3287
Technical Committee 210 + 201 /
Comité technique 210 + 201
3.4 Hydraulic fracture of high ECRD
For high ECRD, the failure of earth core by hydraulic fracture is
one of the key issues that concerned by dam engineers. And, it
is also a controversial problem in geotechnical engineering. At
present, the mechanism and criteria for hydraulic fracture are
still questions and disputes among engineers and scholars.
From the analysis, the mechanism of hydraulic fracture is the
crack developed under the condition of effective stress reduces
to its tensile strength by the action of water load. The failure of
hydraulic fracture is the process of outside water acting on the
initial cracks to produce continuous extension of the cracks, and
then finally run through the whole earth core. From the
traditional point of view, when the increase of pore pressure
leads to tensile effective stress of the soil, hydraulic fracture
will be occurred. But, it should be noticed that many reasons
could lead to the tensile effective stress. Only the reduction of
effective stress is caused by external water load, the produced
cracks are considered as hydraulic fracture.
From numerical analysis, it could be observed that the
direction of principle stress on upstream surface of earth core is
deflected due to the “arching effect” of dam shell. Upon
reservoir impoundment, with the upstream water load, the
direction of principle stress will be further deflected. The
direction of major principle stress turns to parallel with the
direction of water pressure. In this case, when the effective
minor stress of the earth core reduced to the tensile strength of
the soil by the action of water pressure, horizontal cracks will be
produced. This could be the cause of hydraulic fracture.
When the initial cracks of hydraulic fracture are produced on
the surface of the earth core, the further development of the
cracks depends on many factors, which include hydraulic
gradient, stress status and permeability of the soil, etc. The final
failure mode of hydraulic fracture is soil erosion by seepage.
4 SUMMARY
Both in the field of dikes and dams, geotechnical problems are
the essential engineering issues. Problems such as soil erosion
by water flow, internal instibility by seepage, settlement and
seepage control, foundation treatment are all related with the
geotechnical properties of soils. With the changing situations
and the development of modern dam engineering, more and
more challenges will be encountered. Geotechnical engineering
is a subject based on engineering practices. To solve the
geotechnical problems in engineering, the basic principles of
soil mechanics should be followed. Furthermore, the new
concepts and methods are also need to be developed by
systematic studies and careful observations.
The 11 submitted papers in the field of dikes and dams have
covered relatively wide range of the studies and represented
main concerns both in dike engineering and dam engineering.
5 REFERENCES
D. B. Simons, R. Li 1982 . Bank Erosion on regulated rivers.
Gravel-
bed rivers, R.D.Hey
，
J.C.Bathurst, and C.R.Thorne, eds., John
Wiley & Sons, Inc., Chichester, U.K..
H. Brandl, M. Szabo, Hydraulic failure of flood protectin dykes.
Proceedings of the 18
th
International Conference on Soil Mechanics
and Geotechnical Engineering, Paris 2013
J. Briaud, H. Chen, A. Govindasam, and R. Storesund. (2008). Levee
erosion by overtopping in New Orleans during the Katrina
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ournal of Geotechnical and Geoenvironmental
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J. Mecsi, 2013. Some technical aspects of the tailing dam failure at Ajka
Red Mud Reservoirs.
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M. Bernhardt, J. Briaud, D. Kim, R. Storesund, S. Lim, R. G. Bea, J. D.
Rogers, 2011. Mississippi river levee failure: June2008 flood.
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N. Li, J. wang, Z. Mi, D. Li, Deformation safety of high concrete face
rockfill dams.
Proceedings of the 18
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Soil Mechanics and Geotechnical Engineering, Paris 2013
R. E. Terzariol, R. J. Rocca, M. E. Zeballos, 2013. Suffusion in
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S. Messerklinger, 2013. The design of filter materials and their
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Y. Chen, J.J. Fry, F. Laigle, Prédiction du comportement de barrage en
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Z. Xu, 2010. Progress in the construction of CFRDs on deep alluvium.
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