the canal, and also executing a one-sided valve at the bottom of the canal. Findings: After executing the primary type of the canal section in the first 13 kilometers of the beginning of the APC canal, the phenomenon of crack and uplift have been observed in the concrete lining of the canal wall. However, by changing the properties of canal section and replacing the lean concrete and filter with soil-cement mixture, problems of the concrete lining were noticeably reduced. In this research, reasons of probability of creation of phenomena such as failure, crack, and uplift including executive problems, rising of groundwater level, compaction of the canal body soil, problems due to execution of soil-cement mixture, problems caused by construction joints between panels of the floor and wall of canal, and also other factors were investigated. It is resulted that execution of filter and lean concrete under concrete lining of the canal wall and execution of one-sided valve (Barbakan) has had a noticeable effect on preventing from destructive factors of the concrete lining of canal walls and consequently preventing from creation of crack and uplift phenomena. Applications/Improvements: By modifying properties of substructure material of the canal lining, problems of concrete lining will be noticeably decreased and each year a large volume of water resources will be saved.