Documentation and Analysis of Rock Island Underseepage Data.
Final rept. Jan 78-Sep 79,
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
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Piezometer data from 14 pre-1960 piezometer range sites in the Rock Island District RID were documented and analyzed to determine landside and riverside permeability ratios. Only 7 of the 14 sites had complete data, which included piezometric pressures under both the riverside and landside slopes of the levee. Piezometer data obtained in 1979 from 15 new 1977 piezometer range sites were also reviewed, but because the calculated entrance distances, among other things, were significantly greater than the distances to the exposed substratum at the riverbank, these latter data were considered in error and were not used for analysis. Berm widths were also calculated using LMVD, RID, and WES permeability ratios. Observed seepage performance from all 29 piezometer range sites was studied and compared with berm width calculations. Berm criteria based on a creep ratio of 15 to 18, similar to that advanced in 1916 by Mr. W. G. Bligh in his book, Dams and Weirs, were also tried. While berm lengths were more reasonable than those mentioned above, these criteria also failed to adequately distinguish between those locations that needs berms and those that do not.
- Civil Engineering