Selection and Analysis of Longitudinal Cofferdam Type of Sanakham Hydropower Project in LAOS

In this paper,comparisons are made among three types of the longitudinal cofferdams for Sanakham Hydropower Project in Laos,and analyses made in terms of hydraulic characteristics,construction period,construction method,construction difficulties,strength of concrete construction,cost and so on. It is confirmed that the longitudinal cofferdam should use the sinking well and the size of the sinking well and the type of construction are given. The sinking well reduces the excavated volume of the riverbed silt sand and the contraction ratio of the original river bed during the drought period,and it increases the flow width,reduces the flow rate as well as the undermining effect of the water flow on the cofferdam foundation in the dry season at the same time to ensure the safety of the cofferdam,and improve the reliability during the construction of sinking well.