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There is a need in dam engineering to better understand certain failure mechanisms, including embankment cracking and concentrated leak erosion (CLE). This is especially pertinent for Potential Failure Mode Analysis. The present understanding of these mechanisms has been developed from limited case histories, numerical simulations, and bench-scale testing. Centrifuge tests were performed to investigate embankment crack propagation and CLE using the 9 m radius centrifuge at the University of California, Davis. Tests have been performed at 40g to simulate a levee/dam with a height of 10 m and 1.5H:1V slopes. The homogeneous embankments were constructed using a low plasticity clay compacted above 95% standard Proctor maximum dry density. Tests lowered one side of the foundation using a hydraulically actuated table to induce transverse cracking under unsaturated and saturated embankment conditions. Crack propagation was tracked as the hydraulic table was lowered using markers and digital image tracking on the downstream slope. An upstream reservoir was maintained, allowing for flow through the cracks and for CLE to initiate. After testing the final crack geometries were carefully recorded as the model was dissected. These tests provide system-level experimental data under in-situ stress conditions against which current empirically- and numerically-based analysis methods can be evaluated.
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ODA01: CENTRIFUGE MODELING OF VERTICAL DIFFERENTIAL SETTLEMENT-INDUCED CRACKS IN A LEVEE
A centrifuge test (ODA01) was used as a proof-of-concept test to investigate the effect of vertical differential settlement on crack formation in a model levee. The Yolo loam embankment levee and its foundation were 250 mm and 62.5 mm high in prototype scale, respectively. Viscous pore fluid was used to simulate water behind the levee at a height of 225 mm and the test was conducted at 40g. The foundation of the levee included a moving part (a hydraulic table) and a non-moving part (a jointed wood table). The hydraulic actuators were extended to a maximum height of 25 mm before the start of the test. In the centrifuge, the hydraulic table was lowered to a maximum settlement of 25 mm to simulate the differential settlement of the levee. Hairline, transverse and longitudinal cracks were effectively induced in the levee through this vertical differential settlement. Furthermore, seepage flow was initiated through the cracks. The seepage flow stopped after some time without significant erosion, likely due to swelling of the soil around the crack and lowering of the upstream water level.
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- Award ID(s):
- 2047402
- PAR ID:
- 10525876
- Publisher / Repository:
- Designsafe-CI
- Date Published:
- Edition / Version:
- 1
- Subject(s) / Keyword(s):
- Cracking, Concentrated leak erosion, Levee, Centrifuge test, Differential settlement
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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