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|Title:||Verification of empirical method for determining riverbank stability, 1959 data|
|Authors:||United States. Mississippi River Commission.|
U.S. Army Engineer Waterways Experiment Station.
|Publisher:||U.S. Army Engineer Waterways Experiment Station.|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Potamology investigations report ; no. 12-10.|
Summary: This report is the seventh of a series in which new data obtained from borings made for revetment construction are analyzed to determine the applicability of the empirical method for predicting riverbank stability with regard to liquefaction failures. Data obtained in fiscal year 1959 are analyzed, and stability predictions are made for 13 new areas. Failures during 1959 at sites previously analyzed also are discussed. Based on analyses made in 1958 of previous performance data, the classification criteria for overburden soils, zone A sands, and zone B sands were modified. Consequently, in this report the failures at sites previously studied, and new site predictions and 1959 performance are analyzed using the modified criteria. During 1959, 16 bank failures were reported along the Mississippi River near 13 boring locations at 11 sites for which stability predictions had been made. Five flow failures occurred near four boring locations predicted to be unstable, two shear failures occurred near two locations predicted to be unstable, and nine shear failures occurred near seven locations predicted to be stable. Since 1954 when riverbank stability predictions were initiated, data have been studied from 630 boring locations at 71 revetment sites on the Mississippi River in the Memphis and Vicksburg Districts. Flow failures have occurred at 6 boring locations in the Memphis District and at 19 locations in the Vicksburg District. Of the 25 locations where flow failures have occurred, 21 are considered to be unstable according to the modified criteria. Four flow failures occurred at locations predicted to be stable; at three of these locations the total thickness of the zone A sand was not determined and at the fourth location the boring was about 800 ft from the flow failure and probably does not indicate the most critical condition. Therefore, the predictions at these four locations are not considered valid. The modified classification criteria have proved reliable in predicting susceptibility to flow failure. However, many locations predicted to be unstable have not experienced flow failure, and it is possible that either the denseness of the zone A sand may be such that flow failure will not occur or that the severity of river attack has not been sufficient to initiate flow failure.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Potamology Investigations Report|
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|Potamology-Investigations-Report-No.-12-10.pdf||7.01 MB||Adobe PDF|