Centrifuge Model Studies for Evaluating the Performance of Earthen Dams with Chimney Drain Subjected to Tilting
摘要
In the present study, the performance of small-height earthen dams constructed with and without a chimney drain (CD) for seepage control and subjected to inertial loading in a geotechnical centrifuge. A series of centrifuge tests were conducted on a 7.2-m-high earthen dam at 30 g using an in-flight hybrid loading simulator. During reservoir filling and subsequent seepage, the pore-water pressures within the model and surface settlements were recorded using pore-water pressure transducers and linear variable differential transformers, respectively. The front elevations of centrifuge models are captured using an on-board digital camera and analysed for obtaining slope face movements and surface settlements. The earthen dam model with a fully clogged CD (or without any CD) experienced a rapid failure of the downstream side slope during the static condition before attaining the maximum water level. Contrast to this, earthen dam models with functional CD, steady-state seepage conditions were attained and maintained for a minimum of 5 days of seepage before subjecting to inertial loading using the tilt table-based simulator and found to sustain inertial loading without undergoing failure. Further, the effect of inclination of vertical limb of CD on the performance of earthen dam is also explored and presented. The design horizontal seismic coefficient (KH) for small earthen dams could be interpreted based on the analyses and interpretation of centrifuge test results with and without a chimney drain. Based on these findings, seepage and slope stability analyses were performed to undertake parametric studies that included geometry and location of CD, and flatter dam slopes.