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Title: Structural stability evaluation : Winnibigoshish Dam
Authors: United States. Army. Corps of Engineers. St. Paul District.
Pace, Carl E.
Keywords: Concrete
In situ testing
Dam Pressuremeter
Engineering condition survey
Winnibigoshish Dam
Mississippi River headwaters
Publisher: Structures Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; SL-81-27.
Description: Miscellaneous Paper
Abstract: A typical interior monolith of Winnibigoshish Dam was evaluated for adequacy in stability for five load cases: (1.) Normal operation (2.) Normal operation with truck loading (H15-44) (3.) Normal operation with earthquake (4.) Normal operation with ice (5.) High-water condition. By using the conventional stability analysis (rigid body assumptions), the approximate magnitude of loads which are on the foundation piles were determined; but, without knowing the supporting characteristics of the foundation material, an estimation of the adequacy of the structural stability was inconclusive. The supporting characteristics of the foundation material were determined by in situ testing using a pressuremeter to predict the horizontal supporting characteristics of the pile-soil system. Two NX core holes were drilled through typical monoliths to obtain access to the foundation material. One other hole was drilled to sample the supporting decking, beams, and piling. The pressuremeter tests were performed and in situ soils data obtained. The horizontal soil modulus was obtained as a variation with depth into the foundation material and with soil deformation for three test positions in each of the two test holes. The horizontal modulus of subgrade reaction was then used in a three-dimensional direct stiffness analysis to determine the forces and deflections of the foundation piles. A beam on an elastic foundation analysis was performed and the pressure, moment, and deflection along the length of the most critically loaded pile were determined. The axial or compressive loads were below allowables. The shear loads at the top of the piles are excessive, and it is recommended that 135 kips of strut resistance per small pier be provided in case it is required. The pile deflections are not excessive. The piles are not overstressed in flexure. The average unconfined compressive strength of concrete exceeded 7000 psi, which is adequate for this type of structure. The concrete is well consolidated with some alkali-silica reaction. The alkali-silica reaction is not considered significant. The deteriorated surface of the concrete and steel should be repaired (Part VI). After surface concrete and steel deterioration is repaired and strut resistance is provided for pier stability, the dam can be expected to perform satisfactorily for many more years.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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