Internal Erosion and Rehabilitation of an Earth-Rock Dam
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 2
Abstract
This paper describes an earth-rock dam whose filters’ characteristics did not comply with the design criterion. In addition, the degree of compaction and the water content in the impervious core consisted of highly plastic residual clay. Although Terzaghi’s filter design criterion was used, the as-built grain size distribution did not comply with such criterion. Several problems arose right after the first filling of the dam, including the following: (1) water leak at a rate of 200 L/s was observed along the downstream slope, in the vicinity of the outlet pipeline; the dark color of the observed water implied that the core material was being eroded; (2) two sinkholes near the crest (20 m apart) were observed along the outlet axis, one on the upstream and the other on the downstream slopes; right after the occurrence of these two sinkholes, the water leakage decreases significantly, noticing a plugged effect of the material that falls down through the sinkholes. To avoid piping, a notch was installed on the spillway to quickly reduce the reservoir level. A site investigation around the affected zone was performed to find the causes of the observed seepage through the dam. The paper presents a detailed description of the site investigation. In addition, the paper presents the instrumentation, laboratory, and field tests employed as part of the site investigation. After analyzing the information produced in the site investigation, the following conclusions were derived: (1) large variation in the water content was used during the compaction of each lift of the impervious core which resulted in a highly heterogeneous core of the dam; (2) stress analysis of the zones around the outlet pipe demonstrated that the hydrostatic pressure in such zones exceeded the sum of the transverse normal and tensile stresses, inducing hydraulic fracturing; and (3) because of the grain size segregation during the placement of the filter material, the upstream and downstream filters did not satisfy the design criterion. Description of the stabilization of the damage zones through a grouting process, together with the construction of a diaphragm wall and an interface grouting, is presented. Finally, this paper reviews existing criteria for designing filters to protect earth and rockfill dams against internal erosion or piping and applies these criteria to the described dam. A special discussion on this topic is also presented.
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Acknowledgments
The writers wish to express their gratitude to the reviewers of this paper for their magnificent comments and recommendations, which help significantly to its quality and comprehension. We also to thank the National Water Commission of Mexico for the information provided for this work.
References
Alberro, J. (1995). “Cracking and piping in earth and earth-rock dams.” Proc., X Pan-American Conf. on Soil Mechanics and Foundation Engineering, Sociedad Mexicana de Mecánica de Suelos, Guadalajara, México, 1372–1404 (in Spanish).
Bertram, G. E. (1940). An experimental investigation of protective filters, Harvard soils mechanics Series No. 7, Harvard Univ., Cambridge, Mass.
Casagrande, A. (1968). Notes of engineering 262 course, Vol. I, Harvard Univ., Cambridge, Mass./Beijing International Commission on Large Dams (ICOLD), Paris, 237–260 (Question 76).
Foster, M. A., and Fell, R. (2001). “Assessing embankment dam filters that do not satisfy design criteria.” J. Geotech. Geoenviron. Eng., 127(5), 398–407.
International Commission on Large Dams (ICOLD). (1994). “Use of granular filters and drains in embankment dams.” Bulletin 95, ICOLD, Paris.
Lofquist, B. (1988). “Discussion.” J. Geotech. Engrg. Div., 114(6), 740–742.
Lombardy, G., and Deer, D. (1993). “Design and control of grouting using GIN method.” Power & Dam Construction, June.
Ramírez-Reynaga, M. (2003). “Internal erosion at El Batam Dam.” Proc., XII Pan-American Conf. on Soil Mechanics and Geotechnical Engineering, Proceedings Volume 2, Massachusetts Institute of Technology, Cambridge, Massachusetts.
Ramirez-Reynaga, M., Schmitter, J., and Mendez, R. (2003). “Rehabilitation of El Batam dam.” Proc., XII Pan-American Conf. on Soil Mechanics and Geotechnical Engineering, Proceedings Volume 2, Massachusetts Institute of Technology, Cambridge, Massachusetts.
Sherard, J. L., and Dunnigan, L. P. (1989). “Critical filters for impervious soils.” J. Geotech. Engrg., 115(7), 927–947.
United States Soil Conservation Service (USSCS). (1994). “Gradation design of sand and gravel filters.” National engineering handbook, United States Department of Agriculture, Washington, D.C., Chap. 26, Pt. 633.
Wan, C. F., and Fell, R. (2008). “Assessing the potential of internal instability and suffusion in embankment dams and their foundations.” J. Geotech. Geoenviron. Eng., 134(3), 401–407.
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© 2011 ASCE.
History
Received: Jan 24, 2008
Published online: Apr 19, 2010
Accepted: Sep 18, 2010
Published in print: Feb 2011
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