UBC Theses and Dissertations
On the feasibility of mounting bender elements in a flexible wall permeameter Silvester, Adam Thomas Morgan
Zoned embankment dams comprise some of Canada’s largest and most important infrastructure. A phenomenon that has emerged in recent times as a matter of concern for dam safety risk management is seepage-induced internal erosion in embankment dams and their foundations. A candidate method of monitoring the progression of internal erosion in the field is that of crosshole shear wave velocity measurement. To inform the interpretation of shear wave velocity data, the relation between change in shear wave velocity and occurrence of internal erosion must be characterized. This study examines the feasibility of equipping a flexible wall permeameter (FWP) with bender elements in order to measure shear wave velocity. Bender elements were designed and fabricated with a custom mounting system and a FWP was upgraded to accommodate the bender elements. The study was devised to determine if the changes made to the FWP device, including a 6 % reduction in the cross-sectional area available for flow, affect the seepage regime through the test specimen or internal erosion of its finer fraction, from tests conducted on three different gradations of glass beads. Comparisons of tests performed with and without bender elements indicate no systematic change to the seepage regime or the internal erosional response of the specimens. Thus, the inclusion of bender elements in the flexible wall permeameter, for purposes of shear wave velocity measurements, appears feasible.
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